TerRA: Terramechanics for Real-time Application

Abstract

Wheeled mobile robots are popular in planetary exploration and other challenging applications due to their robustness and energy-efficient mobility. Simulation models of such robots have gained importance for both, the development and model-based controller and observer design. The most challenging part to model is the interaction between soil and wheels - called Terramechanics. Although models for that interaction exist, they either have shortcomings in certain effects that are important for the locomotion or are computationally expensive. In this work, the novel empirical model ’Terramechanics for Real-Time Application (TerRA)’ for normal and longitudinal force calculation is presented, which is developed specifically for the locomotion of wheeled mobile robots in sandy terrain. It includes an elasto-plastic normal force, plastic and dynamic sinkage as well as a longitudinal force that is calculated dependent on the history of slip and velocity. By circumventing any spatial discretization, the computational effort of TerRA is low enough to make it suitable for rover optimization and on-board application.