Subject:
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Re: multiple motors
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Mon, 16 Feb 2004 13:49:34 GMT
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Viewed:
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4212 times
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Jona Jeffords wrote:
> Okay I've done it. I have the drive train all figured out with
> the exact gearing I wanted.
Great. My method was to combine the motor outputs down to two axles (left &
right) and then do the gearing down/up. I also played with running the "boost"
motors at a different gear ratio than the other four, but wasn't sure it would
help (much).
> will adding an additional 2 motors to help in forward and reverse
> motion really add enough to the push to justify the rebuild?
Make a basic chassis with the wheels you want, and bulk it up to the limit (4
lbs in this case, correct?). Drive it into a wall using just four motors... does
it stall out (ie, motors can't provide enough torque) or spin the wheels (motors
can generate more torque than can be applied, due to limits on tire friction &
weight). *If* they stall out, then the "boost" motor pair can be added to dump
more torque into the system. If it doesn't stall out, then motors are not the
limiting factor in the maximum pushing force you can deliver.
Another possible advantage is speed - these motors are not running unloaded,
and tossing another two motors worth of torque can boost the output speed of the
system as a whole as well.
> Do I have anything to be concerned with as far as the draw on my RCX?
Well, empirically I've had no problems as yet (I'm also running six motors,
two from each output). Coordinating turns etc. is slightly more complex in code,
but not really a problem. I've not had a chance to contrast this (six powered
from RCX) to the battery box solution (six powered from a non-current-limited
source), but since the RCX (for my specific 'bot) can power all six, the
limiting factor so far is ground friction (ie- how do you get 4 lbs of LEGO onto
the thing?!?)
> Will I burn through batteries much faster?
Probably somewhat less than 50% faster. More power (torque per second) cost
more power (amps).
> Any ideas or information that can help answer these questions
> is greatly appreciated.
Rule #1: Robot should not suicide itself out of the ring.
Rule #2: see rule #1...
--
Brian Davis
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Message has 1 Reply:
 | | Re: multiple motors
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| (...) Thanks Brian, I doubt I will attempt your suggested test of driving into a wall (this scares me very much!) but I hear what you are saying. Based on Steve's reply, I have decided that 6 motors pushing is better than 4. Since I have already (...) (21 years ago, 16-Feb-04, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: multiple motors
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| (...) Okay I've done it. I have the drive train all figured out with the exact gearing I wanted. Now the question to answer before I totally tear down and rebuild a complete robot is; will adding an additional 2 motors to help in forward and reverse (...) (21 years ago, 16-Feb-04, to lugnet.robotics.rcx)
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