PID Tuning Method Based on Dominant Poles and Phase Margin

A simple PID tuning method based on dominant pole placement and phase margin specification is proposed.After transforming such time domain specifications as the settling time,the overshoot,etc,into a pair of dominant poles,the dominant pole placement method combined with phase margin specification is then employed for a PID tuning.A graphical method is applied to obtain the exact gain crossover frequency at which the time domain and phase margin specifications are satisfied,simultaneously.The method transforms the problem of solving a set of nonlinear coupled equations into finding the intersection point of two graphs plotted using the frequency response information of the process.The proposed method in this paper is regardless of the process order,time delay or damping nature and thus is of wide range of applications.