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Tsukasa Mochizuki, Daisuke Fujiwara, Kojiro Iizuka, Takaaki Sakata, and Tatsuhiko Suga
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.
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