Traction modelling of rigid and flexible wheels for planetary exploration rovers

摘要

This paper studies wheel-soil interaction models that can predict traction performance of rigid and flexible wheels for wheel sizes and wheel loads applicable to planetary rovers and lightweight robotic vehicles. New analytical models are presented to overcome the shortcomings of classical wheel-soil interaction models such as additional slip compaction resistance and slip (dynamic) sinkage. These proposed models explain the behaviour of the sinkage at high slip ratios and consequently explain the behaviour of the drawbar pull at high slip ratios. Slip sinkage is caused by rotation of the wheel and depends on the wheel slip ratio, as well as the wheel surface pattern and the soil characteristics. The slip sinkage is modelled by taking into account the adhesion height and the soil shear displacement. The proposed additional compaction resistance models are able to derive the slip resistance and explain the additional slip resistance at high slip ratios. The results from the new analytical model have been compared with experimental results with prototype wheels for the ESA ExoMars mission rover and a discussion is presented. It is demonstrated that the proposed models improve the estimation of the slip sinkage and the slip compaction resistance. Future work is planned to validate the model against measured performance of the NASA/JPL Mars Exploration Rover (MER) vehicles "Spirit" and "Opportunity".