Two-degree-of-freedom fractional order internal model controller design for non-integer order process with time-delay

For the non-integer order process with time-delay, a design and tuning method of two-degree-of-freedom fractional order internal model controller is proposed. This method can over the disadvantages of single-degree-of-freedom PID controller that can not achieve the best performance of the command tracking characteristic and disturbance rejection characteristic at the same time. The time-delay term of the model is approached with the first-order Taylor expansion. The analytical tuning of one parameter is realized based on the cutoff frequency and the phase margin to make the system have strong robustness, and the other parameter is selected according to the dynamic performance. The results illustrate that the proposed method can realize decoupling of robustness and dynamic performance of the system, and provide good performance of target tracking, disturbance rejection and robustness.