Set point response and disturbance rejection tradeoff for second-order plus dead time processes

In this paper, we shall present simple and effective tuning formulas for IMC controllers when they are applied to second-order plus dead-time processes (SOPDT). We have discovered that for controllers designed by applying IMC method, the proportional gain, the integral gain, the derivative gain of the PID part of the controller and an associate filter should all be modified according to the given formulas for the purpose of achieving set-point response and disturbance rejection tradeoff. The study has also shown that the tradeoff between set point response and disturbance rejection is limited by normalised dead time of the SOPDT processes for the simple pole cases.