Research Of The Reflection Model Of The Edge Of Objects And A Method Of Measurement

Modern industrial production and life cannot leave cylinder workpieces, such as spindles and rollers and etc. With the continuous development of technology and industry, the manufacturing industry needs more precise cylindrical workpieces. High precision cylindrical workpiece can reduce mechanical wear and extend the life of the machine. Currently, manual contact measurement is still used in many industrial productions to measure the diameter of the workpieces. The manual contact measurement is very slow, it can not adapt to modern industry with high speed and automation. The commonly used non-contact methods of measuring diameter roughly include projective diameter measurement, image diameter measurement and Laser scanning diameter measurement. The image diameter measurement is the research object of the subject. The image diameter measurement refers to use the machine vision system to capture the image of the analyte, then analyze the image to obtain the analyte’s diameter.The photoelectric measurement system generally uses the common industrial lens. Limited to the manufacturing process and structure, when the general industrial lens is capturing image of the cylinder, the image has some problems such as distortion and magnification change, so using a software algorithm for image correction is necessary. Sometimes, however, it cannot be corrected by this method. But if the photoelectric measurement system uses the telecentric lens, these problems can be overcome to some extent. Compared with the general industrial lens, the telecentric lens has smaller distortion, greater depth of field and higher resolution, so the telecentric lens plays an important role in the field of machine vision measurement.The telecentric optical measurement was the background of this dissertation. Firstly, the dissertation had finished analyzing the ray reflection at the edge of the smooth metal film cylinder when the backlight was an area light source, then the dissertation had finished analyzing the model when the backlight was a telecentric light source. Thereby the light intensity distribution at the edge of the cylinder can be inferred abstractly. The light intensity and the gray value had a corresponding relationship, so the reflection model of the edge of the cylinder can be built. Then the image of the cylinder had been analyzed when the backlight was an area light source or a telecentric light source, and the radius of the cylinder could be calculated by comparing the value of the fringe transition zone of the image and the theoretical value, thereby the method of how to use the model could be solved. At last, the dissertation had verified the reflection model of the edge of the cylinder when the optical magnification was different.The theoretical analysis and the experiments show that the reflection model of the edge of the cylinder could determine the position of the cylinder’s edge more accurately than the traditional image processing algorithms. The precision of the measurement results reached the micron level.