Planetary rover locomotion on soft granular soils - Efficient adaption of the rolling behaviour of nonspherical grains for discrete element simulations

In consequence of growing interests of science exploration on our solar system’s planets and moons, increased mobility demands are arising for planetary exploration vehicles. The locomotion capabilities of these systems strongly depend on the interaction with soft granular soils. Thus a major design challenge is to develop suitable solutions for locomotion equipment and strategies. The mastering of these challenges depends on detailed soil interaction models to predict the system behaviour and get a better understanding of the underlying effects. To meet these demands a new soil interaction model based on the three-dimensional Discrete Element Method (DEM) is developed. The strength of granular materials is highly dependent on the grain’s shape and friction. Since non-spherical particles are less computational efficient than spheres, a new interparticle contact model has been developed to mathematically cover the rotational behaviour of anisotropically elongated and angular grains, while using computationally efficient spheres for contact detection. To show the applicability of the model, bevameter as well as single wheel simulations for planetary rovers were carried out.