A Unified IMC based PI/PID Controller Tuning Approach for Time Delay Processes

This paper proposes a new PI/PID controller tuning method within filtered Smith predictor (FSP) configuration in order to deal with various types of time delay processes including stable, unstable and integrating delay dominant and slow dynamic processes. The proposed PI/PID controller is designed based on the IMC principle and is tuned using a new constraint and without requiring any approximation or model reduction techniques. Meanwhile, the set-point weighting method plays a vital role in achieving a desired performance in both servo and regulatory problems. To have an enhanced disturbance rejection for integrating processes, an improved IMC filter is adopted to design a PID controller. The presented settings are applicable to a wide range of integrating processes. The trade-off between robustness and regularity performance is easily adjustable by tuning only one parameter. Guidelines are provided for the selection of the tuning parameter based on the maximum sensitivity value. Various performance indices are used to measure the performance of the closed-loop control system. Simulation results reveal the effectiveness of the proposed technique over some of the relevant techniques, particularly for integrating processes and stable processes with slow dynamics, by comparing performance indices such as IAE, total variation, overshoot and the maximum peak of error performance indices.