A unified approach of control performance evaluation and PID controller design in industrial process systems

In the challenge to manufacture high quality products it is necessary to regularly monitor performance of control loops that. regulate the quality variables of interest. This paper describes a unified approach of the control performance and the PID controller design which are based on the above control strategy. According to the proposed approach, the control performance is first monitored regularly. If the performance exceeds a user-defined threshold, the system identification is initiated and PID parameters are subsequently updated for the new model. Optimal PID parameters are calculated based on the LQG trade-off curve obtained for the re-identified process model. The behavior of the proposed scheme is evaluated by applying for real chemical processes.