Robust linear estimator for networked control systems with incomplete observations: A dropping over-delayed packets approach

This paper addresses the problem of noise tolerance of a linear estimator for discrete-time networked control systems with incomplete observations and process noise with variable intensity (here expressed by its covariance). Through modified Riccati equation with packet arrival rate and linear matrix inequality theorem (LMI), our approach is to first provide an analytic relation between the filter convergence and the packet arrival process. Then a robust bound of packet arrival rate is proved to exist. We design a dropping over-delayed packet strategy so as to satisfy robust packet arrival rate. Moreover, unified algorithms to find the tradeoff with the process noise with admissible intensity is provided in terms of a given restriction of admitted state estimation error-covariance. Such a tool can help in modern industrial networked control applications. Examples demonstrate its effectiveness.