A state-delay system approach to fault detection for networked control systems

This paper considers the fault detection problem for networked control systems (NCSs) with both network-induced delay and data dropout. By transforming the NCS into a state-delay system, we can obtain a time-independent fault detection filter for the NCS, directly utilizing the fault detection methods for state-delay system. An observer-based fault detection filter (FDF) is firstly proposed for residual generation. Then a performance index is introduced to enhance the robustness of fault detection filter and, based on it, the fault detection filter design problem is formulated as an H infin optimization problem. Considering the unbounded network-induced delay (the worst-case transmission), a delay-independent solution of the optimization problem is derived by applying Lyapunov-Krasovskii approach. The residual evaluation problem is also considered. Finally, an illustrative design example is employed to demonstrate the validity of the proposed approach.