Terramechanics-based model for steering maneuver of planetary exploration rovers on loose soil

This paper presents analytical models to investigate the steering maneuvers of planetary exploration rovers on loose soil. The models are based on wheel-soil interaction mechanics, or terramechanics, with which the traction and disturbance forces of a wheel are evaluated for various slip conditions. These traction forces are decomposed into the longitudinal and lateral directions of the wheel. The latter component, termed the side force has a major influence in characterizing the steering maneuvers of the rover. In this paper, the wheel-soil mechanics models are developed with particular attention to the side force and the validity of the model is confirmed by using a single-wheel test bed. The motion profile of the entire rover is numerically evaluated by incorporating the wheel-soil models into an articulated multibody model that describes the motion dynamics of the vehicle's body and chassis. Steering maneuvers are investigated under different steering angles by using a four-wheel rover test bed on simulated lunar soil (regolith simulant). The experimental results are compared with the simulation results using the corresponding model parameters. The proposed wheel-and-vehicle model demonstrates better accuracy in predicting steering maneuvers as compared to the conventional kinematics-based model.