Traveling performance evaluation of planetary rovers on loose soil

When 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 traversability. In this study, the influence of a rover’s weight on its traversability was evaluated by performing experiments using a mono-track 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 the numerical simulation based on terramechanics. Finally, the influence of the wheel surface pattern on the traversability of planetary rovers was evaluated by conducting experiments using a two-wheeled rover, equipped with wheels, with a different number of lugs (i.e., grousers) on their surface. Based on the results of the above experiments, we confirmed the following influences of the parameters: in the case of the track mechanism, the traveling performance does not change according to 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, rather than the wheel width, contributes more to the high traveling performance. In addition, a comparison between the experimental and simulation results shows that it is currently difficult to accurately predict the traversability of lightweight vehicles on the basis of terramechanics models. Finally, the experimental results show that having lugs always improves the traversability, even at the expense of the wheel diameter.