High–slip wheel–terrain contact modelling for grouser–wheeled planetary rovers traversing on sandy terrains

Grouser-wheeled planetary rovers will continue to be used to cruise Mars in lined up missions. Active perception of wheel–terrain contact mechanics under high slip is necessary to manage time delays in teleoperations in order to prevent rovers from becoming stuck. Owing to severe soil particle flows, existing wheel–terrain contact mechanics models cannot be extended to predict the travelling performance of a driving wheel affected by high slips. Hence, wheel–terrain contact angles are measured using both a newly developed apparatus and computer-vision-based algorithm. The typically accepted entrance angle is considerably larger than the actual one, and the magnitude of ratio of the leaving angle to the actual entrance angle increases linearly with the slip ratio. Based on the actual entrance and leaving angles, wheel travelling performance can be predicted accurately using improved closed-form analytical models. Compared with experimental data, the mean value of relative error of an in-situ estimated drawbar pull can be reduced from 36.88% to 4.73%. © 2020