Research On The Reconstruction Method Of Mechanical Workpiece Based On Grating Projection Technology

With the development of intelligent manufacturing,the demand of intelligent testing equipment is increasing day by day.The Ministry of Industry and Information Technology jointly issued the Action Plan for the development of intelligent testing equipment industry(2023-2025).Facing the transformation and upgrading of the manufacturing industry and the urgent need of the national major strategy,it is clearly put forward that by 2025 the industrial ecology should be formed preliminarily,and the development needs of intelligent manufacturing should be basically met.The 3D reconstruction technology based on digital grating projection has the advantages of high precision,non-contact and high speed,it shows more and more application value in the fields of intelligent detection,manufacturing and bioengineering.This paper makes a lot of research on the 3D reconstruction equipment and technology in the market,combining with the specific requirements of the mechanical workpiece grasping operation in the project,and considering the technical feasibility,cost and other factors synthetically,decided to focus on 3D reconstruction technology based on digital grating projection,and proposed a fast phase-unwrapping algorithm based on complementary Gray code and phase-shifting method,the problem of low decoding efficiency and large error of current structured light decoding algorithm in complex background is improved,and the phase error of the system is pre-corrected.The specific work of this paper is as follows:(1)Choose a camera and programmable projector to build an experimental platform,and write a software system to simplify the experimental operation process.Conduct camera calibration experiments on the constructed platform to lay the foundation for subsequent 3D reconstruction experiments.(2)A fast phase unwrapping algorithm is proposed to address the issue of background pixel interference in the phase shift method combined with complementary Gray code decoding scheme.By performing region segmentation on the collected modulated image to enhance the contrast between the background and the object,the measured object is extracted from the modulated image,avoiding interference from the background environment on decoding and improving the phase unwrapping rate.(3)In response to the problem of phase error in the system’s projection grating,a mathematical model of the entire process from projection to acquisition of the grating is established,and the factors causing phase error are analyzed and derived.A pre correction gamma value scheme is improved.This method projects a set of monotonically increasing pure color maps,collects and calculates the gamma distortion values of the system,and assigns an index of the gamma inverse value to the formula for generating phase fringes,offsetting the errors caused by system nonlinearity and achieving the goal of reducing phase errors.(4)The algorithm proposed in this paper is applied to the reconstruction system,and several repeated experiments are made on the right-angle aluminum fixed angle parts and standard blocks,the applicability of the 3D reconstruction system designed in this paper is proved.The workpiece was measured many times to verify the accuracy of reconstruction.This paper mainly studies the structured light 3D reconstruction based on grating projection technology.The experimental results show that the fast phase unwrapping algorithm designed in this paper can improve the phase velocity by 34%,and the error pre correction can reduce the phase error by 33%,which has certain research value for improving the efficiency and accuracy of 3D reconstruction.