Fault detection of networked control systems: An input delay approach

This paper introduces an input delay approach to fault detection of networked control systems (NCSs) with network-induced delay and data dropout. By using an input delay approach, the NCS is modeled as a continuous-time system with time-varying delays, where the piecewise-constant feedback control input is represented as the state with two additive delay components. A fault detection filter (FDF) is introduced to be the residual generator. Based on a new result on H
_∞
performance for systems with two successive delay components in the state, a sufficient condition for the existence of the FDF is presented in terms of a nonlinear matrix inequality formulation, dependently of time delay. To make the matrix linear, an iterative procedure of linear matrix inequality (LMI) minimum problem is given. A numerical example is employed to demonstrate the validity of the proposed approach.