A Nonlinear Volumetric Contact Model for Planetary Rover Wheel/Soil Interaction

Abstract

A novel nonlinear planetary rover wheel/soil interaction model based on the properties of the penetration volume is proposed. This approach allows for fast multibody dynamic simulation of planetary rover operations by providing a closed-form solution for the contact forces. For the derivation of this contact model, the normal stress distribution under the planetary rover wheel is assumed to be a nonlinear function of the soil compression. The soil foundation with which the wheels of a robotic vehicle may interfere is represented by a continuum of hyperelastic springs. A linear version of this representation of the contact interface as a mattress of springs has been derived previously [1] and validated for the simulation of the interaction between two relatively inflexible objects [2]. However, for contacts involving large deformations, the nonlinear material properties have to be considered. In this paper, a brief summary of the elastic foundation model is given and the extension of the model to a hyperelastic foundation is provided so that it can be used for the intended purpose of modelling rover wheels in contact with soft terrain. A solution for the integral of the normal stress distribution of the rover wheels is proposed and verified in a number of numerical experiments by comparing the results against Bekker’s analytical approach. Although the focus of this work is on wheel/soil interaction, the general form of the volumetric contact modelling approach can be applied to any hyperelastic contact problem.