Research On Technology Of Omnidirectional Multipath Lidar

As a high-precision measurement technology,laser detection plays an important role in both military and civilian fields.In recent years,with the increasing demand for applications such as artificial intelligence,unmanned driving,and target recognition tracking,it has become increasingly important for the research on the technology of lidar omnidirectional scanning detection.Currently,the most widely used large-angle scanning method of lidar is mechanical rotation,which has the advantages of simplicity,low cost and wide coverage angle,but due to the limitations of stepper motor,its durability is not high and the volume is large.In this paper,a non-mechanical rotary multipath laser radar architecture for 360° omnidirectional laser detection.The design of optical system is completed,and the solution of multi-channel time measurement is put forward,the main contents are as follows:First of all,the theory of laser detection has been studied systematically,including the system of laser detection,the transmission characteristic of laser in atmosphere,the optical characteristic of target and the statistic characteristic of laser echo signal,and all those provide theoretical support for the following system design.Then a lidar structure based on 2D MEMS mirror scanning is proposed as a solution for laser omnidirectional detection.The laser provides light signals to 6 scanning subsystem through a 1×6 high speed optical switch and it realizes 360 degree horizontal scanning by adding the field of view of 6 scanning subsystem together.The scanning range of each scanning subsystem can reach 60° x 30°,including an transmitting optical antenna that expands the MEMS mirror scanning angle and a large field of view receiving optical antenna with gain.Since the scanning angle of each axis of the MEMS device is in the range of-10° to +10°,an transmitting optical system is designed in this paper with extended scanning angle according to its characteristics,and extends its corresponding exit angle to-30° to +30°.The field of view of the optical system is 67°.This paper expounds the principle of extended the scanning angle in detail,and gives the initial structure parameters of the optical system.By adding the optimization function,the divergence of the optical system and the length of the system are optimized,and the parameters of the optimized system and the optical properties of the system are given.In this paper,the receiving optical system with gain in large field of view is designed whose receive field angle is 67°,and the design and optimization process is described in detail,and the optical system parameters as well as the optical characteristics of the system are given.Through software simulation analysis,The half image height of the laser echo in the receiving field angle passing through the receiving optical system on the detector is less than 1mm,and its optical gain is 3.65,which satisfies the design requirements to some extent.Finally,the article uses the TDC-GPX chip as a solution to multi-channel signal time measurement.The chip can measure the time interval of up to 8 channels in I mode,with an accuracy of 81 ps,and the theoretical range error is about 0.024 m.This paper uses FPGA chip as the main control chip,expounds the initialization process and workflow of TDC-GPX chip,and completes the function simulation.