Research On Autonomous Scanning Laser Projection Technology Integrating Integrated With Photogrammetry

The laser scanning projection technology can project clear and bright outlines of a certain part at the exact position which based on the CAD model.It can assist workers to fulfill the intelligent assembly operations,improve assembly accuracy and work efficiency.It's worth noting that the key technology of the system is the operation called "calibration",that is the conversion between the coordinate system of the laser projector system and the CAD model.If the "calibration" is not accurate,the position of the projected outlines and patterns will be inaccurate,and it will not be able to meet the requirements of precise positioning and assembly operation in advanced manufacture industry.The existing calibration technology of laser scanning projection system usually requires remote controllers,mouses and keyboards to manually guide the laser beam to the center of the cooperative target.Then the center position of the cooperation targets are extracted by scanning and detecting the area near the center positions of the cooperation targets to get accurate coordinate conversion.This "calibration" process is complicated,time-consuming and with poor applicability.More seriously,once the positons and postures between the laser scanning projection system and the projected object changes,the above mentioned "calibration" operation must be carried out again.This problem can affect the reliability and practicality of the projection system.In order to solve the problem of "manual guidance" in the existing laser scanning projection system,realize active search of cooperative targets' centers and automatic calibration,the autonomous scanning laser projection technology integrated with monocular photogrammetry is studied.It is expected that the laser scanning projection system can independently search and automatically scan cooperative targets,and can also monitor the position change between the projected object and the projection system,improve the reliability of laser scanning projector.The main works completed in the thesis are as follows:(1)Based on the multi-coordinate conversion and unified technical studied in the existing laser scanning projection technology,an autonomous scanning laser projection system integrated with monocular photogrammetry is designed.Furthermore,the mathematical model of the autonomous scanning laser projection system integrated with monocular photogrammetry is established,the autonomous scanning laser projection calibration method fused with monocular vision is proposed.(2)In order to solve the coordinate conversion between the camera,the projected object and the laser scanning projector,the particle swarm algorithm to solve the conversion relationship of multiple coordinate systems is studied and the related simulation experiments are designed.The feasibility and correctness of the autonomous scanning laser projection calibration method integrated with monocular vision is proved.At the same time,in view of factors such as the rotation angle and movement distance of the camera,the calculation accuracy of the studied method is analyzed,and the optimization results such as the rotation angles and movement distances of the camera are obtained to meet the actual application.(3)In view of the problem that the calibration accuracy of camera intrinsic parameters affects the accuracy of the coordinate conversion calculation,the calibration and optimization method of camera intrinsic parameters based on genetic algorithm is studied.This method uses the camera intrinsic parameters obtained by Zhang Zhengyou calibration method as initial data,and uses the genetic algorithm to optimize the obtained camera intrinsic parameters.Then,the re-projected error and average error of the Zhang Zhengyou calibration method and the optimization method of camera intrinsic parameters based on genetic algorithm are solved,and the errors of the two methods are compared,the results show that the research method can obtain higher precision intrinsic parameters.The studied method can provide a calculation basis for the transformation of the coordinate of cooperative targets' centers from the pixel coordinate system to the imaging coordinate system.At the same time,the method of extracting the circle centers of the cooperation targets is also studied,and the position of the circle center of the cooperation target is calculated based on the Zhang Zhengyou calibration method and the studied optimization method of camera intrinsic parameters based on genetic algorithm.The results show that the coordinates of the centers of the cooperative targets obtained by the researched calibration method are more accurate.(4)Based on the above studied technology and method,the autonomous scanning laser projection setup integrated with monocular photogrammetry is developed,and the setup is used to independently search and automatically scan the cooperative targets on the work piece.At the same time,the coordinate conversion calibration experiment is carried out with the studied method.The experimental results show that the studied autonomous scanning laser projection calibration method integrated with monocular vision can realize the search and scanning of cooperative targets,which proves that the studied method is practical and feasible.At the same time,the autonomous scanning laser projection system integrated with monocular photogrammetry can meet the accuracy requirements of the projection system and project the images based on the workpiece's CAD model with good accuracy.