Model reference adaptive control for nonminimum-phase systems using a surrogate tracking error

This paper presents a direct model reference adaptive controller for single-input, single-output, linear, continuous-time systems that are possibly nonminimum phase, provided that the nonminimum-phase zeros are known. The adaptive controller uses a surrogate tracking error, which approximates the true tracking error. The recursive-least-squares-based adaptive law is developed by minimizing an integral quadratic cost of the surrogate tracking error.