Performance limitations of nonlinear periodic sampled-data controllers for Lp disturbance rejection

This note presents a performance analysis of periodic nonlinear sampled-data controllers for the rejection of L_p specific and uniform disturbances. Earlier results on the performance of linear periodic controllers are extended to nonlinear controllers. For a given periodic controller, a time invariant controller is constructed which in general gives strictly better L_p disturbance rejection performance than the periodic controller.