Cartesian-space control and dextrous manipulation for multi-fingered tendon-driven hand

Dextrous object manipulation is a crucial task for the hands of the space humanoid Robonaut 2 (R2), and requires accurate control of fingertip positions and forces. We present a novel Cartesian control for the fingers and thumb of the R2 hand. The controller is designed such that the singularities in the fingers are avoided, and distal joint stiffness is added in the thumb for full controllability. We then present a higher-level object stiffness control law for explicit control of object position, orientation, and grasp forces. The complete algorithm is tested experimentally on the R2 hand, with results demonstrating tracking performance and robustness against disturbances.