Subject:
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Re: Rotational Sensor & Gearing Down
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 24 Jan 2001 18:06:16 GMT
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Viewed:
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888 times
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I guess I didn't word that very well. I didn't mean that you can make an inaccurate sensor
look like an accurate sensor via software. What I meant is that you write your software to
know that the sensor is not accurate, i.e. the software doesn't act on a sensor reading until
it exceeds a threshold greater than the inaccuracy. I find that this gives very reasonable
behavior. It's not perfect, but then again, it's just a toy. ;-)
<soapbox>
In general, I don't understand the complaints about the quality of the LEGO sensors and
motors (not 100% accurate, results are not 100% repeatable) and the lack of functionality
of the RCX (not enough i/o ports, not enough memory). It's just a toy. You can build
wonderful things with it (Bob Fay's milling machines, Mario Ferrari's R2-D2-style robot,
Jim Studt's Magic 8-Ball shaker, and so much more). Sure, they could be better, or they
could be less expensive, or whatever, but IMHO the RIS is pretty dang cool as is.
Please don't take this as a troll or flame-bait - all flames will be cheerfully ignored. ;-)
</soapbox>
--
Mark Haye, mark_haye(@)tivoli(.)com
IBM TSM Server Development, Tucson, AZ
"Rebel Transcanner" <hendryjr@oxford.net> wrote in message news:G7o2sC.BDu@lugnet.com...
> "Dean Husby" <nntp@akasa.bc.ca> wrote in message
> news:3A6E7170.F38BA60@akasa.bc.ca...
>
>
> > How do you compensate in software?
>
> Exactly... you can't. Unless you use another sensor, which totally defeats
> the purpose. For linear positioning, I've always used a light sensor looking
> at a grey-coded bar, with a touch sensor multiplexed on the same port for
> homing. That works fine... and uses just one port per axis (perfect!). But
> I've wanted to do a SCARA-typ robot for quite some time. Accuracy is of
> utmost importance, and I can't have rotation sensors missing a few counts
> every hundred steps. That could mean a difference of a millimetre or two
> every cycle; and when I'm doing accurate pick-and-place, that is
> unacceptable. :(
>
> Absolute encoders would be utterly fantastic... :)
>
> (I supose that can be emulated with potentiometers?)
>
> Iain
>
>
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Message is in Reply To:
 | | Re: Rotational Sensor & Gearing Down
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| "Dean Husby" <nntp@akasa.bc.ca> wrote in message news:3A6E7170.F38BA6...a.bc.ca... (...) accurate sensors would (...) compensate for the inaccuracy (...) disappointed or not to use them. (...) Exactly... you can't. Unless you use another sensor, (...) (23 years ago, 24-Jan-01, to lugnet.robotics)
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