Modified Smith predictor and controller for time delay processes

A modified Smith predictor control scheme is proposed for controlling stable, integrating and unstable processes with time delay. The two-degrees-of-freedom control structure along with simple tuning rules result in improved servo and regulatory performances by independently tuning a single control parameter. A convenient property of the proposed control scheme is that it decouples the setpoint response from the load response. The H2 optimal control method is used to design the setpoint tracking controller and an optimal IMC filter is proposed to design a PID controller that produces good disturbance rejection performances. Simulation results show the simplicity and superiority of the proposed method compared with some reported methods.