Design of an integrated grey-fuzzy PID controller and its application to non-minimum phase systems

An integrated control system which includes the fuzzy PID controller and the grey predictor is investigated on the approaches to non-minimum phase (NMP) systems. Since the grey predictor can predict the undershoot phenomena of NMP systems, it offers the fuzzy PID controller suitable prediction to generate the appropriate control action on undershoot elimination. In addition, the grey predictor provides suitable compensation by a proper step size. Therefore, we design another fuzzy controller to decide the step size of the grey predictor such that the compensation is suitable. The controller design and computer simulations are examined under several different conditions. The results demonstrate that the proposed controller can eliminate the undershoot phenomena of NMP systems effectively.