Research On Distance Measuring Technology Based On Camera In ADAS System

Visual distance measuring technology plays an important role in Advanced Driver Assistance Systems(ADAS)and can provide distance information in realistic road scenarios for advanced driver assistance system.The visual distance measuring technology restricts the performance of the automotive auxiliary system.Therefore,it is very important to develop a visual distance measuring system that can meet the needs of the current driver assistance system.At present,third-party camera calibration software is used in most of the domestic visual distance measuring systems use to get the internal and external parameters of the binocular distance measuring system.At the same time professional processing software is use to get three-dimensional matching information.Finally the target three-dimensional position information is obtained.The existing visual distance measuring platform is mainly developed and operated for distance measuring based on third-party software,and many practical problems tend to appear during camera calibration and image matching.This thesis focuses on the problems in the existing visual distance measuring system,such as insufficient camera installation accuracy,imperfect system calibration function,and lack of image matching function,and develops a camera-based visual distance measuring system to implement various visual distance measuring functions on the Windows platform.The visual distance measurement system mainly has four functions: camera calibration,high-precision assembly of binocular cameras,image matching,and target distance acquisition.The main work of this thesis is as follows:(1)Camera calibration in visual distance measuring is studied.First a detailed derivation of Zhang Zhengyou's checkerboard calibration method is carried out,then SIFT is used to calibrate the camera after the corner detection of the calibration image.This lays a solid foundation for subsequent camera calibration.(2)A high-precision assembly method for visual distance measuring system is proposed.According to the visual distance measuring principle,by individually adjusting a single camera,the projection of the calibration object in the imaging plane reaches a corresponding scale and there is only translation but no rotation between the camera coordinate system and the plane coordinate system.Therefore,the projection planes of the left camera and the right camera are coplanar and aligned,and the assembly is completed and a high accuracy error-free distance measuring image is obtained.(3)Binocular ranging system parallax is obtained by image matching.The distance measuring performance of the binocular ranging system is directly affected by the image matching results.By testing the three feature point extraction techniques,we chose the SIFT corner detection technology as the basis for image matching.The results of image matching experiments show that the method based on SIFT corner detection has faster matching speed and higher matching accuracy.(4)A design scheme based on Windows system is proposed.In order to solve the shortcomings of the visual distance measuring function,improve the adaptability and stability of the visual distance measurement software function,and at the same time facilitate the user,the functions of the design scheme have been tested under the Windows system.The results show that the system has high feasibility and reliability,and it can achieve a stable distance measuring function.