Research On Full-size Measurement Technology Of Power Battery Module Based On Machine Vision

In recent years,with the further progress of national industrialization,the new energy automobile industry has developed rapidly.As one of the core components of new energy automobiles,power batteries directly affect the development and progress of new energy automotive industry,and the size accuracy of power battery modules has a direct impact on the quality of power battery products.In view of this,this paper has carried out the research on the full-size measurement technology of battery modules based on machine vision and completed the following work:(1)According to the actual size measurement accuracy requirements of battery modules,a full size measurement system for power batteries based on machine vision is designed in this paper.By analyzing the actual situation of each measurement item of the battery module,the corresponding measurement algorithm is designed,and the related visual algorithms are briefly introduced.(2)2D vision technology is relatively more mature and has higher measurement accuracy.3D vision can obtain three-dimensional information outside the planar dimensions,so the measurement system uses a combination of the two.For the measurement of 2D measurements of battery modules,a single image calibration algorithm based on monocular vision is presented.The algorithm obtains the physical and pixel coordinates of the corner points of the checkerboard by collecting a checkerboard image,and then obtains the affine transformation matrix from the physical coordinates to the pixel coordinates.By analyzing the relationship between Halcon affine transformation matrix and camera internal parameters,the pixel equivalent is obtained,and then the camera calibration of all 2D cameras used in the battery module full size measurement system is completed.(3)The object of measurement in this paper is battery module,which is large in size,and ordinary 3D vision technology can not meet the requirements of measurement accuracy.In view of this,a method for measuring module width and other items with dual laser 3D camera is presented.Firstly,the calibrator is scanned with a threecoordinate measuring instrument to get the physical coordinates of the calibrator’s feature points,and then the calibrator is scanned with a dual laser 3D camera to get the point cloud coordinates of the corresponding feature points of the calibrator,so as to solve the affine transformation matrices of the two laser cameras.Two laser cameras are used to collect two opposing point cloud data of the battery module simultaneously.The suitable measurement area is selected by visual algorithm,and then the point cloud data is transformed into the same coordinate system by their affine transformation matrices.The distance between the feature point and the fitting surface is calculated,so that the 3D measurement items of the battery module can be measured.By comparing the module standard data and frame number data measured by the battery module full-size measuring system,the measurement accuracy of each measuring item in the full-size measuring system is analyzed,and the stability of the measuring system is verified by comparing the results measured by repeated measurements.