Research On 3D Reconstruction Method Of Mechanical Parts Based On Binocular Structured Light

In the industrial manufacturing process,due to processing technology,equipment wear and other reasons,the produced mechanical parts have defects or errors,which affect the product quality.Unqualified parts not only fail to meet user requirements,but may cause safety accidents in serious cases.Quality inspection is a necessary means to ensure the quality of parts.Traditional quality inspections are mostly manual methods,with low inspection efficiency,inspection instruments are likely to cause damage to parts,and the inspection results are subjectively affected.The application of 3D reconstruction technology to the automatic inspection of parts can improve the inspection accuracy and efficiency.However,because the measurement-oriented 3D reconstruction technology requires very high accuracy and efficiency,there are still many problems.In the three-dimensional reconstruction of mechanical parts,first obtain the three-dimensional point cloud data from various perspectives,then stitch these point clouds into a complete part point cloud,and then convert the complete point cloud into a part mesh model.The first step in 3D reconstruction of mechanical parts is to obtain a 3D point cloud of the parts.Most mechanical parts have smooth surfaces and lack texture features.Active light sources need to be used to increase the surface feature information of the parts.According to the high-precision requirements of parts measurement,this paper adopts the multi-frequency heterodyne method to encode and decode structured light.Multi-frequency heterodyne is to calculate the three-dimensional coordinates of the point cloud through phase matching.The phase error caused by the nonlinear response of the acquisition device and the interference of environmental noise will cause too many point cloud noise points to be generated.In order to reduce the phase error,an area-by-area phase correction method is proposed,which eliminates the phase noise points according to the phase change trend of the local area.Experimental results show that the algorithm can eliminate phase errors and improve the accuracy of point cloud reconstruction.Due to the limitation of the camera’s field of view,the complete point cloud data of the part cannot be obtained through a single measurement,and it is necessary to stitch point clouds from multiple perspectives.On the basis of analyzing various splicing methods,a method based on the parameter calibration of the rotating stage is adopted for point cloud splicing.This method uses the checkerboard calibration board to calibrate the system parameters,and completes the multi-view point cloud splicing according to the calibration parameters.Experiments prove that the method is simple to operate and has high splicing accuracy.Since the point cloud data only contains the three-dimensional coordinates of the points and cannot represent the surface contour and topological structure of the mechanical parts,it is necessary to reconstruct the surface of the point cloud data to obtain a mesh model composed of interconnected polygons.The surface reconstruction adopts the rolling sphere reconstruction algorithm,which continuously rolls and expands on the surface of the point cloud through a fixed radius rolling sphere to generate a triangular mesh model.The experimental results show that,compared with the Poisson reconstruction method,the mesh reconstruction effect of the rolling ball method is closer to the real object,and the reconstruction accuracy is higher.Aiming at the problem of "holes" in the rolling sphere reconstruction mesh model,the rolling sphere algorithm is improved through the idea of multi-radius,which significantly reduces the number of "holes" while ensuring the reconstruction accuracy.In this paper,the research and development of the 3D reconstruction system for mechanical parts is carried out.First,the hardware equipment selection and hardware platform construction are carried out;then the system analysis and design are carried out.The main functions of the system are realized based on the Qt Creator compiler,which can basically meet the needs of 3D reconstruction of mechanical parts.