Design Of Laser Radar Photoelectric Transceiver Module And Control System For Unmanned Driving

Autonomous vehicles are a big step in the upgrading process of the automotive industry and have a broad development prospect.Highly accurate obstacle detection is an essential part of autonomous driving technology,and the ability to collect 3D information efficiently,rapidly and accurately about the surrounding environment plays a key role in the driving decisions of autonomous vehicles.Li DAR-based 3D vision systems offer unique advantages in fast environment perception.As an active detection device,Li DAR enables high-speed,real-time environmental information acquisition by emitting laser pulses.However,in practice,the frame rate and density of the point cloud data generated by conventional Li DAR are limited by the scanning method and cannot be adjusted by the needs of the scene.Based on this,this paper proposes a non-repetitive scanning Li DAR system based on a galvanometer scanner.Starting from the key technologies and implementation methods,a prototype Li DAR system is built and the overall performance of the system prototype is verified through experiments.The main research elements of the thesis are as follows:(1)The principles of phase laser ranging,triangulation and pulse laser ranging are analyzed and discussed.Based on the distance and real-time requirements for obstacle detection in autonomous vehicles,pulse laser ranging is selected as the ranging solution for the system,and the driving circuit of a high-power pulsed laser diode is designed.A narrow pulse high-power laser emission with a repetition frequency of 12 k Hz and a pulse width of 30 ns was realized.(2)A high-sensitivity,large-bandwidth,high-gain optical signal reception and processing circuit based on APD was designed to provide low-noise,low-latency I/V conversion and amplification,in response to the relatively weak optical signal.(3)After comparing the timing of the FPGA-based delay line circuit and the timing scheme of the TDC,the TDC was adopted to record the time of flight for performance and stability.The peripheral circuit of the TDC was designed to let TDC working stably and realize measurement and recording of the time of flight.(4)The driving method of the galvanometer scanner is studied,and a non-repetitive scanning scheme with high frame rate and multiple scanning lines is designed based on it.A high-precision vibrating mirror control signal based on DDS technology is generated by an FPGA and converted to an analogue voltage signal by a high-speed DAC to control the scanning of the mirrors of galvanometer scanner.(5)To verify the scanning performance of the system,a point cloud data generation program was written in the FPGA to calculate the position of each point in 3D space based on the flight time and emission angle of the laser,and to transfer it to PC via UART for reconstruction and display.