| Tube is a common part in modern mechanical equipment.Due to the rebound of the bent tube after processing,the bent tube cannot be assembled well,which affects the use of mechanical equipment.Therefore,it is necessary to measure and feed back the data in a timely manner to correct the processed tube in real time,so that the tube processing can meet the accuracy requirements and reduce the processing cost.The line structured light vision measurement system has the characteristics of non-contact measurement,high accuracy,good real-time performance,etc.,and is widely used in quality inspection,processing and manufacturing fields.Aiming at the problem of non-contact rapid measurement of tube,this paper studies the visual measurement technology based on line structured light,proposes a fast and effective visual measurement method,and conducts experimental verification.The main research contents of this paper are as follows(1)Research on visual measurement systems based on line structured light.The characteristics of direct and oblique type in laser triangulation are studied.The oblique laser triangulation method is chosen as the measurement principle of the system.The main hardware components of the system and the software workflow are designed.(2)Research on calibration method of visual measurement system based on line structure light.The calibration of the line structure light measurement system mainly includes camera calibration and light plane calibration.Firstly,the existing camera calibration method is analyzed.Zhang Zhengyou calibration method is selected for camera calibration.Then several commonly used light plane calibration methods are studied.The optical plane calibration method based on homography matrix and distance constraint factor is validated by MATLAB software as the calibration platform.(3)Research on image processing algorithms.Firstly,the image preprocessing method such as median filtering,threshold segmentation and morphological processing is used to eliminate various noises in the image and improve the image quality.Then several light bar center extraction algorithms are studied,and an extraction algorithm based on a combination of automatic region of interest selection and gray barycenter method is proposed to extract light strip center.(4)Research on ellipse fitting algorithm.In this chapter,the virtual plane based on the vertical axis of the elliptical fitting point is extracted and projected vertically on the virtual plane.The point of normal distribution is used to eliminate the isolated points,and the ellipse is firstly fitted by least squares method.Further fitting is performed by the ellipse fitting method in the form of parameters to improve the accuracy of the shaft diameter fitting(5)The study of bending tube measurement experiments.Obtain the ellipse fitting data of each part of the bending tube,obtain its three-dimensional space parameters,and perform the three-dimensional reconstruction to obtain the three-dimensional model of the bending tube.Compared with the actual model of bending tube,the feasibility of this method is verified. |
