Research On Principle Of Three Axis Intersection Measurement And Device Design Scheme Based On CCD

Axis intersection, which is required in large-diameter reflector frames and frequency doubling crystal framework of SG-Ⅲrange of PV systems, three-axle table, precision centrifuge and some machine tools, is an important precision standard. Measurement methods in existence can only measure particular equipment 's axis intersection and is not universal.Therefore, we need to analyze principle of measurement of axis intersection, and present a new measurement scheme .In recent years, image measurement is a new rising measurement technology that is measured in digital images as carriers of information, to achieve noncontact, flexible and real-time measurement. It has been applied widely. A new method of axis intersection measuring based on image measurement technique is proposed in the paper. This method can measure rotation errors on shaft 's end face directly and extract shaft 's average rotation axis then,achieve the goal of measuring rotation errors and axis intersection rapidly.According to the principle of the CCD camera imaging, a measurement model and the position of the axis relationship model are established. This thesis does research on the movement characteristics of shaft rotation and the evaluation method of rotation errors,calculates the rotation error and average rotation center,deduces the axis equation of shaft's average rotation axis. According to requirements of measurement,after a study on image-forming principle,infinite image diatance optics system is applied and measurement scheme.Image processing technology involved in measurement,the paper also studied. In image preprocessing, through experiments , median filter is selected to remove noise, Sobel operator is used to extract edge points. Through Hough transformation more than once, accurate edge lines of target are obtained. To improve measurement accuracy, using sub-pixel algorithm accurate positioning edge points. It is found through experiments that gray-moment method with high positioning accuracy and convenient calculation fully meets the measurement requirements. The computational formula of feature points in target are deduced after precise positioning of the edge points. According to measurement theory and image processing methods, the software is developed.Finally, through an experiment with CCD camera on one shaft and analysis of measurement error,it can be concluded that the measurement method is easy to use and has a high accuracy.