Robustness against unknown Networked induced Delays of Observer based FDI

In this paper, we are concerned by the problem of Fault diagnosis in Networked Control Systems (NCS). The effect of unknown networked induced delays on conventional observed based residual generator is studied. It is shown that the detection performances may be reduced due to the sensitivity of the residuals to the delays. With the assumption that the network delays belong to a given bounded set , in order to enhance the robustness of fault detection an adaptive evaluation procedure of the residuals is proposed. The detection thresholds which depend on the maximum influence of the network delays are estimated using an optimization approach.