The Topography Measurement Of Depressed Airway Based On Machine Vision

The machine vision is used to realize the precision measurement. And it caneffectively improve the industrial detection efficiency that machine vision isintroduced into the industrial measurement. In the industrial manufacturing, variousmodels were used, and they were very difficult to detect because of the complexity ofthe structure. The paper used a suitable method to measure the depression and nestedsurface of diesel engine work piece and had a higher accuracy. The main contents ofthis paper are follows:1. The work piece parameters in the camera coordinates must be converted intophysical coordinates to compare with standard. So the paper studied the rotatingprinciple of coordinates, and realized conversion of the camera coordinates tophysical coordinate system. Then compared with the actual data and analyzed theerror. In order to eliminate the error, we mainly analyzed the influence of light center,camera calibration and distortion correction. Using Hessian matrix to obtain the lightcenter can reach the sub pixel, and can effectively change the accuracy.2. In order to calculate the cylindrical axis vector, and avoid calculating threedimensional curvature and3D surface fitting, a new method is proposed. Because the3D points got by scanning were in the light plane, the points would intersect withcylindrical points after rotating the light plane. When the intersection was a straightline, the line was cylindrical axis vector. The3D points were analyzed intwo-dimensional light plane to fitting line slope avoiding for3-dimensional curvature,simplifying the computation. The experiment of the measurement for the dieselcylinder head surface hole indicated that this method had a high accuracy, and themethod was simple.3. Considering to the surface characteristics of the cylinder head, we realized theconversion of coordinates based on the local hole. Then we obtained the data of holeto measure by the depth and radius difference of the hole needed and the interferentialhole. The method has certain guiding significance for the measuring of depression andnested morphology.