Discrete‐time multivariable robust model reference adaptive control based on Kp = LDS factorization: an input–output approach

A direct scheme of robust model reference adaptive control is reinvestigated, in an input–output approach, for a large class of discrete‐time multivariable systems with unmodeled dynamics and bounded disturbances. Compared with the existing results, in virtue of a high‐frequency gain matrix factorization, the assumptions required in the scheme are further relaxed without overmuch complicating the controller structure, and a permissible range of the gain parameter in a modified adaptive algorithm is clearly specified. Moreover, paralleling the continuous‐time theoretic framework, robust stability and robust tracking performance are analyzed by using the multivariable versions of some important technical lemmas, such as an exponentially weighted norm‐relation lemma and two swapping lemmas. Copyright © 2012 John Wiley & Sons, Ltd.