面向FMCW激光雷达的改进型apFFT算法处理与硬件实现  

Improved apFFT Algorithm Processing and Hardware Implementation for FMCW LiDAR

作　　者：袁野 姜成昊 刘宇[1,2] 张志坚 朱精果 YUAN Ye;JIANG Chenghao;LIU Yu;ZHUANG Zhijian;ZHU Jingguo(Institute of Microelectronics of the Chinese Academy of Sciences,Beijing 100091;University of Chinese Academy of Sciences,Beijing 101408;Southwest Institute of Technical Physics,Chengdu 610041)

机构地区：[1]中国科学院微电子研究所,北京100029 [2]中国科学院大学,北京100049 [3]西南技术物理研究所,成都610041

出　　处：《长春理工大学学报（自然科学版）》2024年第6期15-25,共11页Journal of Changchun University of Science and Technology(Natural Science Edition)

基　　金：激光雷达与期间重点实验室基金资助(LLD2023-009)。

摘　　要：针对调频连续波(Frequency Modulated Continuous Wave,FMCW)激光雷达后端信号处理FFT频率估计算法存在的栅栏效应、频谱泄露效应及处理速度瓶颈等问题,提出一种改进型apFFT(all-phase FFT,apFFT)时移相差高鉴频精度高处理速度算法,将数字下变频(Digital Down Conversion,DDC)输出信号的相位特征与apFFT算法的初相不变性有效结合,利用功率特征减少FFT运算点数来加速鉴频过程,此外将功率信息处理得到补偿的频谱偏移参数用于apFFT相差法鉴频的频移补偿提高鉴频精度。通过仿真和FPGA验证,该算法在1024采样点时相较于传统FFT算法,均方根误差降低了85%,平均鉴频误差小于100 Hz。最后搭建了FMCW测距测速系统进行外场实验,对10000次测量结果进行统计,测距标准差均小于8 mm,最小测距标准差为0.58 mm,测速标准差均小于0.04 m/s,最小测速标准差为0.0087 m/s,鉴频速率可达25 kHz。To address issues in the backend signal processing of Frequency Modulated Continuous Wave(FMCW)LiDAR,such as the picket-fence effect,spectral leakage,and processing speed bottlenecks of traditional FFT-based frequency estimation algorithms,an improved all-phase FFT(apFFT)time shift phase difference algorithm with high frequency estimation accuracy and processing speed is proposed.This method effectively combines the phase characteristics of the Digital Down Conversion(DDC)output signal with the initial phase invariance of the apFFT algorithm.By leveraging power characteristics to reduce the FFT calculation points,t he frequency estimation process is accelerated.Additionally,t he power-based spectral offset compensation parameters are applied to the apFFT phase difference method to further enhance frequency estimation accuracy.Simulations and FPGA validations demonstrate that,with 1024 sampling points,t he proposed algorithm reduces the root-mean-square error(RMSE)by 85%compared to traditional FFT methods,with an average frequency estimation error of less than 100 Hz.A complete FMCW ranging and velocity measurement system was imple-mented for field experiments.Statistical analysis of 10000 measurements shows that the standard deviation of ranging results is less than 8 mm,with a minimum of 0.58 mm.The standard deviation of velocity measurements is less than 0.04 m/s,with a minimum of 0.0087 m/s.The frequency estimation rate reaches up to 25 kHz.

关 键 词：FMCW激光雷达 测距测速 高速高精度 实时处理 全相位时移相差 

分 类 号：TN958.98[电子电信—信号与信息处理]