Abstract: Actuators are the key agency of the UAV. For fault detection and fault diagnosis purpose of problems such as the dead, gain loss and deviation of the actuator, the fault detection filter and Kalman filter were presented in this contribution. The residual vector with actuator fault information was output by using the detection filter, then the threshold detection and residual direction characteristics were used to detect and isolate the fault. After the fault alarm, the Kalman filter was used to estimate the fault parameters, and the nature and extent of the fault were obtained. According to the different forms of fault, the method of control command compensation or reconstruction was finally used for fault-tolerant control purpose. Based on the turning rate model of the X-tails UAV, simulation test showed that the fault diagnosis method was effective and feasible, which could rapidly obtain the fault information, and the fault-tolerant strategy could well restore the system performance.

Key words: forgetting-factor Kalman filter, control reconstruction, actuator fault, detection filter