A feed-forward and fractional-order feedback control strategy for integrating and unstable systems

A feed-forward fractional-order control strategy employing a feedback loop is developed for unstable and integrating types of processes. The suggested method combines the proactive disturbance rejection capability of the feed-forward concept with fractional-order control, which uses fractional calculus to provide greater flexibility and improved controller tuning. The primary goal is to reduce the disturbances’ effect before they influence the actual process variable, resulting in better control performance, improved stability and more effective operation than conventional control schemes. The forward path control is analytically designed in such a way that it is completely decoupled from the design of feedback control (proportional-integral or proportional-integral-derivative). The proposed methodology provides a sufficiently fast and smooth set-point tracking response even in the presence of noise, disturbance and process parameter perturbations. The results presented in this study further demonstrate the effectiveness of the proposed scheme in achieving significantly improved closed-loop performance (smaller integral square error and integral absolute error) compared to the previous arts under both the nominal and perturbed conditions.