利用数字图像处理技术测量直齿圆柱齿轮几何尺寸

研究了采用数字图像处理技术实现对直齿圆柱齿轮几何尺寸的非接触式测量.首先对CCD摄像机拍摄的图像进行畸变校正与滤波去噪,然后对图像进行阈值分割,采用基于数学形态法的四邻域腐蚀来获得单像素宽的图像边缘.针对齿轮的边缘轮廓形状特征,运用重心法、最小二乘拟合、Bresenham画圆法和Hough变换等原理,建立了测量齿轮齿数、模数、中心孔半径、齿顶圆半径、齿根圆半径和变位系数等齿轮几何尺寸参数的测量算法.使用1280×1024的CCD摄像机及黑白采集卡对分度圆直径为50mm的直齿圆柱齿轮进行测量实验,与人工测量值对比,绝对误差小于一个像素,在各测量参数中,最大尺寸的齿顶圆半径绝对误差值为13μm.研究结果表明:因为CCD摄像设备的分辨率越高、被测物体的尺寸越小,则测量精度越高,且为线性关系,所以,使用高分辨率CCD摄像设备并配备光学放大系统,可实现对高精度和微小直齿圆柱齿轮几何尺寸参数的测量.如使用1280×1024像素以上的CCD摄像设备测量分度圆直径5mm以下的直齿圆柱齿轮时,测量精度可在2μm以下.

Digital image processing technology for spur gear measurement

Non-contact measuring for spur gears using digital image processing technology is studied. At first, distortion correction and filter in the original image captured by CCD camera. Were taken account of edge image of single pixel was achieved after treatments such as threshold segmentation and four-neighborhood erosion based on mathematical morphology. As to the shape character istic of gear, some basic principles such as gravity model, least squares fit, Hough transform, and Bresenham drawing circle were applied synthetically, and the algorithm of measuring numbers of teeth, module, radius of center hole, radius of addendum circle, radius of dedendum circle, modification coefficient, etc. was established. A gear whose diameter of indexing circle is 50 mm was tested using 1280×1024 CCD camera and acquisition block, and the results indicated that absolute error of measuring value is less than a pixel compared with manual measurement; the absolute error of radius of addendum circle-the largest size in all the measuring parameters is 13 μm. The research indicates that by high resolution CCD camera and optical amplifying system, minute gear and high precision gear can be measured,because the higher the resolution of CCD camera is and the smaller the objects are, the higher the measuring precision is, what's more, they are of linear relation. When spur gears whose diameters of indexing circle are less than 5 mm are measured by CCD camera with the resolution of over 1280×1024, the precision of measurement is below than 2 μm.