Subject:
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Re: NXT Bot Idea - Audio Tracking
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 9 Mar 2006 08:56:13 GMT
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Viewed:
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2587 times
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In lugnet.robotics, Brian Davis wrote:
> In lugnet.robotics, Ed Manlove wrote:
>
> > a bird finder/tracker. The bot could simply rotate towards
> > the direction of the sound.
>
> Interesting, although where I live I have a sneaking suspicion the NXT would
> try to home in on every passing car and truck. But the NXT could be used to
> track my kids (since I can't do that myself anyway).
>
> > And taking the idea further you could do an educational
> > experiment using two microphones and asking the question(s)...
> >
> > Why do we have two ears and not one? How does having two
> > ears allow us to better determine the source of a sound?
>
> Well, let's see, the distance between my ears is about 0.3 meters, and the
> speed of sound is close to 300 m/s. So a best-case time-delay is arund a 0.001
> seconds, or one millisecond. You couldn't do that with the RCX and standard
> firmware (sensor reads were only about once every 3 ms), so the question is how
> much faster the NXT firmware might be. 'Course, you could always make the
> spacing between the sensors bigger I guess.
You can do that with the RCX using low-level functions that directly access the
H8 microcontroller. (We actually did it with Ultimate ROBOLAB).
http://www.convict.lu/Jeunes/ultimate_stuff/Nic_1.htm
We already worked out several sound sensors. A particularly interesting one is
used in robot GASTON. But Nic_1's is the best, since the electronics is nothing
else but two audio amplifiers. The RCX samples then at 36000Hz and operates a
very fast cross-correlation. (1.2sec for 2x300 data points. Precision ~5°.)
I guess that NXT basic configuration won't allow sampling at that high speed.
But, the time after the release will be as interesting as it was for the RCX,
since many gifted people will participate in unlocking the last feature of the
device. The RCX was a light-house for 8-9 years now. Many designed great,
admirable LEGO robots with it that could compete other kits, and I think we were
able to press the last drop out of the citron with our robots: GASTON,
Mars-rover, Nic_1 and with our programming: DFT, cross-correlation, RC-servo
control, CMUCam2 drivers, the worlds first and still only RCX virus.
To make it short, I think that the community will see an NXT audio tracking
robot in a few months.
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Message is in Reply To:
 | | Re: NXT Bot Idea - Audio Tracking
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| (...) Interesting, although where I live I have a sneaking suspicion the NXT would try to home in on every passing car and truck. But the NXT could be used to track my kids (since I can't do that myself anyway). (...) Well, let's see, the distance (...) (19 years ago, 8-Mar-06, to lugnet.robotics)
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