Fault detection based on equally divided sampling period to data packet dropout in networked control systems

Considering a class of networked control systems with time-varying delays, the fault detection is carried out with the presence of output delays and packet dropout in sensor data. By increasing sampling frequency in controller and equally dividing the sampling period of the sensor, the time delays could be approximate to an integral multiple of the sampling period of the controller. On this basis and the conditions of data arrival of controller, the error equation of the fault observer was constructed based on a discrete asynchronous dynamical system. And a linear matrix inequality gave the stability condition of this observer. When the system was normal, if the given inequality condition was satisfied, the observer system was stable. When a fault was present, the observer residue could change rapidly and detected the occurrence of the fault. Finally, an illustrative example was given to demonstrate the effectiveness of the proposed method.