Lyapunov redesign for direct adaptive control of nonminimum phase systems

The authors propose a novel direct model reference adaptive pole placement control algorithm which can be applied to continuous-time nonminimum phase systems. The algorithm is based on Lyapunov´s direct method. In this scheme, an adaptive error model for the continuous-time nonminimum phase systems is derived and an estimation law for the estimation of the controller and the auxiliary parameters is proposed. Although the resulting overall closed-loop system is locally stable, assumptions about parameter convergence or the nature of the external input are not considered. It is shown that there exists a certain range of the initial value in which the overall adaptive closed-loop system is globally stable. Computer simulation results are given to demonstrate the effectiveness of the proposed scheme