Subject:
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Re: Competitive MINDSTORMS: Now in a store near you!
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 20 Aug 2004 01:27:29 GMT
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Viewed:
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1193 times
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In lugnet.robotics, Brian Davis wrote:
> In lugnet.robotics, David Perdue wrote:
>
> > Brain-Bot has a fast speed of 1:15 and a slow speed of 1:75
>
> By "speed", do you mean those are the gear ratios? What is the mass and wheel
> radius for Brain-Bot? And how many driving motors does it use (i.e., how many
> motors actually apply torque into the drive train, as opposed to shifting gears
> for instance)? A 75-to-1 torque increase would (assuming 6 Ncm from each of two
> standard gear motors, about what they stall out at) yield a wheel axle torque of
> *900* Ncm, much much more than is needed for *any* of the LEGO wheels (even the
> Power Puller's) under reasonable weight constraints. Help me out here, I must be
> missing something as well.
1:15 and 1:75 are, in fact, the gear ratios. I achieved these ratios not by the
rotations--for instance, an 8t gear turning a 24t would result in a 3:1
ratio--but by counting the teeth--for instance, an 8t gear turning a 24t gear
would result in a 1:3 ratio. And there are actually only two motors applying
torque into the drivetrain--one for each side, acting independently--and the
wheel radius is 81.6 x 15 - these are the large "motorcycle wheels" included
with the RIS. I have not calculated the mass for Brain-Bot. I'm not sure about
the 900 Ncm wheel axle torque, but I hope this info clears things up.
> Any chance you could bring ZR1 or any of the other 'bots from your book to
> Sumo 6 in Ann Arbor? I'd love to see how they work, and in general the 24tooth
> events have been a very good time for all.
I thought that the event was yesterday, but apparently it's in September! I
would like to go - I recently told Jona that I wouldn't be able to go, but I
guess I'll have to write him back and say that I might be able to go after all!
I'm not 100% sure that I can attend, but I'll see what I can do. I'd love to
bring Gargantuan-Bot Version BL58 with me to the event, but I think that one
might be too big under the rule set. :)
Thanks,
David J. Perdue
www.davidjperdue.com
www.davidjperdue.com/competitivemindstorms
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Message has 2 Replies:
 | | Re: Competitive MINDSTORMS: Now in a store near you!
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| (...) Hmm. The way I see it, pushing power is limited (in an ideal world!) by one of two factors: applied torque (a function of motors and gearing), and the frictional force between the wheels and the surface (controled by the weight of the 'bot and (...) (20 years ago, 20-Aug-04, to lugnet.robotics)
| | | Re: Competitive MINDSTORMS - at Sumo-bot 6?
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| (...) David, It would be nice to meet you, and see your robots at Sumo-bot 6 (on Sept 18th). It sounds like you don't have enough pieces to build them all at the same time (along with anything else you may have built). I suggested to Jona that I (...) (20 years ago, 28-Aug-04, to lugnet.robotics)
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Message is in Reply To:
| | Re: Competitive MINDSTORMS: Now in a store near you!
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| (...) By "speed", do you mean those are the gear ratios? What is the mass and wheel radius for Brain-Bot? And how many driving motors does it use (i.e., how many motors actually apply torque into the drive train, as opposed to shifting gears for (...) (20 years ago, 19-Aug-04, to lugnet.robotics)
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