【作者】 王军；

【导师】 伍剑；

【作者基本信息】 北京邮电大学 ， 电子与通信工程， 2019， 硕士

【摘要】 多线激光雷达目前在无人驾驶领域应用十分广泛,可以说是无人驾驶硬件生态中最重要的部分。本文旨在研究高精度多通道的时间测量单元和高速无线传输系统,以满足课题组研制高刷新率、高角分辨率、高精度的多线激光雷达的需求。本文首先对基于FPGA的高精度计时系统进行研究。详细调研和总结了常用的数字时间测量技术,选定了延时链内插法这一方案,并结合应用场景与需求提出了 TDC(Time-to-Digital Converter)模块的详细设计方案。所设计的TDC包括基本计时单元、TDC控制单元和主机接口这3个主要模块。之后在Xilinx XC6SLX9芯片实现了4组8路单精度TDC、2组4路双精度TDC,每路TDC均支持对连续多个停止脉冲的测量。其次对嵌入式环境下的WiFi传输系统进行了调研,选用了STM32F767作为主控,Marvell 88w8686作为WiFi芯片,两者通过SDIO接口进行通信。参照WiFi芯片的寄存器手册和固件接口手册在STM32F767上实现了WiFi驱动,移植了LwIP协议栈,并搭建了 UDP服务与上位机进行通信,以实现雷达点云数据的实时传输。为了验证所实现的TDC和WiFi模块的性能,论文搭建了一套测试系统,并进行了大量的实验和测试。实验结果表明,所实现的TDC测量精度等效为单精度41ps,双精度31ps,分辨率达到单精度74ps,双精度37ps,并对系统误差进行了分析;WiFi模块的平均ping值为1ms,UDP下最高通信速率稳定在24Mbps。TDC和WiFi的性能均满足预期需求,有良好的实用价值。更多还原

【Abstract】 Multi-beam LiDAR is currently widely used in autonomous driving,and is almost the most important part of the autonomous driving hardware ecosystem.In this paper,a high-precision,multi-channel Time-to-Digital Converter and a high-speed wireless transmission module has been designed and reached,which aims to satisfy the requirement of the high-speed,high-angle resolution,high-precision multi-beam LiDAR of the research group.Firstly,this paper investigates and summarizes several methods used to realize a TDC in detail.Based on the research on high-precision FPGA-TDC,a design using delay chain interpolation is proposed.The designed TDC includes three basic modules,the basic timing unit,the TDC control unit and the host interface unit.Four sets of 8-channel single-precision TDC and two sets of 4-channel double-precision TDC is implemented on Xilinx XC6SLX9 chip.Each stop channel of the TDC supports measurement of multiple pulses.Secondly,the WiFi transmission system in the embedded environment is investigated.The STM32F767 is selected as the controllor,and the Marvell 88w8686 is used as the WiFi chip,which communicated through the SDIO interface with the controllor.Referring to the register manual and finnware interface manual of the 88w8686 WiFi chip,the WiFi driver is implemented on the STM32F767,the LwIP protocol stack is also transplanted,and the UDP service is built to communicate with the host computer to realize real-time transmission of the LiDAR point cloud data.In order to verify the performance of the implemented TDC and WiFi modules,the paper built a test system and conducted a lot of experiments and tests.The experimental results show that the achieved TDC’s resolution is up to 74ps with single precision and 37ps with double precision.The measurement accuracy is equivalent to single precision 41 ps,double precision 31ps,and the system deviation is also analyzed.The average ping value of WiFi module is 1 ms,the highest communication rate in UDP is stable at 24 Mbps.The performance of both TDC and WiFi meets the expected requirements and has good practical value.更多还原