Analytically designed dual-loop fractional-order IMC for integrating plants with inverse behavior

A novel double-loop control architecture with a fractional-order IMC (internal model control) in the outer loop is suggested for integrating plants with dead time and inverse response behavior. The inner loop controller is tuned using the maximum sensitivity concept to stabilize the plant, and it also enhances the disturbance response. The IMC controller is analytically designed to achieve improved closed-loop performance and robustness. The proposed tuning rules involve three design parameters \(\beta ,\alpha \) $\beta ,\alpha$ and \(\lambda \) $\lambda$ , whose method of selection is explained through extensive simulations and stability analysis. The suitability of the proposed control is verified for a wide class of processes, including higher-order and double-integrating processes with non-minimum phase characteristics. The suggested control has the capability of producing a fast and smooth set-point tracking response and rejecting the load disturbance effectively even in the presence of measurement noise. Random perturbations are also introduced in the process parameters to further investigate the system’s robustness.