Processing Method Of 3D Dimensional Data Of Workpiece Based On Laser Profile Measurement

Aiming at the problems of the laser profilometer-based workpiece size measurement system,such as the large amount of data processing,rough workpiece edges,and inaccurate dimensional measurement caused by the installation of the laser profilometer,the data processing methods were studied.Ordered grid-like data is obtained by specifying the scanning method and path.The point size data processing,planarization processing,and geometric feature detection techniques are used to measure the plane size of the workpiece.The three-dimensional workpiece size data is obtained by measuring the plane dimensions in the three views of the workpiece.The thesis research work mainly includes the following parts:(1)Using ordered grid-like data,the point cloud processing and feature detection methods for 3D measurement of workpieces were studied.Using the improved synchronous trigger method to obtain ordered grid-like data,using point cloud filtering for hole repair,down sampling,remove sparse outliers and noise,using point cloud registration fusion for all data,the greedy triangulation method is used to reconstruct the surface,and the parameter was adjusted to obtain the optimal mesh quality ratio of93%;According to the index of the triangular mesh,the polygon features of the three-dimensional model were extracted to obtain the image;Using the image to calculate the size after detecting the circle and line,and comparing the experimental results of different methods to detect the circle and line.The smallest error among all methods is the Hough transform.(2)For the workpiece size measurement system based on laser profilometer,the error analysis and error compensation methods are studied.Analyze the main error sources,and mainly study the errors caused by the tilt of the laser profilometer installation.The errors of the coordinate angles?,?,?on the workpiece size coordinate values X,Y,Z are analyzed,and the?,?,?are established based on error compensation model for projection angles?,?,?on the XOY,YOZ,XOZ planes.The measurement error of the workpiece size before error compensation is0.4mm,and the measurement error after compensation is within 0.03mm,and the measurement error is significantly reduced.(3)The dimension measurement experiment is carried out by the method of three-dimensional data processing of the workpiece based on laser contour measurement.Calculate the extended uncertainty U₉₅ for nine positions of the standard parts,and determine the eligibility according to the technical indicators(dimension measurement accuracy:±0.03mm).The results show that:the workpiece size measurement device is qualified,and the measurement error of all types of dimensions is less than 0.03mm;The dimensions of workpiece 1,workpiece 2,and workpiece 3 are measured by the three-coordinate measuring machine and this system.The qualification of the three-coordinate measuring machine to measure the dimensions shall prevail.The accuracy of the three dimensions measured by this system is not less than 83%;Repeat measurement on the dimensions of workpiece 1,workpiece 2,and workpiece 3,and the calculated root-mean-square error is not greater than 0.12mm.