Subject:
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Re: 2 Motors -> 1 axle
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 7 Jan 2000 17:40:13 GMT
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Original-From:
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Joel Shafer <joel@connect.NOSPAMnet>
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Viewed:
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424 times
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Instead of trying to connect two motors to the same axle using the crown
gears, why not attach the two motors to the same axle using axle
connectors. This would avoid the slipping problem that you mentioned and
should have less frictional losses than the backwards differential solution.
At 04:30 PM 1/7/00 +0000, you wrote:
> After the good suggestions from folks (see the Balancing Bots thread) I
> did some experiments with using 2 motors to drive one axle (to double the
> power to the axle) and thought the results might be of interest to others.
>
> I first tried having the motors separately drive the same axle. That is,
> the motors weren't directly connected to each other at all, except
> through the axle. Each motor drove a 24t crown gear, and each crown gear
> drove a separate 24t gear on the axle. The idea was that even if the
> motors weren't matched exactly, there would simply be a bit of a load on
> the "fast" motor.
>
> Unfortunately, the motors were different enough that the gears actually
> skipped teeth occasionally. Running in one direction would probably be
> OK, but in this application I'm switching direction constantly, and it
> didn't work. Also, even if the gears remained meshed, it's not an
> effective use of the power in the motors: one of them is always pulling
> the other one along, robbing the whole system of power.
>
> Then I tried using a differential "backwards": I used a motor to drive
> each of the outside axles, and the body of the differential to drive the
> output. MUCH better, though bulkier. In this case, each motor contributes
> what it can, and any difference between the motors just means the middle
> gear in the differential spins a bit to absorb the difference, but no
> power is lost fighting a mis-matched motor. I think this is the way to go.
>
> Now if I could just figure out how to stiffen the axle torsionally. I
> need a wide base for stability, but the long axle means that the wheels
> aren't locked together very well, there's lots of springy torsional
> wiggle between them, which twists my bot around a lot when it's whipping
> the wheels back and forth. I'm thinking maybe a tripod base with only one
> drive wheel would be good, or maybe treads. Or maybe I should just bug my
> machinist friends to carve me some steel axles :-)
>
> Dave Johnson
> Still trying to balance
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Message is in Reply To:
 | | 2 Motors -> 1 axle
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| After the good suggestions from folks (see the Balancing Bots thread) I did some experiments with using 2 motors to drive one axle (to double the power to the axle) and thought the results might be of interest to others. I first tried having the (...) (24 years ago, 7-Jan-00, to lugnet.robotics)
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