Wheel-ground modeling in planetary exploration: From unified simulation frameworks towards heterogeneous, multi-tier wheel ground contact simulation

Abstract

Today’s growing scientific interest in extraterrestrial bodies increases the necessity of extended mobility on these objects. Thus, planetary exploration systems are facing new challenges in terms of mission planning as well as obstacle and soil traversability. In order to fit the tight schedules of space missions and to cover a large variety of environmental conditions, experimental test setups are complemented by numerical simulationmodels used as virtual prototypes. In this context we present an integrated simulation environment which allows for using different available contact models, ranging from simple but real-time capable approximations based on rigidbody modeling techniques up to very accurate solutions based on Discrete Element Method (DEM). The models are explained and classified for their applications. For this work, a one-point Bekker based approach (BCM) and the so-called Soil Contact Model (SCM), which is a multi-point extension of the Bekker–Wong method taking soil deformation into account, are used for further analysis. These two contact models are applied for homogeneous simulations with only one type of contact model for all wheels as well as for a heterogeneous multi-tiered simulation with different contact models for the wheels. It will be shown that the multi-tiered approach enhances the simulation result accuracy compared to the results of a homogeneous model with a low level of detail while speeding up the simulation in comparison to a homogeneous higher-tier model.