非均匀采样条件下光纤陀螺微小角振动信号检测技术

Signal detecting technique of FOG′s micro angle vibration under nonuniform sampling

航天器在轨运行过程中,由于内部存在多种活动部件,会使结构体产生微小角振动,微小角振动呈现振幅较小、频率较高的特点,微小角振动会造成光学载荷成像质量的下降。光纤陀螺从组成原理上具有宽频带和高灵敏度的特点,能够输出采样周期内的角度增量,可以作为微小角振动测量部件。但是,基于航天器整体时序的综合考虑,无法对光纤陀螺进行均匀采样,提出了非均匀采样条件下的频谱分析方法,将经过非均匀采样得到的整周期时间序列进行傅里叶变换,得到原始信号的幅值和频率,进而实现微小角振动的高精度检测。通过数字仿真和六自由度微振动台试验验证了上述方法的可行性,检测精度优于0.04″。

During the spacecraft′ s in-orbit running, its structure could get a micro angular vibration due to various moving parts inside, which has relatively small amplitude and high frequency and could result in quality reduction of the optical load′ s imaging. With broad bandwidth and high sensitivity, the FOG can output angular increment in a sample cycle, making it the perfect sensor of micro angular vibration.But FOG can′ t be sampled evenly considering the spacecraft ′ s whole scheduling. This paper proposes a frequency spectrum analysis method for nonuniform sampling, which transforms time sequence in a complete nonuniform sampling cycle to the fourier space to obtain original signal ′ s amplitude and frequency so as to achieve high precision measurement of the micro angular vibration. The method has a precision better than 0.04″, which was validated by digital simulation and 6-DOF micro vibration test.