Comparison of lunar rover wheel performance in soils with different cohesive properties

Wheeled mobile robots, rovers, are highly effective in lunar exploration. However, the lunar regolith can cause wheel slippage, resulting in an inability to travel for the rover. A single-wheel testbed is usually used to analyze a rover wheel's driving performance. Our experiment can control the rotation and translation of the wheels separately, realizing experiments in any slippage condition. Moreover, this testbed can conduct experiments using regolith simulant with a cohesive property, in addition to Toyoura sand, which is non-cohesive sand collected from the earth. This paper presents the results of a driving test on two types of loose soil: Toyoura sand and regolith simulant (FJS-1). The wheel used in the experiment is the preliminary version of the actual flight model of a 10 kg class lunar exploration microrover. The results reveal that the traction performance on both sands improves as the slip ratio increases. The performance did not depend on velocity but on vertical load. It should be noted that the cohesive simulant shows a higher difference in traction performance than Toyoura sand. These findings, measured in detail from the low-slip to the high-slip range, contribute to the actual driving operation of the rover missions.