Fault diagnosis of distributed networked control systems

In order to deal with the limited bandwidth of the network and to avoid the uncertainty caused by transmission delays and packet loss, two-level DNCS with deterministic communication logic is presented and central fault diagnosis unit is designed under this communication pattern. The central FDI unit and each subsystem both have identical estimators and thus identical state estimate. For each subsystem, instead of transmitting data to the central FDI unit every sample time, only when the difference between the actual and estimated state of the subsystem is greater than a threshold, the actual state of the subsystem is broadcasted to state estimator in the central FDI unit, otherwise this is no data on the network. Using the inputs and outputs of the subsystems obtained from the state estimator in the central FDI unit, observer-based fault diagnosis is proposed. Finally the simulations are presented and discussed.