DEM simulation and continuation algorithm of granular physical field for planetary wheel-terrain interaction

Terramechanics models are important in the research and development of planetary rovers. However, current models emphasize the motion of wheels and bulk soil parameters, with limited investigation of movement of soil particles. In this study, discrete element methods (DEM) were used to gain in-depth insights into wheel-terrain interaction from granular perspective. Experiments and DEM simulations of single-wheel tests were performed under fixed sinkage conditions to examine the behavior of wheel and granular medium. A convex hull-based continuation method for the granular physical field was proposed, including velocity, bulk density, and pressure fields. This method demonstrated higher efficacy in handling the physical fields of granular medium with boundaries. The distribution characteristics of the physical field of the granular medium for different slip ratios were analyzed to elucidate the reasons for alterations in the drawbar pull. The physical fields provide an analytical basis for understanding wheel-terrain interactions from a soil viewpoint.