Controller design of a two-degree-of-freedom Smith predictor scheme for improved performance

A simple controller design method for a two-degree-of-freedom (TDF) Smith predictor control system is investigated to obtain an improved performance of setpoint tracking and disturbance attenuation. The setpoint tracking controller and disturbance rejection controller in TDF Smith scheme are designed as ideal PID controller and approximate derivative PID controller, respectively. Each controller is tuned by an adjustable parameter only. This provides designers a simple way to tune controllers and allows them to optimize setpoint tracking response and disturbance attenuation response simultaneously. Illustrative simulations and application to BW control in a papermaking process indicate the advantages of the proposed controller design method.