较粗空间分辨率影响下FMCW 激光雷达测距方法研究

Research on FMCW lidar ranging method under theinfluence of coarse spatial resolution

由于环境中杂散光和电磁干扰等原因,以及不同路径的长度和反射特性的差异,FMCW激光雷达系统在接收目标回波信号时会受到多径干扰的影响,存在噪声干扰,使得目标测距结果准确性较低。为此,提出较粗空间分辨率影响下FMCW激光雷达测距方法。根据FMCWN激光雷达系统的发射信号与回波信号获取中频信号;采用EMD算法分解中频信号,计算信号IMF分量之间的互相关系数,确定并剔除存在噪声的IMF分量;采用SFFT算法对去噪后的中频信号频谱局部细化处理,获取其估计值,确定修正方向,修正频率估计值,利用中频信号修正后的频率确定被测目标的距离。实验结果表明,所提方法具有良好的去噪效果、频谱估计精度、测距精度高,测距效率高,测距均方根误差均在0.04以内,耗时最长仅为0.23 ms。

Due to the stray light and electromagnetic interference in the environment,as well as the differences in the length and reflection characteristics of different paths,the FMCW liDAR system will be affected by multipath interference when receiving the target echo signal,and there is noise interference,which makes the accuracy of target ranging is low.Therefore,the FMCW LiDAR ranging method under the influence of coarse spatial resolution is proposed.According to the transmitting signal and echo signal of FMCWN laser radar system,IF signal is obtained.The EMD algorithm is used to decompose the IF signal,calculate the mutual relations between the IMF components of the signal,and determine and eliminate the IMF components with noise.The SFFT algorithm is used to refine the frequency spectrum of the IF signal after noise removal,obtain its estimate,determine the correction direction,correct the frequency estimate,and determine the distance of the measured target by using the corrected frequency of the IF signal.The experimental results show that the proposed method has good denoising effect,high spectrum estimation accuracy,high ranging accuracy and high ranging efficiency.The root mean square error of ranging is less than 0.04,and the longest time is only 0.23 ms.