Implicit Robot Force Control Based on Set Invariance

This paper addresses the problem of robot implicit force control by means of set invariance theory. The proposed control law improves the invariance control approach by avoiding the definition of a nominal stabilizing controller, while simultaneously ensuring the absence of output overshoots with respect to the reference. The resulting set invariance based controller is first introduced for a single-input single-output system and then extended to multi-input multi-output systems, in order to be applied to the robot implicit force control problem. Its effectiveness is experimentally validated and compared to state-of-the-art approaches on a hybrid force/position task performed with a 6 DOF industrial robot equipped with a force/torque sensor.