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In lugnet.org.ca.rtltoronto, Rob Antonishen wrote:
> The idea is an adder/subtractor drive, with the R/C "drive" output
> goes to a motor on the base input and the steering output tied to a
> polarity switch. The polarity switch is connected back to a battery
> box, and the output is connected to a motor on the added/subtracted
> input.
>
> I used the R/C motors for both driving and steering, so it whips
> around pretty fast. It isn't pretty, but it gives me enough
> confidence to make a tracked base with the same drive, now.
Nice idea. I made a similar prototype some time ago, which does not need a
battery pack, but which can not have both tracks running in opposite direction.
Some images here:
<http://www.brickshelf.com/cgi-bin/gallery.cgi?f=177850>
Julien
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In lugnet.org.ca.rtltoronto, Rob Antonishen wrote:
> Well-
>
> I finally got around to testing the idea of a R/C tank. I built a
> little test rig just to see how it would work.
>
> The idea is an adder/subtractor drive, with the R/C "drive" output
> goes to a motor on the base input and the steering output tied to a
> polarity switch. The polarity switch is connected back to a battery
> box, and the output is connected to a motor on the added/subtracted
> input.
>
> I used the R/C motors for both driving and steering, so it whips
> around pretty fast. It isn't pretty, but it gives me enough
> confidence to make a tracked base with the same drive, now.
>
> http://www.brickshelf.com/gallery/ffaat/RC-Tank-Test/img_1882.jpg
>
>
> A front view showing the polarity switch:
> http://www.brickshelf.com/gallery/ffaat/RC-Tank-Test/img_1883.jpg
>
> And a shot of the differential adder/subtractor drive, straight from
> Doug's page here (http://www.visi.com/~dc/adder/index.htm):
> http://www.brickshelf.com/gallery/ffaat/RC-Tank-Test/img_1884.jpg
>
> Also, I put up a video of it in action:
> http://www.youtube.com/watch?v=9PmweX1gc60
>
> -Rob A>
Nice! Can it steer while also moving forward, or does the switch work with just
a 3-position action (turn right/go straight/turn left)? Could you also use 3
12-tooth gears for the side opposite the 2 24-tooth gears, or did you use the 2
16-toothed and 1 8-toothed gear for a specific reason other than stud-length?
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On 2/6/07, Nathan Bell wrote:
> In lugnet.org.ca.rtltoronto, Rob Antonishen wrote:
> > I finally got around to testing the idea of a R/C tank. I built a
> > little test rig just to see how it would work.
>
> Nice! Can it steer while also moving forward, or does the switch work with just
> a 3-position action (turn right/go straight/turn left)? Could you also use 3
> 12-tooth gears for the side opposite the 2 24-tooth gears, or did you use the 2
> 16-toothed and 1 8-toothed gear for a specific reason other than stud-length?
Oh yes! it can steer when going forward. With the current gearing
though, it spins out. I should try to drive the adder/subtractor
input with an 8-tooth gear rather than the current 24 to slow the
turning rate down. Though I suppose I couldn't spin madly in place
then :)
3 12-tooth should work just the same. The only requirement is
reversing the direction of rotation on one side of the differentials
from the other. in either case you will need to insert a 1x1 technic
"beam", or some other technique to hold the idler gear at its 1/2
spacing offset.
-Rob A>
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In lugnet.org.ca.rtltoronto, Rob Antonishen wrote:
>
> Oh yes! it can steer when going forward. With the current gearing
> though, it spins out. I should try to drive the adder/subtractor
> input with an 8-tooth gear rather than the current 24 to slow the
> turning rate down. Though I suppose I couldn't spin madly in place
> then :)
>
>
> -Rob A>
Hi Rob,
You might consider using the auxilary output of the RC to control a gear shifter
to select between "driveable" and "mad spining" modes...
Using the polarity switch is brilliant! I tried a pure mechanical solution (the
steering mechanism would brake one side or the other) before but with
unconvincing results... Maybe I should give it another try.
Greetings,
David
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