Showing papers by "Chun-Hsiung Fang published in 2006"

A new LMI-based approach to relaxed quadratic stabilization of T-S fuzzy control systems

Abstract: This paper proposes a new quadratic stabilization condition for Takagi-Sugeno (T-S) fuzzy control systems. The condition is represented in the form of linear matrix inequalities (LMIs) and is shown to be less conservative than some relaxed quadratic stabilization conditions published recently in the literature. A rigorous theoretic proof is given to show that the proposed condition can include previous results as special cases. In comparison with conventional conditions, the proposed condition is not only suitable for designing fuzzy state feedback controllers but also convenient for fuzzy static output feedback controller design. The latter design work is quite hard for T-S fuzzy control systems. Based on the LMI-based conditions derived, one can easily synthesize controllers for stabilizing T-S fuzzy control systems. Since only a set of LMIs is involved, the controller design is quite simple and numerically tractable. Finally, the validity and applicability of the proposed approach are successfully demonstrated in the control of a continuous-time nonlinear system.

H/spl infin/ Control for Discrete-Time Fuzzy Descriptor Systems

Abstract: This paper investigates the problem of H/spl infin/ control for T-S fuzzy discrete-time descriptor systems. Firstly, an analysis result for H/spl infin/ control is derived and characterized by a set of linear matrix inequalities (LMIs). The derived analysis condition is then applied to design an H/spl infin/ fuzzy controller. In T-S fuzzy discrete-time descriptor systems, due to singularity of E-matrix, Schur complement cannot be applied to solve the nonlinear Lyapunov inequality anymore for H control. The difficulty is overcome by the approach proposed in this paper. Before this presentation, no result about the H/spl infin/ control of T-S fuzzy discrete-time descriptor systems is available in the literature, the paper seems the first one to tackle it from the theoretical aspect.

An Improvement on Robust H∞ Control for Uncertain Continuous-Time Descriptor Systems

Abstract: This paper proposes a new approach to solve robust H ∞ control problems for uncertain continuous-time descriptor systems. Necessary and sufficient conditions for robust H ∞ control analysis and design are derived and expressed in terms of a set of LMIs. In the proposed approach, the uncertainties are allowed to appear in all system matrices. Furthermore, a couple of assumptions that are required in earlier design methods are not needed anymore in the present one. The derived conditions also include several interesting results existing in the literature as special cases.

Robust H2 control analysis and design for continuous-time interval state-space systems

Abstract: This paper considers the robust H 2 control problem of continuous-time interval state-space systems. A necessary and sufficient LMI-based condition is derived for analysis of quadratic stability and robust H 2 control. Using the analysis result, a state feedback controller and a static output feedback controller can be designed so that the closed-loop interval state-space system is quadratically stable and all its transfer matrices have an H 2 -norm bounded by a prescribed value. Two LMI-based conditions are derived respectively for the solvability of the above design problems. To the best of the authors' knowledge, the results of robust H 2 performance of interval state-space systems is scarce in the literature. This paper seems the first one attempting to deal with robust H 2 control analysis and design of interval state-space systems.

Robust H/spl infin/ Control for Interval Descriptor Systems

Abstract: This paper considers robust H/spl infin/. control problem for interval descriptor systems. Necessary and sufficient LMI-based conditions are derived for robust H/spl infin/ control analysis of interval descriptor systems. Using the analysis result, feedback controllers are designed so that the closed-loop interval descriptor systems are admissible and their transfer matrices have H/spl infin/-norm bounded by a prescribed value. This paper seems the first one attempting to deal with robust H/spl inifn/ control problem of interval descriptor systems.

Output Feedback Controllers Synthesis with Practical Pole Clustering for Descriptor Systems

Abstract: The sufficient and necessary conditions for the poles of the closed-loop descriptor systems to locate in an LMI region are given in this paper in terms of only one positive definite matrices P. Hence the controller gain matrix K can be obtained explicitly. Compared to the literature, the exact eigenstructure assignment problem for descriptor systems is usually solved via extremely constrained procedures. On the other hand, for the LMI region pole clustering problem, the solvable conditions are expressed in terms of two positive definite matrices P and Q. Consequently, The controller gain matrix K can not be obtained explicitly. An example has been solved in the literature using a complicated procedure of eigenstructure assignment is solved significantly easier as a demonstration.