| In modern design of solid rocket motor, coated layer has the ability of repressing combustion and protecting the shell from burning through. In the production of coated layer, bubbles generating from the slurry during production process, there are usually some defects on the surface,such as pits(fracted bubbles) or bumps(intact bubbles), which leads to the decrease of the thickness and probable launching failure. Therefore, it is important to detect the surface defects for guaranteeing the quality of the motor.The paper take coated layer of SRM as research object, through the analysis of detection requirements and the characteristics of the solid rocket motor, the paper designs the overall structure of the system and adopts the industrial camera、illuminant、servo motor and related hardware to construct the detection platform. In order to realize the inspection of coated layer of multi-caliber motors, the paper designs the multi-joint measuring arm and puts forward a solution of inspecting with equal interval. For the problem of low resolution, inconsistent gray background and image distortion exist in the original picture, this paper eliminates the influence of the background and improves the resolution of the defects with the method of high and low cap transformation, the paper also uses the method of geometric transformation to reduce the degree of distortion. Through the camera calibration, the paper obtains the relationship between image point and corresponding object point, by which calculates the area of the defects. Since the same defect exist in the different defect images, and the position of defect is different, the paper adopts the method of image matching based on location to further improve the detection precision of the defect size.Experimental results showed that the machine vision detection technology combined with image processing technology can effectively detect the size of the surface defects of the motor coating layer. |
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