Jim Wilkins" on Mon, 3 Sep 2018 08:19:32 -0400
typed in rec.crafts.metalworking the following:
"pyotr filipivich" wrote in message
.. .
"Jim Wilkins" on Sun, 2 Sep 2018
21:06:01 -0400
typed in rec.crafts.metalworking the following:
"pyotr filipivich" wrote in message
news
I may have asked this before, but I have A Project in mind. This
is much simpler than the last time, when I wanted to build 4
humanoid
robots to pick up a shipping container at the corners and move it.
"Hup, hup, hup, ... detail halt!"
What I want to do this time is to just "slide an I-beam under the
outbuilding, attach a wheeled unit to each end, pivot the building
and
roll it to when I want it." No doubt "A simple procedure
involving
lasers." I'm sure. Somewhere.
But, my question is: load capacity of the units. Assume a GW of 3
tons, does that meant that each wheeled unit has to be able to
'carry'
a three ton load, or can I divide the gross weight by 4, add a
"fudge
factor" and hope for the best?
This is one of those things I'd talk to one of the old guys, but I
find I am one of the old guys.
tschus
pyotr
You need to be clearer about the "wheeled unit".
Your one I-beam and four wheels only makes sense to me if you rig it
like a tandem axle trailer. If the two(?) wheels on a side are on a
pivoting bar that lets them adjust to uneven ground then they share
the load, if their axles are rigidly attached to the I-beam then
they
don't.
Can you guys not answer the question I didn't ask? Grumble,
grumble; kids these days. Just like when I was a boy.
Reevaluating, I'm going to be working with nanobots which will
interlace sort of like legos or ants. So what I want to know, if
each
nanobot can lift a gram, do I need the swarm at one corner to be
able
to hoist 3,000,000 grams, or can they just lift a quarter of that?
I
don't want to have to turn out more than I need is why I'm asking.
tschus
pyotr
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."
The answer depends on how well you can make the nanobots cooperate to
share the load, just like the wheels. It's not just a simple matter of
all lifting on the count of 3, they may have to dampen oscillation.
Your 2-story building is an inverted pendulum
http://web.mit.edu/klund/www/papers/UNP_pendulum.pdf
that is inherently unstable if elastically supported below its center
of gravity. If it tips the cg shifts toward the low side and the
bearers' load increases. The nanobots need a reserve of strength to
counter the static increase and dynamic inertia, but if they lift too
hard it will tip the other way. Planes have crashed and ships have
capsized due to this positive feedback oscillation.
https://en.wikipedia.org/wiki/Milburn_G._Apt
Segways require solid-state gyros, feedback and considerable
processing power to remain balanced. They are a 2 element (wheel)
example of your proposed nanobot problem. The quadcopter is a better
model for lifting a building. I've only had a brief introduction to
the math of over-, under- and critical damping and the oscillations of
spring-coupled masses, and none for servo loops.
The questions the customer didn't know enough to ask tend to be the
hardest to solve, and the reasons there wasn't a simple solution
already.
-jsw
Over thinking, again. Coordinating the movements is handled by
Calvin & Hobbes Consolidated. I think they have the late model sonic
transducers for that.
But the load on the bot swarm, that I have to consider.
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."