Design and terramechanics analysis of a Mars rover utilising active suspension

Wheeled rovers have a limited ability to traverse soft terrains and climb loose slopes. This study proposes a wheel-step rover with a modified active rocker-bogie suspension. The rocker and differential shaft fixed to the rocker are divided into three parts and reconnected via a novel angle-adjusting mechanism. The mechanism, which is driven by a single motor, widens and narrows the angle between the two rocker parts periodically to generate a wheel-step motion. Moreover, it adjusts the angle between a rocker part and differential shaft part to keep the bottom side of the rover body parallel to the ground. When fully stretched, the suspension lowers the bottom side horizontally to the lander platform. The mechanism also cooperates with a brake added between a rocker part and bogie to lift the sunken wheels separately. The strategies of wheel-step motion, wheel lifting, and suspension folding/unfolding are practicable as validated by prototype tests. Experiments show that the active suspension considerably enhances the rover's ability to escape from a dune or a crater. The proposed suspension is an important attempt in improving the design of Chinese Mars rovers. (C) 2018 Elsevier Ltd. All rights reserved.