Subject:
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RE: Discontinuous motion.
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 8 Apr 2002 22:05:53 GMT
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Original-From:
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Rob Limbaugh <RLIMBAUGH@GREENFIELDGROUP.COMnospam>
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Viewed:
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731 times
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Here are some quick pics of the new gears:
http://www.abs-robotics.com/other/newgears.htm
Again, my apologies for the crappy photos... but I think you'll get the idea.
There are some other parts of interest in the Bohrok sets that may be useful...
especially if someone is trying to make circular objects or frames.
While I'm on the "Yes, Bionicles can be useful" subject... The original Bionicle
bodies work great as monster-truck frame pieces.
Rob
-----Original Message-----
From: Jed_Anderson@oti.com [mailto:Jed_Anderson@oti.com]
Sent: Wednesday, April 03, 2002 4:14 PM
To: Lego Robotics
Subject: RE: Discontinuous motion.
Could you post some pictures of these new gears?
jkca
Robert Limbaugh
<rlimbaugh@greenfiel To:
"'sjbaker1@airmail.net'" <sjbaker1@airmail.net>
dgroup.com> cc: Lego Robotics
<lego-robotics@crynwr.com>
Subject: RE: Discontinuous
motion.
04/03/2002 03:03 PM
In that case, get one of the new Bionicle Bohrok (the big one's, not the
"Va's") figures. They have two new gear pieces... one is a 1/4 of a full
gear (hard to explain... but it would effectively be a partial circular
gear
of sorts) and the other new gear piece's are 2 arms with gears on each end
(they look like bones).
These pieces are used to lift the heads up.
I'll goof off with some idea's later...
-----Original Message-----
From: Steve Baker [mailto:sjbaker1@airmail.net]
Sent: Wednesday, April 03, 2002 3:20 PM
To: Robert Limbaugh
Cc: Lego Robotics
Subject: Re: Discontinuous motion.
Robert Limbaugh wrote:
>
> I meant using wheels with rubber treads. Rubber treads won't have a • meshing
> problem. Instead of the problem being gear mesh, the new problem should • be
> speed vs. friction.
OH! I see! Very clever.
I guess I should explain why I wanted this thing in the first place.
All the talk last week about building a Turing machine using Lego - and
building primitive mechanical computers in general led me to try to build
a simple adding machine using gears and stuff. (I'm aware of the awesome
pneumatic adder someone presented recently).
So, the first step was to build a counter - like a car odometer - where you
spin one axle and when it's spun a complete revolution, a second wheel
moves
1/10th of a revolution. When the second wheel has undergone a complete
revolution, a third wheel moves forward a tenth of a revolution. This
gives you the 1's, 10's and 100's numbers based on how much the wheels
have moved. It didn't need to be a base 10 system though.
The first step of that was to get a reliable mechanism that would allow
one revolution of the input axle to rotate the second wheel by 1/10th of
a revolution. A 10:1 gear ratio would do that - but car odometers don't
do that. The 10's digit stays absolutely still until the 1's wheel is
just about to clock over from '9' back to '0' - and then it moves quite
quickly onto the next 10's digit.
So, your suggestion certainly does do what I actually asked for - but it's
not accurate enough for what I actually *want*. If the system doesn't use
some kind of solid gear-based mechanism, it'll gradually accumulate error
which will be hopeless for what I ultimately want to do.
> If the drive wheel arm rotates to quickly, the drive wheel may not grip • the
> 2nd wheel enough. Or, it may grip too well and make the 2nd wheel spin • more
> than desired (depending on the load on it's axel).
Yes - that problem exists with the gearwheel solution too.
> Maybe I should just build an example of what I mean... The idea came • from
> how the Pirate Ship carnival rides move the ship back hull back and • forth...
> sets of wheels push the hull right or left.
That's interesting. I didn't know they worked like that. By an *amazing*
coincidence, my son has just finished building one of those in Lego - but
he used RCX software to alternate the direction of drive on the wheels to
sync with the speed he wants the ship to swing. Your way is *much* better!
----------------------------- Steve Baker -------------------------------
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URLs : http://www.sjbaker.org
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