New design method of PID controller for inverse response processes with dead time

Inverse response processes is difficult to control caused by the presence of right half plant (RHP) zeros. In this paper, using Pade approximation, the RHP zeros can be approximated to the form of the dead time. Then, the controller can be designed for the general stable processes plus dead time instead of considering the effect of the RHP zeros. An analytical design procedure is developed based on the conventional unity feedback control structure. The resulting PID controller includes a single adjustable control parameter. By monotonously tuning the single controller parameter, the best compromise between the nominal performance and robust stability of the closed-loop system can be realized