Robust model predictive control : matrix inequality based approaches
魯棒模型預測控制 : 基於矩陣不等式的方法
Student thesis: Doctoral Thesis
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Award date | 2 Oct 2013 |
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Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(cc13d0fc-782f-479b-884a-784430c9da63).html |
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Other link(s) | Links |
Abstract
Model predictive control (MPC) is widely used in many chemical processes. In the
past two decades, a plethora of results on analysis and synthesis of MPC and robust
MPC have been obtained. Many approaches have also been developed to facilitate
analysis and synthesis of MPC and robust MPC, one of which is based on linear
matrix inequalities (LMIs) technique. Many results on MPC using the LMI-based
approach have been obtained. However, few papers investigate MPC for systems
with persistent disturbances. Actually, systems are always subject to disturbances in
practice. Hence, it is desirable to take into account disturbances in the analysis and
synthesis of MPC.
Two classes of control problems are discussed in this thesis. Firstly, predictive
control methods are developed to steer the system states to the origin (equilibrium
point), which guarantees input-to-state stability of the closed-loop control system.
The concept of robust positively invariant set is introduced to guarantee the feasibility
of the optimization problem to be solved online. The results are presented
for linear parameter varying (LPV) systems, and then extended to a special class
of nonlinear systems — Takagi-Sugeno (T-S) fuzzy systems. Secondly, the problem
of steering the system state to a predetermined set is also investigated. Specifically,
control strategies that can guarantee finite settling time are proposed. To this end,
the concept of robust one-step set is introduced. The problem is discussed for both
LVP systems and T-S fuzzy systems. For a special case, that is linear systems without
parameter uncertainties, a varying horizon predictive control strategy is further
proposed, which allows a long prediction length as well as more free variables in the
optimization of system performance. To reduce the online computing work, off-line
computations are considered for the varying horizon MPC strategy.
This thesis also studies robust MPC of a practical energy system - a direct
methanol fuel cell system. After representing the system as a T-S fuzzy model, a
robust predictive controller is employed to regulate the system to a desired operating
point. The simulations reveal the effectiveness of the controller in dealing with
disturbances and uncertainties.
- Matrix inequalities, Predictive control