Contribuições no estudo comparativo entre compensadores de atraso de transporte e controladores PID

Abstract

Recently, the use of the Smith Predictor was questioned due to issues related to its robustness to process dead-time uncertainties. Thus, this work presents a comparison between a structure derived from Smith Predictor, called Simplified Dead-Time Compensator (SDTC), and proportional-integral (PI) and proportional-integral-derivative (PID) controllers in terms of performance and robustness. The main results of this comparison show that the SDTC is better or similar than PI/PID controllers in terms of performance and that robustness to dead-time uncertainties can be better quantified in terms of multiplicative uncertainties and robustness index curves. This work also proposes a proportional-integral controller (PI) tuning rule for unstable processes with dead-time, based on the simplified filtered Smith predictor (SFSP) formulation. The choice of the closed loop time constant, the only tuning parameter, is carried out by means of a mathematical expression, obtained by optimization. The simulation results show the robustness and the best performance of the proposed tuning rule compared to other rules in the literature.