A simple two-degrees-of-freedom control strategy for first order time delay processes

An analytical tuning method for a PID controller cascaded with a lead/lag filter is proposed for FOPDT processes based on the IMC design principle. The controller is designed for the rejection of disturbances and a two-degree-of-freedom control structure is used to slacken the overshoot in the set-point response. The simulation study shows that the proposed design method provides better disturbance rejection than the conventional PID design,methods when the controllers are tuned to have the same degree of robustness. A single tuning parameter closed-loop time constant (A) guideline is provided for several different robustness levels.