基于视觉的螺旋焊管管径测量研究

发布时间：2018-12-07 17:59

【摘要】：螺旋焊管具有生产成本低、强度较大、安全性较高等优点,是目前我国石油、天然气输送管线的最主要用管。为了保证螺旋焊管成型的几何质量,各种钢管生产标准都对钢管的外径允许偏差、椭圆度等几何参数作了规定,实时监测钢管的几何参数对于保证钢管质量具有重要的意义。利用视觉检测的方式对螺旋焊管的几何参数进行测量,精度高、可靠性高、效率高,容易实现对螺旋焊管尺寸的实时监控,提高螺旋焊管的产品合格率。本文搭建了以两台CMOS工业相机和一台线激光发生器为核心的视觉检测系统,相机1垂直于线激光发生器产生的激光平面,用于采集表征螺旋焊管管径的激光弧线图像,采用标定靶标与激光平面重合的方式进行了相机的标定；相机2从上至下垂直拍摄,实时采集螺旋焊管边缘线与激光线图像。通过对采集到的图像进行灰度分析,设计了合理的图像处理算法,包括图像灰度分析、图像滤波以及图像边缘提取等,获得了螺旋焊管与激光平面之间的夹角。根据标定结果计算了激光弧线的实际尺寸,再根据两者之间的角度投影到与螺旋焊管中心轴垂直的平面上,通过最小二乘圆拟合得到了该位置的管径数据。随着螺旋焊管的旋转,不断地测量钢管不同位置的管径数据,然后去除焊缝及附近变形区域对管径的影响,对其余的管径数据平均处理,作为实际管径。通过这种方法对螺旋焊管管径实现了精确测量,同时,根据不同位置的管径数据获得了钢管的椭圆度以及焊缝处的变形量。根据测量原理,基于软件MATLAB,本文建立了数学模型,对测量过程中可能存在的误差来源进行了分析,其中包括镜头畸变、标定误差、螺旋焊管与激光平面之间的角度误差、螺旋焊管与水平面的角度、椭圆度等。通过分析发现,标定误差和测量角度误差对测量影响最大,当在激光平面与螺旋焊管的中心轴线接近垂直时,才能将测量误差降到最小,这为实现螺旋焊管管径的精确测量奠定了理论基础。
[Abstract]:Spiral welded pipe, which has the advantages of low production cost, high strength and high safety, is the main pipeline for oil and natural gas transportation in China at present. In order to ensure the geometric quality of helical welded pipe, the allowable deviation of outer diameter, ellipticity and other geometric parameters of steel pipe are stipulated in various production standards of steel pipe. It is of great significance to monitor the geometric parameters of steel tube in real time to ensure the quality of steel tube. The geometric parameters of spiral welded pipe are measured by visual inspection, which is characterized by high precision, high reliability and high efficiency. It is easy to realize real-time monitoring of spiral welded pipe size and improve the qualified rate of spiral welded pipe. In this paper, a visual inspection system with two CMOS industrial cameras and a line laser generator as the core is built. The camera 1 is perpendicular to the laser plane generated by the line laser generator, which is used to collect the laser arc images representing the diameter of the spiral welded pipe. The calibration of the camera is carried out by the coincidence of the target and the laser plane. Camera 2 shoots vertically from top to bottom, and captures the edge line and laser line image of spiral welded pipe in real time. By analyzing the grayscale of the collected images, a reasonable image processing algorithm is designed, including image gray analysis, image filtering and image edge extraction, and the angle between the spiral welded pipe and the laser plane is obtained. Based on the calibration results, the actual size of the laser arc is calculated, and then projected to the plane perpendicular to the central axis of the spiral welded pipe according to the angle between the two. The diameter data of the position are obtained by least square circle fitting. With the rotation of the spiral welded pipe, the pipe diameter data of different positions of the pipe are continuously measured, and then the influence of the weld seam and the surrounding deformation area on the pipe diameter is removed, and the remaining pipe diameter data are treated in average as the actual pipe diameter. Through this method, the diameter of spiral welded pipe is accurately measured. At the same time, according to the diameter data of different positions, the ellipticity of the pipe and the deformation of the weld are obtained. According to the principle of measurement, a mathematical model based on software MATLAB, is established in this paper. The possible sources of errors in the measurement process are analyzed, including lens distortion, calibration error, angle error between spiral welded pipe and laser plane. Angle of spiral welded pipe and horizontal plane, ellipticity, etc. Through analysis, it is found that the calibration error and the measurement angle error have the greatest influence on the measurement. When the laser plane and the central axis of the spiral welded pipe are close to vertical, the measurement error can be minimized. This lays a theoretical foundation for the accurate measurement of the diameter of spiral welded pipe.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.6;TP391.41

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