Improved Rover Mobility Over Loose Deformable Slopes through Active Control of Body-Rotating Mechanism

Changing the center of mass (COM) by adjusting rover’s posture is a commonly used design and control strategy to improve its mobility over sandy slopes. Different from traditional passive/active suspension system and wheel-leg designs, we use a novel rover design for improved sloped mobility over soft terrains. Our rovers consist of a mobile base (with differential suspension), a main body, and a 2-degree-of-freedom (2-DOF) body-rotating mechanism that can change the pose of the main body relative to the mobile base. By taking full advantage of the main body weight which accounts for most of the robot weight, we can effectively adjust the rover COM and load distributions for improved mobility. Based on mechanics analysis, the wheel-load model and terramechanics model, we propose a control strategy for slope climbing and traversing tasks. When given input information such as slope angle and travel direction, the control algorithm can adjust the rover posture for optimal mobility over slopes. Experimental results indicate that the proposed design and control strategy can effectively improve the rover mobility performance (improved traction, reduced slippages) over soft sloped terrains.