Deviation detection method and deviation detection device
View Patent ↗A deviation detection method and a deviation detection device for detecting positional deviation of an electrode assembly during winding are provided. The method comprises: obtaining a plurality of first images and a plurality of second images by using a photographing unit during the winding process of the electrode assembly, where the first image includes a first electrode sheet, and the second image includes a second electrode sheet; matching a first image with a second image, where the first image and the second image contain the same or corresponding identification objects, and the identification objects are portions periodically formed on each winding layer of the electrode assembly; and determining whether the electrode assembly is deviated according to the boundary of the first electrode sheet in the first image and/or the boundary of the second electrode sheet in the second image in a group of matching first and second images.
1 . A deviation detection method for detecting positional deviation of an electrode assembly during a winding process of the electrode assembly, the electrode assembly comprising a first electrode sheet and a second electrode sheet, wherein the deviation detection method comprises:
an image obtaining step of obtaining a plurality of first images and a plurality of second images by a photographing unit during the winding process of the electrode assembly, the plurality of the first images comprising the first electrode sheet, and the plurality of the second images comprising the second electrode sheet,
an image matching step of matching a first image from the plurality of first images with a second image from the plurality of second images, the first image and the second image containing the same or corresponding identification objects, the identification objects being portions periodically formed on each winding layer of the electrode assembly, and
a deviation determining step of determining whether the electrode assembly is deviated in a pair of the matching first and second images according to a boundary of the first electrode sheet in the matching first image and/or a boundary of the second electrode sheet in the matching second image,
wherein the identification objects are a tab of the first electrode sheet and/or a tab of the second electrode sheet in the same winding layer.
2 . The method according to claim 1 , wherein
in the deviation determining step, comparison regions are set according to the identification objects, and it is determined whether the electrode assembly is deviated according to the boundary of the first electrode sheet in the comparison region of the first image and/or the boundary of the second electrode sheet in the comparison region of the second image.
3 . The method according to claim 1 , wherein
the plurality of first images are images of the electrode assembly before being wound around a winding needle, and the plurality of second images are images of the electrode assembly after being wound around the winding needle.
4 . The method according to claim 3 , wherein
in the image obtaining step, the plurality of first images and the plurality of second images are obtained when the winding needle rotates for a preset angle.
5 . The method according to claim 1 , wherein, in the image obtaining step,
the photographing unit comprises a first camera and a second camera,
the first camera photographs the plurality of first images, and the second camera photographs the plurality of second images, and
the first camera and the second camera photograph two opposite faces of the electrode assembly, respectively.
6 . The method according to claim 1 , wherein
in the imaging matching step, a (n+1)th second images of the plurality of second images and a n-th first images of the plurality of firsts images that are obtained in the image obtaining step are matched.
7 . The method according to claim 1 , wherein
in the deviation determining step,
in a pair of the matching first and second images, a first distance is obtained from the first image, a second distance is obtained from the second image, the first distance is a distance from a first reference point to the boundary of the first electrode sheet, and the second distance is a distance from a second reference point to the boundary of the second electrode sheet,
and when the difference between the first distance and the second distance minus a preset distance between the boundary of the first electrode sheet and the boundary of the second electrode sheet is greater than a first threshold, it is determined that the electrode assembly is deviated.
8 . The method according to claim 1 , wherein
in the deviation determining step,
in a pair of the matching first and second images, a first distance is obtained from the first image, a second distance is obtained from the second image, the first distance is a distance from a first reference point to the boundary of the first electrode sheet, and the second distance is a distance from a second reference point to the boundary of the second electrode sheet,
it is determined whether the first electrode sheet of the electrode assembly is deviated by comparing the first distance with a preset value of the first distance, and
it is determined whether the second electrode sheet of the electrode assembly is deviated by comparing the second distance with a preset value of the second distance.