Subject:
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Re: challenge: LEGO copier
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 6 Aug 2004 02:12:36 GMT
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Viewed:
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1459 times
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In article <4112AF27.7000703@airmail.net>,
lego-robotics@crynwr.com (Steve Baker) wrote:
> The 'constructor' side is a different matter though - I think it's
> a VERY tough problem just to build a robot that can build a solid,
> straight line wall out of one kind of brick. Picking up the
> bricks from some kind of feed 'hopper' - aligning them to the bricks
> already in the wall accurately enough and applying enough force to
> connect them are all very tough problems.
>
> Having it have to deal with bricks of different colours makes it
> MUCH harder - because you need multiple 'hoppers' containing bricks
> of different colours - so the 'picking them up' problem gets much
> more difficult.
One could cheat (if you consider it that) on this pretty easily, though.
Instead of hoppers containing a jumble of bricks, each feedstock source
could be a neat queue of bricks in a constant orientation. Grabbing the
next brick from such a queue shouldn't be too hard. And having multiple
queues doesn't make it all that much harder -- just one more DOF, to
move the tray of queues back and forth to present the one you need.
However, you make a very good point that simply building a single wall
of one kind of brick would be a good (and challenging) first goal.
> and the force you need to apply to snap together larger bricks starts
> to be comparable to the strength of the robot itself (which is made of
> Lego remember!) - and making the 'gripper' both strong enough to do
> that *and* small enough to deal with 1x1's *and* light enough to reach
> across a large distance - yet subtle enough not to destroy a thin column
> of bricks by squeezing them too hard...all of those spell disaster to me.
That's a good point, and the force needed to snap together the bricks is
my greatest concern too. Of course your gripper doesn't need to be made
of bricks; it would probably be made of Technic struts and pins, which
are considerably stronger (at least, in the directions that matter).
But there will certainly be gears involved, and if you try to apply too
much force, I imagine gear slippage will be an issue.
I wonder if this could be alleviated somewhat by using well-worn bricks;
I've noticed that old, well-used bricks are easier to attach than new
ones. One might even experiment with a little bit of oil on the pins,
though that could quickly get very messy.
> Then, finally having to construct things like the letter 'M' example
> (things with arbitary gaps and holes) in an arbitarily complex order
> makes it almost impossible.
> ...
> I VERY much doubt we'll see anyone even attempt this problem...which makes
> it rather futile to think too deeply about it.
I hope you're wrong, and somebody shows such a machine in the next few
years. Otherwise, I'm probably going to end up trying it myself, once
my sons are old enough to get into Mindstorms!
> I think a better (and frankly, more interesting) problem is to build
> an arbitary 3D sculpture from *only* (say) 2x4 bricks and using three
> different colours. This would be more impressive to watch (IMHO) and
> more possible to do.
Hey, that's a pretty neat idea. Though if it's a 3D sculpture, you
don't get to snap the bricks together by squeezing from both sides. You
can only push down from above. That sounds harder to me. But I'm just
reacting; I haven't thought about this problem very much yet.
Thanks for your comments,
- Joe
,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| joe@strout.net http://www.macwebdir.com |
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Message has 1 Reply:
 | | Re: challenge: LEGO copier
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| (...) Actually, I think it would be a good idea to use pneumatics to push the bricks together. Any resistance met by pneumatics simply increases the air pressure required to keep pushing, rather than actually damaging any pieces. (...) Why do you (...) (20 years ago, 6-Aug-04, to lugnet.robotics)
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Message is in Reply To:
| | Re: challenge: LEGO copier
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| (...) No - you'd just use a touch sensor that you could lower down onto the model you are 'scanning' - it would be easy enough to measure whether there was a hole or a brick. (...) The Lego camera isn't really much use because it can't talk to the (...) (20 years ago, 5-Aug-04, to lugnet.robotics)
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