Subject:
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Re: How much weight can a LEGO chassis carry around?
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 11 Dec 2005 16:32:52 GMT
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Original-From:
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steve <SJBAKER1@AIRMAIL.spamlessNET>
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Viewed:
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1750 times
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The answer to the question "How much weight can a LEGO
chassis carry around?" has got to be "Infinite" (assuming
that you have infinite amounts of Lego as some people
here appear to have!).
How's this for a thought experiment:
Build a perfectly square synchro platform with four wheels,
two motors (one for driving and one for steering) and
an RCX to control them. Let's toss in two rotation sensors
so the RCX knows how fast it's driving and in what direction.
That's not rocket science - there are lots of examples of
people having done that.
How much weight can it carry? Let's say 1 pound - it's
probably more - but let's be conservative.
Now - suppose you want to carry 100 pounds.
Well, you just build 100 of those units and connect them
up in a 10x10 square. We can set them up so that one
'master' RCX issues speed and direction commands via IR
so the whole monsterously large mechanism is driven from
one source.
Because you have a regular grid of these units, the
load can easily be distributed fairly amongst them
by building a suitable platform on top of them. The
forces between them as they drive will be close to
zero and therefore the interconnecting structures
will be lightweight and very easy to construct.
This system scales perfectly until the robot is so
large that the furthest unit from the center is out
of IR transmission range of the master RCX. But
even that can be handled with a relay transmission
scheme.
The only drawbacks to this thought experiment are
that the relaying of IR commands would slow the
robot's manouverability because of the time taken
to repeat the command to every RCX - and the
theoretical problem of keeping them all synchronized.
There is another practical drawback.
Suppose you wanted to build a Lego robot that could
carry a car. (say) a 6,400lb carrying capacity.
You'd need a 80x80 grid of synchro platforms - each
with an RCX's.
Such a machine would probably be 40' long x 40' wide
and about six inches tall - so you'd need a relay of
perhaps 64 more RCX's to pass the IR commands from
a master RCX controlling the whole machine.
You'd have to build a pyramid under each wheel of the
car to spread the load evenly - but this is definitely
do-able if you had enough Lego.
Here's the problem though.
When you came to turn the entire machine on (all
6,481 RCX's - then even if you went through the machine
turning one RCX on and starting it's program every
second, it would take you almost two hours to get
them all running - so the odds are good that the first
RCX would be out of battery power by the time you'd
turned the last one on!
...but that wasn't the question.
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Message has 1 Reply:
 | | Re: How much weight can a LEGO chassis carry around?
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| Those master RCX groups could always have their motor outputs setup to perform the act of pushing the on buttons on the other RCXs. The alternative would be a large mechanical switch mechanism made that could be operated, pushing levers down to (...) (19 years ago, 11-Dec-05, to lugnet.robotics)
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Message is in Reply To:
| | Re: How much weight can a LEGO chassis carry around?
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| (...) very (...) Hi I've read the other messages in this thread, got ideas, wondered if I should reply to one of them, then decided to start a new branch instead. Ok, now some food 4 thought: (I never tried any of these, they're the result of some (...) (19 years ago, 11-Dec-05, to lugnet.robotics, FTX)
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