Better solution than RFID?
Better solution than RFID?
Hi,
I am interested in looking at being able to read the order of a set of cards that are stacked on top of each other. Initially, I thought I might be able to do this with RFID, so when the cards are stacked laying on each other I would just need to place them on the reader and judge the signal strength to get the order.
However I believe that most RFID readers have a hard time reading more than one RFID tag at a time, so I wondered if anyone knew any other ‘tagging’ technology I might be able to look into which would help me solve my issue – the best example I can provide is if I had 10 cards numbered 1-10, mixed their order and then placed them on top of the reader, the reader should be able to tell me the current order of them.
Thanks,
Dan
Tags: better, rfid, Solution, than
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1 Comment for Better solution than RFID?
1. Ben | February 15th, 2011 at 8:52 am
Hi Dan,
RFID technolgy could certainly read all the cards (nearly at once) and tell you what cards you have, but reading the order of the stack would be nearly impossible using RFID.
Depending on the thickness of the cards and how flat the sit, you could embed magnets into them (at different posistions on each card), then read the strengths back using some analog hall-effect sensors (http://www.allegromicro.com) – over a few mm the variation in the magnetic field would be enough to make an educated guess at the distance, and perhaps using a duplicate system to confirm you results.
You could look at punched card technology, this miht work if you had enough holes and patterns, but it’s too late at night to give this much thought. Perhaps vision recognition instead of ‘needles’.
If you have access to the edges of the card and could colour code them or notch them, then vision recognition (with a webcam) would definitely work.
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