An output feedback repetitive control(ORC) method is developed for the trajectory tracking control of robot
manipulators with model uncertainty. Despite the fact that only link position is available, the proposed controller obtains
favorable performance. A nonlinear filter is utilized in the controller development to remove the requirement of link velocity
measurement. The repetitive control strategy ensures that the link position globally asymptotically tracks the desired periodic
reference signals. The global asymptotic stability of the resulting closed-loop system is proved by using the Lyapunov’s direct
method. Simulation results on a three degree-of-freedom robot show the effectiveness of the proposed scheme.