The two-degree-of-freedom parallel control for inverse response plus time delay

A two-degree-of-freedom (2-DOF) control method with parallel control structure (PCS) is proposed for inverse response process plus time delay. The parallel control structure decouples the set-point tracking response from disturbance rejection response. Set point tracking control uses the method of internal model control (IMC) based on PCS. This method not only eliminates the non minimum phase parts in the denominator of the characteristic equation, but also has only one adjustable parameter which sets controller parameter using dynamic performance index, which makes the system have a good tracking performance. Disturbance rejection controller uses the principle of internal model controller, and the maximum sensitivity function is also applied to set the controller parameter. It avoids the blindness of parameter selection and improves the robustness and disturbance rejection performance of the system. Theoretical analysis and simulation results show that the proposed method presents good set-point tracking performance, disturbance rejection performance and robustness.