Exploiting Controllability for Vibration Damping in Multiple Planes of Link-Elastic Robot Arms*

Benefiting from the intrinsic safety of link elasticities emerging from lightweight robot structures requires control schemes, which handle unfavourable effects like load-dependent vibrations and deflections. Successive goals are reduced energy consumption for fast motions and safe physical human-robot interaction. To put the latter into practice, force/torque sensing capabilities of elastic links allow for gentle reactions of the robot to its environment. As a first step, the present work addresses the adaptation of a vibration damping scheme taking into account the configuration-dependent controllability of link-elastic robots with multiple vibration planes. It exploits a novel geometric controllability metric with reduced complexity. By experiments with a three DOF (Degree Of Freedom) link-elastic robot, this metric is shown to facilitate adaptive vibration damping over the entire workspace. The consideration of more than one vibration plane constitutes a major contribution to the state of the art.