Subject:
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Re: Robot That Sorts Lego Pieces
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Newsgroups:
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lugnet.robotics.vc
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Date:
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Sat, 12 Apr 2003 11:15:02 GMT
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In lugnet.robotics.vc, John Shearing writes:
> Hi All,
>
> I am running a little robot discovery group at my local elementary school.
> When I started the group, all the pieces were sorted in see through plastic
> ziploc bags. But after only a few days the kids have all the pieces in one
> big mess.
>
> So I would like to build a robot for sorting the Lego pieces when the kids
> are done using them. I would think that the most difficult part of the
> project would be a program for recognizing the pieces.
>
> Does anyone have any ideas on where I might find a program that would work
> with Vision Command for this purpose?
>
> Has anyone already done this?
>
> Also, any other ideas and comments would be appreciated.
>
> Thanks, John
Well this depends on a number of things, primarily how do you sort: by
color, by size/shape, or both?
Several books have been published about LEGO MindStorms, and a large
percentage of them seem to have plans for a "sort bricks by color" robot
that uses the light sensor to sort a sequence of bricks by color. These
designs are cool, but they generally evade the problem of how to get all
your unsorted bricks neatly lined up on a conveyor belt so that your robot
can inspect them for color, and the mechanisms presented would not appear to
be well-suited for handling pieces of different sizes and shapes.
I did some work awhile back on a robot that could determine the size of a
brick that is dropped into a special 3-D caliper chamber. The chamber is
shaped like an inverted pyramid so a brick will always fall into the bottom
corner. I then use three calipers to slide out until they strike the piece
in the chamber, with rotation sensors to measure how far each caliper
travels. This tells me enough information to determine the dimensions of
the piece, which is enough to do a useful sort. I just posted a few quick
pictures on BrickShelf:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=40130
I still haven't built two other important mechanisms: (1) the system that
feeds pieces one at a time into the chamber, and (2) the system that dumps
the piece out of the chamber into one of many sorting bins.
I know you asked about using the Vision Command camera to do this. I am
sure this is possible, since industrial robots do this kind of image
processing all the time, but it is a tricky piece of programming. I have
heard of others trying to do this, but have never read any success stories here.
If you are like many of the people who read LUGNET then the fact that nobody
has succeeded yet will probably only forge your resolve to make it work. If
you do, please let us know how you make out, either good or bad.
One other automatic brick sorter of which I am aware is the Box 4 Blox,
recently announced here. This product is a simple stack of four graduated
sieves that you dump LEGO into the top of and give a little shake. The
smallest pieces tend to fall through to the bottom tray, with larger and
larger pieces ending up in each higher level. I bought a couple of these
and they're OK but definitely not perfect at sorting. Many pieces tend to
end up in the correct tray, but a good percentage do not. Still, I had to
admire the simplicity of this approach after having spent so much time
over-engineering my solution to the Automatic Brick Sorter challenge. You
may find this to be the perfect solution in an elementary school setting,
however.
Hope this helps to give you some ideas!
- Chris.
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Message has 1 Reply:
 | | Re: Robot That Sorts Lego Pieces
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| Hi Chris, It seems to me that for the first time in history, kids could have a robot that can do the thing they hate most. Putting their toys away. This could be a very effective way to show kids the importance of robotics. Clearly, you have given (...) (22 years ago, 13-Apr-03, to lugnet.robotics.vc)
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Message is in Reply To:
| | Robot That Sorts Lego Pieces
|
| Hi All, I am running a little robot discovery group at my local elementary school. When I started the group, all the pieces were sorted in see through plastic ziploc bags. But after only a few days the kids have all the pieces in one big mess. So I (...) (22 years ago, 12-Apr-03, to lugnet.robotics.vc)
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