Realization And Design Of Hierarchical Fault Diagnosis Of Satellite Attitude Control System

Fault diagnosis techniques has provided a new way to improve the reliability of satellite systems, enabling satellite to respond quickly to system abnormality so as to reduce or even avoid catastrophic accidents. This thesis, with the attitude control system of earth-oriented three-axis stabilized satellite as the study object, designs a hierarchical fault diagnosis algorithm and sets up bus protocol-based satellite demo platform to verify effectiveness of the fault diagnosis algorithm.The mathematical models of satellite body, attitude sensor and flywheel are firstly established. In setting conditions, simulations of satellite's three basic flying tasks, namely, initial rate damping, sun capture and earth-oriented, are performed, which lays the foundation for the later studies of fault diagnosis algorithm.Hierarchical fault diagnosis algorithm is designed for the fault that may occur in ACSS. Based on combination of double fault diagnosis observers and parity vector, a system-level fault diagnosis method is presented, which can accurately detect and isolate failure of flywheel actuator, gyro unit and star sensor. Then a method of board-level fault detection is designed based on Built-in Test (BIT) techniques, which can detect if the three RS232 serial ports, AD/DA interface and temperature of the circuit board are working correctly.Finally, a hierarchical fault diagnosis demonstration system of attitude control system in earth-oriented three-axis stabilized satellite is set up. According to the mathematical model of the equipment, eleven equipment simulators'programs are designed, including on-board computer, TT&C transponder, and fault diagnosis modules and so on. Demonstration system can accomplish satellite's three basic missions and equipment emulator's equipment information collection; and realize both system-level and board-level fault injection and diagnosis. Two ground monitoring software, i.e. remote terminal unit and fault diagnosis terminal, are designed with the application of LabWindows/CVI. The software can reflect the satellite'failure location and operational status in the form of indicators and curves through the data transmitted from TT&C transponder and fault diagnosis modules.