| The application of image processing technology in the field of precise measurement generates a new kind of measure technology—image measure technology. It takes measured objects'images as informational carrier and distills useful information inside for measure aim. Its principle is that uses digital image processing technology to detect the edge of the object, thus to obtain its geometric parameters. Compared its high sensitivity, high resolution, high velocity, large dynamic range, non-contactness and low cost of image measure system with other measure instruments in the same grade of accuracy, image measure system is more suitable to real-time precise measurement of geometric parameters of precise and complex components.In this paper, a new method for measuring the parallelism parameters of measured pipelines'edges using digital image processing technology is researched and studied. A measure system with high accuracy has been set up by taking slim and round pipes (bars) of many pipelines as measure objects, adopting numeral camera to attain images, and assorted with frame-grabber board, one computer, corresponding hardware interface and software. Unlike the most of measurement methods of the centre of a circle, in this paper, it presents the practical methods through making a comparison between hough transform detection of circles and least squares mean circle detection, ensures fitful arithmetic for practical measure requirement, and analyzes its academic errors.In this paper, first, compared the advantage of image measure technology with traditional precise measure technology and analyzed the status of parallelism measurement of axis parts using image measure technology; second, during the course of image pre-processing, based on the fundamental principle of digital image processing to carry on edge measurement which is the basic of later measurement. The measure principle of image measure system is elucidated, the measure method of circle parameters which is suitable for practical requirement is presented; finally, solved parallelism errors based on experiment and analyzed the reasons of errors and improvement measures in detail. |
