Robust self-tuning PI decoupling control of uncertain multivariable systems

Abstract

SUMMARY In this paper, for a class of multivariable systems with strong couplings, a robust self-tuning PI decoupling controller is developed by combining a self-tuning PI controller with a feedforward decoupling compensator and a filter. To determine the gains and other parameters of the PI decoupling controller, we first introduced a reduced order model. The parameters of the reduced order model are identified by using a normalized projection algorithm with dead zone. The gains of the PI controller together with other parameters are tuned online according to the certainty equivalent principle. By resorting to time-varying operation, we presented the bounded-input bounded-output stability conditions and convergence conditions of the closed-loop system. Simulation results on a synthetic system and a twin-tank level system show the effectiveness of the proposed method. Copyright © 2011 John Wiley & Sons, Ltd.