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Subject: 
Re: How much weight can a LEGO chassis carry around?
Newsgroups: 
lugnet.robotics
Date: 
Sun, 11 Dec 2005 18:22:27 GMT
Viewed: 
1099 times
  
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 press the RCX buttons. You
would need a lot of levers, and many interconected beams to do it, but
its possible

There is always a way around things, even if they are a bit awkward.
Of course here we are already including a Laptop, so while I might use
Lego in some cases, in a situation where I wanted to mount a laptop, I
would start to consider more the concept of using non-Lego components
in the setup. I would probably not mod the Lego, while I can, its a
little too valuable to me to do so. I would really love to have casts
of aluminium pins, studless beams, and large plates with studless beam
style connectors and lego dimensions. Maybe I could try to cast
something like it from white metal (used in miniture casting) some
time - although I am not sure how its tensile properties compare with
ABS.
--
Danny Staple MBCS
OrionRobots
http://orionrobots.co.uk
(Full contact details available through website)


On 11/12/05, steve <lego-robotics@crynwr.com> wrote:
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.




Message is in Reply To:
  Re: How much weight can a LEGO chassis carry around?
 
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 (...) (19 years ago, 11-Dec-05, to lugnet.robotics)

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