Research On Technology Of Laser 3D Measurement

With the development of intelligent manufacturing,Three-Dimensional(3D)measurement technology has become an increasingly critical role in the industrial production,the laser 3D measurement technology based on line structured light with its such as non-contact,high accuracy and good real-time performance characteristics are more and more attention from researchers,in agriculture,industrial automation,protection of cultural relics,the health care industry and other applications based on line structured light 3D measurement technology is playing an important role.In this paper,the three-dimensional measurement system applied to two different measurement scales was studied,and the structure design and key algorithms in the three-dimensional measurement system of linear structured light were deeply studied.The software interface of the three-dimensional measurement algorithm and system was realized by using C++ and using Microsoft Foundation Classes(MFC)and Open CV library.The specific research work is as follows:(1)The measurement principle of the three-dimensional measurement system of linear structured light is studied and its mathematical model is analyzed,that is,the imaging relation of the system is derived from the Angle of coordinate change and matrix transformation,and the measurement error analysis is carried out on this basis.According to the hardware equipment currently used,the structural parameters of the laser 3D measurement system were designed,and the structural parameters of the system were determined.For the software part of the system,MFC and Open CV library are used to write the operation interface of the software and the 3D measurement algorithm based on vision respectively,to realize the functions of 3D measurement software.(2)The system calibration methods,including camera calibration and optical plane calibration,were studied.The camera calibration method is based on the checkerboard planar target,and the nonlinear model is used to calculate the internal and external parameters of the camera.The optical plane calibration is also based on the checkerboard plane target.The feature points are obtained by intersecting the centerline of the optical bar and the corner point line of the checkerboard target,and more feature points are obtained by using the principle of intersection ratio invariance.Finally,the optical plane equation parameters in the camera coordinate system are obtained by using the least square method.(3)The pre-processing method of the light bar image was studied,including the use of median filtering and morphological transformation to remove the image noise in the light bar image acquisition,and then the light bar was separated from the image acquisition through threshold segmentation,and finally,the center of the light bar was extracted.In this paper,the method of extracting the center of the light bar is studied.To solve the problem of the Hessian matrix method,which requires a lot of computation and takes a long time,the method of geometric center method and Hessian matrix is used.Various evaluation methods of light bar image are studied,including light bar energy and average light bar energy,light bar asymmetry,etc.On this basis,an automatic optimization algorithm for the camera exposure time of light bar image acquisition is proposed based on the evaluation standard of light bar image and the central stability of the light bar.The feasibility of the algorithm for image preprocessing and center extraction of light bars is verified through experiments,and the effect of the algorithm for automatic optimization of exposure time is verified through comparison experiments.The application of the linear structured light 3D measurement system in a large size measurement scene was tested.The measurement performance of the 3D measurement system was tested by measuring the standard block.(4)Design and experiment were carried out on the application of the linear structured light 3D measurement system in the small-size measurement scene,including the design of system structural parameters and system calibration,and the calibration results obtained in the camera calibration process were compared with the results of the large-size 3D measurement system.Finally,the application of the linear structured light 3D measurement system in small size measurement is also tested,and the feasibility and accuracy of the system are verified.