Study On Fault Mode Analysis And Fault Diagnosis Of Satellite Attitude Control System

The satellite attitude control system(SACS) is one of the most important subsystems of satellite, its reliability is the basic guarantee for normal operation of the satellite. Because of the complex structure, poor working environment, unknown disturbance and uncertain factors, SACS is also one of the subsystems which are most prone to failure. In this background, this article takes SACS as the object of study, by analyzing the relationship between the common faults of the different components of attitude control system(momentum wheel, star sensor, sun sensor, and infrared earth sensor) and its characteristic parameters, how to diagnose the potential faults of the SACS based on telemetry data is studied.Firstly, the structure and working principle of the momentum wheel, star sensor, sun sensor and infrared earth sensor are analyzed in detail in this article, combined with relevant literatures, this article has summarized the types, features and causes of the common fault modes of the the components which are studied. It lays the foundation for the fault diagnosis of attitude control system.Secondly, according to the satellite telemetry signal acquired and the working mechanism of the components of SACS, the characteristic parameters of fault diagnosis for SACS are proposed in this article. The validity of the proposed parameters is verified by the analysis of the telemetry signal.For the momentum wheel, this article has established the simulation model of it in the matlab/simulink environment according to the physical relationship between the various observation variables. The validity of the simulation model has been verified by Theil inconsistency coefficient method, grey correlation method and spectral analysis method. Based on the fault mechanism of different fault modes of the momentum wheel, this article has analysed the fault modes of momentum wheel by simulating. According to the fault simulation signal, the influence of the fault mode on the observation variables of the momentum wheel has been described. At the same time, by analyzing the characteristic parameters of the fault simulation signal, the correspondent relationship fault modes and characteristic parameters has been obtained. According to the corresponding relationship between different fault modes and the corresponding parameters of momentum wheel, this article extracted 8 rules for fault diagnosis of momentum wheel by decision tree method. The validity of the diagnosis rules is verified by the analysis of the momentum wheel simulation signal of different conditions.For the attitude sensors, this article established the integrated satellite attitude control system simulation model firstly based on the satellite attitude dynamics and kinematics equations and combined Kalman filtering method for multi sensors attitude determination, And then, the simulation signal of the attitude sensors is obtained by the model of each sensor. According to the fault features of different fault modes of each sensor, the fault simulation of star sensor, infrared earth sensor and sun sensor has been carried out. By analyzing the characteristic parameters of the fault simulation signal of each sensor, the relationship between the fault modes and the characteristic parameters of the attitude sensors is obtained, 19 rules for fault diagnosis of attitude sensors is extracted througth decision tree method. The validity of the diagnosis rules is verified by the analysis of the sensor simulation signals of different conditions.