Research On The Measurement Scheme For Surface Flatness Of Flag Slabs

Natural stone is widely used in the fields of construction and decoration because of its various colors,good texture and resistance to wear and corrosion.Stone wastes in the sawing process,due to blade shaking and other reasons,resulting in uneven saw marks on the surface of the flag slabs,and uneven flag slabs can not be directly polished processing,so the flag slabs in the polishing before the surface flatness measurement.Today,the stone slab processing industry is usually measured by visual inspection and touching the surface flatness of the flag slabs by hand,etc.In order to further improve the efficiency of the flag slabs surface flatness measurement and improve the stone production environment,this paper takes the granite stone flag slabs as the research object,based on the structured light three-dimensional measurement technology for the flag slabs surface flatness measurement.The main research contents of this paper are as follows:(1)The hardware components of the flag slabs surface flatness measurement system are selected and the experimental platform for flag slabs surface flatness measurement is constructed.Analyzing the camera imaging model and lens aberration,obtain the camera’s internal parameters,external parameters,right-to-left rotation and translation matrices,and aberration coefficients from the camera calibration,and complete aberration correction experiments using the aberration coefficient to realize image aberration correction.(2)Encoding and decoding of structured light patterns on the flag slabs surface.Phase-Shifting-Interferometry(PSI)combined with Gray code is selected to generate the structured light encoding stripe pattern that needs to be projected onto the surface of the hairy plate.Finally,the encoding and decoding experiments of structured light patterns on the surface of the flag slabs are conducted to obtain the absolute phase value of the stone flag slabs surface through experiments to verify the feasibility of the encoding and decoding method.(3)The implementation of the software part of the flag slabs surface flatness measurement system.Designs each module of the software part of the rough board surface flatness measurement system.According to the hardware components used in the experiment of surface flatness measurement,the corresponding program is written to realize the functions of image acquisition,camera calibration,structured light encoding and decoding,polar line correction,phase matching and point cloud calculation.(4)Flag slabs surface flatness measurement.Based on the surface flatness measurement model of the flag slabs,polar line correction is performed on the absolute phase so that the two images captured by the left and right cameras can reach the state of co-planarity and "line alignment";based on the polar line constraint,phase stereo matching is performed to obtain the homonymous points of the flag slabs surface image,and the 3D coordinate point cloud of the flag slabs surface are obtained by using the homonymous points according to the principle of parallax.The point cloud information is used to measure the flatness of the surface of the flag slabs and compare with the manual measurement results,the results show that this paper is feasible to measure the surface flatness of flag slabs by using phase shift method combined with Gray code of structured light 3D measurement method.