Subject:
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Re: A robot who knows his position (fwd)
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 28 Apr 1999 13:50:04 GMT
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Viewed:
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1073 times
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In lugnet.robotics, Mike Moran writes:
> I've been doing some robot building aimed at dead reckoning and have found
> that even the home or flat environment is enough to f*&k things up; the
> bumpy slippery floor in my kitchen is particularly bad. Given slippage and
> so on, the technique I was testing was one of timing ie move or rotate by a
> given amount, but sense when you have stopped moving/rotating. Use the time
> moving or rotating as an indication of distance or degree actually turned. The
> reasoning behind this is that you don't need sensors which directly tell you
> the distance or degree, only ones that can react quickly in telling you when
> you've stopped moving/turning. I've managed to make sensors which can do this
> to a limited degree. I'll put up some piccies of them when I get round to it
> :-)
Looking forward to seeing them :)
> For my next robot I'm going to abandon dead reckoning (at least on it's own)
> in favour of some external sensing relative to a landmark.
Dead-reckoning should be used BETWEEN two consecutive (artificial) landmark
sensing. When you get any external reference point you can zero your
accumulated errors.
> My flatmate has
> informed me of a way the Chinese used to navigate before they had compasses.
> Basically, you get a two wheeled vehicle, take the output of each wheel and
> feed it into a differential such the differential is still when they are • moving
> in the same direction. Take the output of the diff. and arrange it so that it
> makes an arrow sticking out of the top of the contraption (think "weather
> vane") turn. Down-gear this turning a bit. The result of this is the fact that
> when you move the vehicle around, the "arrow" always stays pointing in a
> direction parallel to it's original direction. I reckon you could use this
> effect to tie into something external. Don't ask me what just yet ;-)
Seems interesting. But you would still have problem with slippage...
I think a magnetic or gyro compass would work better. Is there anybody around
who did interface a compass to the RCX?
Mario
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Message has 2 Replies:
 | | Re: A robot who knows his position (fwd)
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| (...) I have been thinking about a different approach. I have not actually built anything to use it yet, but I believe it should work reasonably well. The basic idea is similar to the old optical mouse pads -- draw horizontal and vertical lines on (...) (26 years ago, 28-Apr-99, to lugnet.robotics)
| | | Re: A robot who knows his position (fwd)
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| (...) [ ... ] (...) Well, I know this, I was just seeing how far I could get without landmarks. An idea Richard Franks and I had was to use black and white approx. A4 size printed markers. These markers would contain a pattern that was detectable by (...) (26 years ago, 30-Apr-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: A robot who knows his position (fwd)
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| (...) [ talk of Dead Reckoning ] (...) That's a useful idea; I'll take note of that. (...) I've been doing some robot building aimed at dead reckoning and have found that even the home or flat environment is enough to f*&k things up; the bumpy (...) (26 years ago, 28-Apr-99, to lugnet.robotics)
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