Design of a performance-adaptive PID controller

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 design scheme of performance-adaptive PID controllers which are based on the above control strategy. According to the proposed control scheme, the output prediction error is monitored regularly and system identification is initiated if this error exceeds a user-defined threshold. Subsequently PID parameters are 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 control scheme is numerically evaluated by some simulation examples.