Prescribed performance control for robot joint trajectory tracking under parametric and model uncertainties

This work proposes a control law for the robot joint trajectory tracking in free space that achieves a prescribed performance of the joint position error under parametric uncertainties; the control law is extended for the case of bounded disturbances. A performance function incorporating predefined performance indices is used to produce a transformed error that is injected in the controller. Furthermore, asymptotic stability of the velocity error in case of zero disturbances and uniformly ultimate boundedness in an arbitrarily small region for bounded disturbances is achieved. Simulation results confirm the theoretical findings and compare the proposed controller with a conventional one.