| As one of the advanced automated inspection technology, computer vision (CV)has many merits such as non-touch, real-time, flexibility and high accuracy, with increasing of computer technology, the technique of imaging equipment fabricating and development of image processing technology, computer visual inspection technology will be widely used and developed in practicality.In our research project, we take the tail-hole in the hard-disk driving shelves as an object. Lots of works have been done to deal with key technology such as camera calibration, edge detection and methods of vision measurement for diameter of hole as well. Finally high precise measurement of the small hole is achieved using computer visual inspection.Light sources and lenses play an important role on the quality of image just like cameras in the computer visual inspection applications. The LED light source and lenses with little distortion are selected as light sources and lens of imaging for inspection system, which provide high quality images during precise inspection.A simple and high precise method of calibration is given aiming at the character of the inspection system in the paper. A standard hole is regarded as reference, and diameter of the hole in image is calculated by the curve fitting algorithm. The result of the calibration compared with the HexSight software is very satisfied.In the edge detection part, the performance between classical edge algorithm and Canny algorithm is compared. Canny algorithm is better than classical edge detection algorithm in the way of the precision of edge locating and anti-noise. So the canny algorithm is used in the paper. Meanwhile the sub-pixel edge detection is studied in the paper.Two methods for inspecting the circle are given on the basis of study of visual inspection in the paper. One method is used to detect circle by an improved algorithm that is faster and more precise than old one, another method is used to detect circle by...
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