Comments on a robust model reference adaptive control for non-minimum phase systems with unknown or time-varying delay

Abstract

In the above paper Makoudi and Radouane, 2000 [A robust model reference adaptive control for non-minimum phase systems with unknown or time-varying delay. Automatica, 36, 1057-1065.], a model reference adaptive control (MRAC) algorithm is presented for non-minimum phase systems with unknown or time-varying delays. Unfortunately, this paper contains several mathematical mistakes that render the proofs of the claimed results erroneous. Furthermore, there are no obvious ways to correct these errors, so that the results presented in this paper are questionable.