Controle PI/PID robusto baseado no preditor de Smith

Abstract

This work presents a control strategy based on Smith predictor for uncertain linear delayed systems. The main goal of this research is to overcome the Smith predictor lack of robustness in case of modeling error, especially in the time-delay term. In order to compensate the modeluncertainties, the open-loop observer in the traditional Smith Predictor structure is replaced by a closed-loop observer. Moreover, since the system time-delay may not be precisely known or it can also be time-varying, the proposed modified Smith predictor takes into account only a constant time-delay value that represents an uncertain time-delay estimative or the estimated average of a time-varying delay. Thus, real time measurement of the time-delay is not required. Furthermore in the proposed approach is considered a PI/PID controller and the problem is formulated by means of Linear Matrix Inequalities (LMIs). The main advantage of the proposed method is that the overall closed-loop system stability is guaranteed under the prescribed uncertain conditions. Numerical examples are presented to illustrate the performance of the proposed method and to compare its effectiveness over other methods described in literature.