Robustness of adaptive controller based on pole-zero placement

Abstract

The robustness of a pole-zero placement adaptive control algorithm in the presence of unmodelled dynamics and bounded external disturbances is studied. The algorithm is designed based on the reduced-order plant, which is assumed to be stable, but it does not necessarily have minimum phase. The overall plant is assumed to be stable, but it may have non-minimum phase. By using a normalizing signal and a projection in the adaptive law, a condition for stability is derived. The extra a priori information required is that bounds on the unknown plant parameters are known.