Vývoj fotogrammetrického systému pro měření rotačně symetrických výkovků

Development of a photogrammetry system for the measurement of rotationally symmetric forgings

conference paper

en

The paper presents development of system for the measurement of shape and dimensions of rotationally symmetric forgings under high temperature. Demands on measurement accuracy of these large semifinished products are in the order of millimetres. The challenge is to design a measurement system that overcomes problems caused by high temperature and provide instant results without interrupting the production process. Proposed approach exploiting the fact, that the measured parts have simple rotationally symmetric shape and contrast between them and background is very high. Basic idea is 3D remonstration of actual forging shape from four boundary curves which lie in two mutually perpendicular planes (in the simplest case). Four boundary curves can be obtained by detecting forging edges in two images. This approach has been incorporated into a software application that was created in Matlab programming environment. Main parts of the system, such as calibration, edge detection, spatial orientation and evaluation of information about shape and dimensions of measured parts, have been designed so that the entire measurement process takes only a few seconds. The article focuses on individual parts of the software application. It discusses the suitability of usage of particular mathematical models and designed multi-step edge detection method, which is based on thresholding, directional median filter, validation and correction of detected edge points.

Článek se zabývá návrhem systému pro měření tvaru a rozměrů rotačních výkovků s vysokou teplotou. Popisuje metodiku měření a softwarovou aplikaci, která byla vytvořena v prostředí Matlab. Navržené řešení využívá fakt, že měřené díly mají jednoduchý rotačně symetrický tvar a díky vysoké teplotě mají vysoký kontrast vůči pozadí. Článek se zaměřuje na řešení dílčích kroků jako je kalibrace kamer, prostorová orientace, detekce hran a výpočet tvarových a rozměrových parametrů výkovku.

The paper presents development of system for the measurement of shape and dimensions of rotationally symmetric forgings under high temperature. Demands on measurement accuracy of these large semifinished products are in the order of millimetres. The challenge is to design a measurement system that overcomes problems caused by high temperature and provide instant results without interrupting the production process. Proposed approach exploiting the fact, that the measured parts have simple rotationally symmetric shape and contrast between them and background is very high. Basic idea is 3D remonstration of actual forging shape from four boundary curves which lie in two mutually perpendicular planes (in the simplest case). Four boundary curves can be obtained by detecting forging edges in two images. This approach has been incorporated into a software application that was created in Matlab programming environment. Main parts of the system, such as calibration, edge detection, spatial orientation and evaluation of information about shape and dimensions of measured parts, have been designed so that the entire measurement process takes only a few seconds. The article focuses on individual parts of the software application. It discusses the suitability of usage of particular mathematical models and designed multi-step edge detection method, which is based on thresholding, directional median filter, validation and correction of detected edge points.

Forging, optical measurement, image analysis, photogrammetry

2015

22.06.2015

SPIE-INT SOC OPTICAL ENGINEERING

Munich, GERMANY

9781628416855

0277-786X

Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 952501 (June 22, 2015);

95250R–95257R

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