Feb 14, 2008

Coin Sorter (how to save enough money for your next NXT)

Here's a nice YouTube video of an NXT-based coin sorter. While it certainly doesn't compete with CoinStar yet as far as speed goes, it shows not only an interesting problem and solution... but a whole lot of wonderful mechanisms, as well as a pretty well done video explanation:

I can't quite see how it only grabs one coin, but the two-stage grab-&-dump mechanism driven by a single motor is one of my favorite techniques. Very often, you do not need more motors, just a clever mechanical solution to get multiple motions out of a single motor, as kevquest does here. The actual sorting mechanism is also very well done, and adaptable - by adjusting those limiting elements, a lot of different sized objects could be sorted. Yet another important point is the sorting tray - I've seen a lot of folks get hung up on linear motion, and go through a lot of exertion to try to get it, when many times it's simply not needed - like here, where a carrousel style system is perfectly sufficient. About the only thing I don't quite understand is the reseting pattern (I think there might be quicker ways to do it) and the speed (could it be speeded up? If not this mechanism, I'll bet there are faster mechanisms that might work). Again, a nifty creation, and a nice YouTube documentation. Take a look!

Brian Davis


Jonathan Daudelin said...

Hey, I know the guy who made that... he was called kevinsquest on the LMSF, and he's REALLY good at robots, especially ones that have homebrew electronics in them.

I think the way he separated one coin was by making the yellow container (that gets one coin) one plate lower than the container that dumps all the coins in it. So when it dumps the coins back into the first container, one gets stuck because of the height difference, but the rest slide over.


Eric D. Burdo said...

@Jonathan - That's what it looks like to me too.

peter hoh said...

Yes, it looks like the front compartment of the coin bucket is one plate lower than the back part. There's a tile at the open end of the front compartment.

You can try this yourself. Put a tile on one side of a 6x4 plate. Put two coins on the plate. Slide them back to the tile. The bottom coin will catch on the plate, allowing the top coin to slide over the tile and onto the table.

Anonymous said...

Wow, all you robot builders got talent, say, how did you program the nxt? I seen similar machines that sorts out marbles but who thought of an NXT?

Anyways, I was wondering if you can make the robot sort coins any faster.

chamila said...
This comment has been removed by a blog administrator.
Anonymous said...

how do you build the two stage mechanism. Anyone have instructions?

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