A two degree-of-freedom PID controller tuning method

A simple parameter tuning method was developed based on the design of the desired dynamic equation for two degree-of-freedom (2-DOF) PID controllers. The 2-DOF PID controller can be simplified to the function of the desired dynamic equation and the system disturbance observer. The desired dynamic equation coefficients and the disturbance observer parameters were chosen as the controller parameters to analyze the relationship between the system performance and the controller parameters and then to present a parameter tuning rule. Simulations show that satisfactory performances can be obtained using the developed tuning method in integrating processes, non-minimum-phase processes, time delay processes, high-order processes, and unstable processes.