| Nowadays, with the development of Chinese economy, the increasing rate of GDP is quite high. One of the most vital factors is the growth of manufacturing industry. Because of Non Contact, Real Time, High Accuracy and Flexibility, the detection system based on machine vision is more and more widely used than ever before, which can extremely improves the productivity and the product quality in manufacturing industry.Currently, there are various types of photoelectric measuring instruments in the market; however they can not satisfy customer's particular demand and accuracy requirements*. This paper is based on the contract project between ChangChun Institute of Optics, Fine Mechanics and Physics (CIOMP) and AVIC I ShenYang Liming Aero-Engine CO. LTD. It is to design a photoelectric measuring instrument for special type of turbine blade. The system can precisely measure special turbine blade which is irregular shape, such as size of holes, distance between holes on the turbine blade and casting quality of turbine blade. In the paper, I mainly research on the particular image-processing algorithm for the irregular shape workpiece and program the system control software for the measuring instrument.For this system, there are three main steps as the following: First, the system software controls the X, Y, Z, U, V motors to correct the attitude of irregular-shape turbine blade. Second, the 1028x1024 CMOS camera gets the image of the hole on turbine blade. Finally, the image processing algorithm treats the image based on the industrial computer. The most important features of this photoelectric measuring instrument are:①Software controls the X, Y, Z, U, V motors to correct the attitude of irregular-shape turbine blade②The real-time data feedback from grating scale and axis-angle position encoder③To design a new, special image processing algorithm in machine vision detection area. The algorithm can process (1280×1024) image of irregular-shape turbine blade quickly. The detection precision reaches to sub-pixel level.④Real-time data storage, EXECL generationAs the vital part, the image processing algorithm is specially designed for the irregular-shape workpiece; it is a new kind of image-processing algorithm in machine vision area. The algorithm is divided into two sub-parts: the pretreatment based on the image, the coarse-positioning by centroid detecting method and the accurate-positioning by twice of the least squares method (LSM). Then, we will get the data about the circle center, radius of holes and the distance between holes on workpiece. The precision came to sub-pixel level.System Software: to program control software of hardware system, image acquisition software and image processing algorithm based on Microsoft, Visual C++6.0 platform. Image acquisition software and image processing algorithm are stable and reliable; the user interface is friendly and easy to operate for consumers, which can generate EXCEL report for detection result. The system software is divided into six modules: system preparation module, calibration location module, motion control module, image acquisition module, size detection module and result show module.The Photoelectric Image Measuring Instrument has been applied in the practical production. The system hardware is reasonable and practical; the system control software is stable and reliable; image high-speed detection and processing algorithm can meet customers' precision requirements. This instrument greatly improves the production efficiency as the design goal. |
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