Token detection.

Hey there,

I am planning a project where I need to make various tokens that represent various characters, and when I place the token on a surface, I am able to recognize which character that is.

Can you guys give me ideas on how I could approach this in a cheap way?

RFID?

For more help provide more details about your project. Do you just have to know that a specific token is on that surface or do you have to know where it is? How do we have to imagine these tokens?

I just need to detect the token, and be able to know what type of token it is. No need to know its position. RFID seems like a too expensive solution.

MichaelBarneyJr:
I just need to detect the token, and be able to know what type of token it is. No need to know its position.
RFID seems like a too expensive solution.

How many different types of tokens are there?
What is the size and shape of the base of the tokens?
What are the tokens made of?
How thick/tall are they?
Are the different types of different colours, weights, shapes?
What is the size and shape of the surface?
What is the surface made from?
How thick is it?
Without that knowledge, how do you expect us to help you?

Without that knowledge, how do you expect us to help you?

Based on most Newbie posts , everyone thinks we are psychics... XD

RFID seems like a too expensive solution.

http://imall.iteadstudio.com/wireless/rfid/im120618002.html

Less than 6 bucks is too expensive? Or is it the 50 cents for the tag? In this case you definitely have to define your budget and/or the number of tokens you have.

You're hiding most of the information from us but want some help finding a technology for your project. Do you want to waste our time?

Based on most Newbie posts , everyone thinks we are psychics…

When we know we’re really psychotics.

raschemmel: Based on most Newbie posts , everyone thinks we are psychics... XD

My crystal ball has clouded over. Must be because it's running XP! 8)

and when I place the token on a surface, I am able to recognize which character that is.

RFID is one way to approach this but generally in my experience RFID somewhat requires that the tag be placed in the vicinity of the coil and moved away before the second tag is recognized. With many tags in the field, I'm not certain that the simple RFID hardware will recognize a new-token ... and I am not certain it will not.

I think the critical question is, "How many tokens?" Are you planning on tracking Colonel Mustard from the drawing room to the Library? This would be much more complex.

The more we know, the more we can badger harass HELP you!

Ray

I don't think there is a cheap solution to this. I think you are unrealistic to think so. If you want a solution that produces useful data you can get a laser displacement sensor , mount it on an X/Y frame that moves the sensor back and forth with one stepper motor and moves the slide across the other axis with another stepper motor. I guarantee if you collect the displacement data and map the readings to your x/y coordinates the tokens will show up as readings of the same height that occupy the same area per token. I really couldn't tell you if an arduino has enough memory to process the data but you could certainly store to an SD CARD and process it on a PC. Do you have any other ideas that produce reliable data ?

I don't think there is a cheap solution to this. I think you are unrealistic to think so. If you want a solution that produces useful data you can get a laser displacement sensor , mount it on an X/Y frame that moves the sensor back and forth with one stepper motor and moves the slide across the other axis with another stepper motor. I guarantee if you collect the displacement data and map the readings to your x/y coordinates the tokens will show up as readings of the same height that occupy the same area per token. I really couldn't tell you if an arduino has enough memory to process the data but you could certainly store to an SD CARD and process it on a PC. Do you have any other ideas that produce reliable data ?

Either you or me have completely misinterpreted the rare information the OP provided yet. If he just have a bunch of objects that he wants to put on some kind of detector surface and he just has to know which one is there, your solution would be completely over-engineered and the RFID solution was realistic and feasible. Your solution makes sense if he cannot change the objects but has to identify them by their shape and size. But in that case I would forget the Arduino, take a standard PC (could be one of the cheap ARMs) and connect a camera to it. OpenCV will help identify the tokens. But that's a huge amount of guess-work, the OP has to deliver more information about his project.

I may have misinterpreted the OP's question because I did not see where he said the tokens could be tagged. If they can then RFID is definitely the simpler solution.

raschemmel: I may have misinterpreted the OP's question because I did not see where he said the tokens could be tagged. If they can then RFID is definitely the simpler solution.

He didn't say ANYTHING about the tokens, or the surface! Your crystal ball must be malfunctioning... :)

So we don't know if it's ok to stick RFID tags on the token with double-sided tape ? (that almost sounds like cheating...)

raschemmel: So we don't know if it's ok to stick RFID tags on the token with double-sided tape ? (that almost sounds like cheating...)

His tokens may be 10 microns * 10 microns. I don't think double sided tape is going to work on those! ;)

His surface could be a 3 feet thick block of polished granite, for all we know. Where would you stick the RFID readers? 8)

He hasn't given us any clues, maybe because he doesn't have one...

You mean RadioShack doesn't carry 10 micron double sided tape ? (darn..) @Henry, Has anyone noticed we are on Reply#18 and the OP hasn't posted again since his initial ?

Has anyone noticed we are on Reply#18 and the OP hasn't posted again since his initial ?

Well, raschemmel, you noticed! XD

Ray

Yeah but I’m slow… :smiley:

I’ll be right back, I have to run to Radioshack for some 10 micron sticky tape…

raschemmel: You mean RadioShack doesn't carry 10 micron double sided tape ? (darn..) @Henry, Has anyone noticed we are on Reply#18 and the OP hasn't posted again since his initial ?

Reply #2 was from him, but not much help in describing what he wants.