A Method for Evaluating Contact Points with the SCOUT-Rover-Rimless-Wheels

Abstract

Efficient locomotion in unpredictable and unstructured environments is a major challenge in mobile robotics, especially in planetary exploration. Scouting lava tubes on Mars or on the Moon is the primary mission of the Space Cave explOration UniT (SCOUT), developed at the Robotics and Mechatronics Center of the German Aerospace Center. The SCOUT is equipped with six rimless wheels combining the conventional locomotion capabilities of legged and wheeled robots. A major challenge for efficient locomotion on challenging terrain is the reliable detection and localization of contacts between each rimless wheel and the ground. This work shows that it is possible to implement ground contact detection for rimless wheels without installing additional sensors by relying solely on the motor currents. We present an algorithm based on experimental data recorded with the SCOUT. Beyond contact detection, the presented approach allows the inference of additional angular information of the respective foot contacting the ground and, subsequently, the contact position with respect to the rover's body frame. The contact detection approach has promising implications for the operational performance and energy efficiency of the SCOUT.