Graphical IMC-PID Tuning Based on Maximum Sensitivity for Fractional-order Uncertain Systems

This paper proposes to use a fractional-order digital loop In this paper, a novel graphical tuning method based on internal model control (IMC) strategy of proportional integral derivative (PID) controller is proposed for an uncertain fractional-order plant family with time delay. Firstly, an approach is presented to solve the problem of disturbance rejection and model mismatch of the uncertain fractional-order plant using IMC. Secondly, to further guarantee the system with certain robust stability and dynamic performance, the concept of maximum sensitivity (Ms) is introduced to tune parameters of the PID controllers for the uncertain fractional-order plants. The Ms can describe the constant gain margin and phase margin boundaries and determine the range of the adjustable parameter of the filter for IMC. Finally, the intersection region satisfying multiple objectives can be found by using the proposed graphical method. Simulation results are given to demonstrate the flexibility and effectiveness of the proposed method.