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Quick digital image correlation measurement method based on stochastic parallel gradient descent optimization technology

A gradient descent and digital image technology, which is applied in the direction of measuring devices, instruments, and optical devices, can solve problems such as poor accuracy and robustness, inability to guarantee the global optimal value of the correlation coefficient, errors, etc.

Inactive Publication Date: 2011-10-19
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

[0004] In practical applications, how to improve the accuracy and speed is the core and difficult problem in the DIC measurement method. The current DIC implementation methods include dual-parameter iteration method, Newton-Raphson iteration method, cross search method, hill climbing method, least square method, etc. These methods are complex in principle, poor in accuracy and robustness for complex or large deformation situations, and sometimes may even get wrong results
In addition, the above method does not guarantee that the correlation coefficient reaches the global optimal value, and the accuracy and reliability of the measurement are also affected.

Method used

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  • Quick digital image correlation measurement method based on stochastic parallel gradient descent optimization technology
  • Quick digital image correlation measurement method based on stochastic parallel gradient descent optimization technology
  • Quick digital image correlation measurement method based on stochastic parallel gradient descent optimization technology

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Embodiment 1

[0050] Embodiment 1: Displacement measurement of rigid body

[0051] The rigid body displacement is u 0 =0.01, 0.05, 0.1, 0.5, 1, 3 pixels, the comparison of the results obtained by using SPGD DIC and the Newton-Raphson measurement method commonly used abroad is shown in Table 1:

[0052] Measuring method of the present invention and Newton-Raphson method result contrast of table 1

[0053]

Embodiment 2

[0054] Example 2: Rotation measurement of rigid body

[0055] The rotation angles are respectively θ=0.01°, 0.05°, 0.1°, 0.5°, 1°, 3°, using the SPGD DIC-based measurement method of the present invention and the results obtained by the Newton-Raphson method as shown in Table 2:

[0056] Measuring method of the present invention and Newton-Raphson method result contrast of table 2

[0057]

[0058] It can be seen from the above two cases that the SPGD-based DIC measurement method of the present invention can significantly improve the measurement accuracy. In addition, because the method does not need to calculate the secondary partial derivative of the deformation matrix parameter, it can greatly save measurement time and be used in working conditions. Measured in real time.

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Abstract

The invention provides a quick digital image correlation measurement method based on stochastic parallel gradient descent optimization technology, comprising the following steps of comprehensively considering related parameters such as displacement, differential coefficient and the like of any one point in a speckle field of an object to be measured; and utilizing the stochastic parallel optimization technology to realize quick digital image correlation measurement. In the method, by adopting stochastic parallel disturbance on a deformation parameter, the correlation coefficient is convergentto a global unique extremum, thus obtaining the deformation parameter. The method has a simple principle, can be realized easily, is a DIC (digital image correlation) measurement method with totally new concept, can realize the aim of quickly measuring DIC with high precision and high reliability, and is expected to realize the real-time online measurement on the DIC.

Description

technical field [0001] The invention relates to a fast digital image correlation measurement method, in particular to a method for realizing fast digital image correlation measurement by using stochastic parallel gradient descent optimization technology, which can be used to quickly measure deformation field parameters of an object online. technical background [0002] Digital Image Correlation Measurement (DICM) or Digital Speckle Correlation Measurement (DSCM) was developed by Japanese I.Yamaguchi (Yamaguchi I.A laser-speckle strain gauge[J] in the early 1980s). .Journal of Physics E: Scientific Instruments, 1981, 14:1270~1273) and W.H.Peter and W.F.Ranson of the University of South Carolina (Peter W H, Ranson W F.Digital imaging technique in experimental stress analysis[J].Optical Engineering, 1982, 21(3): 427-431) etc. independently proposed. It realizes the measurement of the deformation field of the object by performing correlation processing on two images (speckle fi...

Claims

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Application Information

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IPC IPC(8): G01B11/16
Inventor 龙学军伏思华李松洋梁永辉王三宏
Owner NAT UNIV OF DEFENSE TECH
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