Design of PID controllers for improved performance of higher order systems

In this paper, a frequency response based design method of PID controller is proposed for higher order (HO)/-plus delay time (HOPDT) systems. The HO/-PDT models are converted into real and imaginary part at a frequency where a criteria similar to amplitude and phase margin is utilized to get the constraints on the parameters of the controllers. To reject noise and load disturbances, the constraints given by sensitivity and complementary sensitivity function are also considered. The proposed method has superior features for systems with high order, time delays and monotonic or oscillatory responses. Three simulation examples are included to show the effectiveness, simplicity and applicability of the proposed method.