Research On Fault Diagnosis Of Satellite Attitude Control System

Fault diagnostic technology is essential to ensure the reliability and safety of system, Especially in the spacecraft attitude control system. As the studied satellite attitude control system in the dissertation. The paper studies fault diagnostic problem of the satellite attitude control system from the theoretical point of view, applying the nonlinear unknown input observer(NUIO) and adaptive observer to diagnose the executing agency and measuring agency on the satellite attitude control system. Working papers include the following aspects:First, the paper analyzes two descriptive methods of satellite attitude , attitude kinematics and dynamics are established, By analyzing the characteristics of satellite attitude control system, the executing agency and measuring agency which used in satellite attitude control system are identified. The faults which may occur are analyzed and modeled in the reaction flywheel and measuring agency.Secondly, Based on the basic design ideology of the unknown input observer(UIO), Robust fault diagnosis method based on NUIO and LMI is proposed, Disturbance decoupling principle of UIO and LMI is applied to design NUIO parameter matrix so that the residual is robust to model uncertainty and external disturbance. At last, mathematical simulation results demonstrate the effectiveness the proposed method.Thirdly, For the traditional fault diagnosis method based on adaptive observer, the error system meets strictly positive real conditions, the paper studies the application scope of adaptive fault diagnosis observer. In order to broaden application scope of adaptive fault diagnosis observer, a novel method of fault estimation and a augmented fault diagnosis observer are proposed. It applies LMI and regional pole assignment theory to design the augmented fault diagnosis observer and adaptive fault estimation parameter. At last, simulation results on the linearization lateral dynamic of a Boeing 747 airplane demonstrate the effectiveness the proposed method.Forth , satellite nonlinear attitude control system is established by use of MATLAB/simulink, NUIO is designed to diagnose the flywheels and the star sensors faults. satellite linear attitude control system is established by use of MATLAB/simulink a augmented fault diagnosis observer and adaptive fault estimation parameter is designed to estimate the flywheel faults by use of LMI and Regional pole assignment theory. At last, simulation results applied in the satellite attitude control system demonstrate the effectiveness of the proposed two methods.