Automatic Tuning of Industrial PID Controllers

A novel method for automatically tuning Proportional-Integral-Derivative (PID) controllers is presented. After closed-loop identification of the process, the tuning constants of the regulator are found by optimization. The representation of the closed-loop system by a series of Laguerre functions is seen as the key to the robustness of the method. The method is intended for use of distributed instrumentation and computer control systems. It was implemented on such systems in two Canadian pulp mills. Successful tests were Performed on several loops in both plants. Results are presented and discussed.