Subject:
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Re: legway :only lego parts
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 4 Mar 2003 04:16:15 GMT
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Original-From:
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Steve Baker <sjbaker1@NOSPAMairmail.net>
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Viewed:
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776 times
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Brian B. Alano wrote:
> There were other contributions to his solution.
>
> 1. Reading the babelfish translation (babelfish.altavista.com), I note that he
> used a non-Lego part to increase the amount of light reflected to the sensor.
It's hard to imagine what that could be - a lense maybe?
> 2. He used a freely pivoting weight, I think to primarily to dampen the
> corrective action of the motors, helping to prevent over-correction. I
> speculate that it allows the angle to be corrected quickly without having to
> also deal with a large momentum change.
Yes - I guess so.
> 3. He mounted his RCX and weight high. Someone explain to me how this helps.
> It's counter-intuitive to me. Does the increased angular momentum make it less
> likely to fall once it's balanced ("an object at rest tends to stay at rest")?
> But doesn't this also make it harder to correct once it has started falling
> ("an object in motion tends to stay in motion")?
Yes - exactly. It takes more force to start it moving once it's balanced.
f = m * a
so if the mass is higher, it accellerates more slowly for a given amount of
force - hence it's initially more stable.
But - as you say, once it starts falling, it's gonna take more force to
stop it.
So I guess so long as it's well balanced, it'll have a greater tendancy
to stay that way.
> > From the pictures it looked like the "solution" was to place an
> > out-rigger on it to keep it from falling over.
No - you need to watch the video. It balances alright.
> > From the video it's clear the thing really is balancing. It did need help to
> initially "find its feet". Perhaps a SMOP (small matter of programming) would
> allow it to get off its outrigger on its own, as Legway II does so dramatically.
It might get up off the outrigger - but not from lying on it's back.
That's what we'd expect from it's higher center of gravity - once it's balanced,
it's better able to stay there...but it has no chance to get started in the way
Legway II does because it's gonna take a lot more force to get it up there and
still more to decelerate it to a stop at the balance point.
That (and the swinging weight) may be unnecessary if one started with the
Legway design and simply used the idea of putting the sensor out on an arm
to increase it's sensitivity.
---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net> WorkEmail: <sjbaker@link.com>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net http://tuxaqfh.sf.net
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Message has 1 Reply:
 | | Re: legway :only lego parts
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| 1: It's an ordinary telephone prepayment card with the light sensor peering through a hole in its center. It's supposed to decrease the amount of reflected surrounding light that would interfere with the sensor. Toni (...) (22 years ago, 5-Mar-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: legway :only lego parts
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| (...) There were other contributions to his solution. 1. Reading the babelfish translation (babelfish.altavista.com), I note that he used a non-Lego part to increase the amount of light reflected to the sensor. 2. He used a freely pivoting weight, (...) (22 years ago, 4-Mar-03, to lugnet.robotics)
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