Studies On Robustness Of Constrained Receding Horizon Predictive Control

Predictive control is a class of digital control algorithms developed in the late 1970's. Its current control action is obtained by solving, at each sampling instant, a finite horizon open-loop optimal control problem, using the current state of the plant as initial state; the optimization yields an optimal control sequence and the first control in this sequence is applied to the plant.The popularity of these methods is due to the facts that they can offer good performance, be understood and formulated easily, robustness to the model uncertainty and accommodate input/output process constraints. Because of all of these, predictive control strategies have been applied in industries widely, especially in complex chemical process control. The dissertation first gives a systematic summary on the development of Predictive Control and the present research state of stability and robustness. Based on this, the research is focused on robustness of constrained receding horizon predictive control. The main contents of this thesis are stated as follows:1.It analyzed the three characteristics of the MPC(model for prediction, receding horizon optimization, feedback)and obtained the conditions of the close loop stability of MPC by using the Lyapunov method.2.By applying the Lyapunov method and the Taylor formula to the optimal value cost function, the robustness properties of the receding horizon predictive control system with terminal equality constraint is studied. The robustness properties of a class of linear system in the presence of model error is analyzed. A sufficient condition and upper -bound for closed –loop system robust stability is presented. The robust domain of a class of nonlinear system in the presence of control system perturbations is analyzed.3.The robust control for a receding horizon predictive control system with terminal inequality constraint is discussed. The system with terminal inequality constrain has a dual-mode structure. As results, A sufficient condition of robust stability of nonlinear predictive control system with a dual-mode structure and corresponding robust dual- mode receding horizon predictive control algorithm are given.