Subject:
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Re: Newbie needs Help (diff sensor)
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 7 Jun 2006 12:15:22 GMT
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Viewed:
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4069 times
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In lugnet.robotics, Philippe Hurbain wrote:
> > do you think that the performace would be improved if the
> > tire were filled with a kind of PFE tubing (so as to make
> > it a run flat kind of tire) so that it did not suffer from
> > excessive compression of the rubber tire?
A rather inventive young man that I know did try exactly that - using the
ribbed tubing from the Mindstorms set inside the Mindstorms motorcycle tire.
It's a good fit, and a good idea, but I'm not sure how effective it was.
> it would be interesting to perform static (no slip) tests
> too, but that's even more difficult due to the transient
> nature just at the limit...
One simple way (that honestly doesn't work very well... shows how complex
friction is): the coefficient of friction is just the tangent of the slope angle
when the object "breaks free" and begins sliding down the hill. So you can build
a four-wheeled platform (with the axles locked, so the tires don't turn) and put
it on a board, raising one end of the board until the platform starts sliding.
I've done this, but for various reasons I don't completely trust the results.
It's still interesting and informative, however.
--
Brian Davis
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Message has 1 Reply:
 | | Re: Newbie needs Help (diff sensor)
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| (...) The problem is that this is measuring the static friction ("stiction"). That's the wrong thing to measure if your strategy is to jam all the motors full on and progress forwards (we hope!) with all wheels spinning. To measure the dynamic (...) (18 years ago, 7-Jun-06, to lugnet.robotics)
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Message is in Reply To:
| | Re: Newbie needs Help (diff sensor)
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| (...) It does happen - if you use more that 2 motors or if you try to use a RC motor. The driver circuit limits current around 500mA, and at that rate it is not long before going in thermal shutdown mode. (...) No, you won't see smoke... RCX motor (...) (18 years ago, 7-Jun-06, to lugnet.robotics)
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