Subject:
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Re: Problem with auto-steering mechanism.
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 30 Oct 2002 00:04:43 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail.SPAMLESSnet>
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Viewed:
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788 times
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Gareth Bestor wrote:
> If I understand the concept correctly, the front (single) wheel is driven thru
> a freely rotating turntable. When the front wheel stalls due to the robot
> hitting something in the direction of motion, the power to this wheel is
> transferred into rotating the turntable via the locked up gears. The being the
> case, I think you want the front wheel to be able to spin in place easily, i.e.
> not have a wide grip.
That's *not* entirely obvious.
There is a tradeoff between ease of twisting of the turntable and ease of
slippage in forward drive. A nice chunky tyre with tons of grip is hard to
twist - which makes the robot drive forwards better without turning when
it's not supposed to - and it makes the wheel less likely to skid when it's
supposed to be stalled and causing the turntable to twists.
On the other hand, that very resistance to twisting makes it harder to twist
and MORE likely to skid.
Just as with the gear ratios, there seem to be arguments in both directions.
> The only thing biasing the robot to drive straight is the fact the the rear
> wheels are connected (ie dont slip), therefore the whole device has a
> preference to drive straight.
Yes - but that also reduces it's ability to steer out of trouble.
> As someone mentioned before, the device seems rather finicky, at least when
> built in Lego. But maybe I'm missing something obvious...
Yep - that seems to be the entire problem.
---------------------------- Steve Baker -------------------------
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HomePage : http://web2.airmail.net/sjbaker1
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Message has 1 Reply:
 | | Re: Problem with auto-steering mechanism.
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| (...) Ahhh. I see your point now. Independent of what the back wheels are doing, you still want a bias in the front wheel itself to go straight rather than spinning in place. Otherwise, all the power could just as easily spin the front wheel in (...) (22 years ago, 30-Oct-02, to lugnet.robotics)
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Message is in Reply To:
| | Re: Problem with auto-steering mechanism.
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| (...) Well with all this discussion I couldn't resist trying it myself! :-) If I understand the concept correctly, the front (single) wheel is driven thru a freely rotating turntable. When the front wheel stalls due to the robot hitting something in (...) (22 years ago, 29-Oct-02, to lugnet.robotics)
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