Predictor based two-degree-of-freedom control design for industrial stable processes with long input delay

In this paper an analytical two-degree-of-freedom (2DOF) control design method is proposed for stable processes with long input delay in industrial applications. Based on using a predictor based control structure, the plant time delay can be taken out of the control loop for the nominal plant, such that an analytical design of the controllers is developed in terms of the delay-free part of the nominal plant model. The controller for load disturbance rejection is designed by proposing the desired closed-loop transfer function, and the set-point tracking controller is designed in terms of the internal model control theory. Both controllers can be monotonically tuned by a single parameter to make a good trade-off between nominal control performance and robustness against process uncertainties. At the meantime, the control performance for set-point tracking and load disturbance rejection is quantitatively analyzed in terms of the integral-absolute-error (IAE) specification, along with robust stability conditions. Illustrative examples from the literature are shown to demonstrate the effectiveness and advantage of the proposed method.