Research And Design Of Two-dimensional Lidar Ranging System

With the development of information technology,autonomous driving technology has been widely used in the field of smart mobile devices such as mobile robots.Smart mobile devices not only reduce human labor and facilitate life,but also improve work efficiency.In this context,two-dimensional lidar,as the core obstacle avoidance sensor of autonomous driving technology,has developed rapidly.The two-dimensional lidar can obtain information such as the distance,direction and speed of the target by analyzing and calculating the transmitted and received laser signals.Because of its fast working speed and good resolution,it also plays a huge role in other fields such as security.The development of lidar technology is improving day by day,but the promotion and use still face certain challenges.Since the entire production process of lidar involves software and hardware design,system integration,and test verification,the threshold of lidar technology is high,competitiveness is low,and production cost is high.Among them,the laser ranging system is one of the core structures of the lidar,and its function is to complete the collection of distance data,and its ranging performance directly affects the use effect of the lidar.Therefore,designing a two-dimensional lidar ranging system with light structure,accurate measurement and low cost has good use value,and it is also the basis for the overall design of the later two-dimensional lidar.This subject mainly completes the following design work:(1)Researching the principles and hardware structure of various laser ranging methods,combining their respective characteristics and the small size and high speed characteristics of the two-dimensional lidar ranging system,and choosing pulsed laser ranging technology for ranging system ranging,And complete the overall plan design.(2)Select photoelectric components,various chips,etc.for laser circuit design,including laser emitting and receiving circuits,signal processing circuits and power supply circuits;and install optical lenses at the end according to optical principles.(3)In order to ensure the measurement accuracy of the laser start and stop signal time interval,this subject uses the latest high-precision time-to-digital conversion chip TDC-GPX2 for time measurement.Study the use of TDC-GPX2 chip and complete the design of its peripheral circuits.Write the program in the KEIL5 environment,use the SPI bus to establish the communication between the single-chip microcomputer and TDC-GPX2,use the single-chip microcomputer to control the TDC-GPX2 to complete the time measurement,and calculate the distance value.(4)Use C# to write host computer system program.Using the designed host computer,real-time numerical and curve display of the measurement results can be performed,and the data can be saved.(5)In view of the deviation between the distance value measured by the ranging system and the actual value,this subject proposes the use of a polynomial piecewise fitting method to achieve fitting correction.For the influence of temperature changes on the distance measurement results,an experimental plan was designed to collect data at different temperatures for verification.At the same time,a BP neural network improved by genetic algorithm is proposed to compensate the temperature of the ranging system.This method obtains the mapping relationship between temperature and distance through learning without changing the hardware circuit structure,and uses the mapping relationship to correct the measurement result,which greatly reduces the interference of temperature changes on the measurement result.At the same time,the related software and hardware design was completed for the compensation system.Experimental verification shows that the two-dimensional lidar ranging system designed in this subject works stably and has good reliability.Within the range of 0.300-9.000 m,the error does not exceed 45 mm,and the sampling points per second are not less than 2000.