A robust discrete-time adaptive controller

This paper proposes a discrete-time model reference adaptive control algorithm which is robust with respect to stable additive and multiplicative plant uncertainties. The algorithm employs the same controller structure as the one that would be used if the parameters of the dominant part of the plant were known and a robust adaptive law for adjusting the controller parameters. Using essentially the same assumptions that are necessary to design a fixed controller based on the exact knowledge of the dominant part of the plant, we show that the proposed algorithm guarantees boundedness for all signals in the closed loop and "small" residual tracking errors for any bounded initial conditions. In the absence of plant uncertainties, the algorithm guarantees zero residual tracking errors.