Tracking control of a class of nonlinear systems with unknown periodic time-varying parameters via output feedback

The paper considers the problem of tracking control of a class of nonlinear systems with unknown periodic time-varying parameters via dynamic output feedback. Both matched disturbances and unmatched disturbances are considered. A new method for asymptotic rejection of multiple general periodic disturbances is presented. The method can guarantee that all signals in the closed loop system are bounded and the tracking error approaches zero.