Soft Soil Contact Modeling Technique for Multi-Body System Simulation

Abstract

In the context of planetary exploration with mobile robots a soil contact model (SCM) for prediction and assessment of locomotion performance in soft uneven terrain has been developed. The SCM approach provides a link between the classical, semi-empirical terramechanics theory of Bekker and the capabilities of multi-body system (MBS) simulation technique for general, full 3D simulations of soil contact dynamics problems. Beyond the computation of contact forces and torques SCM keeps track of the plastic soil deformation during simulation. For this purpose it comprises features such as generation of ruts and displacement of soil material that allow computing typical terramechanical contact phenomena like bulldozing, multi-pass effects and drawbar-pull–slippage relations. Unlike volumetric, Finite Element/Discrete Element Method-like approaches SCM applies exclusively surface oriented algorithms with relatively small complexity constants. Moreover, most of the algorithms are of linear complexity. Therefore, the computational efficiency is quite high and adequate for MBS simulation requirements.