Traveling performance evaluation of planetary rovers on loose soil

In designing a planetary rover, it is important to consider and evaluate the influence of parameters such as the weight and dimensions of the rover on its traveling performance. In this study, the influence of a rover's weight on its performance was evaluated by conduct experiments using a monotrack rover and an inline four-wheeled rover with different rover weights. Then the influence of the wheel diameter and width was quantitatively determined by performing experiments using a two-wheeled rover, equipped with wheels, with different diameters and widths. The results of the experiments were compared with those of a numerical simulation based on terramechanics. Finally, the influence of the wheel surface pattern on the traveling performance of planetary rovers was evaluated by conducting experiments using a two-wheeled rover equipped with wheels with different numbers of lugs (i.e., grousers) on their surfaces. Based on the results of these experiments, we confirmed the following influences of the parameters: In the case of the track mechanism, the traveling performance does not change with the increase in rover weight. On the other hand, in the case of the wheel mechanism, an increase in rover weight decreases the traveling performance. Moreover, the experimental results show that the wheel diameter contributes more to the high traveling performance than the wheel width. In addition, a comparison between the experimental and simulation results shows that it is currently difficult to accurately predict the traveling performance of lightweight vehicles on the basis of terramechanics models. Finally, the experimental results show that having lugs always improves the traveling performance, even at the expense of wheel diameter.