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The Design Of Micro Shape Error Measurement System Based On Image Processing

Posted on:2012-01-24Degree:MasterType:Thesis
Country:ChinaCandidate:W Q GuoFull Text:PDF
GTID:2218330344950945Subject:Measuring and Testing Technology and Instruments
Abstract/Summary:PDF Full Text Request
With the development of digital image acquisition and processing technology, image has become an important means by which human obtain environment information. The geometric parameters of machine parts are evaluated by using of image information, which is one of important contents of image processing. The design of shape error measurement system based on image processing combined with the powerful data processing capability of computer, which is the application of digital image processing and analysis technology to the field of accurate measurement. The paper realized precise measurement of tiny shape error by using of the means of processing image edge to obtain geometric parameters. So, the key and foundation of image measurement is image processing technology.Chongqing University of Technology do engaged in long term research on time grating angular displacement sensor. Measurement accuracy of the angular displacement sensor which they researched and developed reaches±1″. When the effect that machining precision of time grating sensor rotor make on time grating sensor is researched, shape error of time grating sensor rotor must be measured precisely, diameter of time grating sensor rotor is 100~300mm, 360 grooves are machined in one circle mostly. Due to many number of grooves and small dimension, Artificially measurement squanders time and vigour. So automatic measurement system must be designed to measure shape error of time grating rator.The research content of this dissertation is the design of an image measurement system based on CMOS image sensor by using of digital image processing technology . The measurement object of image measurement system is flute pitch of time grating rotor. The image measuring system is made up of optical system, image gathering system, and PC image processing system.The mainly work and contents of this dissertation are assigned as follow:(1) Whole design scheme of the image measuring system is given, and system measurement principle, experiment calibration principle, factors which influence measurement accuracy of image measurement system are analyzed. Active visual sensing technology is selected in this dissertation to select light source, illumination method and optical amplifier system.(2) Hardware platform of image acquisition system is set up, which consist of CMOS Image Sensor OV9121, STM32 control module, FIFO buffer control module, and serial interface communication module. According to requirements of system, hardware diagram of image acquisition system is given, various and module design and device selection are elaborated in detail.(3) Software flowchart of image gathering system is given, and design ideas and realization of STM32 control module FIFO buffer control module, and serial communication module are introduced respectively.(4) Image processing algorithms include image preprocessing, edge detection, Hough transform, Least-square method are discussed in detail, and the results of all kinds of image processing algorithms are analyzed and contrasted.(5) According to image processing algorithms and Visual C++6.0,upper machine image processing software is designed based on image processing algorithms and program flow chart is given. A set of completed image processing system is developed.(6) An experiment on one rotor teeth is carried out, experimental datas are processed, and the error is analyzed. analysis results show that measurement accuracy of system is superior to 0.15%, and satisfies acquirements of system.Due to the design of image measurement system, image acquisition, transmission, shape error measurement are realized in this dissertation, Exprerimental results show that the system meet requirements expected. The measurement system posses the following advantages, such as, high measurement accuary, rapid measurement speed, not contact measurement and low costs, which is successor of traditional measurement instruments. The system extend measurement field and range to a large extent. The designation of the measurement system can change present situation about underdevelopment of domestic measurement instruments and has higher popularizing value and widely application prospects.
Keywords/Search Tags:image measurement, shape error, CMOS Image Sensor, image acquisition, edge detection, curve fitting, OV9121, image processing
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