High-density packaged element positioning method based on speeded up robust features (SURFs)

A positioning method and component technology, applied in the direction of instruments, measuring devices, optical devices, etc., can solve problems such as large errors, failure to meet production requirements, and decreased positioning accuracy of key points

Active Publication Date: 2012-09-12
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although SURF is superior to SIFT in terms of calculation speed, the accuracy of key point positioning will decrease due to the use of a simplified Hessian matrix to detect key points.
The error of simply using the SURF algor...

Method used

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  • High-density packaged element positioning method based on speeded up robust features (SURFs)
  • High-density packaged element positioning method based on speeded up robust features (SURFs)
  • High-density packaged element positioning method based on speeded up robust features (SURFs)

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Embodiment

[0056] like figure 1 As shown, a SURF-based high-density packaging component positioning method of the present invention comprises the following steps:

[0057] S1 Rough positioning: Input the image to be registered I(x, y), use the SURF registration method to calculate the rough transformation relationship (m, n, β) between I(x, y) and the template image f(x, y), Among them, m and n are the translation parameters in the x and y directions respectively, and β is the rotation angle; specifically, the following steps are included:

[0058] S1.1 Generate integral images according to images I(x, y) and f(x, y):

[0059] For a given image, such as I(x, y), point (x, y) is a certain point in the integral image, then the integral image value I∑ of this point is the origin of I(x, y) and (x, y) The sum of the pixel values ​​of all the pixel points in the rectangular area formed by the pixel points. Using the integral image, the calculation of the sum of all pixel values ​​in any re...

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Abstract

The invention discloses a high-density packaged element positioning method based on speeded up robust features (SURFs), which comprises the following steps: (1), coarse positioning: coarse transformation parameters (m, n and Beta) are obtained by adopting a SURF registration method; (2) fine positioning: an image I (x, y) to be registered is inversely transformed by utilizing the coarse transformation parameters (m, n and Beta) to obtain an image g (x and y), the minimum energy equation E of the image g (x and y) and a template image f (x and y) is calculated, each partial derivative of the E is solved and enabled to be zero, and transformation parameters (a, b and Theta) are solved; m' is enabled to be equal to m plus a, n' is enabled to be equal to n plus b, and Beta' is enabled to be equal to Beta plus Theta; the energy equation E under a transformation relation (m', n' and Beta') is calculated; whether the E is smaller than a set value or not is judged, and if no, next iteration is conducted; and if yes, the iteration process is finished, m' is taken as the final translation parameter in an x direction, n' is taken as the final translation parameter in a y direction, and Beta' is taken as the final rotation angle. Compared with the prior art, the high-density packaged element positioning method realizes high-precision sub-pixel positioning and has great robustness on illumination transformation and noise.

Description

technical field [0001] The invention relates to the field of identification and positioning in precision electronic assembly, in particular to a high-density packaging component positioning method based on SURF (Speeded up robust features, accelerated robust features). Background technique [0002] SMT has entered a fully mature stage after 50 years of development since the 1960s. At present, SMT has not only become the mainstream of contemporary circuit assembly technology and the pillar manufacturing technology of the electronics industry, but also continues to develop in depth to maximize the use efficiency of equipment and meet the rapidly growing production needs. Visual inspection is a necessary process for surface mounting. It separates components of various shapes and specifications from the background. Accurate position and angle compensation information. Therefore, the accuracy of visual inspection determines the quality of surface mount. At present, the placeme...

Claims

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Application Information

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IPC IPC(8): G01B11/02G01B11/26
Inventor 高红霞陈鑫源褚夫国麦倩胡跃明刘屿
Owner SOUTH CHINA UNIV OF TECH
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