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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Tue, 25 Nov 2003 03:26:29 GMT
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Viewed:
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3522 times
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Steve Hassenplug wrote:
> I've had a reasonable amount of success building sumo robots,...
...I love understatment. sigh...
> and I always try to use 2 motors per port.
OK, in trying to implement this I've come to an interesting impasse.
Calculations suggest that for a 4 lb sumobot with reasonable tires would
"benefit" from six motors, three on each side (differential drive, or turning).
I tried running the two of the left motors from OUT_A, two of the right motors
from OUT_C, and the remaining two motors (one left & one right) from OUT_B.
All's well and good when running forward or backward, but to turn I'm in
trouble: the last two motors will try to fight each other. Obviously I don't
power OUT_B during a turn, but if OUT_B is set to Float those last two motors
will fight each other. Help!
A) Besides acting as a brake on the other four motors, has anyone ever
damaged motors in a situation like this?
B) Is there a better way to do this? Run six motors in two triplets from a
single RCX, and allow turning free & clear?
Steve, when you said "two motors per port", are you using all three ports,
six motors?
> It's my understanding that the motors draw ~250 milliamp when stalled
The test I've seen suggest stall current for the original geared minimotor is
a bit higher (360 mA), but the point still seems valid - just try to use them
such that any one motor doesn't exceed about half it's maximum torque, thus
keeping the current draw below 250 mA for each motor.
> And my BIGGEST piece of advice for your sumo robot: make SURE it
> does not leave the sumo area on it's own.
I'll second that. Boy, will I ever...
--
Brian Davis
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Message has 1 Reply:
 | | Re: multiple motors
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| (...) Well, I've never actually tried running six motors directly from the RCX. However, I have used three motors to drive a sumo robot. And I've also used four motors (two on each side) to drive six wheels (two on the right, two on the left, and (...) (21 years ago, 25-Nov-03, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: multiple motors
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| (...) Travis, I've had a reasonable amount of success building sumo robots, and I always try to use 2 motors per port. (some rules don't allow that) It's my understanding that the motors draw ~250 milliamp when stalled (that's when they draw the (...) (21 years ago, 4-Nov-03, to lugnet.robotics.rcx)
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