Robust adaptive control of plants with unknown order and high frequency gain

Abstract

An adaptive control scheme is presented which has a simple structure and guarantees global stability of the closed-loop plant and asymptotic zero tracking error for a class of reference signals. The plants to be controlled are of minimum phase and relative degree one. No a priori knowledge for the order, the parameters of the plant or the sign of the high-frequency gain is required. The number of adjustable control parameters is proportional to the number of frequencies in the reference signal and is independent of the order of the plant. The proposed algorithm is then modified, by using a variable structure for generating the control signal, to guarantee robust stability of the closed-loop plant and asymptotic zero tracking error in the presence of bounded disturbances and unmodeled dynamics. © 1991 Taylor and Francis Group, LLC.