H-shaped Steel Cross Sectional Dimension Measurement Based On Line Structured Light

In the cutting process of the H-shaped steel, the steel may be out of shape orposition deviation, so the steel size must be measured to input correct command tocutting robot and complete cut. The measurement should have impressively accuracy，validity and real time in practical production. Therefore, we measured H-shaped steelcross sectional dimension and key point based on line structured light. Themeasurement based on line structured light is widely used in industry, which belongsto the system of3D vision measurement method. This method is of high accuracy,simple and non-contacting. It can bring about automation and capture images easily.So this method is selected in the dissertation. The main contents of this dissertationare as follow:(1) Describes the classification of3D vision measurement method based oncomputer. The principle of the line structured light measuring is described.(2) The Hardware setup of image acquisition module is described. Thisdissertation select the equipments which can meet the measurement requirement.These hardware device include laser, CCD camera lens, Image acquisition card and soon. The important parameters of all devices have been determined.(3) Image processing algorithm and image processing result are introduced. Theimage processing is an major step in the whole measuring system. For this reason, themedian filtering, binarization, region marker, centerline extraction and Houghtransform are all investigated in detail. VC++6.0programming has been used toprocess the written image programs, and get satisfactory treatment results.(4) As a part of researches to improve accuracy, camera calibration is proposed,which is a key link and a bridge between two dimensional coordinate andthree-dimensional coordinate. The quality of calibration result effects the accuracy ofsystem directly. Zhengyou Zhang template calibration method has been employed inthis dissertation, which is practicable and high precision. After calibration, both of theintrinsic and extrinsic parameters of the camera and the distortion factor can beobtained. Then, the repeatability of measurement system has been analyzed throughexperiment. The results indicated that the measurement system can meet themeasuring demand after calibration. In this study, by doing theoretical analyses and experiment verifies, the crosssectional dimension measurement of H-shaped steel can be carried out based on linestructured light. The measurement accuracy can directly satisfy the requirement ofindustry.