A robust decentralized model reference adaptive control for non-minimum-phase interconnected systems

Abstract

In this paper, we present a decentralized model reference adaptive control for interconnected subsystems in the sense that no information exchange occurs between the subsystems. The approach is based on the interconnection output estimation using the polynomial series which offers a general solution for interconnected subsystems. The parameter estimation scheme is a combined adaptive data filtering with a recursive least-squares algorithm with parameter projection and normalization. The problem of minimum phased subsystems is handled by an adaptive input–output data filtering. Hence the zeros of each subsystem estimated model are relocated inside the unit circle. This estimated model which is minimum phased is then used for the control synthesis. It is shown that the stability conditions based on weak interconnections are relaxed. Also the robustness of the proposed adaptive control against unmodeled dynamics is stated. Finally, the results are illustrated by numerical examples.