Automated approach to design predictive PI control scheme for gain margin specification

In this work, a relay based automatic tuning method is proposed for the Predictive PI control scheme. The proposed method comprises of two steps, namely process model identification by utilizing the standard relay feedback test and ultimate gain determination by once applying again the test of standard relay feedback. First Order Plus Dead-Time model is identified from the first relay feedback test information. By using that model, the dynamic part of the controller is designed and augmented with the process. Once again, feedback test for relay is performed for process augmented with dynamic part of the controller to find the ultimate loop gain. Then, the controller gain is tuned for the user specified gain margin specification. Simulated outputs are exhibited to show the performance and easiness of the proposed automatic tuning method. Further, real-time validation on two-tank non-interacting system is presented. The proposed relay based method is more suitable for industrial process control applications due to the autotuning feature, easiness and performance.