基于线性最小均方差估计的星敏感器故障诊断

针对使用两个星敏感器进行姿态测量的三轴稳定控制系统,利用星敏感器输出值与陀螺输出值的解析冗余关系,通过设计两个滤波器实现对不同星敏感器的故障隔离.考虑到陀螺测量噪声以乘性噪声的形式出现在姿态运动学方程中,利用陀螺输出测量值和目标星敏感器的测量值,采用线性最小均方差估计器得到包含目标星敏感器故障信息的残差; 以无故障情况下残差的统计方差为基础得到阈值,通过检验残差评价值是否超过相应的阈值,实现对目标星敏感器故障的检测; 分别将两个星敏感器作为目标星敏感器,综合两个故障检测结果隔离故障.对星敏感器出现测量偏差和精度逐渐下降两种故障的仿真验证了该方法的有效性.

Fault Diagnosis for Star Sensors Based on Linear Minimum Mean Square Filter

Based on the temporal analytical redundancy between the available star sensor and gyro measurements, two filters are utilized to isolate the star sensor faults in a three axis stabilized attitude control system with two star sensors. Considering that gyro measurement noise is multiplicative noise in the attitude kinematics equations, a residual generator based on the linear minimum mean square filter is designed to obtain residuals containing the fault message of the target star sensor. The target star sensor fault detection is realized by comparing the residual evaluation with the corresponding thresholds, which is computed according to the residual variances in fault free case. Star sensor faults are located by setting one sensor as the target each time and checking the detection logic afterwards. Numerical simulation results show that either abrupt faults or slow degradation of the measurement accuracy of star sensors can be isolated by the designed method.