This note investigates the problem of output feedback H _∞ control for linear discrete-time systems. Three types of H _∞ controllers are considered, namely, static output feedback controllers, dynamic output feedback controllers, and observer-based output feedback controllers. New design conditions for the three type of output feedback controllers are introduced in terms of unified linear matrix inequality (LMI) representations, which guarantee the prescribed H _∞ performances of the closed-loop systems. In contrast to the existing LMI conditions for designing the output feedback H _∞ controllers, the improvement of the proposed results over the existing ones is shown by theoretical proof and numerical example.

This paper is concerned with the problem of nonfragile H _∞ filtering for a class of continuous-time fuzzy systems. Attention is focused on the design of a filter such that the filtering error system preserves a prescribed H _∞ performance, where the filter to be designed is assumed to have gain variations. By using the quadratic Lyapunov function approach and adding slack matrix variables, sufficient conditions for designing the nonfragile H _∞ filter are proposed in terms of solutions to a set of linear matrix inequalities (LMIs). Finally, a simulation example will be given to show the efficiency of the proposed design methods.

This paper is concerned with the problem of nonfragile H _∞ filtering for continuous-time Takagi-Sugeno (T-S) fuzzy systems. The filter to be designed is assumed to have two types of multiplicative gain variations. First, two relaxed H _∞ filtering analysis conditions are proposed based on useful linear matrix inequality preliminaries. Whereafter, the results are exploited to derive sufficient conditions for designing a nonfragile H _∞ filter, which guarantees a prescribed H _∞ performance of the filtering error system. Compared with the existing results, the proposed design methods not only suit for a standard form of the fuzzy filter but also give more relaxed design conditions. Finally, simulation examples will be given to show the efficiency of the proposed design methods.

This paper is concerned with the H_∞ filtering problem for continuous-time Takagi-Sugeno (T-S) fuzzy systems. Different from existing results for fuzzy H_∞ filtering, the proposed ones are toward uncertain fuzzy systems with linear fractional parametric uncertainties. Attention is focused on the design of a fuzzy filter such that the filtering error system preserves a prescribed H_∞ performance, where the filter to be designed is assumed to have gain variations. By a descriptor representation approach, two sufficient conditions for the H_∞ filter design are proposed in terms of linear matrix inequalities (LMIs). When these LMIs are feasible, an explicit expression of the desired filter is given. A simulation example will be given to show the efficiency of the proposed methods.

In this article, the H∞ static output feedback tracking control problem is studied for discrete-time nonlinear networked systems subject to quantization effects and asynchronous event-triggered constraints. The Takagi-Sugeno (T-S) fuzzy model is utilized to represent the investigated nonlinear networked systems. A novel asynchronous event-triggered strategy is given to reduce the network communication burdens in both communication channels from the plant to the controller and from the reference model to the controller. The objective of this article is to design a quantized event-triggered tracking controller such that the resulting system is asymptotically stable and the given H∞ tracking performance is guaranteed. The sufficient design conditions for the tracking controller are formulated in the form of the linear matrix inequalities (LMIs). Furthermore, a simulation example will be utilized to show the effectiveness of the developed design strategy.