CN111650392A - Metal sheet movement speed detection method based on linear array camera stereoscopic vision - Google Patents
Metal sheet movement speed detection method based on linear array camera stereoscopic vision Download PDFInfo
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- CN111650392A CN111650392A CN202010632538.XA CN202010632538A CN111650392A CN 111650392 A CN111650392 A CN 111650392A CN 202010632538 A CN202010632538 A CN 202010632538A CN 111650392 A CN111650392 A CN 111650392A
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- 239000002184 metal Substances 0.000 title claims abstract description 75
- 238000001514 detection method Methods 0.000 title claims abstract description 16
- 238000005070 sampling Methods 0.000 claims abstract description 7
- 238000011897 real-time detection Methods 0.000 claims abstract description 6
- 230000000007 visual effect Effects 0.000 claims description 13
- 238000004364 calculation method Methods 0.000 claims description 3
- 230000007547 defect Effects 0.000 abstract description 6
- 238000000034 method Methods 0.000 description 13
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000003384 imaging method Methods 0.000 description 2
- 208000032544 Cicatrix Diseases 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 231100000241 scar Toxicity 0.000 description 1
- 230000037387 scars Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
- G01P3/68—Devices characterised by the determination of the time taken to traverse a fixed distance using optical means, i.e. using infrared, visible, or ultraviolet light
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention provides a linear array camera stereoscopic vision-based metal plate movement speed detection method, which comprises the following steps of: acquiring surface images of the metal plate to be detected at different positions through a plurality of linear array cameras based on the movement of the metal plate to be detected; determining the position difference of any pixel position on the surface of the metal plate to be detected in the two linear array cameras acquired images through stereo matching; and the real-time detection of the movement speed of the metal plate to be detected is realized by combining the sampling line frequency set by the linear array camera. The invention is suitable for real-time detection of the movement speed of the metal sheet, so that the surface image of the sheet acquired by the area-array camera is not lost, the surface image of the sheet acquired by the line-array camera is not distorted, and the positioning of the surface defect of the metal sheet is more accurate.
Description
Technical Field
The invention relates to the technical field of speed detection methods, in particular to a linear array camera stereoscopic vision-based metal plate movement speed detection method.
Background
The surface defects of the metal plate have important influence on the quality of the metal plate strip. The method is influenced by factors such as raw materials, rolling process, system control and the like, and defects on the surface of the metal plate, such as cracks, scratches, roll marks, scars, impurities and the like, not only have different degrees of influence on the wear resistance, fatigue resistance, corrosion resistance and electromagnetic property of the metal plate, but also can cause serious accidents such as strip breakage and parking in production and cause unpredictable economic and brand losses to production enterprises. Therefore, all the manufacturing enterprises pay attention to the detection of the surface quality of the metal plate, and the detection technology is improved and the detection level is improved with great expense.
The online detection technology of the surface defects of the metal plate based on machine vision is an important advanced means and technology for monitoring the surface quality of a metal plate production line. The machine vision-based online detection can be used for detecting the quality of the metal surface in real time, full continuity and full coverage, is widely concerned by production enterprises and is widely applied. The existing metal plate surface defect detection method based on machine vision mainly has two modes, namely a method of combining an area camera with a surface light source and a method of combining a linear array camera with a linear light source. No matter which method is adopted, when the camera is used for imaging the metal surface, the image acquisition speed needs to be matched with the movement speed of the metal plate, otherwise, the acquisition of the surface image of the steel plate is influenced: for an area-array camera, the mismatching of the motion speeds can cause the missing or overlapping of the surface images of the plate between the adjacent frame images; for the linear array camera, the mismatch of the motion speed can cause the spatial resolution of the image on the surface of the plate to be inconsistent in the motion direction, and the image distortion exists.
Aiming at the problem that the surface image of the metal plate needs to be strictly matched with the movement speed of the plate, the current method for acquiring the movement speed of the plate is realized by an encoder arranged on a metal plate conveying roller. However, the method of acquiring the conveying speed of the metal plate using the encoder on the conveying roller is not accurate enough due to the slip between the conveying roller and the metal plate.
Disclosure of Invention
According to the technical problem that the accuracy of the method for acquiring the conveying speed of the metal plate by using the encoder on the conveying roller is insufficient due to the fact that the conveying roller and the metal plate slip, the method for detecting the moving speed of the metal plate based on the stereoscopic vision of the linear array camera is provided, and is characterized by comprising the following steps of:
step S1: acquiring surface images of the metal plate to be detected at different positions through a plurality of linear array cameras based on the movement of the metal plate to be detected;
step S2: determining the pixel position difference of any point on the surface of the metal plate to be detected in the images acquired by the two linear array cameras through stereo matching;
step S3: and the real-time detection of the movement speed of the metal plate to be detected is realized by combining the sampling line frequency set by the linear array camera.
Furthermore, the linear array cameras are all arranged on the same surface of the metal plate to be detected.
Furthermore, the visual field positions of the plurality of linear array cameras on the surface of the metal plate to be measured are different.
Further, the line camera is a common line camera or a time delay integral line camera.
Furthermore, the position difference of any pixel position on the surface of the metal plate to be measured in the two linear array camera collected images is determined through stereo matching, and the calculation method of the movement speed of the metal plate to be measured comprises the following steps:
V＝Pf/S；
wherein V represents the movement speed of the metal sheet to be detected, P represents the visual field distance of the linear array camera on the surface of the metal sheet to be detected, f represents the sampling line frequency of the linear array camera, and S represents the pixel position difference in the collected images between the linear array cameras after any point on the surface of the metal sheet is subjected to stereo matching.
Compared with the prior art, the invention has the following advantages:
the invention is suitable for real-time detection of the movement speed of the metal sheet, so that the surface image of the sheet acquired by the area-array camera is not lost, the surface image of the sheet acquired by the line-array camera is not distorted, and the positioning of the surface defect of the metal sheet is more accurate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic view of a camera arrangement according to the present invention. Wherein, (a) the linear array cameras have parallel visual angles; (b) the linear array camera has opposite visual angles; (c) the linear array camera has opposite visual angles.
FIG. 2 is a schematic view of a light source and a camera according to the present invention. Wherein, (a) the visual field positions are similar, and the light sources are shared; (b) the field of view is far away, and the light source is independent.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1-2, the present invention provides a method for detecting the moving speed of a metal plate based on the stereoscopic vision of a line camera, which uses the movement of the metal plate itself as the basic principle, and in this application, 2 line cameras are taken as an example for corresponding description. Firstly, based on the movement of a metal plate to be detected, two-dimensional scanning images of the surface of the metal plate are obtained through two linear array cameras arranged at different visual angles, the two-dimensional images at the two different visual angles are matched, the time difference of any point on the surface of the metal plate in the two-dimensional images at the two different visual angles is obtained, and finally, the sampling line frequency set by the linear array cameras is combined to realize the real-time detection of the movement speed of the metal plate.
Determining the pixel position difference of any point on the surface of the metal plate to be detected in the images acquired by the two linear array cameras through stereo matching, wherein the calculation method of the motion speed of the metal plate to be detected comprises the following steps:
V＝Pf/S；
wherein V represents the movement speed of the metal sheet to be detected, P represents the visual field distance of the linear array camera on the surface of the metal sheet to be detected, f represents the sampling line frequency of the linear array camera, and S represents the position difference of any point on the surface of the metal sheet in the acquired images among the linear array cameras after stereo matching.
In fig. 1, the arrangement of the two linear cameras may be parallel, opposite or opposite, and the two linear cameras have different viewing field positions on the surface of the metal plate.
In fig. 2, according to different arrangement modes of the cameras, the light source can be used to supplement light to the surface of the board to improve the image quality: 1) when the view field positions of the two linear array cameras on the metal surface are basically the same, the same LED strip-shaped or linear light source or laser light source is adopted to be shared to carry out projection in a direction perpendicular to the movement direction of the metal sheet; 2) when the two linear array cameras are different in view field position on the metal surface, no matter the two linear array cameras face to each other or are opposite to each other, two groups of independent light sources are selected and used, and the independent light sources are LED strip-shaped light sources, linear light sources or laser light sources. Each visual angle linear array camera is matched with a group of independent light sources, and each group of independent light sources projects towards the metal surface along the imaging plane of the linear array camera matched with the independent light sources.
In the application, the two linear array cameras are arranged on the same surface of the metal plate to be detected. And the linear array cameras are different in view field positions on the surface of the metal plate to be detected.
Meanwhile, in the present application, the line camera is a common line camera or a time delay integral line camera.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments. In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described apparatus embodiments are merely illustrative.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (5)
1. A linear array camera stereoscopic vision-based metal sheet movement speed detection method is characterized by comprising the following steps:
s1: acquiring surface images of the metal plate to be detected at different positions through a plurality of linear array cameras based on the movement of the metal plate to be detected;
s2: determining the pixel position difference of any point on the surface of the metal plate to be detected in the images acquired by the two linear array cameras through stereo matching;
s3: and the real-time detection of the movement speed of the metal plate to be detected is realized by combining the sampling line frequency set by the linear array camera.
2. The linear array camera stereoscopic vision-based metal plate movement speed detection method as claimed in claim 1, wherein: and the linear array cameras are arranged on the same surface of the metal plate to be detected.
3. The linear array camera stereoscopic vision-based metal plate movement speed detection method as claimed in claim 1, wherein: the visual field positions of the linear array cameras on the surface of the metal plate to be detected are different.
4. The linear array camera stereoscopic vision-based metal plate movement speed detection method as claimed in claim 1, wherein: the linear array camera is a common linear array camera or a time delay integral linear array camera.
5. The linear array camera stereoscopic vision-based metal plate movement speed detection method as claimed in claim 1, wherein:
determining the pixel position difference of any point on the surface of the metal plate to be detected in the images acquired by the two linear array cameras through stereo matching, wherein the calculation method of the motion speed of the metal plate to be detected comprises the following steps:
V＝Pf/S；
wherein V represents the movement speed of the metal sheet to be detected, P represents the visual field distance of the linear array camera on the surface of the metal sheet to be detected, f represents the sampling line frequency of the linear array camera, and S represents the pixel position difference in the collected images between the linear array cameras after any point on the surface of the metal sheet is subjected to stereo matching.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010632538.XA CN111650392A (en) | 2020-07-03 | 2020-07-03 | Metal sheet movement speed detection method based on linear array camera stereoscopic vision |
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| CN202010632538.XA CN111650392A (en) | 2020-07-03 | 2020-07-03 | Metal sheet movement speed detection method based on linear array camera stereoscopic vision |
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