Design Of A High Precision Absolute Angle Measurement System For Scanning Lidar

Lidar is a modern high-precision active remote sensing detection technology that can accurately detect atmospheric parameters such as aerosols,clouds,water vapor,and temperature in the atmosphere.The detection accuracy of the scanning lidar is often affected by the accuracy of the scanning angle.In order to make the detection result consistent with the actual distribution of atmospheric parameters,the scanning lidar also needs to perform an absolute angle calibration before detection.In view of the above problems,the absolute angle measurement system of scanning lidar has been studied.Firstly,several main angle measurement technologies at the present stage are analyzed,including absolute angle encoding technology,radial radiation grating angle measurement technology and tangential grating angle measurement technology.The overall plan of the absolute angle high-precision measurement system is formulated and designed Absolute angle coding,in which the key issue of absolute angle coding design,namely solving primitive polynomial coefficients,is explained in detail,and the decoding method of absolute angle coding is given;according to the design requirements,the light source,accurate and accurate according to the absolute angle coding size The straight focus lens was designed,the linear array CCD model used for coded image recognition was determined,the CCD model and the absolute angle code size were considered comprehensively,the imaging optical system was simulated using ZEMAX design,the CCD signal acquisition module was designed,and the test was finally set up.The experimental system can accurately read the grating encoding information and calculate the absolute angle value.The error of the absolute angle high-precision measurement system is analyzed,and the main error component-the influence of the eccentricity error on the accuracy is analyzed.The eccentricity error model,the eccentricity parameter measurement model and the eccentricity error compensation model are established and verified by simulation.After the actual error compensation experiment,the accuracy of the absolute angle measurement system reached 1'32".Based on the existing scanning laser radar system,a set of application schemes of absolute angle measurement system on scanning laser radar is designed.The absolute angle measurement system is installed on the rotating shaft of the scanning lidar frame,so that it can accurately measure the current scanning angle of the lidar,and correct the existing open-loop scanning system to form a closed-loop control.Finally,preliminary experimental observations were carried out,using cloud information with strong echo signals as a reference,and comparing the laser radar echo signals without angle calibration and those with angle calibration.The experimental results show that the cloud distribution information after angle correction is more reasonable,indicating that the absolute angle measurement system has a good application effect on lidar.