Design of state observer for discrete-time fault complex interconnected networks with different nodes

For a class of discrete-time complex interconnected networks with time-varying delay and linear coupling, a state observer is designed based on linear matrix inequality technique in order for the further design of the fault diagnosis observer in the case of un-observable system state. Then a fault diagnosis observer is designed to realize the fault detection. For the unknown uncertainty, an online approximator is designed to approximate the uncertainty, which will further help to reduce the modeling error. Stability analysis of the approximator is proved in detail. Finally, a simulation example is used to verify the validity of the presented results.