Author Topic: Coin identfying  (Read 1330 times)

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Offline kpmcgurkTopic starter

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Coin identfying
« on: July 08, 2009, 06:59:03 AM »
So for my whole life I have always loved collecting coins!! so I have always dreamed of making a robotic type machine that could easily sort out different coins. No not pennies from nickels and Dimes. but wheat cents from from regular pennies. If you do not know what this is, basicly pennies made before 1950ish have a couple heads of wheat on the "tales" side instead of the memorial.

Now my question is what would be the best way of roboticly distiquishing between these coins? I have been looking into robo realm, and thought it looked like a great solution to the problem. I could create a coin using probes and lines, and if the coin underneath the camera does not match the coin in the computer, It will be kept for further investigation!

I have the mechanical aspect of it down, that will be the easy part, next I want to work of the actual coin recognition.

The questions...

will roborealm work for this?
which camera?
Axis Cam

NOTE: there will be a slight weight difference in these two coins because coins made before the 80's are made of copper and weigh different, but then once sorted I would still need to go through like 40 percent of the coins...
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Offline airman00

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Re: Coin identfying
« Reply #1 on: July 08, 2009, 08:13:20 AM »
I'm a coin collector myself, even have the 1909 VDB wheat penny.

Pennies of different years have different weights:
According to wikipedia:
Bronze (1909–1942)
    * Composition: .950 Copper, .05 Tin and Zinc
    * Weight: 3.11 grams
Zinc-plated steel (1943)
    * Composition: 100% Steel plated with Zinc
    * Weight: 2.70 grams
Shell casing bronze (1944–1946)
    * Composition: .950 Copper .05 Zinc
    * Weight: 2.70 grams
Bronze (1946–1958)
    * Composition: .950 Copper, .05 Tin and Zinc
    * Weight: 3.11 grams
However, I would double check these weight specifications because Wikipedia isnt the most reliable source.

Besides for weight, you could distinguish pennies by resistance. Different metals have different resistance values. Or you might even be able to distiniguish them by resonance - hit a penny and have a microphone figure out what frequency is being produced.  A couple of google searches or even an experiment would provide you with the data you need.

Or you can have a coin slot sandwhiched by two cameras. Illuminate the coin slot with white LEDs for good quality images. Then run Roborealm to figure out which side is top, and which side is bottom, and then do a Image comparison to see what that coin is. The problem with that is that it won't work if the coin is dirty or scratched.
« Last Edit: July 08, 2009, 08:16:27 AM by airman00 »
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