Adaptive Threshold Real-Time Condition Monitoring and Assessment of Unmanned Aircraft Actuator Based on Two-Stage Observer

With the wide applications of unmanned aircraft, the flight safety of unmanned aircraft has attracted the attention of many scholars. The actuator controls the flight direction and attitude, and its actuating performance affects the whole unmanned aircraft. Real-time dynamic monitoring of actuator operation status is critical to unmanned aircraft flight safety. However, the existing fixed-threshold-based monitoring methods do not pay enough attention to the unmanned aircraft flight environment and operating conditions, resulting in false alarms or insufficient accuracy. This paper proposed a condition monitoring and quantitative assessment method of unmanned aircraft actuator based on radial basis function two-stage observer. We constructed the fault detection observer by fitting the relationship between the command signal and the position signal of the actuator, and the adaptive threshold observer is constructed by the command signal, output position, and standard threshold. The residuals between position signal and observer output represent the state of the actuator, and the dynamic threshold can reduce the interference of operational conditions in monitoring assessment results. Finally, we monitored the actuator performance of an unmanned aircraft during flight based on the proposed method. The results showed that the method accurately monitored and assessed the actuator under different flight conditions.