Terrain modelling in simulation-based performance evaluation of rovers

Abstract

In this work, we investigate the effect of terrain modelling on the performance of planetary rovers by evaluating various design concepts under typical rover manoeuvres. The analysis is based on implementations in CMLabs’ Vortex, a dynamics simulation environment for complex mechanical systems. Vortex can be used to model the contact of wheels under various terrain conditions. The particular focus is on motion on soft terrain, investigating the physical phenomena exhibited by such terrain, and the possibility of modelling these with the primary purpose of representing the effects of the terrain on rover behaviour. Two semi-empirical terramechanics models are used to represent the effect of soft soil. The implementation of these terramechanics models in Vortex and their adaptation to fit a multibody dynamics simulation environment are explained in detail. The effects of terrain modelling approaches on the performance of rover concepts under typical rover manoeuvres are investigated. These include: (i) straight line motion on a flat terrain or climbing a given slope and (ii) climbing over a rock with one wheel-set while the other wheels move on flat or inclined terrain. The primary characterizations and comparisons are based on performance measures that characterize the vehicle–terrain interaction such as energy expenditure and efficiency.