Robust design of fractional order IMC controller for fractional order processes with time delay

This article presents a novel approach to the robust design of fractional order IMC controller for the fractional-order (FO) plus time delay processes. The proposed methodology provides the flexibility to adjust the controller performance based on the application requirement using a single parameter. Also, it does not require any external filter. Thus, it ensures a better response over existing methods. A mathematical analysis is provided to select the tuning parameter to obtain the optimal solution. The effectiveness of the proposed methodology is measured for different FO processes with time delay using time-domain specifications, performance indices and frequency domain parameters. Load disturbance analysis under various disturbances and robust analysis under uncertainty in process gain in the presence of the disturbances is carried out to study the sensitivity and robustness of the controller. The performance parameters are estimated in both analyses and compared with the different approaches available in the literature.