Subject:
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Re: Struggling with encoder wheel
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 12 Apr 2001 04:19:36 GMT
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Viewed:
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909 times
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Pretty neat Chris. You've very nearly recreated a special kind of
optical encoder that was developed by my former employers called a virtual
absolute encoder. It didn't use diferent colors but it used a "time-window"
to read the last few states off of a disc which had "white noise" encoded on
the data track. The look up is *very* fast becuse the "white noise" is
generated using a simple linear feedback shift register.
As for speeding up the system you've got, I'm not sure I can help
there... It seems that you've done a very good job optimizing it for compact
storage. I was trying to fathom a hash function to help here, but I haven't
come up with one that wouldn't take much more space to store the table. I'm
intrigued though : )
-JSM
"Chris Osborn" <fozztexx@pez.fullsystem.com> wrote in message
news:GBn6Mw.L02@lugnet.com...
>
> I'm having a hard time finding a good algorithm for the encoder wheel
> I came up with for use on my webcam. The way I packed the bits in the
> lookup table has made it hard to get any speed out of the algorithms.
>
> I'm using NQC, and the LEGO OS seems incredibly slow.
>
> I've got a write-up with pictures on the whole thing at
>
> http://www.fozztexx.com/LEGO/Webcam/
>
> --
> Chris Osborn Full System, Inc.
> fozztexx@fullsystem.com 2160 Jefferson St., #240
> http://www.fullsystem.com/ Napa, CA 94559
> Webhosting that *works* - 99.99% uptime - First 3 months free
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Message has 2 Replies:
 | | Re: Struggling with encoder wheel
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| (...) If I had room for a 64 element array, I'd just use that and make a lookup table. Unfortunately I don't, and I can't figure out a way to pack things in and still look them up with any speed. I also can't find any way to mathematically convert (...) (24 years ago, 12-Apr-01, to lugnet.robotics)
| | | Re: Struggling with encoder wheel
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| Chris, This idea would require an additional motor, but, an alternate approach might be to create your wheel with 36 alternating grey and white (perhaps by having a third or fouth shade/color you could have more information) segments. Then, in each (...) (24 years ago, 12-Apr-01, to lugnet.robotics)
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Message is in Reply To:
| | Struggling with encoder wheel
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| I'm having a hard time finding a good algorithm for the encoder wheel I came up with for use on my webcam. The way I packed the bits in the lookup table has made it hard to get any speed out of the algorithms. I'm using NQC, and the LEGO OS seems (...) (24 years ago, 11-Apr-01, to lugnet.robotics)
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