Retuning oscillatory PID control loops based on plant operation data

This paper addresses an integrated identification and PID tuning procedure for chemical processes. Identification is done by comparing disturbance responses of two controllers with different parameter settings, and requires no explicit external perturbation signal. The PID tuning procedure employs loop-shaping approach, which does not assume any particular form of a transfer function, but requires only frequency characteristics for some critical range and is applicable for varieties of process dynamics. The proposed procedure is demonstrated on a simulated chemical plant to show its practical applicability.