AUTOTUNING OF MULTILOOP PROPORTIONAL INTEGRAL CONTROLLERS USING RELAYFEEDBACK

In this paper, a simple method for autotuning multiloop PI controllers for multivariable systems is presented. The procedure is a combinatio n of sequential loop closing and relay tuning often used for tuning si ngle-loop PI/PID controllers. The proposed design offers three major a dvantages. Firstly, overall closed loop stability is guaranteed; secon dly, very little knowledge of the process is required; thirdly, it is an autotuning procedure. Set point and load disturbance responses are improved by introducing set point weighting factors. Some simulation a nd comparative results are shown for distillation column models common ly used to demonstrate multiloop designs.