Research On Surface Reconstruction Measurement System Of Thin-walled Blade Parts Based On Monocular Structured Grating

With the rapid development of modern industry,a large number of thin-walled blade parts with better performance are applied in various industrial fields.The surface quality of such parts usually has a great influence on their working performance and service life,and the surface structure of small and medium-sized thin-walled blade parts is generally more complicated and it is difficult to measure it,so it is of great significance to use the more advanced monocular structured grating reconstruction measurement technology to realize the non-contact measurement of the surface of such parts,and to carry out the research on the design of related measurement system.Firstly,the theoretical part of the measurement technology of monocular structured grating reconstruction was studied.The new monocular structure grating reconstruction measurement model was described,and the mapping relationship between the three-dimensional coordinates of the reconstruction point on the surface of the thin-walled blade part and the phase of the object point and the pixel coordinates of the object point were given,and the calculation formulas of the calibration parameters of the measurement system were derived.At the same time,the theoretical analysis of the multi-frequency heterodyne unwrapping method was carried out.Then,through the parameter setting,lens adjustment and white balance adjustment of the color industrial camera,the acquisition error of the camera could be reduced,and to further compensate for the measurement error,this paper proposed a method to reduce the gamma nonlinear response of projector by determining the appropriate contrast and brightness value of projector,and optimized the traditional calibration method of Zhang Zhengyou camera by noise reduction of calibration picture and circular calibration plate.Thirdly,combined with the structural characteristics of thin-walled blade parts,the automatic positioning reconfiguration measurement system based on monocular structured grating was studied,and in the lens automatic positioning module of the measurement system,a lens automatic positioning algorithm was proposed,which could determine the centroid coordinates of the measured object contour in the picture and convert the pixel distance into the actual distance.At the same time,a software development environment of VS + Open CV + pcl was built for the measurement system.Finally,a reconstruction measurement experiment was carried out on the surface of a typical small and medium-sized thin-walled blade part by using the designed measurement system,and the lens automatic positioning effect of the reconstruction measurement experiment and the reconstruction measurement results of the measured part surface were analyzed.The experimental results showed that the measurement system designed in this paper had a high degree of automation,the overall time of a single measurement was within 4min,and the accuracy of the reconstructed point cloud was between 0.3 ～ 0.6mm.