Abstract
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.
