Whole-Body Impedance Control for a Planetary Rover with Robotic Arm: Theory, Control Design, and Experimental Validation

Future planetary rovers will gain the ability to manipulate their environment in addition to the maneuverability of current systems. For dedicated contact interaction, Cartesian impedance control is a well-established approach from numerous terrestrial applications. In this paper we will present a whole-body Cartesian impedance controller for a planetary rover equipped with a robotic arm. In contrast to classical terrestrial whole-body controllers, the issue of proper wheel force distribution will be addressed within the control framework. A global optimization solves this redundancy in the over-actuation of the mobile base while additionally handling the kinematic redundancy in the serial kinematic sub-chain of the robot. The approach is experimentally validated on the DLR Lightweight Rover Unit. It can be used for versatile manipulation in rough terrain such as encountered in planetary exploration or terrestrial search-and-rescue scenarios.