Model Reference Adaptive Control for Non-Minimum Phase System by 2-Delay Feedback

Abstract

In most of the studies of model reference adaptive control (MRAC), the controlled systems are confined to minimum phase systems, since the MRAC techniques utilize the control laws involving cancellations of zeros of the systems. It makes the scope of application of MRAC too restrictive, for nonminimum phase discrete-time systems can often appear. In this paper, we propose a design method of model reference adaptive control systems for non-minimum phase systems by utilizing 2-delay input control. In our method, the poles and zeros of the controlled systems are relocated by the 2-delay feedback control laws with 2-delay sampling. Since no cancellation of zeros occurs, the stable model reference adaptive control systems can be constructed even if unstable zeros exist. Some simulation results for non-minimum phase systems also shown the effectiveness of the proposed method.