Extended filtered high-gain output feedback controller for a class of uncertain nonlinear systems subject to external disturbances

Abstract

ABSTRACT In this paper, an extended filtered high-gain output feedback controller is developed for a class of uncertain nonlinear systems subject to external disturbances. The design philosophy of the extended filtered high-gain output feedback controller is that the extended state observer (ESO), high-gain and low-pass filter are integrated together. The ESO can not only estimate the unknown internal state, but also deliver a good property of disturbance rejection simultaneously due to the presence of high gain. Since the high gain deteriorates the robustness of the system, a low-pass filtering mechanism is added in the control law to filter away aggressive signals and recover the robustness. The filtered control law is designed to compensate the nonlinear uncertainties and deliver a good tracking performance with guaranteed robustness. The uniform performance bounds are derived for the states and control signals via comparison with the virtual reference system.