Terramechanics and Path Finding

Planetary rovers on rough terrain are likely to encounter hazards such as rocks as well as loose soil or regolith that causes the wheels to slip and potentially get stuck. These missions need autonomous navigation for avoiding these hazards. The slippage of the wheels depends dynamically on the wheel properties, soil mechanical properties, speed and pose of the rover. In this paper, we investigate the path finding problem for a planetary rover on rough sandy terrain. Insights from terramechanics, ie. the wheel soil interaction model, is used to determine path cost to be used for the A∗ algorithm, which is used on a sample grid to determine the best path. The proposed model incorporates the slippage required to develop drawbar pull to climb up a slope, as well as steering angle needed to counter lateral force. The path thus found is evaluated based on the slip ratio and steering angle required to traverse it.