The Fault Diagnosis Technology Based On Models And It's Application In The Electro-mechanical Actuator

The research object of this paper is the electro-mechanical actuator system. The main aim is researching the technology and application of fault diagnosis and detection (FDI) for the electro-mechanical actuator to improve the rapidity of fault detection and the level of intelligence. Now the method to break down into subsystem and replace testing is mainly used in the fault detection of the electro-mechanical actuator, but it has some shortcomings that it is inefficient and difficult to find the source of fault, so the fault diagnosis for the electro-mechanical actuator should be further studies. The model-based fault diagnosis is able to diagnose incipient faults and separate sources of fault, this method will increase the diagnosis efficiency of the electro-mechanical actuator. A systemic and deep study on diagnosis technique based on model is made in this dissertation. The main work is as follows.Firstly, the author introduced the theory of model-based fault detection, described the normal and fault model of system, the methods of generating residual, the selection method of threshold, and proved this method had ability to detect faults when the system was in faulty.Secondly, the author built the mathematical models of the electro-mechanical actuator in the normal system, and analyzed and simulated the faults of the integrate amplifier,the electromotor, the potentiometer and some other common faults.Thirdly, the author introduced the method to construct fault detection observers, analyzed the error between fault detection observer and the actual system, and diagnosed the correcting amplifier in perfect state through constructing the fault detection observers. The observer which considered the external disturbance and model error as the unknown input diagnosed the faults of sensor, the theoretical analysis and simulation results showed the validity of this method.Lastly, a fault diagnosis method based on Kalman filters was studied; the residual generated by Kalman filters could be used to diagnosis faults on-line. A residual generator based Kalman filters was constructed, the simulation results proved the validity of this method.The research results of this paper provide the important references to the fault detection of electro-mechanical actuator system in engineering.