Identificação e sintonia usando o relé em malha fechada.

Abstract

I n this work new frequency domain relay based closed loop experiments and a new PID controller tuning technique are presented. Controlled oscilations at the plant output with the proposed relay experiments are obtained i n a closed loop operation. Given a closed loop system and a chosen transfer function, the frequency at which the chosen transfer function achieves a user defined gain is determined. The Loop Transfer Function and Sensitivity Transfer Function are the chosen transfer function considered in this work. The estimated frequency points of the Loop Transfer Function are used to obtain a reduced order plant model. The Sensitivity Transfer Function experiment is used for evaluating performance and stability of the closed loop. The P ID controller tuning is based on the symmetrical optimum approach, which has well defined performance and stability properties. Frequency domain least squares is used to obtain the controller's parameters. The proposed method is more general than the original one and yields Loop Transfer Functions that are symmetrical optimum in a least squares sense for a frequency range of interest.