Stability Robustness of Repetitive Control Systems With Zero Phase Compensation

Abstract

It is shown that a special zero phase control (ZPC) system introduced by Tomizuka is L ∞ stable against a large class of common nonlinearities. However, it still suffers from the generic nonrobustness problem associated with a linear repetitive control system when subjected to a saturation nonlinearity. For the special ZPC system, however, three solutions exist for the problem, two of which do not degrade the repetitive tracking performance.