Study On Method Of Extracting Surface Information For Workpieces With Free Curved Faces Based On Cross Line Structured Light

Structured light measurement technology is one of the main means to obtainingthree-dimensional information of the measured workpiece surface based on principle of opticaltriangulation. Through studies, method of extracting surface information for workpieces withfree curved faces based on cross line structured light has been established, which can extract thespatial three-dimensional information of workpiece surface accurately and ensure the workpieceend face information can not be lost. Main research contents and results are included:1) Basic principle of structured light vision measurement and the model of perspectiveprojection transformation was analyzed.On this basis, a planar calibration board was made andthe subpixel coordinates of corners wrer extracted by using Harris corner detection algorithm andsubpixel refining method. Calibration method was adopted based on planar target nonlinearmodel. At the same time, a camera calibration software was developed which was used tocalibrate the camera internal and external parameters and calibration error was about0.2pixels.Mechanical adjustment method was adopted to obtain the corresponding linear structured lightplane parameter equation.2) Cross line structured light image processing was introduced. Different thresholdsegmentation methods were compared and OTSU was choosen for image segmentation.Parabolic fitting gray centroid method was adopted to obtain the light strip center coordinates,and a method for classification of light centers was put forward.3) A artifacts scanning model has been established,and the experimental platform wasbuilt based on this model; Based on VC6.0for software development platform, a correspondingcontrol processing software was developed. and collection and processing of the image,extraction of light strip center, reconstruction of three-dimensional coordinates, extraction ofworkpiece surface information were all realized.4) A sole was used as experimental object. Then cross line structured light and word linestructured light was adopted to scan surface of the sole and the extraction of sole surfaceinformation was realized. The experimental results show that precisions respectively was0.018mm and2.12mm.At the same time, the workpiece end face informations were ensured and the accuracy of the extraction was improved by using cross line structured light. As a result, thefeasibility of this method was verified.