Design and Control of a Compliant Wheel-on-Leg Rover Which Conforms to Uneven Terrain

This article presents the design, control, and implementation of a new compliant wheel-on-leg robot, named Complios. This robot is able to spontaneously adapt its configuration while it is rolling on unknown uneven terrain. The constant contact of all wheels with the ground is ensured by a series elastic actuation at the top of each leg. It provides a force control that allows the robot to freely balance its posture, while the load can be distributed as evenly as possible on each wheel for any relative height differences of the ground. The compliant structure of the Complios also gives access to the measurement of horizontal forces applied on the legs, which constitutes a valuable information when it comes to choose an appropriate response during obstacle crossing. Finally, the robot is tested on different ground shapes and proves its capability to adapt, in real time, to the ground profile.