FMCW激光雷达精密测量技术及振动特性研究

Research on precision measurement technology and vibration characteristics of FMCW lidar

针对激光器调频非线性对FMCW激光雷达测距精度的影响,研究利用辅助光路提取峰谷值点对测量光路进行重采样的方法。推导重采样测距公式,当测量环境中存在振动时,振动会使得待测目标出现移动,并在拍频信号中引入多普勒频移,增加拍频信号频谱宽度。因此,针对振动情况,利用交叠分时傅里叶变换计算不同时间窗内的频率值来对振动特性进行分析与回归校正。可得到测距中心距离为4.998 0 m,信号的平均振动周期为17.993 Hz,校正后得到目标物体的振幅为12.2μm,所提方法的测距精度均保持在90%以上。

Aiming at the influence of laser frequency modulation nonlinearity on the accuracy of FMCW lidar, the method of using auxiliary optical path to extract peak and valley points to resample the measuring optical path is studied. The re-sampling ranging formula is derived. When there is vibration in the measurement environment, the it will cause the target to be measured to move. The Doppler shift is introduced in the beat signal to increase its the spectrum width. Therefore, in view of the vibration situation, the frequency values in different time windows are calculated by using the overlapping time-sharing Fourier transform to analyze and regress the vibration characteristics. It can be obtained that the distance of the ranging center is 4.998 0 m, the average vibration period of the signal is 17.993 Hz, and the amplitude of target object after correction is 12.2 μm, and the ranging accuracy of the proposed method is maintained above 90%.