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8421 code coding efficiency is high, identification difficulty is low, more and more PCB carrier manufacturers use 8421 code instead of two-dimensional code for information tracing.
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1). Project background:
Detection requirements:
The products are divided into 9 codes and 10 codes. The products grab dynamic and random incoming materials through suction cups. The scheme needs to adapt to the two products and the output results within 500ms are sent through TCP to coexist. (The tested object is the perforated PCB material plate captured by the suction cup in the following figure, which is identified by lighting the backlight).
Pain points and problems:
There will be random horizontal image inversion without mark and signal, and there will be code deformation, imaging blur, image adhesion of code holes, and different size of code holes occasionally. Complex imaging conditions make it difficult to identify the conventional matching mark bit reading algorithm stably.
2). Solution architecture:
Scheme diagram:
Solution idea description:
1. The hole position of 8421 yards is identified by contour matching
2. Use the script module to identify the XY mirror of 8421 code through 8421 code flag bit and column flag bit and obtain the four vertices of 8421 code external quadrilateral
3. Use OpenCV perspective transformation to correct and repair the deformed 8421 code (the following figure is the perspective transformation effect) to facilitate the subsequent 8421 code decoding.
3). Program advantages:
1. The scheme algorithm takes about 200ms, and can adapt to complex situations such as code deformation, imaging ambiguity, code hole imaging adhesion, and different code hole sizes.
2. each machine can recognize about 1000 boards per day, and the recognition rate of 8421 codes reaches 100% after debugging.
3. No deep learning modules are used to reduce costs.
4. can be reused for more PCB industry 8421 code identification needs.
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