The combined diagnosis approach for the satellite attitude control system based on observer redundancy

The satellite attitude control system is composed of measuring component, executing component and controller. When the satellite works in the space, the fault probability of optical sensors, inertial sensors, and the reaction flywheels is very high. Fault diagnosis for each subsystem is the premise to identify the cause of the malfunction and avoid the disaster, which can guarantee the safe and reliable running of the satellite. In this paper, a combined diagnosis approach based on observer redundancy is proposed to isolate the faults of optical sensors, inertial sensors and the flywheels. It solves a diagnosis problem that the common diagnosis method based on state estimation has difficulty in separating the input fault (actuator fault) and output fault (sensor fault) of the system. Then the attitude control system of earth-oriented three-axis stabilized satellite has been studied, and the fault isolation strategy for flywheel, gyro and star sensor based on observer redundancy is given. Finally, the results of simulation show that this method can accurately diagnose the faults of the three key components and proved effectiveness of the combined diagnosis method based on observer redundancy.