Performance enhancement in disturbance rejection by PID controller in series with low pass filter

In this paper a new tuning procedure is described for the ideal PID controller in series with the first-order low pass filter. It is based on the direct synthesis approach. Analytical expressions for the PID controller are derived for a common type of process model. Although the controller is designed for disturbance rejection, the set point response is satisfactory and can be improved by adjusting a single set point weighing factor b. Three simulation examples demonstrate that the proposed design method results in very good control for process models. IAE (Internal absolute error) of the proposed method is having smaller value than DS-d controller. In example 2 it is reduced up to 85%. As a result the proposed design method provides better disturbance rejection than the standard direct synthesis.