视觉传感是智能化焊接生产制造中实现焊接坡口尺寸参数、焊枪空间位姿等在线检测的关键技术,其有效应用的前提是视觉传感器内参的准确标定。该文针对独特设计的基于组合激光结构光的视觉传感器,提出一种视觉传感器内参一体化标定方法,基于普通的棋盘格标定板,通过标定相机内参,采用骨架细化法与Hough直线检测提取图像中的激光线中心线,求取投射在标定板上的激光线中心线上点在相机坐标系中的三维坐标和拟合激光结构光平面方程参数等,可实现视觉传感器内参的一体化标定,有效提高视觉传感器内参的标定精度和效率及标定过程的便捷性。在平面工件焊接坡口尺寸参数检测验证试验中,焊接坡口尺寸参数的检测误差均值和重复误差皆不超过0.04 mm,表明该视觉传感器的标定精度良好,可以满足焊接领域对焊接坡口尺寸参数的检测需求。
Visual sensing is a key technology for online detection of welding groove size parameters, and welding torch positions and postures in intelligent welding systems. Accurate visual sensing requires accurate calibration of the internal visual sensor parameters. This paper describes an integrated calibration method for the internal parameters of a visual sensor based on combined laser structured lights. The method is based on an ordinary checkerboard calibration board with the calibration system extracting the centerline of the laser line in the image using the skeleton thinning method and Hough line detection. The system then determines the three-dimensional coordinates in the camera coordinate system of the points on the laser center line of the calibration board to fit the parameters in the laser structured light plane equation. This integrated calibration method improves the calibration accuracy, efficiency and convenience. Tests measuring the welding groove size on a flat workpiece gave mean and repeated measurement errors of the welding groove size of not more than 0.04 mm, which verifies that the sensor calibration accuracy meets the needs for welding groove size measurements.
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