# 21st International and 12th Asia-Pacific Regional Conference of the ISTVS ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan {% hint style="info" %} **Keynote announced**\ We are pleased to share that Mr. Naoki Sato of JAXA will keynote:\ \&#xNAN;*Pressurized Rover as the Japanese Contribution to Artemis Program*\ Full details: {% endhint %} {% hint style="success" %} **Conference program**\ We are pleased to announce the 2024 Conference Program:\ {% endhint %}
The conference is an opportunity to present and disseminate the latest scientific and technological achievements in the field of vehicle-terrain systems. Both representatives of science in the field of mechanical engineering, vehicles and machines, mechatronics and automation, soil science, agriculture and environmental engineering, as well as professionals from industry, business environment and government agencies for whom the issues discussed at the conference are an important merit are invited to participate. The organizers also count on the participation of students from under- and postgraduate courses.
The intention of the organizers is to create a friendly atmosphere and comfortable conditions for holding plenary sessions. The conference includes the following thematic tracks: * soil mechanical characterization * off-road mobility modeling * soil compaction * driving systems of off-road vehicles and machines * innovative concepts of tires, wheels, and tracks * propulsion systems and engines * vetronics * autonomous and robotic systems * metrology in terramechanics **Prof. Junya Yamakawa**\ \&#xNAN;*Conference chair ::* [*yamakawa@nda.ac.jp*](mailto:yamakawa@nda.ac.jp)\ [Automotive Engineering Laboratory | National Defense Academy](http://www.nda.ac.jp/cc/mech/en/automotive-engineering.html#faculty) **Prof. Taizo Kobayashi**\ \&#xNAN;*Conference co-chair ::* [*kobat@fc.ritsumei.ac.jp*](mailto:kobat@fc.ritsumei.ac.jp)\ [Dept. of Civil and Environmental Engineering | Ritsumeikan University](https://en.ritsumei.ac.jp/gsse/academics/researchers/article.html/?id=86) **Prof. Genya Ishigami**\ \&#xNAN;*Conference co-chair ::* [*ishigami@mech.keio.ac.jp*](mailto:ishigami@mech.keio.ac.jp)\ [Keio University](http://www.srg.mech.keio.ac.jp)
{% hint style="info" %} ## Program overview **Monday, October 28** — BoD Meeting, Icebreaker Party **Tuesday, October 29** — Opening Ceremony, Keynote Speech, Sessions, Banquet **Wednesday, October 30** — Sessions, Poster Session, Closing Ceremony **Thursday, October 31** — Technical Tour at Komatsu IoT Center {% endhint %} ## Key dates | Date | Event | | ---------------------------------------------------------- | ---------------------------------------------------- | | **SUBMISSIONS** | | | February 15, 2024 | Abstract submission opens | |

March 23, 2024
March 15, 2024

| Abstract submission closes | |

April 7, 2024
March 31, 2024

| Notification of acceptance/rejection sent to authors | |

June 10, 2024
May 31, 2024

| Full paper submission | |

July 10, 2024
June 30, 2024

| Notification of peer review result sent to authors | |

August 10, 2024
July 31, 2024

| Final paper submission | | | | | **REGISTRATION** | | | June 10, 2024 | Registration opens | |

August 10, 2024
July 31, 2024

| Early bird registration closes | | October 18, 2024 | Registration closes | | | | | **PROGRAM** | | |

July 10, 2024
July 1, 2024

| Preliminary program published | |

August 10, 2024
August 1, 2024

| Detailed program published | |

September 23, 2024
September 13, 2024

| Final program published | | | | | October 28-31, 2024 | Conference |
# Overview ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan {% hint style="success" %} We are pleased to announce the publication of ISTVS2024 Conference Program. For the interactive view, the live link is here:\ {% endhint %} ## Current program as of 2024-08-15
# Authors ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan {% hint style="success" %} For interactive list of authors:\ {% endhint %} ## Authors as of 2024-08-15
# Registration ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan {% hint style="info" %} Register now online by credit card. Choose the appropriate registration below, then complete the checkout process on the payment page. • To register on behalf of multiple attendees, complete the registration process for each. You'll be asked for the attendee's name and email address. • To register as an ISTVS member, a current ISTVS member number is required; check status and member number in ISTVS Member Portal: [istvs.org/members](https://www.istvs.org/members) **• Registration closes October 18, 2024.** {% endhint %}
Member Registration¥80,000
Non-Member Registration¥95,000
Student Registration¥40,000
ISTVS uses Stripe for simple and safe online payments. All prices are in ¥. *** ## Accompanying Guests The conference welcomes accompanying guests. If you are bringing guests, please use these links to purchase attendance at the opening and closing events.
Icebreaker opening event - GUEST¥8,000
Banquet closing event - GUEST¥11,000
# Keynote ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan ## Mr. Naoki Sato Senior Advisor, Pressurized Rover Engineering Center \ Human Spaceflight Technology Directorate \ JAXA (Japan Aerospace Exploration Agency)

Mr. Naoki Sato, JAXA

Naoki Sato graduated Aeronautics Engineering Department, Kyusyu University in 1986, and gained master degree of applied engineering of Kyusyu University in 1988. At the same year, he entered in National Space Development Agency of Japan (predecessor of JAXA). Since 1990, he had been involved in the International Space Station program for about 16 years. After that, he started to work for the international space exploration program formulation. He is currently working as a senior advisor of the Pressurized Rover Engineering Center at JAXA. ### Pressurized Rover as the Japanese Contribution to Artemis Program **Abstract** | Recognition of great success of International Space Station (ISS) program from the view of technology development and international relationship maturation, space agencies around the world started discussions for promoting this success toward the human space exploration beyond Low Earth Orbit (LEO) in early 2000’s. After long discussion and coordination among agencies, it was agreed to go to the moon first and demonstrate many technologies and operation, then go to the Mars. Especially, United States has begun Moon to Mars program, so called, Artemis program. Japanese government decided to participate in the Artemis Program in 2021, and then concluded an agreement with NASA to provide a Pressurized Rover (PR), and to get a right to send two Japanese astronauts onto the moon in 2024. The PR is like a camping car providing living environments with shirts sleeve and traversing capability on lunar surface for more than 10 years. Because the lunar environment is much harsh than LEO such as gravity, strong radiation, long night, dust, etc., the development of the PR is a huge challenge. # Awards ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan As part of the ISTVS mission to advance the knowledge of terrain-vehicle systems in engineering practice and innovation, ISTVS has awarded exceptional work with an awards program that includes St. Christopher’s Lectures, Bekker-Reece-Radforth Awards, and Best Paper Awards. *** ## 2024 St. Christopher’s Lecture Honoree Since 1966, ISTVS has honored distinguished workers in the field of terrain-vehicle interaction by offering them the opportunity to deliver the St. Christopher Lecture at an international ISTVS conference, held every three years. Named for the patron saint of travelers, this is the highest award offered by the society. The recipient need not be an ISTVS member. Selection and invitation of recipients is the responsibility of the conference organizing committee. [**Professor Kazuya Yoshida**](#id-2024-st.-christophers-lecture-honoree)\ \&#xNAN;*Roving the Moon — Steeper, Faster and Smarter*\ Department of Aerospace Engineering, Graduate School of Engineering Tohoku University, Japan
Professor Kazuya Yoshida

Professor Kazuya Yoshida

[Read full St Christopher Lecture citation](#id-2024-st.-christophers-lecture-honoree) *** ## 2024 Bekker-Reece-Radforth Award Honoree This award was established in 2002 and honors exceptional research and/or industrial achievements in engineering practice of the principles of terramechanics. The award recognizes the exceptional contributions of Dr. M. G. Bekker, Dr. A. R. Reece, and Professor N. W. Radforth to the field of terramechanics and to the ISTVS. [**Professor Schalk Els**](#id-2024-bekker-reece-radforth-award-honoree)\ Vehicle Dynamics Group\ Department of Mechanical and Aeronautical Engineering\ University of Pretoria\ Pretoria, South Africa

Professor Schalk Els

[Read full award citation](#id-2024-bekker-reece-radforth-award-honoree) *** ## 2024 Best Paper Awards We are pleased to share that these seven papers received Best Paper Awards at the conference: > 2919\ > **Takahiro Fuke, Sora Ishikawa, and Genya Ishigami**\ > \&#xNAN;*Accurate Rover Mobility Analysis Using HILS-DRFT with Real-Time Parameter Tuning Approach* > 4213 \ > **Tomoyasu Nakano, Takuya Omura and Genya Ishigami** \ > \&#xNAN;*DEM-Based Analysis and Optimization of an Excavation Bucket Drum for In-Situ Resource Utilization* > 5620 \ > **Ryosuke Eto, Hayatake Sato and Junya Yamakawa** \ > \&#xNAN;*Step-Climbing Motion Acquisition of Tracked Robot with Flippers without Using Environment Information by Reinforcement Learning* > 9295 \ > **Takuya Omura and Genya Ishigami** \ > \&#xNAN;*Granular Scaling Laws for Accurate Prediction of Wheel Mobility on Slopes in Low-gravity Environments* > 3769 \ > **Michael Parker, Clifford Witte, Susan Frankenstein, and Allan Wheeler** \ > \&#xNAN;*Mobility During the Transition Seasons in the Arctic* > 4715 \ > **Herman Hamersma, Christian van Aswegen, Glenn Guthrie, and Schalk Els** \ > \&#xNAN;*UAV-Based Three-Dimensional Rough Terrain Modelling* > 6422 \ > **Arthur Candalot, James Hurrell, Malik-Manel Hashim, Brigid Hickey, Mickael Laine, and Kazuya Yoshida** \ > \&#xNAN;*Sinkage Study in Granular Material for Space Exploration Legged Robot Gripper* # St Christoper Lecture ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan ## St. Christopher’s Lecture Since 1966, ISTVS has honored distinguished workers in the field of terrain-vehicle interaction by offering them the opportunity to deliver the St. Christopher Lecture at an international ISTVS conference, held every three years. Named for the patron saint of travelers, this is the highest award offered by the society. The recipient need not be an ISTVS member. Selection and invitation of recipients is the responsibility of the conference organizing committee. *** ### *2024 Honoree* ### Professor Kazuya Yoshida Department of Aerospace Engineering \ Graduate School of Engineering\ Tohoku University, Japan #### *Roving the Moon — Steeper, Faster and Smarter* Professor Kazuya Yoshida has been working on lunar and planetary robotics research since 1997. From the beginning, he demonstrated the terramechanics, specifically the wheel-soil traction mechanics, of wheeled rovers on soft and deformable terrain. He conducted a series of experiments and simulations, using Particle Image Velocimetry (PIV) to observe soil particle flow around the wheels and Discrete Element Method (DEM) to simulate soil particle interactions. These methods provided insights into how rovers could enhance their mobility, particularly on steep and challenging lunar slopes. By investigating soil compaction, shear forces, and slip ratios under various loads and conditions, Yoshida’s work has advanced traction models essential for navigating rugged extraterrestrial surfaces. More recent research focuses on two key aspects of lunar rover design: faster locomotion and smarter navigation. By increasing rover speed, Yoshida observed a more dynamic soil flow, which demands refined terramechanics models to maintain traveling performance on loose terrain. Additionally, he and his team have developed a vision-based AI system for smarter navigation in unstructured environments. This AI system interprets complex visual information to identify obstacles, optimize path selection, and enhance rover safety on unpredictable lunar surfaces. Together, these innovations in high-speed terramechanics and AI-powered navigation will shape the future of lunar exploration, equipping rovers to operate reliably and autonomously across extreme terrains. #### ACHIEVEMENTS In 2011, Professor Kazuya Yoshida established the International Center for Extreme Robotics Research at Tohoku University and became its Director. He also built an exploration robot for the Fukushima Daiichi Nuclear Power Plant accident that occurred in the same year. He specializes in space robotics, including the development of SPRITE-SAT, and was the technical director of the Google Lunar XPRIZE team “HAKUTO.” For Hayabusa2, he developed Minerva II2, a small robot to be dropped into Ryugyu.
Professor Kazuya Yoshida

Professor Kazuya Yoshida

#### RESEARCH CAREER
2010–2012Chief Technology Officer of White Label Space Japan, the predecessor of ispace
2003–presentGraduate School of Engineering, Tohoku University, Professor
1998–presentInternational Space University, Visiting Faculty
1997–2003Faculty of Engineering, Tohoku University, Associate Professor
1995–1997​Faculty of Engineering, Tohoku University, Associate Professor
1994–1995Massachusetts Institute of Technology, Visiting Scientist
1993Swiss Federal Institute of Technology, Exchange Researcher
1986–1994​Faculty of Engineering, Tokyo Institute of Technology, Research Associate
*** ## Previous St. Christopher Lectures
YearRecipient
2017Prof. György SitkeiUniversity of Sopron, HungaryNew Challenges and Opportunities for Terramechanics
2014Dr. Tae Kyeong YeuRemote control of a deep-seabed mining robot vehicle on extremely cohesive soft soil
2011Professor Ray ArvidsonJames S. McDonnell Distinguished University Professor, Washington University, St. Louis, Missouri, USA
2008Professor Ronie NavonProfessor, Technion, Israel Institute of Technology, Israel
2005Professor Yasunori MatogawaJapan Aerospace Exploration Agency, Japan
2002Dr. Ronald A. ListonCold Regions Research and Engineering Laboratory, USA
1999Professor Iwan WästerlundSwedish University of Agricultural Sciences, Sweden
1996Mr. Henry C. Hodges, Sr.CEO, Hodges Transportation Inc. Nevada, USA
1993Dr. F. KovacGoodyear Tire & Rubber Company, USA
1990Dr. K.-J. MelzerBattelle Motor, Germany
1987Professor Alessandro OrlandiUniversità degli Studi, Bologna, Italy
1984Professor Masanori KitanoNational Defense Academy, Japan
1981Professor Walter JureckaInstitute of Construction Management and Economics, Technical University Vienna, Austria
1978Dr. A. J. Soltynski
1975Dr. Ernest N. PetrickChief Scientist, U.S. Army Tank-Automotive Command
1969Dr. Walter Söhne
1965Dr. M. G. Bekker
# Bekker-Reece-Radforth Award ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan The Bekker-Reece-Radforth Award was established in 2002 and honors exceptional research and/or industrial achievements in engineering practice of the principles of terramechanics. The award recognizes the exceptional contributions of Dr. M. G. Bekker, Dr. A. R. Reece, and Professor N. W. Radforth to the field of terramechanics and to the ISTVS. *** ## 2024 Bekker-Reece-Radforth Award Honoree ### Professor Schalk Els Vehicle Dynamics Group\ Department of Mechanical and Aeronautical Engineering\ University of Pretoria\ Pretoria, South Africa **Professor Schalk Els** founded the Vehicle Dynamics Group (VDG) within the Department of Mechanical and Aeronautical Engineering at the University of Pretoria in 1999. Under his leadership, the VDG has grown into a sustainable and widely-recognized research group comprising over 20 postgraduate students and seven staff members, with more than 60 alumni benefiting from his expert mentorship. His research prowess is evidenced by 148 publications listed on Google Scholar, accumulating nearly 3000 citations. Highlights of Professor Els's career include the development of a wheel force transducer widely utilized in off-road terrains, notably in successful tests with the US Army Corps of Engineers at their Cold Regions Research Engineering Laboratory (CRREL) and the Geotechnical & Structures Laboratory (GSL). He also pioneered the T2CAM, an innovative in-wheel, camera-based system capable of three-dimensionally measuring tire deformation across various terrains. Professor Els has been a dedicated member of ISTVS for years, playing an influential role in the society's journal and spearheading the 2012 ISTVS conference held in Pretoria, South Africa. His involvement dates back to the 1997 ISTVS conference in Ferrara, marking his initial contributions, with his first publication in the Journal of Terramechanics published in 1998. He has attended each ISTVS conference since the 2008 conference held in Turin. His exceptional achievements have been honoured with several best-paper accolades across different ISTVS conferences. Professor Els continues to embody a spirit of continuous learning, striving for technical excellence in the fields of off-road vehicle dynamics and tire-terrain interaction. His leadership in establishing and leading the VDG underscores his profound impact on the field. Profosser Els's pioneering work with the wheel force transducer and T2CAM exemplifies his dedication to advancing the understanding of tire-terrain interaction. His extensive publication record and significant citations underscore the influence of his research within academia and beyond. Furthermore, Professor Els's dedication to ISTVS is evident through his longstanding membership, editorial contributions, and successful conference organization, further illustrating his leadership in advancing global understanding of off-road vehicle dynamics.
ISTVS thanks the Vehicle Systems Development Corporation, Toronto, Ontario, Canada, for sponsoring the award this year. > Vehicle Systems Development Corporation (VSDC) is based in Toronto, Ontario, Canada. The company specializes in the development of advanced vehicle mobility models, including the Nepean Tracked Vehicle Performance Model (NTVPM-85) and the Next-Generation Wheeled Vehicle Performance Model (NWVPM). VSDC collaborates with various defense and research organizations to enhance vehicle performance metrics and mobility solutions. *** ## Previous Honorees
YearNameAffiliation
2021Dr. Sally ShoopCold Regions Research and Engineering Laboratory, Hanover, NH, USA
2014Prof. Radhey Lal KushwahaProfessor Emeritus, University of Saskatchewan, Canada
2011Dr. Anders BodinAlvis Hägglunds AB, Sweden
2008Yukio NakajimaDirector of Engineering
Tire Research Department, Bridgestone Corp., Japan
2005Mr. Robert D. WismerVice President, Deere & Company, USA
2002Mr. Alfons FalkHaegglunds Vehicle AB, Sweden
We thank Vehicle Systems Development Corporation, Toronto, Ontario, Canada, for sponsoring the award this year. > Vehicle Systems Development Corporation (VSDC) is based in Toronto, Ontario, Canada. The company specializes in the development of advanced vehicle mobility models, including the Nepean Tracked Vehicle Performance Model (NTVPM-85) and the Next-Generation Wheeled Vehicle Performance Model (NWVPM). VSDC collaborates with various defense and research organizations to enhance vehicle performance metrics and mobility solutions. # Call for Papers ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan {% hint style="info" %} #### Copyright Assignment Form Copyright assignment form is intended for original material submitted to conferences of the International Society for Terrain-Vehicle Systems (ISTVS) and must accompany any such material in order to be published by the ISTVS. Before publication of your paper in conference proceedings, the ISTVS must receive a completed and signed copy of this form via the conference submission platform, EasyChair: [ISTVS Copyright Assignment Form\_2024v1.pdf](https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDSUIEqgaPlFzlCt7TKJP%2Fuploads%2F4JevVzklzazZoDaOCXEv%2FISTVS%20Copyright%20Assignment%20Form_2024v1.pdf?alt=media\&token=776ba519-537f-46ab-8787-f34bbdb8eec0) \ **Author action required:**\ **Log in to EasyChair and click the icon on "View" column:**\ [**https://easychair.org/conferences/?conf=istvs2024**](https://easychair.org/conferences/?conf=istvs2024)\ **-> Click "Add or update files" on the upper left list.** \ **-> Attach the file on "Submission of COPYRIGHT ASSIGNMENT"**\ \ \&#xNAN;*2024-10-03 UPDATE* {% endhint %} {% file src="/files/hJrp5g3jNOa8eZbcvG4t" %} *ISTVS2024*, the *21st International and 12th Asia-Pacific Regional Conference of the ISTVS* welcomes original and previously unpublished research and review papers describing results of research which are relevant to the conference topics and to terrain-vehicle systems. * Authors wishing to make a submission are requested to submit an abstract by **March 15**, 2024. * Submission opens on **February 15**, 2024. * Abstracts are requested to be under 1800 characters and must emphasize the objectives and results. * Authors may choose between the following two types of submissions:\ **full paper** and **abstract-only**. * For either type of submission, authors can choose to do an **oral presentation** at the conference or submit a poster for the conference **poster session**. **Abstract review** // All abstracts will be reviewed by the conference Scientific Committee.\ Abstract acceptance will be notified to the corresponding author by **March 31**, 2024. **Full paper submissions** // After abstract acceptance, authors submitting a full paper must make their submission by **May 31**, 2024. Each full paper will be subject to peer review by reviewers selected by the conference Scientific Committee. Each paper will be either accepted, accepted with revisions or rejected; the decision will be notified by **June 30**, 2024. If a revision is requested, the revised paper must be submitted by **July 31**, 2024. All accepted submissions of either abstract-only or full-paper type will be included in the conference program and will be published in the conference proceedings, on the condition that **at least one author attend the conference** to present the work. **Only full papers** will be assigned a **DOI** and will have a permanent individual page on the conference website; so, if your abstract is accepted, we strongly encourage you to submit a full paper to maximize the visibility of your work. ## Key dates Key dates are listed [here](/#key-dates). ## Technical tracks The conference includes the following thematic tracks: * soil mechanical characterization * off-road mobility modeling * soil compaction * driving systems of off-road vehicles and machines * innovative concepts of tires, wheels, and tracks * propulsion systems and engines * vetronics * autonomous and robotic systems * metrology in terramechanics ## CFP poster You can view the Call for Papers poster [here](/conference/call-for-papers/cfp-poster). ## Submission platform As in previous years, the conference submission platform is [EasyChair](https://easychair.org/conferences/?conf=istvs2024). If you’ve participated in a recent ISTVS conference, you will be able to log in with your existing account. If you’re new to ISTVS conferences, use the *Create an account* link on the login page to get started.\ Access here:

Login page for the ISTVS2024 submission platform

## Submission guidelines * Make sure that the authors you list in the *EasyChair* form are **the same** as in your full paper and/or poster, and in the **same order**. * Adopt the same **consistency** also for the **authors’ affiliations**. * If at any time you need to make changes to the list of authors, please **promptly notify the conference organizers**. * If the same authors appear in **multiple submissions**, please write the author **names** and **affiliations** in the **same way**, for **all submissions** (both in *EasyChair* and in the papers/posters). * If the latin alphabet is not your native alphabet, please make sure that you use the **same transliteration** for your name across all submissions (both in *EasyChair* and in the papers/posters). * If at any time - provided it's compatible with the conference organization schedule - you wish to **change your submission type** (abstract-only vs full paper) or **change your presentation type** (oral presentation vs poster session), please **promptly notify the conference organizers**. ## Templates for submissions ### Abstract **No template** is required to submit your abstract.\ Submission is done directly on the [EasyChair](https://easychair.org/conferences/?conf=istvs2024) submission platform. ### Full paper Papers must be submitted in *Microsoft Word* format and must **comply with the conference template**. {% file src="/files/64nIxGPMaKfrtrYxwfz1" %} ISTVS2024 paper template {% endfile %} The zip archive provided includes a **reference PDF**, in case the *Word* document breaks when opened locally. ### Presentation The following presentation template in *Microsoft PowerPoint* format is provided for your convenience. {% file src="/files/6g1U9iSwR2ZXRHy1K8VU" %} ISTVS2024 presentation template {% endfile %} **IMPORTANT:** The use of this template is **NOT** mandatory.\ If you choose to use your own template please maintain the **widescreen layout** and include **slide numbers**. We also recommend choosing a clean and clear layout.\ Whenever possible, aim for visual consistency throughout your presentation. ### Poster A template and instructions for posters will be added to this page soon. ## Additional author resources Additional author resources: * copyright assignment form will be added to this page as well, so keep an eye on it for updates. # CFP Poster ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan ## Help us spread the word Here below is the conference call for papers poster. You can help us spread the word and increase the visibility of our conference by downloading the poster and **sharing** it with your colleagues. Feel free to either print it and pin it to a bulletin board or share it directly in electronic format. Your help is deeply appreciated!

ISTVS2024 call for papers poster

# Sponsors ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan *We actively welcome conference sponsors. Please contact*[ *yamakawa@nda.ac.jp*](mailto:yamakawa@nda.ac.jp)*.* ***
**NISHIO RENT ALL CO., LTD.** | Pioneers in the construction machinery rental business. Since we began renting road work machines in 1965, we have been one of the leading companies in this industry. Expanding our network services, we have over 200 domestic branches, with additional branches and subsidiaries in Malaysia, Thailand, Singapore, Vietnam, China and Australia.
***
**SAKAI HEAVY INDUSTRIES, LTD.** | Manufacture and sale of construction equipment and industrial machinery, and sale of out sourced industrial machinery. ***
**KOMATSU LTD.** | Manufacture and sale of construction and mining equipment, utility equipment (compact machines), forest machines, industrial machinery and others.\ # Technical Tour ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan The 2024 technical tour will visit the demonstration site for smart construction vehicles with information and communication technology (ICT) at the Komatsu IoT Center in nearby Chiba. Participants will receive an overview of smart construction, observe a demonstration, and have the opportunity to test drive an ICT construction vehicle. Detail: \ [www.komatsu.jp/en/aboutus/innovation/technology](https://www.komatsu.jp/en/aboutus/innovation/technology)\ [kcsj.komatsu/ict/smartconstruction/location](https://kcsj.komatsu/ict/smartconstruction/location)

Komatsu IoT Center — kcsj.komatsu/ict/smartconstruction/location

# Location and Travel ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan ## Location Yokohama Minato Mirai (harbor of the future), Japan.
### Yokohama Japan’s second largest city. Yokohama (横浜) is Japan's second largest city with a population of over three million. Yokohama is located less than half an hour south of Tokyo by train and is the capital of Kanagawa Prefecture. Towards the end of the Edo Period (1603-1868), during which Japan maintained a policy of self-isolation, Yokohama's port was one of the first to be opened to foreign trade in 1859. Consequently, Yokohama quickly grew from a small fishing village into one of Japan's major cities. ### Minato Mirai Yokohama’s new city center. Minato Mirai 21 (みなとみらい 21) is a seaside urban area in central Yokohama whose name means "harbor of the future". It has many large high-rises, including the Landmark Tower, which was Japan's tallest building from 1993 until 2014. The area was a large shipyard until the 1980s, when development began to turn it into a new city center. ## Conference venue APA HOTEL & RESORT YOKOHAMA BAY TOWER ### Room reservations

Conference room

Conference room

# Committee ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan ## Organizing committee **Junya Yamakawa** | National Defense Academy, Japan :: *General chair*\ **Taizo Kobayashi** | Ritsumeikan University, Japan :: *General co-chair* **Shingo Ozaki** | Yokohama National University, Japan :: *co-chair, Program Committee*\ **Genya Ishigami** | Keio University, Japan :: *co-chair, Program Committee* **Ryosuke Eto** | National Defense Academy, Japan :: *General secretary* **Kojiro Iizuka** | Shibaura Institute of Technology, Japan :: *paper award selection* **Shinichiro Miyai** | Komatsu Ltd., Japan :: *local arrangements*\ **Takeshi Hashimoto** | Public Works Research Institute, Japan :: *local arrangements* **Massimo Martelli** | ISTVS General Secretary, Italy\ **Jenna Dixon** | ISTVS digital operations, U.S. ## International Scientific Committee **Schalk Els** | University of Pretoria, South Africa\ **Vilas Salokhe** | Kaziranga University, India\ **Corina Sandu** | Virginia Tech, USA\ **Dror Rubinstein** | Ariel University, Israel\ **Jarosław Pytka** | Lublin University of Technology, Poland\ **József Kövecses** | McGill University, Canada\ **Peter Kiss** | Hungarian University of Agriculture and Life Sciences, Hungary\ **Massimo Martelli** | National Research Council, Italy\ **Vladimir Vantsevich** | Worcester Polytechnic Institute, USA\ **Lutz Richter** | SoftServe, Inc., Germany ## Reviewers **Fabian Buse** | German Aerospace Center, Germany\ **Guangming Chen** | Nanjing University of Aeronautics and Astronautics, China\ **Klara Cibulova** | University of Defense, Czech republic\ **Felix Dietrich** | Technische Universität München, Germany\ **Liang Ding** | Harbin Institute of Technology, China\ **Vladyslav Fediukov** | German Aerospace Center, Germany\ **Daisuke Fujiwara** | Suwa University of Science, Japan\ **Herman Hamersma** | University of Pretoria, South Africa\ **Kojiro Iizuka** | Shibaura Institute of Technology, Japan\ **Valentin Ivanov** | Ilmenau University of Technology, Germany\ **Hiroshi Kanamori** | Shimizu Corporation, Japan\ **Alex Keen** | ISTVS UK National Secretary, UK\ **Tetsuya Kinugasa** | Okayama University of Science, Japan\ **Noriaki Mizukami** | International Professional University of Technology in Tokyo, Japan\ **Kenji Nagaoka** | Kyushu Institute of Technology, Japan\ **Ayush Nuwal** | Bahrain Defence Force, Bahrain\ **Takashi Okayasu** | Kyushu University, Japan\ **Takuya Omura** | Keio University, Japan\ **György Pillinger** | Hungarian University of Agriculture and Life Sciences, Hungary\ **Péter Kiss** | Hungarian University of Agriculture and Life Sciences, Hungary\ **David Rodriguez Martinez** | École Polytechnique Fédérale de Lausanne, Switzerland\ **Marian Rybansky** | University of Defence, Czech Republic\ **Shreya Santra** | Tohoku University, Japan\ **Tomoaki Satomi** | Tohoku University, Japan\ **Takuya Tsuji** | Osaka University, Japan\ **Kentaro Uno** | Tohoku University, Japan\ **Tomohiro Watanabe** | Niigata University, Japan # Statement on Publication Ethics and Malpractice ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan ### A. Publication and authorship 1. All manuscripts submitted to 21st International and 12th Asia-Pacific Regional Conference of the ISTVS (hereinafter the Conference) are subjected to strict peer-review process by at least two independent reviewers that are experts in the field of the submitted paper. Acceptance is based on scientific significance, originality, and clarity. 2. The factors that are taken into account in review are relevance, soundness, significance, originality, readability, and language. 3. Based on the reviewers’ comments, a decision (*acceptable in the present form; acceptable with revision; reject*) is made by the members of the Conference Scientific Committee in charge of the review process. At the end of the review process, the Conference Chair makes the final decision. 4. If authors are encouraged to revise and resubmit a manuscript, there is no promise made or commitment given that the revised manuscript will be accepted. 5. Rejected manuscripts will not be re-evaluated. 6. Only manuscripts that are not tainted by libel, copyright infringement, and plagiarism are eligible to be accepted. ### B. Authors’ responsibilities 1. Authors must ensure that the manuscript is entirely their original work, that the manuscript has not previously been published elsewhere, and that the manuscript is not currently being under consideration for publication elsewhere. 2. Authors must participate in the peer review process. 3. If at any point in time the authors discover a significant error or inaccuracy in the submitted manuscript, they are obliged to report the error or inaccuracy to the editor immediately. 4. Every author listed in the manuscript must make a significant contribution to the conception, design, execution, or interpretation of the reported study. Authors must also ensure that all the authors have seen and agreed to the submitted manuscript and their inclusion as co-authors. 5. Authors must provide a proper description of the sources and methods used to obtain and analyze data. 6. Authors must notify the editors of any conflicts of interest. 7. Authors must ensure that the manuscript has been proofread and corrected for clarity, grammar, and spelling of the text. ### C. Reviewers' responsibilities 1. Reviewers should respect the confidentiality of peer review and not reveal any details of a manuscript during or after the peer-review process. 2. Reviewers should be objective and constructive, refraining from being hostile or inflammatory and from making libelous or derogatory personal comments. 3. Reviewers should evaluate the manuscript based on its suitability for the conference and its originality. Reviewers should also evaluate whether the manuscript has clear objectives, sound methods, and clear and sufficient results supporting the conclusions with appropriate figures, tables, and references. 4. Reviewers should report their review results clearly with supporting arguments. 5. Reviewers should notify the authors about any published work they deem relevant that has not been cited in the paper. 6. Reviewers should bring the editor’s attention to any substantial similarity or overlap between the manuscript under consideration and any other published paper of which they have personal knowledge. 7. Reviewers should not review manuscripts in which they have conflicts of interest resulting from competitive, collaborative, or other relationships or connections with any of the authors, companies, or institutions connected to the papers. ### D. Editors’ responsibilities 1. Editors are held accountable and should take responsibility for everything they allow to be published. 2. Editors must base their decisions solely on the papers’ importance, originality, clarity, and relevance to the conference’s scope, without regard to race, gender, sexual orientation, religious belief, ethnic origin, citizenship, or political orientation of the authors. 3. Editors must not share information about the manuscripts, including whether they have been received and are under review, their content and status in the review process, any criticism by reviewers, and their ultimate fate, to anyone other than the authors and reviewers. Editors must also make clear that reviewers should keep manuscripts, associated material, and the information they contain strictly confidential. 4. Editors must preserve the anonymity of the reviewers. 5. Editors must make sure that the funding source of the research is should be declared and published, and that the role of the funding source in the conception, conduct, analysis, and reporting of the research is stated and published. 6. Editors must not allow any conflicts of interest between editorial staff, authors, reviewers, and editorial board members. 7. Editors must guard the integrity of the publication by issuing corrections and retractions when needed and pursuing suspected or alleged research and publication misconduct. ### E. Plagiarism All articles submitted to the Conference must contain exclusively original research. Passing off another’s research as the author’s own, copying or paraphrasing substantial parts of another’s paper (without attribution), or claiming results from research conducted by others are all considered to be forms of plagiarism. Plagiarism in all its forms constitutes unethical publishing behavior and is unacceptable. ### F. Duplicate submission Authors should not submit for consideration a manuscript that has already been published in another journal or conference. Submission of a manuscript concurrently to more than one journal or conference constitutes unethical publishing behavior and is unacceptable. ### G. Data fabrication and falsification Authors should not include spurious data or false research results in the manuscript. Also, manipulation of the research process or the arbitrary alteration or omission of data which leads to the distortion of the contents or the results of the research should not be done. ### H. Citation manipulation Authors should not include citations whose primary purpose is to increase the number of citations to an author’s given article. ### I. Improper author contribution or attribution All listed authors must have made a significant scientific contribution to the study in the paper and approved all its claims. It is important to list everyone who made a significant scientific contribution, including students and laboratory technicians. ### J. Redundant publications The artificial division of study outcomes into multiple articles for the sole purpose of increasing the quantity of publications constitutes redundant publication is unethical publishing behavior and is unacceptable. Multiple papers generated from the same study can be accepted if they focus on different aspects of the study, in a sensible and meaningful way. ### K. Rejection of manuscripts In the case of unwillingness of the authors to cooperate with the Scientific Committee (e.g., refusing to improve the manuscript as requested or not having a proper communication with the Scientific Committee), the manuscript is rejected. A manuscript is rejected also in case of plagiarism, data fabrication, or falsification. # Contact ISTVS 2024 | October 28–31, 2024 | Yokohama, Japan For all general inquiries with respect to the conference or to request a formal letter of invitation: **Junya Yamakawa**\ \&#xNAN;*Conference chair ::* [*yamakawa@nda.ac.jp*](mailto:yamakawa@nda.ac.jp)\ [Automotive Engineering Laboratory | National Defense Academy](https://www.mod.go.jp/nda/english/) # Papers # 0356 / Hammering Energy Requirements For Surveying Lunar Surface With Dynamic Cone Penetrometers And Seismic Methods. ## Authors Karlis Slumba, Brendan Scott, Mark Jaksa, and Samuel Ximenes {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Lunar regolith; Geotechnical survey; Cone penetrometers; Shallow seismic methods\ {% endhint %} ## Abstract Surveying is necessary before anything can be built on the Moon. Exploration Architecture Corp. (XArc) proposed that geotechnical surveying on the Moon could be performed with a SurveyorBot; a robot equipped with cone penetrometers and seismic instruments. This research consists of development and testing of a mini dynamic cone penetrometer (Mini-DCP) with variable impact energy. The Mini-DCP acts both as a penetrometer and a seismic source, that is used in tandem with seismic instruments – geophones. Experiments are performed at the Extraterrestrial Environmental Simulation (EXTERRES) laboratory at the Andy Thomas Centre for Space Resources at the University of Adelaide. The experiments are performed to test the hammering energies that are required for the Mini-DCP to both penetrate the soil at a certain speed and for the seismic signal to be detectable at certain distances. Hammering energies that are too large penetrate through the soil too fast, not providing enough data about the layering. But hammering energies that are too low produce seismic waves that are too weak to be detected. Exact values depend on many parameters of the soil (e.g. relative density, cohesion), environment (e.g. atmosphere, gravity), and instruments (e.g. cone shape and size, instrument mass). Several of these parameters are being explored in this research. Mini-DCP testing as a penetrometer and a seismic source are performed using Lunar Highlands simulant (LHS-1E) in the regolith pit at the EXTERRES lab. AKNOWLEDGEMENTS This work supported by NASA under contract award Number 80NSSC23PB427. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NASA. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 0412 / Evaluation Of Grouser Wheel Traction Performance At High-Speed By Single-Wheel Test ## Authors Keisuke Takehana, Kenta Sawa, Kentaro Uno, Shreya Santra, and Kazuya Yoshida {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: High-speed mobility; Single-wheel test; Lunar exploration rover; Grouser wheel\ {% endhint %} ## Abstract This study focuses on the locomotion characteristics of a high-speed lunar exploration rover. On the loose soil such as lunar regolith, wheeled mobility systems often encounter wheel sinkage and slippage, leading to trafficability challenges. While conventional exploration rovers are designed to improve mobility using grouser wheels, their exploration speed remains relatively slow (\~10^-2 m/s). High-speed traversal is essential for expanding exploration areas in future missions. In this paper, we conduct single-wheel tests under high-speed conditions and provide detailed results from force measurements. Three types of wheels are prepared: no grouser, low grouser, and high grouser, and their traction performance are compared. The testbed allows speeds of 1 m/s, which is about a hundred times faster than conventional exploration speeds. We measured traction coefficients (the ratio of drawbar pull to vertical load) and traction efficiency (the ratio of input energy to output energy) for variable slip ratios to assess traction performance. Our results revealed a trend where traction performance decreases as driving velocity increases. This behavior of performance at various speeds differs from that at low speeds. Each performance exhibited substantial dependence on the slip ratio, with efficiency peaking around a slip ratio of approximately 5% to 10%. Additionally, experiments varying grouser height under identical driving conditions demonstrated improved traction performance with higher grouser wheels. Through this experimental evaluation, we confirmed the effectiveness of grouser wheels even at high speeds. These terramechanical findings contribute to the wheel design and locomotion control of next-generation exploration rovers. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 0906 / Experimental Investigation Of Increased Bearing Capacity When Imparting Vibration To Loose Ground In Low Atmospheric Pressure ## Authors Tomohiro Watanabe and Kojiro Iizuka {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Loose soil; Bearing capacity; Vibration; Rovers for planetary exploration\ {% endhint %} ## Abstract Recently, legged robots have attracted considerable attention as highly mobile rovers for planetary exploration. However, the surfaces of celestial bodies such as Mars and the Moon are primarily loose, causing slippage due to surface deformation from the rover’s leg movements. To mitigate this, we proposed a walking method aimed at preventing slippage. In our previous study, we evaluated the effectiveness of this method using a legged testbed on sloped, loose ground. The results demonstrated improved mobility performance of the legged rover. It is crucial to investigate the increase in bearing capacity by imparting vibration in a realistic space environment to validate the effectiveness of the proposed method. This study examines the change in bearing capacity due to vibration under low atmospheric pressure, a condition found on Mars and the Moon. This condition affects the characteristics of ground sand due to decreased air resistance. Our findings provide valuable insights into using vibration in planetary exploration to enhance the performance of legged rovers. The experimental results indicate that the bearing capacity under low atmospheric pressure is nearly identical to that under standard atmospheric pressure, suggesting that atmospheric pressure conditions have minimal impact on the supporting force when vibration is applied. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1204 / Measurement And Visualization Of Soil Cutting And Throwing Behavior By A Rotary Tillage Blade ## Authors Toyohiro Katou, Yuta Hirayama, Yasumaru Hirai, Muneshi Mitsuoka, Koki Nakatani, Kenji Kaida, Mutsumi Hidekawa, and Takashi Okayasu {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Soil mechanical behavior; IMU (Inertial Measurement Unit); Tillage simulation; Three-dimensional discrete element method (3D DEM)\ {% endhint %} ## Abstract Soil cutting and throwing behavior during rotary tillage is useful to evaluate the mechanical design of the tillage blade. For this reason, several evaluation methods have been proposed in the past. In this study, a device to measure the angular velocity and acceleration of soil clods was fabricated in a laboratory test. The measured soil cutting and throwing behavior was compared with the behavior computed by the three-dimensional discrete element method (DEM), and the validity was also evaluated. As a result, it was found that the soil cutting and throwing behavior obtained by the inertial measurement device almost agreed with that obtained by the image analyses. Furthermore, the soil cutting motion by the rotary tillage blade differed between the measured results and the 3D DEM analysis results. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1241 / Study On Classification Of Excavated Soil Using Internal Sensor Data Of Hydraulic Excavator ## Authors Naoki Morisawa, Masaya Imanishi, Masaki Yanagishita, Teiichirou Chiba, Hiroshi Yamamoto, Takeshi Hashimoto, and Daisuke Endo {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Soil Classification; ICT; Hydraulic Excavator; Internal sensor; Automation\ {% endhint %} ## Abstract In these days, construction sites are facing workforce shortages caused by declining labor and lack of young workers. Therefore, “Improve Productivity” is very important. Automation and autonomy of construction machinery is one of the solutions. As above, ICT hydraulic excavators and bulldozers are widely used in many sites, but the scope of the application is limited. In particularly, automated digging in hydraulic excavators still has many difficulties in actual use. The root cause is needed to the complicated operation during digging affected by the soil conditions. Since the soil conditions change anytime, if the operation is not adjusted to match to them, the efficiency will be decreased significantly. In other words, to achieve automated digging, the machine must recognize variation of soil conditions first. While digging, the operator has been sensing the machine's response affected by the soil conditions to consider it and adjusting machine operation simultaneously. In other words, human senses were used to recognized soil conditions to perform efficient operations. In that case, we thought that if we could replace human senses with internal sensors of the machine, the machine could recognize the soil conditions by itself. In this study, based on this hypothesis, we conducted measuring sensor data during digging in various soil conditions (e.g. hardness, materials…). The test results indicated that the soil hardness measured by simplified N-value meter, has a high correlation with the work efficiency and bucket tooth speed calculated from internal sensor data. This implicated that the sensor data from the excavator can be used to be determine soil conditions. In addition, there is a possibility that machine could recognize soil conditions by itself. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1525 / Photogrammetry Based Mobility Mapping For Small Scale Model Vehicle ## Authors Dávid Körmöczi and Peter Prof. Kiss {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: off-road mobility; terrain model; mobility map\ {% endhint %} ## Abstract Mobility on terrain is one of the key factors of off road vehicles. In conventional vehicle technology, an experienced driver can assess the obstacle negotiation capability of their vehicle, hence mobility models for manned vehicles usually have smaller resolution and are less detailed. However, unmanned vehicles can only rely on an algorithm both for global path planning and local vehicle control, thus such an algorithm for mobility mapping needs to be more detailed and have higher resolution than convnetional mobility models. In this paper, a method is shown to create a mobility map for a ClearPath A200 small scale test vehicle based on a drone-borne photogrammetry survey of the test area. The vehicle specific mobility model examines the vehicle-terrain interaction from the perspective of obstacle negotiation capability, while also taking into account the soil deformation and the stability of the vehicle. The vehicle-wheel deformations are characterized by a parallel element rheological model. Apart from the perspectives of off road mobility, the computational capacity requirement of the model is also examinded, which is a key factor for real time applications of unmanned vehicles. At the end, a method and test setup is proposed for the validation of the theoretical mobility model via field measuremets. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1649 / Dynamic Mode Decomposition For Piv-Based Sand Flow Field Beneath Traveling Wheel ## Authors Ohta Kuramoto, Jorge Ruben Casir Ricano, and Kenji Nagaoka {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: dynamic mode decomposition; PIV; wheel-soil interaction\ {% endhint %} ## Abstract Grouser wheels are effective for robotic mobility in soft, loose terrain. So far, particle image velocimetry (PIV) has been widely used to observe sand flow beneath a traveling wheel. Although the PIV-based spatial velocity field at a moment in time has been discussed, but few studies have discussed its time evolution, or spatio-temporal dynamics. This could be due to the fact that the sand flow vector field is complex high-dimensional dynamics and a mixture of spatial and temporal information. Thus, we apply dynamic mode decomposition (DMD) to the sand flow data obtained by the PIV method to reduce its dimension and decompose it into major modes. A mode is a characteristic pattern or correlation. The DMD can extract temporal and spatial information separately, allowing the dynamics to be analyzed by the major modes. We first conducted PIV experiments using the traveling wheel on sand at high-slip (slip ratio is approximately 70%) and low-slip (slip ratio is approximately 20%) conditions. Then, the DMD was applied to decompose the PIV-based sand velocity data into major modes. As a result, the obtained modes were mainly divided into two dynamics, one representing the inter-grouser sand flow trapped in the grouser motion and the other representing soil compaction and failure, affecting deeper soil. It was found that the low-slip condition included both modes, whereas the high-slip one did only inter-grouser sand flow. The DMD analysis confirmed that two major modes can explain wheel-soil interaction. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1710 / A Novel Measurement Method To Aid Development Of Soft Soil Tyre-Terrain Interaction Models ## Authors Thomas Bernd Kabutz and Schalk Els {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: tyre deformation; digital image correlation; tyre-terrain interaction\ {% endhint %} ## Abstract Most forces on a ground vehicle go through the tyre contact patch. Because the tyre interfaces with the road surface, it is not possible to directly measure the contact patch. This presents a significant challenge in assessing soil characteristics. Predictions of the tread deformation allow estimates of total soil deformations. This can be used to determine elastic and plastic deformation of soil under moving vehicles, giving insight into soil parameters. Soil deformations and parameters are beneficial for vehicle control as well as evaluating the environmental impact. Previous studies utilized digital image correlation techniques to measure tyre deformation on the inner surface of the tyre. This paper investigates the feasibility of developing a measurement system that uses deformations on the inner surface of a tyre to predict the deformation on the outside. The proposed method involves offsetting the inner surface along its normal directions by the tread thickness to obtain the outer surface of the tyre. A 2D proof of concept was developed, showing the ability to predict tread deformation based on inner surface measurements. Reasonable accuracy was achieved, thus confirming the feasibility of predicting tyre tread deformations from inner surface measurements by a geometry offset. The identified errors are deemed acceptable for the given problem, with the errors due to the simplification of the problem proving significantly smaller than measurement-induced errors. A full 3D model was consequently developed to predict tread deformation over the full contact patch region. The findings pave the way for the development of a real-time system to predict soil volume displacement, providing crucial insights for vehicle control and environmental impacts in offroad scenarios. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1882 / Spatio-Temporal Analysis Of Sand-Density Distribution Beneath Traveling Wheel Based On Particle Image Velocimetry ## Authors Kenji Nagaoka and Seigo Sakai {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Wheel-soil interaction; Sand-density distribution; Sand flow field; Particle image velocimetry\ {% endhint %} ## Abstract This paper proposes a spatio-temporal analysis of sand-density distribution beneath a traveling wheel based on a particle image velocimetry (PIV) method. With the advancement of image processing technology and the higher resolution of commercially available digital cameras, the PIV methods have been widely used to directly visualize the sand flow field without tracer particles. They can output the numerous sand velocity vectors at a moment in time. By continuously connecting sand flow fields obtained, we can surmise their spatio-temporal changes, though, each flow field is obtained as a spatio-temporally independent feature. Thus, we attempt to propose a PIV-based spatio-temporal analysis accumulating the sand flow vectors, and thereby show a spatio-temporal change of the sand-density distributions beneath the traveling wheel, where the sand density is represented by the relative density. Although the method requires some assumptions, it can represent the spatio-temporal behavior of the sandy terrain, which has not been shown before. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1902 / The Combination Of Exhaust Gas Recirculation And Water Injection In A Modern Diesel Engine ## Authors Dániel Szőllősi and Peter Prof. Kiss {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: NOx; water injection; exhaust gas recirculation (EGR); Retrofit emission control; Tier 4; Stage V.\ {% endhint %} ## Abstract Diesel engines are commonly found in off-road, agricultural and forestry equipment because of giving the best option in terms of weight, range and fuel storage. Given the current potential of electric powertrains, in this area, electrification does not seem to be competitive in the near future. Regulations tighthening for on road (EURO7) and non-road vehicles (Tier 4, Stage V) in many parts of the world and tends increasingly focusing on to ensure that as many as possible of the vehicles with low or no emission standard can be retrofitted to reach decreasing emissions. The overwhelming majority of vehicles fall into this category, around the world. Retrofitting should be as simple and cost-effective as possible. One such option could be the retrofitting with water injection systems. The exhaust gas recirculation (EGR) achieves the lower temperature required for reduced nitrogen-oxide (NOx) emissions by reducing the oxygen content and thus impairing combustion, water injection achieves this essentially by enriching the charge air and thus increasing its heat capacity and by the heat dissipation effect of the liquid-vapour phase change. Contrary to common belief, the two techniques are not only able to reduce NOx separately, but also together they cause further emission reductions on NOx and on other emission components. This has been shown through the use of practical applications, as the operation of EGR and water injection is linked to different engine operating conditions. This is also an important achievement, as it means that when the water injection system is installed in an existing vehicle, after that only software intervention is needed to make the system work properly and reach the emission reductions. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 1928 / A Novel Soil Stress Estimation Method Of Wheel-Soil Interaction Using Photoelasticity ## Authors Kenji Nagaoka and Yuto Yoshida {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Wheel-soil interaction; Soil stress distributions; Photoelastic method\ {% endhint %} ## Abstract This paper proposes a new approach to understanding the wheel-soil interaction, which is an indirect estimation method of soil stress distributions beneath a traveling wheel soil using a photoelastic method. Thus far, in the conventional studies applying the photoelastic method to the wheel-soil terramechanics, the terrain has been emulated by photoelastic disks or plates, which enable visualization of internal stresses in the simulated terrain. In particular, the photoelastic disks have performed visualization of two-dimensional dynamic stress distributions of the simulated granular terrain. With this method, we have visualized and analyzed the dynamic force chain structure of the terrain under different wheel slip conditions. Still, it is difficult for the previous configuration to simulate the dynamic behaviors of natural soil, e.g., compaction, failure, or wheel ruts. Accordingly, achieving both the stress visualization and the dynamic behaviors of soil is a significant challenge to make the photoelastic method more practical. To cope with this challenging issue, we have developed a novel experimental setup consisting of a photoelastic wheel (top layer), soil (middle layer), and a photoelastic plate (bottom layer). By vertically sandwiching the soil between the photoelastic wheel and plate, the soil stresses can be indirectly estimated to satisfy the boundary stress conditions. To achieve this approach, we have conducted calibration tests of the photoelastic wheel and plate, and then identified the force vector and contact patch corresponding to the visualized stresses. In this paper, we demonstrate that it is possible to indirectly estimate how the stress propagates and attenuates in the soil by the proposed method. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 2369 / Experimental Verification Of Particle Behavior During Crushing And Mixing Of Deteriorated Asphalt Pavement Layers By Stabilizer ## Authors Takatomo Fujii, Takashi Kurosu, Osamu Oikawa, Takashi Okayasu, Toyohiro Katou, Yuta Hirayama, and Yukinori Tsukimoto {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Road stabilizer; Experimental verification; Reclamation; Crushing and mixing behavior; Three-dimensional discrete element method (3D-DEM); Particle size distribution\ {% endhint %} ## Abstract In the road-subbase reclamation method, a stabilizer's rotor bits (teeth) are rotated to crush deteriorated asphalt pavement in-situ while mixing it with additives such as cement and asphalt emulsion, which are then compacted with rollers to create a new, stable subbase. The uniformity and the quality of crushing and mixing is affected by the shape and arrangement of the rotor bits, rotational speed, and working speed. Therefore, it is important to understand the behavior of the crushed materials. However, since those actual behaviors inside the rotor hood cannot be observed, an attempt was made to analyze and visualize particle behaviors using the three-dimensional discrete element method (3D-DEM). In this study, an actual stabilizer was used to crush and mix the deteriorated pavement layer in a test section to compare with the analysis results. The surface of the test section was painted with spray paint in six different colors, square grid lines were drawn with white chalk, and a total of 780 numbered stickers were pasted within each grid. After the mixing test, all particles with the numbered stickers were recovered (these particles are called as “marking particles” hereafter), and the moving distance in the front-back direction were measured and a number of particles distributed in the left-right direction was counted. Test results show that about 80% of the crushed marking particles are blown away once and deposited behind the rotor, never to be mixed again. The number of marking particles counted in the left-right direction was similar and uniform. Since the test results were generally similar to the 3D-DEM results, it was concluded that this analytical method is capable of simulating the behavior of crushed material in the rotor hood. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 2411 / Proposing Turning Motion Of The Small And Lightweight Push-Rolling Rover With Mimimal Configuration ## Authors Daisuke Fujiwara and Kojiro Iizuka {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Turning motion; Wheel walking robot; Push-Pull Locomotion; Planetary explorations; Loose soil; Mobile robot\ {% endhint %} ## Abstract Some organizations in Japan have planned planetary explorations using a small rover. However, the rovers with cylindrical wheels have a risk of failing to move in the loose soil area, such as the surface of the lunar/planet. The movement using the supporting force of the locked wheel, for example, a wheeled walking, or push-pull locomotion, can reduce the risk. Previous studies have mainly developed relatively large rovers over a mass of 10 kg. Meanwhile, our group has developed a small and lightweight (under a mass of a few kg) push-rolling rover with minimal configuration, and our previous studies indicated that the rover could climb steep slopes over 30 degrees with low slip. Planetary exploration rovers are required to move in an arbitrary direction; therefore, the developed rover also needs to have a function of a turning motion. This paper proposes the turning motion while inching for the push-rolling rover with minimal configuration and evaluates its performance by the traveling experiments at different conditions (driving conditions, and wheel shapes). The experimental results indicated that the proposed turning motion using high wheel slip and lug’s wheel realized turning with low slip on loose surfaces with steep slopes. Additionally, the experimental results also showed that the slip amount of the rotational center is lower than that of a normal skid-steering. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 2651 / Rapid Assessment Tools For Estimating Trafficability On Low-Volume Roads ## Authors John Rushing, Lulu Edwards, Haley Bell, and Margarita Ordaz {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Rapid assessment; soil strength; mobility\ {% endhint %} ## Abstract Rapid assessment of low volume road surfaces remains a challenge when attempting to forecast allowable vehicle crossings. Variations in moisture content of the soil can greatly affect trafficability, and predictive equations for soil deformation under vehicle loads often have reduced reliability for low-strength materials. Portable tools to characterize soil stiffness and corresponding relationships to load-induced deformation are needed. In this effort, researchers performed comparative testing of multiple rapid assessment tools as potential devices for giving estimations of vehicle trafficability. The test devices included a Clegg hammer and lightweight deflectometer as instruments that measure response from impulse loading. A dynamic cone penetrometer was used as a basis for comparison. Silty sand with and without chemical stabilizers at varying moisture content were used for testing. These soil conditions represented very weak conditions capable of supporting fewer than 50 vehicle passes to moderate strength conditions capable of supporting several thousand vehicle passes. Data from full-scale tests were used to correlate allowable traffic with data obtained from the rapid assessment tools. Recommendations from the effort include ranges of response data to categorize low-volume road surfaces based on their ability to handle ranges of vehicle loadings. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 2812 / An Interaction-Aware Two-Level Robotic Planning And Control System For Vegetation Override ## Authors Charles Noren, Burhanuddin Shirose, Bhaskar Vundurthy, Sebastian Scherer, and Matthew Travers {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Trajectory Optimization; Planning; Vegetation Override; Off-road Driving; Robotics\ {% endhint %} ## Abstract During off-road operations, mobile robotic platforms often encounter objects that influence the platform’s route. As determining the outcome of an interaction with an object (e.g., overriding) is difficult, many robotic planners are designed to avoid interactions with all environmental objects. Yet, this object-adverse planning behavior is not reflected in the actions of expert human operators, who may interact with objects in order to find a viable path towards their goal. This work intends to emulate that human operator intuition. Our objective is to improve the performance of robotic traversals in off-road terrains through the development of a planning paradigm that allows certain safe contact with environmental objects. Specifically, we design a two-level hierarchical planning and control system which couples a contact-informed regional motion planner with contact-constrained local nonlinear trajectory optimization techniques. The approach is demonstrated for classes of vegetative objects which are characterized by existing parameterized collision models from the terramechanics community. The top level of the hierarchy combines sampling-based planning techniques with a set of override (velocity) constraints derived from these collision models during the search for a minimum-time trajectory towards the platform’s goal. This minimum-time trajectory is then passed to the lower-level of the architecture, which utilizes direct collocation and model predictive control techniques to ensure that the velocity constraints are enforced during trajectory execution. The capabilities of the architecture are shown both in simulation and onboard a robotic platform, where vegetation is reasoned about and then overridden depending on the environment, platform, and object geometry. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 2919 / Accurate Rover Mobility Analysis Using Hils-Drft With Real-Time Parameter Tuning Approach ## Authors Takahiro Fuke, Sora Ishikawa, and Genya Ishigami {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Terramechanics; Resistive Force Theory; Hardware-In-the-Loop Simulation\ {% endhint %} ## Abstract Offroad mobility of extraterrestrial exploration rovers can be significantly degraded by vehicle slippage on soft terrain covered with fine powdery sand known as regolith. Comprehensive design analysis and verification of the rover’s mobility have been widely investigated using numerical and experimental approaches. Numerical simulations for the mobility analysis require accurate modeling of the contact forces between the wheel and sand. While several wheel-sand interaction models have been proposed based on the Bekker-Wong-Reece theory, the Dynamic Resistive Force Theory (DRFT) proposed in the early 2020s is a notable approach for its low computational cost and adaptability to high-speed motion. The scaling factor used in DRFT is the only parameter for representing soil-dependent parameters, and its value needs to be empirically tuned to achieve accurate and reliable mobility analysis. Therefore, the authors have integrated a single-wheel test bed into a closed-loop Hardware-In-the-Loop Simulation (HILS) associated with DRFT. This HILS-DRFT experimentally observes the characteristics of the wheel sinking phenomenon in the wheel test bed, and then, the value of the scaling factor is tuned in real-time based on the difference between the observed wheel sinkage and the DRFT simulation. This real-time parameter tuning method accurately reproduces wheel mobility, particularly in its transient states, which were previously unachievable with DRFT alone. The proposed HILS-DRFT with the real-time tuning method will contribute to the efficient and reliable development of rovers. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 3181 / Assessing Sensitivities Of Off-Road Pneumatic Tire On Clay: A Finite Element Investigation On Tire Operational And Design Parameters ## Authors Destiny Mason, Varsha S Swamy, Corina Sandu, Alba Yerro, David Gorsich, and Katie Sebeck {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Finite Element Analysis (FEA); Tire Modeling; Sensitivity analysis\ {% endhint %} ## Abstract Military and agriculture vehicles alike often experience uncertainties regarding sinkage and traction while traversing non-linear deformable soils. The off-road tires of these vehicles are equipped with stiffer sidewall characteristics to reduce puncture risk, increase load bearing capacity, and improve stability and traction. Since physically testing tires is time-consuming and costly, enhancing the virtual physics-based modeling capabilities can be beneficial for design decisions. Identification of crucial design parameters is essential to ensure that modelers prioritize these parameters to improve the model's accuracy. As a result, a tire sensitivity analysis is proposed to evaluate the tire model's robustness. The tire used for this study is a lugged bias-ply tire with improved self-cleaning characteristics for muddy terrains. An advanced FE tire model is developed with detailed modeling of the distinct tire parts, including the bead, apex, inner layer, 2-ply carcass, sidewalls, under tread, and lugs. Two types of parameters are of focus: (a) tire operational parameters and (b) tire design parameters. The influence of tire operational parameters, i.e., tire normal load, inflation pressure, and velocity are first conducted and verified with existing studies in the literature. As a novel contribution, the tire design parameters, i.e., tire width, tire diameter, number of lugs, orientation of lugs, and lug size, are also considered. The advanced FE tire is made to negotiate on the rigid ground first and then on low plasticity CL clay to analyze the trends in sensitivities. The results of this sensitivity analysis provide valuable insights into the reliability of the FE tire, enabling more informed conclusions to be drawn from simulated data. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 3303 / Soil Instrumentation For Measuring Normal Stress Distribution Under Off-Road Tire ## Authors Alexandru Vilsan, Nikhil Ravichandran, Chaitanya Sonalkar, and Corina Sandu {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Off-road mobility; Soil instrumentation; Terramechanics; Soil compaction; Normal stress distribution\ {% endhint %} ## Abstract The distribution of normal stress within soil plays an important role in determining the tire-soil interaction dynamics, affecting tire traction performance, soil compaction, and overall vehicle stability. A comprehensive analysis of the normal stress patterns will allow researchers to refine tire designs, tread characteristics, and inflation pressures for enhanced off-road performance across diverse terrains. This study presents a novel soil instrumentation device designed to measure normal stress distribution in soil following a single pass of an off-road tire. The developed device employs an array of piezoresistive vertical load sensors for providing real-time, accurate data of normal stress distribution beneath the tire during operation. Several tire-soil interaction tests were performed at the Virginia Tech Terramechanics Test Rig to verify the output of the load sensors. The sensor array was embedded in GRC-1 Lunar Soil Simulant at a depth of 150 mm while an off-road tire loaded with a vertical force of 2000 N traversed over the surface of the terrain. The results obtained showed significant differences in pressure patterns under different toe angles, indicating a good correlation between the actual normal stress distribution and the readings from the sensor array. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 3649 / Modeling The Resistive Forces On Vehicles In Deep Snow ## Authors Micah M. Borrero and Orian Welling {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Mobility Modeling; Deep Snow; Off-Road; Snow Compression; Drag; Plowing\ {% endhint %} ## Abstract The ability to determine whether a vehicle can traverse a particular winter surface is crucial for planning and executing successful off-road operations in cold regions environments. Various works have detailed strategies and improvements to vehicle mobility models snow and ice surfaces, and others have proposed initial methods to estimate the forces required for vehicles to travel through deep snow exceeding the height of the vehicle bumper or undercarriage These methods demonstrate a strong correlation between their approach and measurements examined in the field. However, they lack sufficient field-based measurements in varied snow conditions to fully capture real-world force estimates. In this paper, we build upon prior work to develop a preliminary model with the ability to estimate the resistive forces acting on a vehicle traveling through deep snow. We draw upon a wide range of disciplines, discussing the strength of a model based on the present knowledge of snow compression against a methodology based on fluid dynamics techniques. Both models exhibit promising results. However, these results demonstrate a stronger positive correlation using the snow compression model when compared with field-based measurements taken over a variety of winter seasons. These measurements were obtained using a purpose-built plowing apparatus, which simulated a range of bumper ride heights and profiles. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 3769 / Mobility During The Transition Seasons In The Arctic ## Authors Michael Parker, Clifford Witte, Susan Frankenstein, and Allan Wheeler {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Off-road Mobility; Vehicles; Frozen; Thawed; Soil; Arctic\ {% endhint %} ## Abstract Mobility in the Arctic involves more than operating on only snow and ice surfaces. Vehicles must be able to navigate the during the summer, fall and spring which include both frozen and unfrozen soil surfaces and the transition periods where the ground is freezing in the fall and thawing in the spring. Each of these ground states present a unique challenge to vehicle mobility and must be studied to see fully understand the impacts on mobility. They either get covered by a blanket of snow which insulates the surface slowing and sometimes preventing freezing, or the experimenting team arrives to the test site a day late finding the surface already completely thawed. To solve this problem U.S. Army Corps of Engineers researchers have constructed three frost susceptible soil surfaces for full scale vehicle testing at the Cold Regions Research Laboratory in Hanover, NH. Inside its Frost Effects Research Facility, CRREL researchers may freeze and thaw the soil as needed without relying on the difficult timing of mother nature. The facility allows the user to directly control the freeze and thaw cycles allowing multiple vehicles to be tested on different surfaces over the course of a single winter. This speeds up the research on frost susceptible soils during these difficult transition periods and provides much needed mobility data for predictive modeling and planning purposes. Multiple soil conditions and freeze thaw states have already been studied and this paper will discuss the results for light tracked and wheeled vehicles. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 3773 / Evaluation Of The Multi-Pass Effect Of An Exploration Rover By Single Wheel Testing Assuming Lunar Gravity And Soil ## Authors Tomomi Tanaka, Keisuke Takehana, James Hurrell, Kentaro Uno, and Kazuya Yoshida {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Multi-pass effect; Lunar regolith; Single-wheel test; Rovers\ {% endhint %} ## Abstract The exploration of the lunar surface requires a wide range of mobility, thus wheeled mobile robots, called rovers, which are capable of traveling on the loose soil, called lunar regolith. To investigate the traction performance of wheels on such loose soil, it is essential to consider the multi-pass effect. That is the influence to the wheel’s traction performance due to the alteration in the soil property caused by the previous wheel’s traveling (compaction and digging). The single-wheel testing is helpful to analyze the driving performance of a wheel. In this study, the soil with a cohesive property and heterogeneity in particle size and shape, which offers a nonlinear characteristics of lunar regolith, is prepared in the sandbox of the single-wheel testbed. To investigate the multi-pass effect, Toyoura sand, which is a non-cohesive and homogeneous sand, is compared with the lunar regolith simulant: FJS-1. This paper presents the experimental results of a repetitive running experiment conducted to measure the multi-pass effect. In this experiment, the wheel was run 5 times in a row over the same area from the same direction, and the traction coefficient, sinkage, and the shear strength of the soil were measured each time. This experiment was also conducted under several conditions by varying the vertical load applied to the wheel and the slip ratio. The wheel employed in the experiments is the same model of grouser wheels as installed on the Rashid Rover that was actually planned to be deployed on the lunar exploration mission. The results revealed that the soil compaction was observed only at a deep level of FJS-1 sand. This is because FJS-1 sand flows in shallow locations due to the action of the grouser, on the other hand, Toyoura sand has no adhesive force. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4093 / The Role Of Tire-Soil Interface Characteristics On Performance Parameters Through Experimental And Numerical Investigation ## Authors Jasleen Kaur Bheora, Varsha S Swamy, Mason Destiny, Alba Yerro, Corina Sandu, Katherine Sebeck, David Gorsich, and Bernardo Castellanos {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Tire-terrain interaction; Friction; Direct shear test; Saturated soil; Tire-clay failure envelope\ {% endhint %} ## Abstract The capacity of off-road vehicles to navigate unprepared terrain is determined by the forces imparted by the terrain. The strength of the tire-soil interface is typically lesser than the soil's internal strength. In particular, the interface friction characteristics between the tire and terrain influence the drawbar pull performance and are often overlooked in studies. As a result, accurate experimental determination of the interface friction and its influence on physics-based modeling is the focus of this paper. The tire interaction with fully saturated low plasticity clay (CL) in the plastic state is studied. A large-scale direct shear test between the off-road lugged tire and clay at different contact pressures is conducted to determine the interface failure envelope. As a novel contribution, the tire is sheared in both the longitudinal and transverse orientations. The reliability in the experimental findings is increased by conducting more small-scale direct shear tests with tire rubber samples. The results of the tests are imported into the numerical model consisting of an advanced FE tire interacting with the FE clay. The sensitivity of the drawbar pull and sinkage to friction is studied. Comparative analysis employing different terrain strengths (firm and soft ground) and tire designs (lugged and smooth) are conducted. The advanced FE tire consists of 11 parts including Mooney-Rivlin rubber and orthotropic elastic carcass plies. The research highlights the scenarios where the interface friction influences the drawbar pull, contrasting with situations where the clay deformations dominate. As a conclusion, the proposed methodology shows the importance of accurate interface modeling, providing insights for better correlation between modeling and experimentation. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4142 / Root System Analysis After Vibratory Roller Compaction In Dry Direct Seeding Of Rice Field ## Authors Koichiro Fukami, Naoki Matsuo, Keiko Nakano, and Kimiyasu Takahashi {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: dry direct seeding of rice; vibrating roller; prevent water leakage; root system analysis\ {% endhint %} ## Abstract To improve the efficiency and optimization of compaction work using a vibratory roller to prevent water leakage in dry rice direct seeding fields, we investigated how the number of compaction passes affects soil physical properties (hardness and permeability), crop growth, and root system development. Cultivation tests showed that compaction operations effectively prevent leakage and increase the number of seedlings. We analyzed its effect on 3D X-ray CT image-confirmed vertical root elongation under all conditions. In addition, we qualitatively confirmed that the roots tended to become thinner when the number of compactions was 5 compared to other conditions. Additionally, WinRHIZO analysis revealed the following: the root dry weight per number of stems decreased with 1- and 3-pass compaction and increased with 5-pass compaction, compared to uncompacted soil. The total root length per the stems decreased after 1- and 3-pass compaction and increased after 5 passes of compaction. The composition of roots with a diameter of 0.38 mm, or more, increased after 1 and 3 compactions and decreased after 5 compactions. In addition, the composition of roots with a diameter of 0.28 mm or less increased after 5 passes of compaction. The above suggested that excessive compaction may have a negative effect on the root system of paddy rice (roots become thinner). *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4213 / Dem-Based Analysis And Optimization Of An Excavation Bucket Drum For In-Situ Resource Utilization ## Authors Tomoyasu Nakano, Takuya Omura, and Genya Ishigami {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: In-situ Resource Utilization; Bucket Drum; DEM Simulation; Excavation Efficiency\ {% endhint %} ## Abstract Lunar infrastructure construction involves leveling of the lunar surface and collecting lunar regolith as a building material. RASSOR 2.0 developed by NASA is one of the typical robotic vehicles as a lunar excavator. It features cylindrical rotating bucket drums for collecting regolith, positioning it as a pivotal tool for future lunar in-situ resource utilization and infrastructure development. However, the optimization of the bucket drum’s shape and its motion remain as open issue. Therefore, this study aims to find an optimal design of the bucket drum through numerical simulation using the discrete element method (DEM). We introduce five key design parameters of the bucket drum: two of them are related to the bucket shape (scoop throat length, scoop inlet number) and the rest of them are to motion (bucket vertical force, horizontal velocity, and angular velocity). These five parameters were examined in accordance with two performance indices: the sand fill ratio in the drum and the power consumption of the excavation. Solving the multi-objective problem of increasing the fill ratio and reducing power consumption, we found an optimal bucket drum shape and motion. Subsequently, a bucket drum reflecting the optimal shape was fabricated, and the optimal motion was tested. The test results qualitatively matched with the results derived from the DEM analysis. This outcome highlights the validity of the relationship between the design parameters and two performance indices. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4476 / Spectral Determination Of Soil Moisture Content Based On The Dry Colour Of The Soil ## Authors György Pillinger, Ahmed Elawad Eltayeb Ahmed, and Peter Kiss {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: spectroscopy; porosity; soil compaction; particle density; moisture content; spectral signature; sandy soil; soil color; reflectance; saturation\ {% endhint %} ## Abstract During our previous tests, we determined the change in colour due to moisture content in the case of sandy soil of three colours that can be easily distinguished with the naked eye. To characterize the colour, we used the average of the 600 and 700 nm range of the reflectance curve, because in this range the curves are more linear and the points are better separated, i.e. their resolution is better. Also, this wavelength range corresponds to yellow and red colours, which are better absorbed by water molecules, compared to the 400-600 nm range, which includes violet, blue, green and yellow colours. We found that the parameters characteristic of the colour of the examined sandy soils react more sensitively to the influence of soil moisture up to a moisture content of \~4-5%. The created function used the coordinates of this breaking point to determine the moisture content based on reflectance. In our current article, we continue the further processing of the measurement results, as well as carry out new measurements to clarify the functional relationships. We examine the effect of soil porosity and grain density on the reflectance value. This means that in the future, reflectance is given as a function of saturation. The results predict that reflectance is more highly correlated with saturation than with moisture content alone. Another goal is to determine the effect of the initial colour of the sandy soil on the moisture content. As a reference point, we use a characteristic of the reflectance curve for 0% moisture content. We are looking for an answer, how the water content of wet soil can be determined based on the data of dry soil and the reflectance of wet soil. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4715 / Uav-Based Three-Dimensional Rough Terrain Modelling ## Authors Herman Hamersma, Christian van Aswegen, Glenn Guthrie, and Schalk Els {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Terrain modelling; Road profiling; Photogrammetry; UAV surveying; Off-road mobility; Vehicle dynamics simulation\ {% endhint %} ## Abstract Accurate modelling of the interaction between a tyre and the terrain is crucial for successful vehicle dynamics simulation, particularly in challenging off-road conditions. This study introduces a novel approach for obtaining highly accurate three-dimensional terrain models for vehicle simulation. Utilizing an unmanned aerial vehicle (UAV) equipped with a high-resolution camera, we developed three-dimensional terrain models of an undulating test track with two approaches. To validate the accuracy, these models were compared with measurements obtained from a traditional mechanical road profilometer. The results demonstrate a strong correlation between the two measurement approaches. The primary advantages of the UAV method lie in its speed of data acquisition without compromising accuracy and that the measurements are immune to the terrain macro roughness. In contrast to the labour-intensive measurements required by a mechanical road profilometer and extensive subsequent post-processing, the UAV approach requires minimal time and effort. Additionally, since the UAV method is not coupled to the terrain roughness, it eliminates the integration drift associated with other ground-based approaches which are subjected to terrain excitation. This opens the door to the possibility of modelling very rough terrains and using these terrain models for vehicle dynamics simulations in extreme off-road environments. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4859 / Trafficability Conditions For Military Wheeled Trucks On Cultivated Fields ## Authors Kersti Vennik, Priit Põdersalu, Tamur Kusnets, and Tõnu Tõnutare {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Vehicle cone index; Military truck; Cultivated fields; Sandy loam soil; Silt loam soil\ {% endhint %} ## Abstract Military maneuvers performed with different types of vehicles often happen outside of the road network. Essentially, areas trafficked by tracked and wheeled machinery can be divided as arable land and natural areas, depending on the impact of human activity. The latter type typically includes natural grasslands, forest and swamp areas. From the perspective of soil strength, the main difference between these land types lies in the compaction state. Compared to natural grasslands, cultivated fields are in a precompacted state. The most well-known mobility performance parameter for military vehicles is the Vehicle Cone Index (VCI). In short, this entails the minimum soil strength required for a successful passage, whereas the soil’s shear strength is determined with a cone penetrometer. There are many reports and scientific papers describing trafficability experiments and validation of VCI as a Go/No-Go indicator for different soils and vehicles. However, the majority of the test results concern natural grassland areas while the applicability of the VCI calculation concept for agriculturally used areas is lacking. The aim of this study is to carry out trafficability tests with wheeled military trucks in order to validate VCI as a mobility performance parameter for cultivated fields. Moreover, changes in soil strength and moisture conditions were monitored for selected field parcels throughout the warmer half of the year. The 70 kN and 125 kN military trucks were used as test vehicles. The soils under observation included sandy loam and clay textures as well as highly organic soils. The paper provides an overview of the experiment’s results and a discussion about trafficability conditions on cultivated areas. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4927 / Tip Angle Dependence For Resistive Force Into Dry Granular Materials At Shallow Cone Penetration ## Authors Naoki Iikawa and Hiroaki Katsuragi {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Granular materials; Discrete Element Simulation; Stress analysis; Shallow penetration\ {% endhint %} ## Abstract In relation to the interaction of the earth's surface with machines and organisms and its engineering applications, there has been a recent increase in interest in the penetration resistive force into granular materials at shallow depths. Recent studies have proposed the model in which penetration resistive forces into dry granular materials have a coefficient dependent on the angle of repose and increase in proportion to the penetration volume. In these studies, the model has been validated for various geometries such as cylinders, cones and spheres. However, for cones, the model has only been validated under conditions of a tip angle close to the angle of repose. In this study, the effect of cone tip angle on penetration resistive force is investigated under several conditions with different angles of repose. This study carries out cone penetration simulations using the discrete element method. For the cone geometry, this study prepares five tip angles ranging from sharp to blunt. The results show that the penetration resistive force for cones with blunt tip angles is much higher than that computed by the model proposed in previous studies. To solve the discrepancy between the model and simulation results, this study modifies the penetration volume by assuming that the stagnant zone formed in front of the cone penetrating the granular material behaves as an effective cone. Thereby, the proposed model can calculate penetration resistive forces more accurately for cones with a wider range of tip angles than in the previous model. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 4966 / Real-Time Implementation Of Non-Linear Controllers And Predictors For Off-Road Vehicle Dynamics On Embedded Systems ## Authors Andries J. Peenze, A. Glenn Guthrie, and P. Schalk Els {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Off-road vehicle dynamics; Real-time control; Embedded control; Non-linear control\ {% endhint %} ## Abstract The vehicle dynamics of off-road vehicles tend to be non-linear concerning suspension dynamics, tyre-terrain interactions, and subsystem kinematics. These non-linearities limit the performance of control due to the need for linearization to enable real-time application. Implementing real-time non-linear controllers and prediction methods on embedded systems, such as the dSPACE MicroAutoBox 2 (MABX2), is challenging due it being computationally intensive. This challenge is particularly pronounced for controllers utilizing optimization schemes with non-linear solvers to solve optimal control problems. In this paper, we explore the possibility of embedding non-linear optimal controllers and predictors on a MABX2 for real-time applications. The implementation uses CasADi to formulate and code-generate the problems, and then executes this code using S-Functions in Simulink or off-loading the execution to a powerful external computer. We discuss the limitations and special considerations for these real-time implementations for off-road vehicle applications. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 5295 / Model-Based Online Optimal Control For Vehicles In Reduced Gravity. ## Authors Chaitanya Sonalkar, Adwait Verulkar, and Corina Sandu {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Off-road mobility; Vehicle dynamics; Extraterrestrial rovers; Optimal control; Terramechanics\ {% endhint %} ## Abstract There has been an interest in the exploration of planetary bodies for more than half a century. Scientific research has been focused on understanding the origins of life, potential for habitability in extraterrestrial environments, and discovery of rare minerals and energy sources. Extraterrestrial rovers have been used previously by space agencies for the exploration of Lunar and Martian surfaces. Reduced gravity on such surfaces influences the performance and mobility of extraterrestrial vehicles. Gravity can change how the soil behaves under the wheel as well as the traction force and sinkage developed by the wheel. The sinkage rate and depth of a wheel and motion resistance are also impacted by gravity. As the rovers are operated by interplanetary telemetry, autonomous real-time control is employed in these systems due to communication delays. Optimal online control with a high-fidelity terramechanics model may not be feasible and it necessitates the development of simplified models which consider the effect of reduced gravity on dynamics of a vehicle. The goal of this work is to study the effect of reduced gravity on Lunar terrain and its effect on vehicle performance of rovers through analytical modeling of tire-terrain interaction. We have developed an optimal control algorithms to improve vehicle stability and trajectory tracking performance in standard maneuvers. The simplified terrain models can also be extended for hardware-in-loop simulations. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 5334 / Enhanced Open-Loop Control Of Automatic Gear Shifting In Hydromechanical Cvt For Agricultural Tractors ## Authors Massimo Martelli, Pietro Marani, Silvia Gessi, and Damiano Chiarabelli {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Continuously Variable Transmission; Agricultural tractor; Power-shift; Lumped-parameter modeling\ {% endhint %} ## Abstract Continuously Variable Transmissions (CVTs) are typically implemented in agricultural tractors by means of a power-split configuration between the diesel engine and infinitely-variable hydrostatic unit (IVHU). The present work is based on an optimized output-coupled/compound architecture developed by the authors for a 200-kW reference tractor, originally equipped with a standard input-coupled CVT. A two-stage planetary gearset – serving as the power-split device – is complemented by a four-gear mechanical gearbox, to efficiently cover the full velocity range, up to 40 km/h, with power-shift capability, to supply an uninterrupted traction torque even during gear change. At any given constant engine speed and for each gear, an ideal reference condition is considered – in which the hydraulic units have ideal efficiencies – to analytically define a theoretical open-loop function, providing the requested IVHU transmission ratio as a function of vehicle velocity, and the theoretical shaft synchronization point, to shift to the previous/next gear. Real-world efficiencies affect the synchronization dynamics and, consequently, the traction force while shifting gears. An enhanced control has then been devised, keeping the simple open-loop foundation, with an additional smoothing contribution, triggered by the shaft speed feedback when speed matching is detected. The problem is studied via a lumped-parameter simulation model, focusing on the effect of the control on the longitudinal dynamics of the vehicle-wheel-terrain system. An exploratory investigation is carried out to tune the function, based on vehicle speed, drawbar pull and gear, for a smooth operation in a suitable range of operating conditions. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 5620 / Step-Climbing Motion Acquisition Of Tracked Robot With Flippers Without Using Environment Information By Reinforcement Learning ## Authors Ryosuke Eto, Hayatake Sato, and Junya Yamakawa {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: tracked robot; flipper; step-climbing; reinforcement learning\ {% endhint %} ## Abstract Tracked robots, which have flippers on the front, back, left, and right sides, are expected to be used for disaster investigation because of their high performance to overcome obstacles such as debris and bumps. However, it is difficult for the operator to control the robot because of its high degree of freedom. Therefore, the system that automatically controls the flippers and crawlers is required. In this study, we examined the acquired motion of a tracked robot with flippers to climb a step without using environment information by reinforcement learning. The learned motions are targeted to climb a step efficiently with a small amount of motion and to prevent the large impact when landing on a step. In order to reduce the amount of information required for the decision of the motion, only the information obtained from the internal sensors is used without the information of the surrounding environment. The agent Learned in a simulation environment using multi-body dynamics. First, the robot was trained to climb a step from the front, and the effectiveness of the acquired motion was confirmed from the results of a step climbing simulation and experiments using the trained agent. Then, the motion of the robot for climbing a step from an angle acquired by randomly changing the robot's initial orientation was clarified. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 5720 / Suppress Slip While Crossing Loose Slopes Using Reverse Rotation Behavior Of Rovers With Function Of Independent Contraction/Expansion Mechanism ## Authors Tsukasa Mochizuki, Daisuke Fujiwara, Kojiro Iizuka, Takaaki Sakata, and Tatsuhiko Suga {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Rover; Soft ground; Slip; Sideslip\ {% endhint %} ## Abstract In recent years, many organizations have developed lunar rovers for traveling over uneven terrain. Our research team has studied a rover using independently extending/retracting left and right wheelbases. In the case of four wheels, this method allows three wheels to remain stationary while moving. The independent extending/retracting locomotion of the wheel enables the traction to increase. This method provides a greater support force and improves the climbing performance on a loose slope. However, increased load on a sloped surface causes sideslipping, and the rover tilts its posture in downward. Our previous study confirmed that intentionally increased sinkage by the large wheel slip increased side forces from the soil. However, the lateral force is still insufficient and cause sideslipping on steep slopes. To increase the side force, this study focuses on the resistance between the wheel and the ground, along with the direction of wheel rotation. Specifically, we propose reverse rotation of the upper side wheel of the rover. This method increases dynamic sinkage by increased resistance from the soil during wheel driving. To confirm the effectiveness of method, this study conducts experiments that traversing loose slope with the rover. The results suggest that the proposed method greatly reduces sideslipping. In addition, the results indicated that the wheel sinkage increased. Therefore, the reverse rotation could increase the normal force of the wheels on the upper side. In summary, proposed method increased side forces and suppressed sideslipping. Hence, the reverse rotation prevents tilting the rover’s posture downward on the slope. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 6086 / Traveling Analysis Of Wheel For Lunar Exploration Rover Based On Extended Terramechanics Model: Examination Of Similarity Law Of Gravity ## Authors Mai Shimizu and Shingo Ozaki {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Terramechanics; Simulation; Ground deformation; Trafficability; Similarity law of gravity\ {% endhint %} ## Abstract The development and operation of exploration rovers is important for human lunar exploration, which is considered an international space exploration goal. However, the lunar surface is a completely different environment from that on the Earth because it is under 1/6G and is covered with regolith. Hence, it is difficult to evaluate rover’s traveling performance in advance. Under these circumstances, the extended terramechanics (xTerramechanics) model has been proposed that takes terrain surface deformation into account. In this study, systematic single-wheel traveling analyses assuming a lunar surface are performed based on the xTerramechanics model. First, the effect of soil parameters assuming Toyoura sand and regolith simulant (FJS-1) is examined. Then, the similarity law of gravity is examined by setting gravity levels as 1G and 1/6G under three different soil conditions (dense Toyoura sand, dense FJS-1, and loose FJS-1). Furthermore, an analysis is also conducted under the condition in which the wheel load is adjusted to the lunar surface (1/6M under 1G), and the significance of the simulated environment experiments on the Earth was discussed. As a result, it is revealed that the similarity law of gravity may be valid only when a cohesion of soil is negligible. In addition, it is shown that when conducting experiments on the Earth ground, it is important to consistent the sinkage and wheel contact area to the 1/6G condition than to consistent the wheel load to the 1/6G condition. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 6325 / Proposal Of A New Manual For Telescopic Penetrometer ## Authors Klara Cibulova and Martin Priesner {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: trafficablity; penetrometer; low endurable terrain; terrain mobility\ {% endhint %} ## Abstract Mobility is solved in almost all areas of our lives. The importance of transportation of people and material is increasing every day. Mobility has many subareas, but the authors of this article focus on the mobility of wheeled vehicles in the terrain. Off-road mobility is necessary not only in crisis situations such as road damage, floods, but also in everyday life in agriculture, forestry and it is an essential part of the military sphere as well. In order to avoid getting stuck, it is important to be able to evaluate whether the given route is trafficable or not. Penetrometers are used for such evaluation; they measure the resistance of penetration to the ground - the bearing capacity of the soil. In the Czech army, a telescopic penetrometer is used for this evaluation. Based on many years of field measurements, this instrument measures reliably but it has unreliable evaluation system. Therefore, the authors decided to propose a new evaluation manual. To develop it, a comparison of existing evaluation methods was made. Next, the authors analysed the parameters influencing trafficability of wheeled vehicles and decided which ones to include in the procedure. Based on their previous research, they also decided to include a new driver parameter. New forms and evaluation tables were created. The whole manual was verified by the field measurements. The contribution of the work is the creation of a reliable manual for the evaluation of the trafficability for wheeled vehicles by the telescopic penetrometer, which is already established in the Army of Czech Republic. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 6412 / Traversing Abilities Simulation Of A Biomimetic Robot On Granular Soil Terrain ## Authors Zhenwen Zhou, Xiang Lei, Dehai Guan, Yan Zhang, Gabriel Lodewijks, and Guangming Chen {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: biomimetic robot; dynamics; discrete element method; foot/soil interaction; co-simulation\ {% endhint %} ## Abstract Biomimetic robots that adopt structure properties of desert animals have shown improved traversing abilities on granular soils over wheeled vehicles. To conveniently assess traversing abilities of these biomimetic robots, simulations for predicting robot behaviors on soil terrains can be used. Nonetheless, available simulation methods have not yet capable of predicting interactions of between robot foot and soil subjected to arbitrary motions. This work develops EDEM-Recurdyn-Simulink co-simulation method to simulate robot behaviors when traversing granular soil terrain. Using soil simulation parameters determined by experiment tests with a type of Mars soil analog, the traversing behaviors for robot to move forward and turn are simulated. Meanwhile, dynamic forces of robot foots are numerically estimated. The simulated robot behaviors and dynamics are in agreement with experimental tests. Therefore, this paper introduces an effective simulation method to assess traversing abilities of biomimetic robots on granular soil terrains. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 6422 / Sinkage Study In Granular Material For Space Exploration Legged Robot Gripper ## Authors Arthur Candalot, James Hurrell, Malik-Manel Hashim, Brigid Hickey, Mickael Laine, and Kazuya Yoshida {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Pressure-sinkage; Toyoura sand; Lunar regolith; Soft gripper; MotionSolve EDEM; Legged robot; Space exploration\ {% endhint %} ## Abstract Wheeled rovers have been the primary choice for lunar exploration due to their speed and efficiency. However, deeper areas, such as lunar caves and craters, require the mobility of legged robots. To do so, appropriate end effectors must be designed to enable climbing and walking on the granular surface of the Moon. This paper investigates the behavior of an underactuated soft gripper on deformable granular material when a legged robot is walking in soft soil. A modular test bench and a simulation model were developed to observe the gripper sinkage behavior under load. The gripper uses tendon-driven fingers to match its target shape and grasp on the target surface using multiple micro-spines. The sinkage of the gripper in silica sand was measured by comparing the axial displacement of the gripper with the nominal load of the robot mass. Multiple experiments were performed to observe the sinkage of the gripper over a range of slope angles. A simulation model accounting for the degrees of compliance of the gripper fingers was created using Altair MotionSolve software and coupled to Altair EDEM to compute the gripper interaction with particles utilizing the discrete element method. After validation of the model, complementary simulations using Lunar gravity and a regolith particle model were performed. The results show that a satisfactory gripper model with accurate freedom of motion can be created in simulation using the Altair simulation packages and expected sinkage under load in a particle-filled environment can be estimated using this model. By computing the sinkage of the end effector of legged robots, the results can be directly integrated into the motion control algorithm and improve the accuracy of mobility in a granular material environment. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 6476 / Improved Trafficability Over Soft Soils Using Ground Matting ## Authors John Rushing, Brad Hansen, and Michael Parker {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Terrain surfacing; matting; site stability; mobility\ {% endhint %} ## Abstract Soft soils provide mobility challenges, even for vehicles designed with superior off-road capabilities. When numerous vehicles travel the same path, permanent deformation of the soil can result in rut depths that exceed vehicle ground clearance. These challenges can be overcome by modifying ground conditions to improve bearing capacity or spreading wheel loads over a greater area. Researchers at the U.S. Army Engineer Research and Development Center conducted field testing to quantify performance benefits from using a ground matting system comprised of connected fiberglass panels and designed to improve soft soil vehicle mobility. Soil conditions included soft sand, silt, and peat/sand mixtures with varying soil strength. Test vehicles included wheeled trucks with gross weights of approximately 14,000 lbs. per axle. Performance of the matting system was assessed by the number of allowable vehicle crossings with and without matting present. Results from testing showed that allowable number of vehicles could be increased by a factor of ten on the weakest soils. Data presented herein includes geotechnical site characterization, soil deformation as a function of traffic, and material characteristics for the fiberglass matting system. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 7322 / Lateral Tyre Characterization: Rolling Tyre Vs Static Tyre Testing ## Authors Carl Becker and Schalk Els {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Tyre characterization; tyre stiffness; field testing; laboratory testing; large tyres\ {% endhint %} ## Abstract Tyre models used in soft soil simulation analysis requires tyre parameters in the form of stiffness in multiple directions. These parameters are obtained from measurements on hard terrain as these parameters are a function of the tyre carcass construction. Vehicles used on soft terrain are also used on hard terrain. Many off-road vehicles used in construction, mining, agriculture and forestry use large tyres operating under heavy loads. Testing of large tyres is not a trivial or inexpensive exercise and outdoor testing has limitations on repeatability and load application. This is the case for testing on soft terrain/soil and hard terrain, thus it is preferred to conduct laboratory tests when characterizing tyres as higher loads can be applied and conditions can be controlled. This study investigates the lateral tyre characteristics measured during dynamic/rolling and static tyre tests. Tests are conducted on the actual concrete surface of interest, typically used in field tests with the use of a Dynamic Tyre Test Trailer. Static tests are conducted on the same tyre over representative surfaces in a laboratory with the use of the Static Tyre Test Rig. Multiple tyres are tested and measured tyre characteristics compared. The data can be used to parameterize tyre models of special, large off-road tyres. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 7453 / The Impact Of Changes In The River Regime On The Mobility Of Off-Road Vehicles ## Authors Marian Rybansky, Filip Dohnal, Martin Hubacek, Jaromir Capek, and Vladimir Kovarik {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: off-road vehicle; military vehicle; vehicle wading; water regime changes; hydrological transformation; river depth; flow velocity; river bed characteristics\ {% endhint %} ## Abstract The mobility of off-road vehicles, especially military vehicles, integrated rescue system vehicles and civilian vehicles in an open terrain where it is necessary to cross rivers, is dependent on the current hydrological conditions and technical parameters of the vehicles. In addition, we can also calculate the ability of drivers to maneuver the vehicle while crossing water courses. The article describes the methodology for determining the parameters of changes in the depth and speed of the water flow and also includes the results of testing the ability to wade through water bodies or overcome them by swimming amphibious vehicles. The mentioned classification of changes in the characteristics of water courses is important for a better understanding of the influence of watercourses on the mobility of vehicles in open terrain outside the road network. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 7603 / Evaluation Of Off-Road Uninhabited Ground Vehicle Mobility Using Discrete Element Method And Scalability Investigation ## Authors Dr. Ayush Nuwal, Ajay Kumar, and Professor John Economou {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Scalability; Tyre soil interaction; Discrete element method; Uninhabited Ground Vehicle\ {% endhint %} ## Abstract Modern militaries are exploring the teaming of military vehicles with smaller uninhabited ground vehicles (UGVs), to improve the success of operations in the off-road terrains. The UGVs can be used to perform initial mobility testing on soft soils, to predict the go/no-go performance of vehicles. Because of the variation in the sizes of the UGV and military vehicle, it is imperative whether the scalability of tyre-soil interaction exists or not. The scalability assumes that similar systems behave in a similar manner at different dimensional scales. Dimensional analysis is carried out to determine similarity between the systems and identify design parameters affecting scalability. In this study, the lightweight vehicles (FED Alpha) are considered as the full-scale systems (as upper boundary) and UGVs (Husky or Warthog) as scaled system. The 335/65R22.5 tyre with operational range of loading for full scale vehicle is considered. The smaller UGV tyres (0.7, 0.5 and 0.25 scale) represent scaled system. The 2NS and fine-grain sands were modelled using the DEM (EpAM contact model). The direct shear and pressure-sinkage tests were simulated to calibrate the soil model (cone index from 14.79-149 kPa). Validated simulations of tyre-soil interaction, show that 'drawbar-pull vs slip' and 'tractive-efficiency vs slip' are scalable, within given size and loading conditions. However, the prediction is dependent on soil parameters and size of the scaled systems (0.7 and 0.5 scale demonstrated the scalability clearly). The prediction was better in 2NS sand due to higher cone index. Up to 0.5 scale-system can predict the full- scale system’s mobility performance on sandy soils. This finding can be used to develop lighter UGVs to support full-scale vehicles in the off-road terrains. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 7829 / Development Of Foot In Balloon Biped Robot Using Buoyancy Force For Traveling Soft Ground ## Authors Noriaki Mizukami, Masanori Aragane, and Mami Nishida {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Soft biped walking robot; Planetary surface exploration; Soft robotics\ {% endhint %} ## Abstract In planetary exploration mission, an exploration robot has to travel on unknown and uneven, soft ground. Thus, a locomotion mechanism is an important, and the locomotion systems are discussed three types such as wheel, crawler and legs. The leg type has advantages of adaptability and an effective locomotion for terrains. Because a walking robot is able to avoid rocks and depressed areas. However, the biped robot is structurally complex and fall down easily. In this research, we developed the biped robot that is made of a soft balloon body fulfilled by helium. Since the body of the robot is always floating by helium balloon, the robot cannot fall down while walking. The leg structure for walking is made of an artificial muscle actuator. When the control command applies to the actuators, the legs swing up lightly. When the control command stops applying, the legs swing down slowly. The robot is able to move forward when the legs swing up and down repeat alternately. We have achieved the walking movement by a manual ON-OFF control of actuators on firm grounds. The purpose of this research is to clarify the interaction between the leg mechanism and soft soil. In this paper, we performed walking experiments on soft soil to estimate states of walking movements on flat soft soil using original flat shape of foots. It was confirmed that the foots did not sink and slip and the robot moved forward. Furthermore, we propose a new type of foot parts that is able to travel on uneven, soft or slope grounds, and perform experiments for verifying effectiveness. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 8084 / Log Detection For Autonomous Forwarding Using Auto-Annotated Data From A Real-Time Virtual Environment ## Authors Mattias Lehto, Håkan Lideskog, and Magnus Karlberg {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Transfer learning; Domain generalization; Virtual training; Auto-annotation; Real-time; Co-simulation; Logging; Tree harvesting; Forwarder; Cut-to-length; CTL\ {% endhint %} ## Abstract An integral part of autonomous forestry is the ability of the vehicles, e.g., forwarders and harvesters, to perceive their environment. At Luleå University of Technology, object detectors have previously been developed, allowing forestry vehicles to detect and position important objects in forestry, such as tree stumps, stones, and logs. These detectors have been developed by training on physical manually annotated data, which is both time-consuming and costly. Training on virtual data allows for significant time- and cost reductions. Since the ground truth in the virtual model is known, the training data can be auto-annotated, allowing for the creation of larger training datasets, at a lower cost. In this work, a virtual environment in Unity is used in co-simulation with a real-time digital twin of a physical forestry vehicle, to generate auto-annotated training data, as captured by an onboard stereo camera. A detailed emulation of the stereo camera is used to achieve realistic results. First, a log detector trained on physical manually annotated data, is evaluated on virtually created data. It is shown that the log detector trained on physical data can detect logs in the virtual environment. Second, new detectors are trained, using different shares of physical and virtual data. It is shown that a detector trained using only virtual data, can learn to detect logs in the physical world. Moreover, virtual pre-training is shown to improve the performance of physically trained and tested detectors, both at low availability of physical training data, and in terms of domain generalization. Furthermore, the real-time capable virtual models also enable future machine learning tasks utilizing different levels of Hardware-in-the-Loop. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 8590 / Modeling Of Terrain Deformation By A Grouser Wheel For Lunar Rover Simulator ## Authors Junnosuke Kamohara, Vinicius Ares, James Hurrell, Keisuke Takehana, Antoine Richard, Shreya Santra, Kentaro Uno, Eric Rohmer, and Kazuya Yoshida {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Robotics; Lunar Simulator; Wheel trace\ {% endhint %} ## Abstract Simulation of vehicle motion in planetary environments is challenging. This is due to the modeling of complex terrain, optical conditions, and terrain-aware vehicle dynamics. One of the critical issues of typical simulators is that they assume terrain is a rigid body, which limits their ability to render wheel traces and compute the wheel-terrain interactions. This prevents, for example, the use of wheel traces as landmarks for localization, as well as the accurate simulation of motion. In the context of lunar regolith, the surface is not rigid but granular. As such, there are differences in the rover's motion, such as sinkage and slippage, and a clear wheel trace left behind the rover, compared to that on a rigid terrain. This study presents a novel approach to integrating a terramechanics-aware terrain deformation engine to simulate a realistic wheel trace in a digital lunar environment. By leveraging Discrete Element Method simulation results alongside experimental single-wheel test data, we construct a regression model to derive deformation height as a function of contact normal force. The region of interest in a height map is retrieved from the wheel poses. The elevation values of corresponding pixels are subsequently modified using contact normal forces and the regression model. Finally, we apply the determined elevation change to each mesh vertex to render wheel traces during runtime. The deformation engine is integrated into our ongoing development of a lunar simulator based on NVIDIA's Omniverse IsaacSim. We hypothesize that our work will be crucial to testing perception and downstream navigation systems under conditions similar to outdoor or terrestrial fields. A demonstration video is available here: *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 8774 / Proposal Of Hybrid Locomotion Lunar Rover With Crawling Mechanism ## Authors Paweł Tomiło {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Crawling mechanism; Lunar Rover; Hybrid locomotion\ {% endhint %} ## Abstract The Moon's surface is covered with a layer of loose, weathered rock (fine regolith) several meters thick. This type of surface can create problems for the movement of small lunar rovers, especially in sloping areas. Legged robots are able to perform complex operations, but their design requires appropriate sensors to maintain balance, on the other hand, in the case of wheeled robots there is a risk of slipping. In order to combine the advantages of both, it was decided to create a hybrid robot. The main purpose of the article is to present the design and testing of a prototype lunar rover. The design of a hybrid robot, which combines the characteristics of wheeled and legged robots, is shown in the article. The center of gravity may be dynamically adjusted thanks to the use of two robot arms with wheels attached. Furthermore, the robot can "crawl" on sloping areas where a wheeled vehicle could slip owing to loose ground. Crawling is possible through the use of a mechanism for swinging the blades, which are mounted on the arms. The article describes the design of the rover, describes the results of research regarding the performance of crawling mechanism, and presents the limitations of the current design of the rover and presents possible improvements and further development work. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 8812 / Energy Method To Compare Performance Of New Types Of Sugar Cane Transport Equipment ## Authors Jorge Lopera, Fernando Casanova, Adolfo Leon Gomez Perlaza, and Carlos Daniel Muñoz Delgado {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Sugar cane transport; Agricultural Equipment; Tracked Vehicles; Mobility Index\ {% endhint %} ## Abstract Mobility indexes (MI) have been used to understand and compare the performance for ground vehicles, which must complete tasks or follows paths for several types of environments. The MI research has been studied by several authors (Wong 2008, Larin 2007, Chudakov, Vantsevich 2022). There are multiple methods that supports the evaluation of mobility, from experimental, numerical, and simulated (VCI, MMP, NTVPM). To estimate the MI is a key feature in an initial stage of concept and design of new types of ground vehicles. At the agriculture industry, the challenges for a MI estimation could be like the ones at military industry, but with different points of interest (soil conservation, reduce load transfer to soil, crop protection). For the sugar cane industry at the Valle del Cauca region (Colombia-South America), these considerations have become important since the sugar cane in that region, is a whole year crop growing, that means harvesting activities are developed no matter if there is dry or wet season. The conservation concerns for the industry at wet seasons appears, because the sugar cane supply equipment (harvester, cranes, trailers) with wheels and even with tracks, reduce the reliability, with the sinkage and compaction phenomena with heavy vehicles. This work proposes the application of mobility index concept for a new type of vehicle to transport the sugar cane on the field. For the sugar cane sector, the adoption for these methodologies would help reducing the risk to deploy unreliable technologies and to compare design alternatives at conceptual phases *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 9028 / Uncertainty Quantification For Wheeled Locomotion Machine Learning Predictions On Soft Soil ## Authors Vladyslav Fediukov, Felix Dietrich, Fabian Buse, and Jana Huhne {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Terramechanics; Rover Locomotion; Uncertainty Quantification; Multi-Fidelity; Machine Learning\ {% endhint %} ## Abstract In predicting locomotion on soft-soil, we have to deal with a consistent uncertainty surrounding this process, from the input noise to the uncertainties produced by an approximation. Available data comprises limited sets of experimental data and various numerical approximations. Machine learning models, gaining recognition in the terramechanics community, need to work with these limited data set. By deploying probabilistic frameworks, like Gaussian processes, for our tasks, we can implicitly work with the resulting uncertainties. Accurate uncertainty quantification and further analysis can provide more robustness and understanding of terramechanical machine learning models. In our work, we concentrate on the uncertainty's propagation, uncertainty calibration, and uncertainty decoupling for a wheel locomotion prediction. Our machine learning models work in a multi-fidelity framework using experimental data from the DLR’s TROLL testbed and numerical simulations using TerRA and SCM, approximating the high-fidelity target function in the training process. The experimental setup involves runs with various velocities and movement scenarios, including tilting, steering, for- and backward, as well as up- and downhill movements. Complete analysis of uncertainties will give engineers and operators a more in-depth understanding of the reliability of ongoing simulations and predictions. Moreover, uncertainties quantification can help us improve our data generation and modeling process, allowing us to make a self-improving model. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 9295 / Granular Scaling Laws For Accurate Prediction Of Wheel Mobility On Slopes In Low-Gravity Environments ## Authors Takuya Omura and Genya Ishigami {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Granular scaling laws; Wheel mobility prediction; Low gravity; Lunar regolith simulant\ {% endhint %} ## Abstract Analyzing the mobility of wheeled rovers on loose sand in low-gravity environments remains a significant challenge. Among several experimental techniques, such as parabolic flight and reduced-weight tests, granular scaling laws (GSL) have recently been proposed to predict wheel mobility under low-gravity conditions via earth-gravity tests. Although the GSL accurately predicts the wheel mobility on flat terrain in low-gravity environments, its capability to predict the wheel mobility on slopes in such environments still needs to be verified. In this study, we developed a GSL and investigated its accuracy for predicting wheel mobility on slopes in low-gravity environments. The discrete element method (DEM) was utilized to test wheel mobility at various slope angles under Earth’s gravity. Subsequently, by applying a multiple scaling function, the GSL converted the results from the Earth-gravity tests to predict the wheel mobility under lunar gravity. The GSL-based predictions were compared with DEM simulations conducted under lunar gravity conditions. The results indicated that the wheel mobility under lunar gravity predicted by the GSL closely corresponded to that calculated via the DEM. These findings indicate that the GSL can accurately predict wheeled-rover mobility on slopes in low-gravity environments. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 9663 / Year-Round Measurements Of The Soil Cone Index On Grass Airfields For Ground Performance Of Airplane ## Authors Jarosław Pytka, Anna Zalewska Tytłak, Paweł Tomiło, Michal Kuszneruk, and Dawid Tatarynow {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Cone Index; Grass airfield; Airplane performance; Weather impact\ {% endhint %} ## Abstract The paper concerns the performance of ground-based aircraft operating from grass airports, in particular the take-off and landing distances. These performances are strictly dependent on the conditions on the runway, and in the case of a grass runway, they depend on the influence of weather factors. Year-long measurements of the soil cone index were carried out on the runways of 5 grass airports, which are characterized by different ground soils. The measurements were carried out in the period from July 2019 to June 2020. The paper presents a statistical analysis of the measurement results. Generally, it was found that weather factors have a significant impact on the values of the cone index and changes in the CI value reach up to 400% (the highest relative to the lowest). Moreover, it was observed that the type of soil underlying the grass on the runway had a significant impact on the CI index values. The most sensitive ground was marl, with a high chalk content, which constitutes the foundation of one of the tested grass airfields. The results will be used to parameterize and verify the model describing the road wheel and ground performance of the aircraft. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # 9747 / Application Of A Rockie Bogie Suspension For A New Type Of Sugar Cane Transport System ## Authors Jorge Lopera {% hint style="info" %} Paper presented at ISTVS 2024 | 21st International and 12th Asia-Pacific Regional Conference of the ISTVS\ Keywords: Agricultural Equipment; Sugar cane transport; Rockie bogie suspension\ {% endhint %} ## Abstract The rockie-bogie suspension arm is a topic fully studied for experimental rovers (Nildeep Patel, 2010), (Weihua Li, 2013). These types of suspensions allow vehicles to increase the stability and move across with multiple obstacles on the ground. It has been tested this suspension system for some academic studies for the agricultural research topics, but it doesn’t have yet an industrial deployed application for agriculture sector. The agricultural sector is looking for solutions to increase the productivity without harming the environment and improve the health of soils. This global challenge must be faced with improved technological developments. For instance, the sugar cane industry at Colombia, South America has challenges to adopt new technological system to complain about. At the Cauca River Valley (24MTon/year sugar cane production), 75% of the fields to harvester and transport the sugar cane stalks is used with commercial harvesters and a system of trailers to move the sugar cane from the field to the mill factories. The main surface it has low slopes, otherwise. for the remain 25%, the industry faces with high slopes terrains, additionally with the lower capacity of the soil at the rainy and wet seasons. This condition increases the risk with commercial agricultural machinery (harvester, trailers and tractors). This work is inspired with the rockie-arm suspension, to propose a concept to transport sugar cane from the fields. A CAD Model has been developed to understand the kinematical and kinetics for the suspension and compared with other types of suspensions considered for this industry. This work aims to explore new possibilities to adopt technologies developed from other industries to solve the agriculture challenges. *** Full paper purchase: \ ISTVS members receive three complimentary papers per year: # Abstract-only ## 0178 / Model To Estimate The Force Exerted On The Sphere Rolling On The Sandy Road Takeshi Fukumoto, Ken Yamamoto, Makoto Katsura, and Hiroaki Katsuragi\ Keywords: getting stuck; terramechanics model; fundamental research\ Abstract: The importance of the rover for exploring the planetary surface is recently increasing. It is important to move off-road (e.g. regolith) ground safely without getting stuck. To do that, it is necessary to predict the force exerted on the tire while moving on an off-road environment. The traditional terramechanics model has been widely used to predict the force since a half-century ago by many researchers. However, there are some drawbacks to that model. There are many parameters (\~10) to predict the force and it takes a lot of time and effort to determine the reasonable parameter values. We would like to establish a way of predicting the force easily. This research aims to develop a semi-empirical model to predict the force with few parameters based on the traditional terramachanics model. In this work, we carried out a simplified experiment to obtain the relation between soil and tire. Here, we experimentally investigated the dynamics of the spheres (without driving force and their radius is 6.4 mm) rolling up a sandy slope (consisting of 0.8 mm glass beads). We systematically varied the density of the sphere (0.93, 1.4, 2.6, 3.9, and 7.8 g/cm3), the slope angle (from 0 to 20 deg), and the initial velocity (0.2-0.7 m/s). As a result, the dynamics of the sphere show a constant deceleration in both translational and rolling motions. We assume there are 2 forces (normal force and tangential force) exerted on the sphere at one point with these constant acceleration. The ratio between normal force and tangential force is constant, and the point angle is about 0.4 times the angle of the sinking depth. This relationship suggests that we can compute the forces exerted on the object (sphere, tire) with the relations we obtain from this research. ## 0376 / Improvement Of Formulations Of Clegg Impact Hammer And Rammsonde Penetrometer For Use In Compacted Snow Mohit Shenvi, Corina Sandu, and Costin Untaroiu\ Keywords: compacted snow; Clegg Impact Hammer; Cone penetrometer; penetration resistance; sinkage\ Abstract: From the terramechanics viewpoint, assessing sinkage and penetration resistance in a deformable terrain is crucial for on-site terrain characterization. Existing devices often encounter limitations when characterizing compacted snow, as documented in the literature. The Clegg impact hammer and the Russian snow penetrometer (utilizing the Rammsonde principle) are extensively employed tools for gauging the penetration resistance of compacted snow. Despite the widespread use of the Clegg impact hammer, there are relatively few studies, primarily conducted by CRREL, focusing on its application in snowy conditions. This study aims to propose enhancements to classical literature formulations of two devices that have been used in compacted snow conditions to evaluate snow characteristics. One such device viz. the Clegg impact hammer has outputs correlated to the evaluation of sinkage and Young’s modulus. Modifications to the classical methodologies have been proposed in this work. The in-house device yielded consistent measurements even when the CTI gauge exhibited variations on a commercial test track used for winter tire evaluations. In this case, formulations have been developed that contribute to a more analytical assessment of the resistance pressure. Additionally, these formulations may aid in evaluating the compacted zone forming in front of the cone as it penetrates deeper into the terrain. The comparison results offer insights into the potential variation in calculating these parameters, with a subsequent discussion of the findings from a physics-based perspective. Future work in this field could entail evaluating the resistance pressure across various terrain types to validate the proposed hypotheses or offer correction factors based on field testing results. ## 0677 / Adaptive Particle Refinement In Terramechanical Dem Simulation Markus Pogulis and Martin Servin\ Keywords: Discrete Element Method; Particle Scaling; Adaptive particle refinement; Computational efficiency; Granular Material\ Abstract: DEM is computationally intensive for granular dynamics simulation, leading to a need for efficient strategies. This study explores using local particle refinement, scaling particle size based on expected spatial resolution needs, inspired by adaptive mesh refinement in FEM. Finer particles are used where intense interaction occurs, and coarser particles further away. We hypothesize this method can maintain good accuracy while reducing particle count and computational effort. Fine particles are used on the soil bed's top, with coarser particles at greater depth, creating a particle size gradient. By adjusting the gradient we introduce a “scaling aggressiveness”, allowing control over the trade-off between efficiency and accuracy. We use triaxial tests to verify that the method is scale invariant. Pressure-sinkage and shear-displacement tests are then used to evaluate the method's effectiveness and accuracy in terramechanics applications. All beds were compared to a reference bed with homogenous particle size, where the mean static sinkage was 1.25 mm for a 50 kPa load. The dynamic sinkage was 73 mm for the full simulation time. For quasi-2d simulations, mild scaling aggressiveness reduced the particle count by 2-4 times with relative error up to 4% for dynamic sinkage (11% for static sinkage). For medium aggressiveness, 4-6 times reduction with relative error of 4% (19% static). For highest aggressiveness, 6-8 times reduction with relative error of 7% (29% static). The internal friction proved to be very resistant to gradient changes, with errors within 1%. When extending the model to full 3D, we estimate up to a reduction in particle count of up to a factor 25. ## 0815 / Using Simulation To Characterize Rassor Excavation In Lunar Environments Luning Bakke, Zhenhao Zhou, Alexandra Kissel, Ruochun Zhang, and Dan Negrut\ Keywords: Off-road mobility modeling; Robotic system; Excavation; Discrete Element Method (DEM); Terramechanics\ Abstract: We describe modeling and simulation approaches used to investigate the operation of NASA’s Regolith Advanced Surface Systems Operations Robot (RASSOR) excavator while operating in lunar gravitational environments. With a total mass of 66 kg, RASSOR is equipped with four wheels and two arms, each of the latter connected with a rotating bucket drum for soil excavation. The design compensates for the low mass and low gravitational pull by digging using two counter-rotating bucket drums. The rover can raise its drums when transporting the soil, and it unloads the material by reversing the drum's rotation at destination. We simulate digging operations at two levels of fidelity using Project Chrono, an open-source multi-physics simulation platform that provides terramechanics modeling, robot modeling, sensor models, and a ROS2 autonomy stack for synthesizing RASSOR’s autonomy in simulation. We discuss two terrain modeling techniques – the Continuum Representation Method (CRM) and the Discrete Element Method (DEM). CRM employs the μ(I)-rheology model for describing the elasto-plastic behavior of the granular material, with the partial differential equations for the mass, momentum, and Cauchy rate of change spatially-discretized via the Smoothed Particle Hydrodynamics (SPH) method. The interaction between the implement and terrain is captured using Boundary Conditions Enforcement (BCE) markers. Unlike CRM, DEM represents the terrain discretely, by describing frictional contact forces at particle level. In this study, we compare the CRM and DEM results in terms of accuracy and time to solution. ## 1169 / (Cancelled) Cold-Weather Performance Analysis On The Us Army’S Polaris Alpha Side-By-Side Clifford Witte and Michael Parker\ Keywords: Lightweight Tactical All Terrain Vehicle; LTATV; Cold Regions; Arctic Mobility; Snow Mobility; Off-road mobility\ Abstract: The US Army recently updated its fleet of light tactical vehicles with an upgraded version of the Polaris MRZR, named the MRZR Alpha. The Polaris MRZR Alpha has substantially different characteristics in overall dimensions, drivetrain, suspension, electronics, and so on over the older model. Therefore, the Polaris Alpha has significantly different driving dynamics from the older model. The Army Corps of Engineers Cold Regions Research & Engineering Lab (USACE-CRREL) has previously identified and tested this new vehicle for its potential mobility in artic conditions. For artic conditions, the vehicle can be equipped with tracks and an artic cab enclosure kit. CRREL owns two older MRZR D4 and two newer MRZR Alphas and has substantial test data for both vehicles. This research includes field test data from USACE CRREL engineers on various types of snow surfaces and transition season soils and provides engineering feedback on the positives and negatives of the changed systems, and qualitative feedback from US Soldiers. The goal of this project is to characterize the vehicle on wheels and tracks on cold weather surfaces, as well as provide early insight into systems on the vehicle requiring improvement, as well as illuminate key successes and failures in comparison to the older MRZR D4. ## 1499 / Development Of Evaluation Technology For Tire Traveling Performance On Soft Soil Of Lunar Surface Kei Tsuchiya, Kon Seiji, Masahiro Katayama, Tomoya Arai, and Shingo Ozaki\ Keywords: Wheel Test Bed; Terra mechanics; Lunar Vehicles; Mobility\ Abstract: Bridgestone Corporation is taking on the challenge of developing tires for lunar vehicles. In this development, evaluating the tire traveling performance on the soft soil of the lunar surface is important because it is nearly impossible to conduct pre-testing using actual tires under actual conditions. Therefore, we are developing both experimental and simulation technologies for performance evaluation. In this presentation, we will explain two testing devices developed by Bridgestone Corporation for evaluating the performance, including examples of measurement results. The first device is an indoor installation type that uses scaled-down model tires. The device incorporates special features to simulate various traveling conditions such as constant slip ration mode, cornering, and climbing. The second device is an outdoor testing type that allows for testing with tires equivalent in size to those used on lunar vehicles. This device is portable and can be taken to various testing sites. Additionally, while conducting outdoor tests, it can reproduce steady-state traveling conditions which are important for accurate evaluations of tire traveling performance. Furthermore, in this presentation, we will briefly introduce the evaluation technology that combines experiments and simulation using the extended terramechanics model proposed by the Ozaki Laboratory at Division of System Research, Faculty of Engineering, Yokohama National University, with whom we are conducting joint research. ## 2520 / Efficient Tire-Terrain Interaction Modelling: Effect Of Flexibility On Traction Mahdi Maleki and Jozsef Kovecses\ Keywords: Tire Dynamics; Flexible Tires; Tire-Terrain Interaction\ Abstract: The analysis of tire dynamics is essential in the simulation of vehicle behaviours. The forces exerted on a tire depend on the tire and terrain interaction, and the tire structure directly influences this interaction. Complex models with a high number of degrees of freedom, such as lumped parameter models or finite element models, are typically required to represent tire flexibility appropriately. These models, however, can lead to high computational costs that can be a significant challenge for real-time simulation. In this work, we developed a reduced model for the flexible tire that can represent the effects of tire flexibility with low computational costs in the simulation. By calculating the effective stiffness of a flexible tire model (base model) and augmenting it with a model representing the rigid body motion of the wheel, we could represent the flexibility of the tire more efficiently. The tire deformation affects the tire contact patch size, influencing the traction forces acting on the tire. By having the effective stiffness at hand, we are able to calculate the contact patch size at each instant of time. The traction forces acting on the wheel depend on the size of the contact patch since a larger contact patch would be capable of carrying more tangential load. In order to observe the effect of the contact patch size on the traction forces, we scaled the friction coefficient based on the size of the contact patch. This way, we could take the effect of tire deformation on traction forces into account. Our simulations show efficient real-time performance while maintaining accuracy. By integrating effective stiffness and adjusting friction, we effectively capture tire dynamics, making them a practical solution for diverse vehicle simulation applications. ## 2800 / Granular Flow In Reduced Gravity: Analysis And Insights From Centrifuge Experiments At The International Space Station Genya Ishigami, Shingo Ozaki, Masatsugu Otsuki, Hideaki Miyamoto, Koji Wada, Masataku Sutoh, Takao Maeda, and Taizo Kobayashi\ Keywords: Granular media; Low gravity experiments; Discrete element method\ Abstract: Gravity-dependent characteristics of regolith, fine-grained granular media covering extraterrestrial surfaces, are essential for reliable design and feasible operation of space probes. Parabolic flight or drop tower facilities for simulating reduced gravity experiments on Earth can only perform short test durations and a limited number of tests with less quality artificial gravity. A numerical simulation requires an accurate interaction model of space probe and regolith. Further, the model parameters must be carefully identified for verification and validation. Therefore, the experimental dataset of granular media under stable reduced gravity is essential for solving the abovementioned issues. We performed a granular flow experiment under varied artificial gravity generated by a centrifuge on the International Space Station. An hourglass-shaped apparatus containing granular media was used to observe the granular flow in high-quality, long-term, and stable gravity conditions. We also performed a numerical simulation that calculates the granular flow in both artificial and natural gravity environments. The simulation verifies that the granular flow at the hourglass’s orifice in artificial gravity is equivalent to natural gravity. The mass flow rate of the granular media measured from the experiment follows a well-known physics-based law, while some deviations are found in low- and micro-gravity conditions. The deviation implies that the bulk density of the granular media decreases as the gravity decreases. This finding provides a useful insight that improved simulation of space probes in reduced gravity can be realized by reducing the bulk density of the granular media, resulting in reliable design and analysis of the space probes. ## 3071 / Study On Applicability Of Extended Terramechanics Model To Various Traveling Modes Of Wheels Tomoya Arai, Kei Tsuchiya, Seiji Kon, Masahiro Katayama, and Shingo Ozaki\ Keywords: Simulation; terramechanics model; ground deformation; wheel-soil interaction; braking\ Abstract: To promote lunar and planetary exploration missions, the development and operation of exploration rovers is essential. However, it is difficult to evaluate prototypes of wheels and vehicles under environments corresponding to extraterrestrial gravity and atmosphere conditions. Therefore, systematic evaluation of vehicle traveling characteristics using a numerical simulation is required. Under these circumstances, an extended terramechanics model based on cellular automaton that considers terrain surface deformation was proposed by Yokohama National University group, and its validity was confirmed through comparison with the results of traveling experiments using a rigid wheel. In this study, we propose a model that can handle various traveling modes to improve the versatility of numerical analysis simulations that implement extended terramechanics theory. First, we conduct single-wheel experiments using a rigid wheels and obtain data for model verification of both straight traveling and braking. Then, we extend the extended terramechanics model by implementing braking logic, etc., and establish a simulation model for a single rigid wheel using the commercial software package Simscape. In addition, systematic simulations are performed under forced-slip condition in which the angular velocity is fixed, while the translational velocity is varied. Here, the wheel specification and traveling conditions are the same as those of the experiment equipment. Finally, we demonstrate the effectiveness of the proposed model by comparing it with the results of experiment under various conditions. ## 3304 / Development Of An Unmanned Exploration Robot For Lunar Surface Geotechnical Investigation Taizo Kobayashi, Atsushi Kakogawa, Shinichi Ito, Masafumi Nakagawa, Takeshi Tsuji, Shingo Ozaki, Satoshi Matsumura, Akihiko Kondo, Masanori Takigawa, Keitaro Kitamura, Takahito Hiramatsu, Hisatoshi Sano, Takeshi Yoneoka, Junichiro Odaka, Kenji Hosobori, Taichi Ikenaga, and Ryu Taniguchi\ Keywords: Lunar regolith; Geotechnical investigation; Three-dimensional surveying; Active seismic exploration; Radioisotope density gage; Bevameter\ Abstract: The lunar surface is covered by a thick layer of soil known as regolith, which remains largely unexplored from a soil mechanics perspective. Additionally, significant uncertainties exist in geology and topography, posing risks to the safety and efficiency of lunar surface operations. Effective geotechnical risk assessment and management are essential for the safe planning and execution of lunar activities. To address these challenges, we are developing an unmanned exploration robot, named the Robotic Geotechnical Investigation System (RGIS), aimed at gathering critical data on the lunar surface. The RGIS is equipped with four key components: (1) a positioning and surveying system for detailed micro-topography measurements, (2) an active seismic survey system to investigate subsurface stratigraphy and bulk density distribution, (3) a radio isotope density meter for precise soil density measurement, and (4) a plate loading and shear testing system to evaluate the deformation and strength characteristics of lunar regolith. Data collected by the RGIS will enable the construction of a three-dimensional geological and geotechnical map of the lunar surface. This map will aid in predicting the behavior of exploration vehicles, construction robots, and designing earthworks such as excavation, filling, leveling, and module/structure installation. This presentation offers a comprehensive overview and outlines the current development status of RGIS. ## 3352 / Sph Modelling To Understand Wheel Locomotion In Uneven Terrain Z Lei\ Keywords: SPH; Wheel-soil interaction; Robot locomotion\ Abstract: We use Smooth Particle Hydrodynamics to model the interaction of small wheel robots with uneven, soft, terrain. The SPH modelling approach is validated against experimental results before we test numerically the interaction of wheel passes on terrain of various inclinations, from flat to steep angles of up to 35 degrees. We show the dependency of sinkage, translational velocity, and wheel size for different input wheel torques (angular velocities). The mapped parameters allow the creation of non-dimensional groups that can be applied to other situations not included in the original modelling. An independent verification of these proposed similarity laws are checked against SPH results. ## 3456 / Tire-Soil Interactions For Large Deformation Problems Diana Jimenez, Siamak Arbatani, Jozsef Kövecses, and Marek Teichman\ Keywords: RANCF; tire-terrain interaction; tire modeling; soil modeling\ Abstract: This work explores the simulation of tire-soil interactions in the multi-body system framework by using the rational absolute nodal coordinate formulation (RANCF). This method accurately represents large deformations and rotations while representing rigid body motion exactly. This approach is suitable for potential real-time simulations of off-road vehicle dynamics. More specifically, RANCF elements make it possible to model initially deformed geometries with relatively few degrees of freedom and higher fidelity than their ANCF counterparts. This study employs a first-order time-stepping integration scheme that treats the internal elastic forces of the RANCF elements as relaxed quadratic constraints approximated by Gaussian quadrature points along the elements. The quadrature approximation leads to a set of stabilizing implicit damping forces that are incorporated into a stabilized semi-implicit Euler integration scheme. This method exhibits excellent stability even for large timesteps, allows for stiff elastic forces, and does not artificially dampen rigid body modes. A penalty-based approach using signed distance fields handles collisions or contacts between the tire and terrain elements. The signed distance field efficiently represents the element's deformed surface geometry for collision detection. Normal and tangential contact forces can then be distributed over the collided surface regions to resolve penetrations and sliding constraints. An iterative process resolves only the penetrations requiring positive contact forces, avoiding artificial deformations from correlated grid points. The results of this work showcase the potential of the proposed RANCF modeling method for computationally efficient simulations of tire-terrain interactions. ## 4021 / Ecological Performance In The Wltc Test Of A Diesel-Hydrogen Dual-Fuel Ci Engine Dawid Tatarynow, Rafał Longwic, Jarosław Pytka, Michał Kuszneruk, and Przemysław Sander\ Keywords: Hydrogen; compression-ignition engine; dual fuel injection; WLTC; alternative fuel\ Abstract: Even though regulations in the European Union talk about banning the registration of combustion cars after 2035, yet no such regulations have been introduced in other parts of the globe. The rapidly changing economic and political situation creates many complications for business including the automotive sector. Tests were carried out on a CI engine with a common rail injection system and an additional hydrogen system. Hydrogen was injected sequentially into the intake manifold with an injector opening time of 3 ms at a pressure of 0.115 MPa. The energy and ecological parameters of the engine installed in the Fiat Qubo were recorded in a mapped WLTC test on a MAHA chassis dynamometer. The effect of adding hydrogen on the above-mentioned parameters was analyses in relation to the use of diesel fuel alone. The use of hydrogen for co-firing with diesel can contribute to extending the life of current compression-ignition engines. ## 4046 / Study On Mobility And Strategy Of Mars Rover With Faulty-Driven Wheel Zhicheng Jia, Jingfu Jin, Xinju Dong, Yingchun Qi, Meng Zou, and Lianbin He\ Keywords: Mars Rover; Faulty-Driven Wheel; Mobility; Emergency Control Strategy\ Abstract: Due to the particularity of planetary exploration mission, the Mars rover cannot be recovery and repaired in time when it fails like a conventional field robot. The failure of its core components such as wheels may directly lead to the interruption of detection tasks and even the loss of its own mobility. In this study, the motion state and model of the Mars rover with faulty-driven wheel are analyzed, and an emergency movement mode based on active suspension wheel lifting driving and faulty wheel dragging driving is established. In order to restore the hidden danger scene on the ground and accumulate experience in advance, the mobility test was carried out using the Zhurong Mars rover prototype based on the simulated Martian terrain. The test results show that the mobility of the Mars rover under the two emergency mobility modes is reduced. The average driving power of active suspension wheel lifting driving increases by about 30.1 %, the average current increases by about 24.8 %, the sinkage is larger and the terrain adaptability becomes weaker. The average driving power of faulty wheel dragging driving is increased by about 167.6 %, the average current is increased by about 112.6 %, the bulldozing resistance is larger and the heading deflection occurs. To maintain the subsequent basic detection capability of the Mars rover, this study concludes by summarizing and proposing an emergency control system that integrates fault movement mode switching strategy and intermittent heading correction. These test results on ground can provide valuable reference for Mars rover operators and related researchers, and help them take timely and effective measures when facing similar accidents. ## 4375 / Development Of A Multi-Legged Robot Capable Of Ground Stiffness Detection Tomoya Nishiyama, Tatsuki Honjo, Yugo Hosizawa, Ryota Hayashi, Koji Yoshida, and Tetsuya Kinugasa\ Keywords: Multi-Legged Robot; i-CentiPot; Ground Stiffness Detection\ Abstract: Centipedes move by generating retrograde waves in their legs in an antiphase pattern left and right, and they increase their stride by undulating their trunk as their speed increases. On branches, they move with the legs on both sides in phase, stretching and contracting their trunk. Furthermore, they can swim by relaxing their legs and undulating their trunk on the water, demonstrating high mobility in various environments. The changes in gait adapted to the environment shown by such animals are interesting and provide essential clues for realizing vehicles that can move in multiple environments. Terramechanics focuses on propulsion mechanisms on terrain, especially on soft terrain. Understanding the movement strategies animals adopt in various environments and how they achieve their gait patterns are significant in ground vehicles. Hence, the objective of this study is to analyze the gait of centipedes on sand and to develop a prototype multi-legged robot, which is designed to emulate the observed gait. First, it was confirmed that centipedes change to a gait with legs moving in phase on both sides on the sand. It was also confirmed that, whereas the swing phase is longer than the propulsive phase on rigid terrain, the opposite is true on sand, with a longer propulsive phase. Next, to realize a robot that can recognize the ground stiffness and alter its gait accordingly, a system was introduced that has a bending sensor in the flexible legs and can actively rotate each leg. Finally, it was clarified that the flexibility and rotational angle of the legs recognize the terrain stiffness. ## 4695 / An Image Analysis Method For Obtaining Wheel Performance Of Rover Using Wheel Tread Traces Remained On Lunar Simulant Soil Yujin Lim and Viet D. Le\ Keywords: Rover wheel; image analysis; lunar soil; wheel tread; pattern recognition; machine learnining\ Abstract: An image analysis procedure was proposed and adapted in this study to obtain rover wheel performance by analyzing wheel tread images remained on the surface of lunar simulant soil. Wheel-soil interaction is usually simulated by using Bevameter test results and adapting sinkage model such as Bekker’s and Wong and Reece methods. However, the pressure-sinkage models obtained from the Bevameter test do not clearly provide in-detail information about sinkage and slip of the wheel when a rover runs on loose and fine dry soil. The wheel tread images captured by a camera mounted on the single wheel tracking device were analyzed successfully by using a specific pattern recognition procedure that is composed of Gabor wavelet filter, Principal Component Analysis (PCA), and Support Vector Machine (SVM). Next, We do successfully develop a required scheme of machined learning that was used to obtain an improved calculated torque of the wheel that is required for the next movement of the rover running on lunar terrain. ## 4998 / Dynamical Modeling Of The Power Hop Phenomenon In An Agricultural Tractor With Front Axle Suspension Masahisa Watanabe, Keisuke Kazama, and Kenshi Sakai\ Keywords: Agricultural tractor; Power hop; Axle suspension; Nonlinear dynamics\ Abstract: Power hop refers to the coupled oscillation of vertical, longitudinal, and pitch motions observed when four-wheel-drive tractors tow moderate to high draft loads on dry soils or operate on slippery roads or slopes. The severe vibrations resulting from power hop reduce operational precision, ride comfort, and tractor stability, while also increasing soil compaction and damage to operators and tractor body. Unlike forced oscillations, power hop is a self-excited oscillation caused by the nonlinear dynamics of agricultural tractors, including stick-slip and impact dynamics. Our previous paper investigated how these nonlinear elements contribute to the power hop phenomenon in farm operations. In this study, we explore the efficacy of front axle suspension in mitigating the occurrence of power hop and its associated vibrations. Although front axle suspension is generally employed to improve ride comfort during tractor operation at higher speeds, its efficacy on power hop have not been investigated thus far. We newly developed a power hop model for an agricultural tractor equipped with front axle suspension and conducted numerical simulations varying model parameters of the developed model. Our results demonstrate that front axle suspension can effectively suppress power hop even under load and soil conditions that would induce power hop in a tractor without such suspension. However, we also observed occurrences of power hop in front axle suspension tractors under more severe conditions including higher draft loads and drier soils. ## 6277 / Comparison Of The Energy Performance Of A Diesel Engine Fueled By Alternative Fuels Along With The Addition Of Hydrogen Michał Kuszneruk, Rafał Longwic, Jarosław Pytka, Dawid Tatarynow, and Sławomir Tarkowski\ Keywords: hydrogen; diesel engine; dual fuel injection; alternative fuels; emission standards\ Abstract: A review of the literature shows that the use of hydrogen improves the energy performance of an internal combustion engine. These properties are of interest in the context of improving the combustion processes of vegetable oils. Tests were carried out on a 1.3 Multijet compression-ignition engine built in a Fiat Qubo, which was fuelled with four different mixtures: diesel with hydrogen, diesel with LPG, rapeseed oil with 10% n-hexane solution, rapeseed oil with 10% n-hexane solution and hydrogen. The diesel engine, with a common-rail injection system, was adapted to run on various liquid fuels and an additional gaseous fuel supply system. While running on the MAHA chassis dynamometer, power and torque measurements were taken. The injection control parameters were also recorded each time. The results of the tests were synthesised in the context of the influence of the alternative fuel used on the injection control and the energy parameters achieved. ## 6865 / Extended Terramechanics Model Considering Ground Surface Deformation And Its Application To Wheel Traveling Analysis Shingo Ozaki, Tomoya Arai, and Mai Shimizu\ Keywords: Wheel; Ground deformation; Trafficability; Simulation; Cellular automaton\ Abstract: Based on the pioneering work by Bekker, Wong, and Reece, terramechanics models have been used to evaluate the traveling performance of off-road vehicles of a wide range of scales, from small robots to mining dump trucks. Recently, it has also been used to study the performance of lunar and planetary exploration rovers. Meanwhile, multi-body dynamics analysis implementing the terramechanics model is a typical method to study the performance of off-road vehicles on soft ground. This approach can be a powerful tool not only for evaluating the overall vehicle behavior, but also for evaluating safe work plans. The quality of a multi-body dynamics analysis of an off-road vehicle depends on the terramechanics model that describes the interaction between the driving parts and the ground. In this study, the effectiveness of an extended terramechanics model (xTerramechanics model) is demonstrated, which considers soil deformation actions based on cellular automata, for the evaluation of traveling performance of a rigid wheel. First, the results of single-wheel traveling analysis are compared with experimental results under the forced-slip condition, and it is shown that drawbar-pull and sinkage are represented with good accuracy. We then apply the xTerramechanics model under the self-propelled traveling condition at a constant towing load and slope climbing. The model successfully reproduced the well-known “difference in traveling performance depending on traveling conditions.” ## 7116 / Dem-Sph Analysis For Interaction Mechanics Of Tracked Vehicle On Wet Sand Hiroki Yanagawa and Genya Ishigami\ Keywords: Soil deformation; Tracked vehicle; Construction robots; moist sand\ Abstract: Tracked vehicles are extensively employed in unstructured environments, traversing on uneven and deformable terrains. The mobility facilitated by the track unit which is composed of interconnected metal plates, is pivotal for enhancing vehicle mobility and safety. In the context of construction machinery, there is a paramount need for stable traversability across sand imbued with moisture. Despite this, the existing research on evaluating tracked vehicle performance in wet sand conditions is significantly limited in contrast to the extensive research conducted on dry sand. This study aims to develop a DEM-SPH-based simulation methodology for assessing tracked vehicle traversability on water-laden soil. The DEM, or Distinct Element Method, is a proven technique for soil-machinery interaction analysis, but it inaccurately represents water-infused sand dynamics. Incorporating the Smoothed Particle Hydrodynamics (SPH) addresses these difficulties, allowing it to improve the simulation accuracy of moist soil behavior. Our approach involves calibrating and validating DEM-SPH parameters through cone penetration tests across various soil moisture levels and resistance force variations. Subsequent cross-validation of the calibration was performed by examining the deposition angles of differently moistened sand in a cylindrical container. By calibrating DEM-SPH parameters, our simulations of track unit vehicles on moist sand considering various slip ratios of the track provide insights into the complex dynamics of vehicle-soil interactions. This research highlights the potential of DEM-SPH in delivering precise analyses of tracked vehicle performance on moist sand. ## 7555 / Practical Applications Of Hybrid Terramechanics Model Using Machine Learning Eric Karpman, Jozsef Kovecses, and Marek Teichmann\ Keywords: Terramechanics; Machine Learning; Hybrid Modelling\ Abstract: Real-time wheel-soil models in terramechanics primarily rely on traditional semi-empirical terramechanics models as a foundation. Because of the steady-state assumption that these models are formulated with, their accuracy can suffer in dynamic simulations. Methods such as the Finite Element Method (FEM) and the Discrete Element Method (DEM) can capture transient effects that traditional semi-empirical models cannot, but their computational cost is prohibitive for real-time applications. Using a machine-learning (ML) approach in combination with the semi-empirical models, the authors have previously shown that it is possible to create a hybrid model that can run in real time while capturing transient wheel-soil behaviour. This was achieved by generating training data in the form of DEM simulations and using the resulting forces to compute the difference between the force prediction of the semi-empirical and DEM models. A neural network was trained to predict the difference between these forces. This work builds off the authors’ previous work to expand the scope of this modelling approach so that it can be used in a wider range of practical applications. This is achieved by studying the ideal network input and output parameters and creating DEM simulation scenarios that result in high quality training data. Notably, the idea of having the neural network predict a force per unit width of the wheel is explored as strategy for saving computational resources and creating neural networks that work for a wider range of problems. Detailed description of the creation of training data and network training procedure as well as various examples of the trained network implemented as part of a hybrid wheel-soil model in real-time dynamic simulations will be presented. ## 8330 / Semi-Empirical Terramechanics Model For Variable Terrain Height In 3D Eric Karpman, Wing Hang Ho, Jozsef Kovecses, and Marek Teichmann\ Keywords: Terramechanics; Rough Terrain; Semi-empirical\ Abstract: When employing semi-empirical terramechanics models, dynamic simulations typically rely on the assumption that all terrain, even rough terrain, can be approximated as a plane in any given simulation time step. This assumption is made necessary by the fact that traditional semi-empirical terramechanics models are formulated to compute wheel-soil interaction forces for a wheel travelling over a flat plane, and adapting these models to compute the reaction forces for a wheel travelling on a sloped plane is straightforward. In many cases, approximating the contact between a wheel and a complex terrain mesh as contact between a wheel and a sloped plane - whose normal direction is determined by the terrain nodes that intersect with the collision geometry of the wheel - can give a reasonable approximation for the contact forces. However, there are conceivable scenarios where important terrain features, such as gaps in the wheel-terrain contact patch, can be overlooked when using this approach. The authors have previously proposed an alternative method for adapting the traditional semi-empirical models for rough terrain without the need to simplify the contact problem to a wheel on a sloped plane. This is accomplished by treating the terrain as a height field and integrating the contact stresses along the wheel's rim by computing the sinkage at each point along the rim based on the un-deformed height field height at that position in space rather than based on the wheel's position relative to an approximate contact plane. In this work, the previous 2-D implementation of the proposed approach is extended to three dimensions to illustrate how it can be used in full-scale dynamic simulations. ## 8506 / Introduction Of Hourglass Mission To Investigate Characteristics Of Granular Materials In Low Gravity Environment Masatsugu Otsuki, Shingo Ozaki, Genya Ishigami, Takao Maeda, Masataku Sutoh, and Taizo Kobayashi\ Keywords: Hourglass; Low gravity; Granular materials; Dynamics; Regolith; Spacecraft design\ Abstract: The Hourglass mission has been conducted to investigate the gravitational dependence of basic parameters for reproduction of behavior of granular materials such as regolith and ground sand, and to obtain information that contributes to future spacecraft design. In the Hourglass mission, the behaviors of regolith and ground sand in an arbitrary gravity environment are observed with an artificial gravity generator included in the Cell Biology Experiment Facility (CBEF) in the Kibo module of the International Space Station (ISS). The purpose of this mission is to investigate the effect of low gravity on the properties of granular materials. An hourglass-type container and a measuring-cylinder-type container including particles such as simulated regolith of planets and ground sand are packed into a sealed metal box mounted on the artificial gravity generator. The behavior of particles is observed with an optical camera while the containers are periodically flipped under arbitrary low gravity. Eight kinds of specimens are employed for the target samples, and dynamic behavior and sedimentation state (bulk density, angle of repose, etc.) of these granular materials are evaluated. Hourglass mission would have the contribution of understanding of the celestial growth process, provision of basic data for the construction of terramechanics on celestial bodies, optimization of design for future landers, exploration rovers, automatic construction machines on the lunar surface and manned pressurized rover for lunar exploration, and the appeal of the value and ability of Kibo artificial gravity environment. This presentation outlines the Hourglass mission, from start-up to development, and provides application examples of the results obtained. ## 8861 / An Efficient And High-Fidelity Track Model For Dynamic Simulation Of Off-Road Tracked Vehicles Oz Ben-Yosef and Dror Rubinstein\ Keywords: track model; drawbar pull; multi-body model; track high-fidelity; track efficient\ Abstract: A high-fidelity simulation model of tracked vehicles is required for proper prediction of the mobility of tracked vehicles traveling over soft soils. The vehicle components can be modelled using standard tools of multi-body programs. A track model was developed and successfully worked together with Altair's MotionSolve multi-body program. The model based on classic soil mechanics equations. The grousers, which are a significant part of many types of track-links, are taking into the account. The plasticity and viscosity properties of the soil are considered in the model. Verification tests were conducted in an agricultural field in the Jezreel Valley. The tests were run over soils with varying mechanical prop-erties, achieved through irrigation and tillage. The chosen test vehicle was an M113 armoured carrier. Several drawbar pull loads were applied on each soil condition. Reasonable correlation between the tests and simulation results were achieved. However, this model is not efficient and require consumption of large amount of CPU time. On the other hand, the more efficient models are based on simplifying assumptions with lack of accuracy. This work proposes a method for creating an efficient high-fidelity model. This can be implemented by representing the interaction between the track and the ground according to the previous work. The solution for the track-links will be done independently to the solu-tion of the entire vehicle. The solution of the track link will be obtained through a solver that will be developed for this purpose. The solution of the entire vehicle will be done by the solver of the multibody program (Altair MotionSolve). Good correlation between the efficient model and the previous model were achieved. ## 9688 / Evaluation Of The Dynamic Sinkage And Its Effect On The Compaction Force Prediction Of Off-Road Vehicles Yang Jiao, Jozsef Kovecses, and Marek Teichmann\ Keywords: slip-sinkage; off-road vehicle; discrete element method; symbolic regression\ Abstract: In off-road wheel/tracked vehicle operations, shearing and compaction actions of- ten occur simultaneously, with both contributing to the total sinkage of the vehicle. The sinkage induced by the vehicle’s compaction is typically referred to as static sinkage. This type of sinkage can be accurately quantified using pressure-sinkage relations such as the Bekker equation or the Wong and Reece equation. The sinkage resulting from the shearing behavior of the wheel and track is referred to as slip-sinkage (or dynamic sinkage in some literature). Compared with the first part, the slip sinkage is usually neglected in simulation. However, neglecting slip-sinkage can lead to inaccuracies in predicting motion resistance and traction, both of which are closely tied to vehicle performance. In past literature, slip sinkage has typically been calculated based on the slip ratio and static sinkage. In this research, the Discrete Element Method (DEM) virtual experiments were conducted to investigate the physical causes of wheel slip sinkage and identify the main contributing factors. The experimental results demonstrated that, in steady-state conditions, slip-sinkage increased with higher slip ratios, while also being influenced by the shear velocity of the wheel. In transient states, the primary contributor appears to be shear displacement rather than the slip ratio. The DEM virtual experimental results were utilized to develop an empirical equation for calculating slip sinkage, incorporating shear displacement, shear velocity, and slip ratio through symbolic regression. The normal force calculation based on the pressure sinkage equation was also modified to better accommodate slip-sinkage, thus improving the accuracy and stability of the simulation. # Editorial Board Editorial Board for the Conference Book of Proceedings **Junya Yamakawa**, National Defense Academy, Japan, *Co-Chair* **Shingo Ozaki**, Ritsumeikan University, Japan, *Co-Chair* **Ryosuke Eto**, Yokohama National University, Japan **Kojiro Iizuka**, Keio University, Japan **Schalk Els**, University of Pretoria, South Africa **Vilas Salokhe**, Kaziranga University, India **Corina Sandu**, Virginia Tech, USA **Dror Rubinstein**, Ariel University, Israel **Jarosław Pytka**, Lublin University of Technology, Poland **József Kövecses**, McGill University, Canada **Peter Kiss**, Hungarian University of Agriculture and Life Sciences, Hungary **Massimo Martelli**, National Research Council, Italy **Vladimir Vantsevich**, Worcester Polytechnic Institute, USA **Lutz Richter**, SoftServe, Inc., Germany # Book of Proceedings Proceedings of the 21st International and 12th Asia-Pacific Regional Conference of the ISTVS [*Book of Proceedings*](https://www.istvs.org/store/istvs2024) [ISBN *978-1-942112-57-0 (pdf)*](https://www.istvs.org/store/istvs2024) # Page 1
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