UC Berkeley

Current Mars rovers feature large, complex suspensions to overcome obstacles. Unfavorable contact force distribution can cause slip and high drive torque demands. When traversing step-like obstacles, the vehicle is most likely to slip when the back wheels start trying to ascend the obstacle. Minimizing the ratio of tractive force to normal force on each wheel is one traction control strategy to reduce slip. This work analyzes the potential integration of a control moment gyroscope on a four-wheel rover to induce pitch moments on the rover and more effectively distribute contact loads, such that slip is avoided and drive torque requirements are reduced. For the baseline 400 kg rover considered with 0.5 m diameter wheels ascending a 0.35 m step, maximum drive torque was reduced by 40%, and maximum tractive to normal force ratio was reduced by 70%, with a total mean power comparable to normal driving. While there are mechanical challenges associated with implementing control moment gyroscopes, this analysis motivates further theoretical and experimental work in the evaluation of gyroscopic force redistribution for improving rover mobility.