Research On Digital Laser Plummet And Calibration System Of Coaxiality Based On Image Processing

Laser plummet is a kind of instrument which can provide plumb line.It is widely used in construction,deformation observation,equipment installation and other industries.At present,the domestic laser plummet needs to be leveled by observing the bubble level,and the leveling accuracy is affected by the error of artificial observation.When the shaft of laser plummet is installed and calibrated,the coaxiality of the shaft is calibrated by observing the center of cross lines and laser spot,and the error of calibration is large.The purpose of this thesis is to develop a digital laser plummet which can digitize the leveling process and a calibration system of coaxiality based on image processing.This thesis proposes a leveling method which can display the position of the bubble digitally.This method uses electronic bubble level sensor to measure the inclination angle of the laser plummet,and uses the relevant circuit modules to meet the needs of leveling process of laser plummet and calibration method of the long bubble level by being rotated to two angles,and develops a new digital laser plummet.Furthermore,this thesis proposes a new calibration method for coaxiality of laser plummet based on image processing.When calibrate the camera,using image difference to solve the interference from background,and Otsu algorithm is used to binarize the image.After image correction,using Hough transform algorithm to recognize the scale and get mapping relation of two kinds of coordinate.When detect the target,K-means clustering method is used to segment the cross lines,Hough transform is used to locate the center of cross lines,using single channel method to segment the laser spot area,and the centroid of the area is taken as the spot center.Based on the least square method,the center point trajectory is caculated to obtain the coaxiality error of the laser plummet.Finally,the calibration system of coaxiality based on image processing is built based on RK3399 embedded platform.Experimental results show that the digital laser plummet developed in this thesis can improve the resolution of the long bubble level,and reduce the error of artificial observation,the resolution is up to 1.29’’.The new calibration system of coaxiality based on image processing can accurately calibrate the coaxiality error of the laser plummet,and the calibration accuracy is up to 0.1’’.