关键词：非线性网络物理系统；故障检测；传感器
摘 要：A fault is deviation of a characteristic property of a system from acceptable, standard condition. That is, some components of the process under consideration may not respond according to their desired behavior, for example, there may be blockage in pipes, the valves controlling the flow rates of fluids may stuck up, the gears in mechanical systems may be broken, the sensors measuring position, temperature, pressure or any other quantity may give incorrect results. Faults may have several effects on plants, for example, if there is a sensor fault, the plant will be operating away from its nominal/optimal operating point resulting into reduced efficiency of the plant and lower quality of product. Furthermore, in dynamic systems, if the sensor measurements are also being fed back, the stability of the process may be at risk. Likewise, if there is fault in actuator of the process, it will stop responding (or will respond incorrectly) to the inputs; this will reduce the availability of the plant. All these factors cause economic losses. In certain safety critical processes, faults not only cause economic losses, but may also be fatal. For example, there was a fatal accident in the isomerization unit of British Petroleum operated oil refinery in Texas, USA. Five people were killed and over 170 harmed as a result of the explosion. The investigations showed that the reason was a faulty sensor in the unit which was stuck to measure a constant liquid level despite it was continuously increasing. The disastrous effects of faults may be avoided/ minimized if faults are quickly detected and remedial actions are timely taken. For example, there was an accident in American Airline DC10 which crashed at Chicago O'Hare International Airport. Later studies indicated that the accident could have been avoided. Boeing 747-200F lost both of its engines while taking off from Schiphol International Airport. The post-accident analysis showed that this accident could have been avoided if the faults were detected and controllers were reconfigured accordingly.