基于希尔伯特变化的微小振动激光多普勒信号处理

Micro-vibration laser Doppler signal processing based on Hilbert transform

为了实现对固体目标微小振动参数的测量,建立了微小振动的激光多普勒信号模型。采用希尔伯特数字运算,将激光多普勒振动信号的即时信号采样转化为信号的谱采样。通过频谱计算得到每个振动周期中瞬时频率的平均数,应用差值采样序列积分计算得到振动频率,最后根据振动信号频率变化与振幅的关系得到振幅。采用希尔伯特方法对实验测试结果进行处理验证,并分析了误差来源。实验结果表明:实验测量目标的振动振幅约为1.85×10-4m,转动的圆频率约为170 Hz。因此,应用希尔伯特变换方法处理测量的目标微小振动信号,获取目标运动的参数是可行的。

To measure the micro-vibration parameters of a solid target, the laser Doppler signal model of mi- crovibration for the solid target was established. First, the laser Doppler vibration instantaneous samples were converted into signal spectral samples based on Hilbert transform. Then, the mean value of the instantaneous frequency per vibration period was determined by spectral method, the value of vibration frequency was ob- tained by the quadrature procession of the difference sample sequences, and the amplitude was estimated ac- cording to the relation between frequency deviation and amplitude of vibration signal. Finally, experimental re- sults were verified according to the Hilbert measuring method and the error source was analyzed. Experimental results indicate that the vibration amplitude of the target is about 1.85 x 10 -4 m, and the rotation frequency is about 170 Hz. It is feasible to obtain the motion parameters by using Hilbert transform to measure target micro- vibration.