A Unified Filtering Framework of Networked Control Systems Subject to Variations in Quantization Density

In this article, a novel approach toward addressing the filtering problem for a class of networked control systems (NCSs) with a mixed $\mathcal {H}_{\infty }$ and passive (MHP) performance index is proposed. The underlying NCSs may manifest different characteristics (called quantization density herein) when subjected to channel switching. As such, it is possible to model the NCSs as a class of switched systems. A mode-dependent and quantization-error-dependent Lyapunov-like function is first adopted in order to conduct stability and MHP performance analysis with less conservatism. Based on the developed stability and MHP performance analysis, a set of MHP filters suitable for the controlled system is designed such that the filtering error system is globally uniformly asymptotically stable with a specified MHP performance index. The effectiveness and potential applications of the derived results are demonstrated via a numerical simulation.