Delay-Dependent H∞ Filtering for a Class of Time-Delayed LPV Systems

In this paper, we examine the problem of designing parameter-dependent H-infinity filters for the output estimation in an LPV plant that includes a constant state delay. The state-space data are assumed to depend on parameters that are measurable in real-time. We develop LMI-based delay-dependent conditions to guarantee both asymptotic stability and an L-2 norm bound performance, and we provide an explicit solution for the filters' state-space matrices in terms of LMI solutions. By taking the estimation error into account as the H-infinity criterion output, the designed filters have the capability of tracking the desired outputs of the plant in the presence of external disturbances. Our technique is shown to be reduced to delay-independent analysis conditions by relaxing some of the LMI decision variables, and some previous results are also shown to be particular cases of the current work. We examine both memoryless and state delayed filters that include delay terms to reduce conservatism in the design. Illustrative examples are used to demonstrate the proposed methodology for filter design and show the superiority of using the proposed delayed configuration for H-infinity filters compared to the memoryless filters.