IMC based robust PI/PID controllers for time-delayed inverse response processes

In the last decade, several works have been reported for stable and integrating processes to achieve a specified maximum sensitivity. Also, internal model control (IMC) is a popular controller design strategy as it has only one tuning parameter. IMC based controllers are available in literature for time-delayed inverse response processes but none of the reported works provide guidelines for selecting the tuning parameter. In the present work, IMC-PI/PID controllers for time-delayed inverse response processes are reported. To achieve a specified maximum sensitivity in the range of 1.4 to 2.0, set of tuning rules is proposed for the tuning parameter. Normalized form of the transfer functions are used in the present method which simplifies the design procedure. Novelty of the proposed approach is that the user can not only tune the tuning parameter for desired maximum sensitivity, but can also switch from smooth (M_s = 1.4) to tight (M_s = 2.0) control. Simulation results illustrate the effectiveness of the proposed tuning rules.