Novel tuning rules for adjusting the parameters of the PI-PD controller for controlling unstable processes

Unstable processes plus time delays are very frequent in the industry. PI-PD controllers are used for controlling unstable industrial operations as they give more robust performance relative to PID controllers. However, designing the parameters of PI-PD controllers is quite difficult. Recently, the centroid of the stability region based on the Weighted Geometrical Center (WGC) approach has been proposed for overcoming the tuning difficulty of the controller. Nevertheless, the current version of WGC available in the literature is time-consuming. Thus, this paper proposes new simple tuning rules to implement WGC when it is used for computing the parameters of the PI-PD controller for controlling unstable processes with time delays. An isothermal continuous stirred tank reactor is used for evaluating the performance of the proposed method.