Implementation of force control on redundant robot

We deal with implementation of force control on a planar 4 DOF experimental redundant robot. A globally stable impedance force control law is used to control force and trajectory in the operational space. Redundancy is solved by a gradient optimization technique using dynamically consistent pseudo-inverse. In our case we implemented two optimization criteria-obstacle avoidance and torque optimization, important for force controlled redundant robots. The desired null space motion is controlled with a new formulation of the null space velocity controller, that assures globally stable behavior in null space. The performance of the proposed control law was tested on the experimental 4 DOF planar manipulator.