The dynamic output feedback controller design is a difficult hotspot in control fields.The dynamic output feedback controller design for continuous-time Takagi-Sugeno(T-S)fuzzy system is researched by analyzing the role of free variables in stability conditions.The details are as follows:1. The robust filtering design for discrete-time linear system is studied. First of all,the first filtering design method is obtained by introducing ‘outer’ variables, and its advantages and disadvantages are analyzed. The second filtering design method is acquired by introducing ‘inner’ variables, and the advantages and disadvantages are studied. Second, based on the analysis in the possible source of conservatism of the original system, an iteration algorithm is proposed to reduce the conservatism. Finally,the comparison of the three methods shows the following conclusions: generally, the former two methods are easier to operation than the third method, but the iteration algorithm can further reduce conservatism when the technique of introducing variables fails. And the relationship between introducing ‘outer’ and ‘inner’ variables is discussed and there is no necessary between them.2. The dynamic output feedback controller design for T-S fuzzy system is studied.Based on the study of part 1, the slack variables are applied to the dynamic output feedback controller design for fuzzy systems, and play an important role in the control conditions. First, the derivative of the membership function is studied. Using the Schur complement, the boundary condition is transformed into Linear Matrix Inequality(LMI).Then, the non-quadratic Lyapunov function with diagonal structure is proposed and some LMIs are obtained by scaling to meet the requirement that the derivative of Lyapunov function should be less than zero. |