| The size measurement accuracy of large workpieces is an important standard to measure the production quality and assembly quality of the whole workpieces,and the relevant dimensions can be feedback to the production process in time.With the rapid development of science and technology,the heavy equipment industry needs more and more large parts,and the quality requirements are also higher and higher.However,at present,the measurement technology of large-scale parts mainly relies on workers holding large-scale mechanical measurement tools.These measurement methods have the problems of poor accuracy and low efficiency,which can not meet the needs of current production.Therefore,the dimension measurement technology of large parts needs to be improved and improved urgently.According to the development of modern measurement technology and the requirement and application of dimension measurement of large parts,the line structured light measurement technology is applied to the dimension measurement system of large parts.A vision measurement system of large parts based on line structured light scanning is proposed,and its measuring principle and related technical problems are mainly studied.In this paper,the technology of dimension measurement for large size parts is studied.For the purpose of online measurement system with high measurement accuracy,strong practicability and simple operation,the following research work has been accomplished in this paper.Firstly,a mobile vision measurement platform based on line structured light scanning is designed and built.The basic idea is to take the intersection point of the projected line structured light strip and the industrial camera as the characteristic point,and realize fast scanning measurement by the line laser and camera driven by the platform.Based on the line structured light vision analytical model,3D coordinate data point cloud is obtained by image information,position and angle information.Aiming at the large axial dimension of the measured object,the coordinate unification problem of multi-station and multi-segment data is solved by using point cloud data mosaic method.Secondly,the calibration method of linear structured light vision measurement system is studied,including camera calibration and light plane calibration.The traditional ICP(Iterative closed point)algorithm is improved.The algorithm has strong adaptability to complex deformation and illumination changes.It can match and locate image feature points measured at different sites.It effectively solves the problem of locating data points without definite correspondence,improves the speed and accuracy of operation,and achieves good matching results.Finally,a large-scale part size measurement system is built as an experimental platform,and the experiments of line structured light scanning measurement and line structured light strip extraction algorithm,line structured light vision measurement system calibration,measurement accuracy verification and three-dimensional profile measurement are carried out.The experimental results verify the effectiveness and practicability of the structured light strip center extraction algorithm and the calibration method of the measurement system. |
