Research On Measurement Technology Of Rectangular Spline Shaft Based On Planar Structured Light

Rectangular spline shaft is commonly used in the mechanical industry of shaft gear parts,widely used in all kinds of mechanical products in the torque transmission devices,its processing error will not only affect the transmission efficiency of torque,but also lead to the wear of the machine,reduce the service life of the machine,therefore,assure its accuracy is particularly important in the production and processing.The traditional detection of spline shaft typically adopt gauge and coordinate measuring machine,measuring efficiency is low,unable to realize the online detection,and because the rectangular spline shaft has the characteristics of shaft gear parts,for its measurement technology can provide other shaft gear parts rapid detection,so this paper push forward the correlation dimensions by using the surface structured light measurement,combine the stereo vision technology and structure light measurement technology,set up a surface structure light measurement system based on the stereo vision,concrete research content is as follows:(1)The imaging model of the camera is analyzed,according to the imaging model of the camera and the characteristics of the measuring system,Zhang Zhengyou’s plane calibration method is used to calibrate the measuring system in this paper,the calibration results are obtained and the accuracy of the calibration is analyzed.(2)The phase extraction and unwrapping technology of grating fringe is studied.The phase principal value is extracted by four-step phase shift method.Several typical temporal-phase unwrapping algorithms are compared by simulation and experiment system analysis,and the algorithm with good anti-noise and high efficiency is selected for the research in this paper.(3)The combination of stereo vision polar and grating fringe phase constraints,realized the point-to-point dense matching of stereo vision,calculate the three-dimensional coordinates of the measured parts according to the matching parallax,through the rectangle spline shaft measurement’s experiment proves that the method can better reconstruct the rectangle spline shaft surface profile.Through standard ball precision verification peformed in this paper,the precision of the measurement system is verified by the experiment.(4)Based on Point Cloud Library PCL,the measured surface point cloud data of the rectangular spline shaft was preprocessed,including point cloud denoising and de-sampling.According to the surface geometrical characteristics of the rectangular spline shaft,the measurement models of the rectangular spline shaft’s large diameter,small diameter,coaxiality and key width are established:using Random Sample Consensus algorithm segment the large and small diameter,rectangular facade,based on cylindrical model fitting out large and small diameter;PCA coordinate system is established,point cloud data is converted to this coordinate system,large and small diameter spatial axis equations are fitted.The small-diameter spatial axis is used as the reference axis to measure the coaxiality;Two lines of the key width are obtained through the point cloud boundary feature extraction technology and conditional filtering,and the distance between the two lines is calculated by fitting the straight line to get the key width.The established model is used to carry out several measurement experiments,and the measurement results are analyzed.The uncertainty of measuring the rectangular spline shaft’s large and small diameter,key width and coaxiality are obtained,which proved the correctness and feasibility of the method.