Trajectory tracking for manipulators with flexible joints using link variable feedback

In this paper, a simple nonlinear controller is proposed for robust link trajectory tracking for robot manipulators with joint flexibility. The controller uses only the feedback of link angle variables and ensure satisfactory performance in link path trackings. The linear term of the controller is a PD type controller and the nonlinear term is a simple polynomial in the link tracking errors. The control design parameters are chosen based on the limited knowledge of the robot dynamics and disturbances. The fast mode due to the joint flexibility is regarded as a disturbance to the rigid-body dynamics by using the singular perturbation technique