Hierarchical control of end-point impedance and joint impedance for redundant manipulators

This paper proposes an impedance control method for redundant manipulators, which can control not only the endpoint impedance using one of the conventional impedance control methods, but the joint impedance which has no effects on the end-point impedance. First, a sufficient condition for the joint impedance controller is derived. Then, the optimal controller for a given desired joint impedance is designed using the least squares method. Finally, computer simulations and experiments using a planar direct-drive robot are performed in order to confirm the validity of the proposed method.