Research on Dimensional Inspection System of Thin Sheet Part Based on Machine Vision

Abstract: Key technologies of dimensional inspection system of thin sheet part based on machine vision are investigated, and an entire machine vision inspection system is developed. A cad information-based line scanning step adaptive optimization method used for image grabbing of inspected part is proposed. A rectangle lens subpixel edge detection method based on cubic spline interpolation used for edge detection is advanced. A planar contour primitive recognition method based on curvature and HOUGH transform used for image recognition is raised. The inspection accuracy of the inspection system can reach to 1μm, and the inspection time can satisfy the requirements of on-line real-time inspection, so the inspection system is feasible. Introduction In the mass production of thin sheet part, in order to ensure the quality and enhance the production efficiency of the thin sheet part, the dimension of the finished thin sheet part must be inspected 100 percent and online, and the inspection system must be real-time, and it can obtain dimension information of the inspected part as much as possible in the shortest possible time on the condition that the inspection accuracy is guaranteed to meet the requirements, so as to satisfy the requirements of the tact time. Since the thin sheet part is very thin, a big measurement error will be produced due to the deformation of the thin sheet part under the loading of contact force, so the thin sheet part must be inspected with non-contact inspection method. The shapes of the thin sheet part are irregular and the dimensional accuracy requirements of the pitches of holes and apertures are high, so the inspection system must have the ability to inspect the pitches of holes and apertures with high accuracy. The traditional inspection technologies and instruments cannot satisfy the inspection requirements of thin sheet part with high accuracy, efficiency, automation and so on. The Machine Vision inspection technology can be used to satisfy the inspection requirements of thin sheet part with the advantages of non-contact, good flexibility, high accuracy, high inspection speed, high automation and intelligence, easy to integration with the information of design and control, and so on. The development of dimensional inspection system of thin sheet part based on machine vision with independent intellectual property rights has significant value both in theory and application