Alt-BEAM Archive

Message #03099



To: Wouter Brok w.j.m.brok@stud.tue.nl
From: Chiu-Yuan Fang chiumanfu@home.com
Date: Sat, 08 May 1999 17:04:28 -0700
Subject: [alt-beam] Re: First Top'Bot


http://www.xs4all.nl/~sbolt/e-spider_sound.html

Steven has done this on his uP controlled Spider.

Chiu

Wouter Brok wrote:
>
> Hello,
>
> While I was still busy with microprocessor controlled robots I've been
> experimenting with what you suggested, but a whole pile of problems came up:
> - the first and the biggest: reflection; in a room or any other environment
> with obstacles there are quite a lot of sound-reflections, so basicly the
> signal you get from one source is quite complex. Of course you can think up
> something to get this problem out of the way. I tried do do it like this:
> as a sound-source use something that generates bursts with silences
> inbetween of a second or so (the typical time for sound to die out in a
> normal room is 0.5 seconds. longer is irritating when you are talking in it
> with someone) So then you can detect the direction of the first signal you
> receive; all the reflections will come in later (easily to calculate with a
> speed of sound of about 340 m/s in a normal environment). With that problem
> out of the way:
> - the second, as well difficult to solve: hoe can you make the microphones
> direction-sensetive. the commercial microphones which are direction
> sensitive are placed in a reasonably long tube, which isn't something you
> want on your small robot. You can use more microphones pointing to
> different directions and compare the signals from them (actually two woulk
> be a good start), but the differences in signals are quite small, and with
> me felt within the tollerance of the microphones (of course you can correct
> for this ...).
>
> Those were two physics-problems; my bet is that the electronics will also
> pose a problem; I didn't come that far yet; when I saw the
> oscilloscope-waveforms of the signals of the microphones I decided that it
> would be easier to make a person-following robot with three PID-sensors -
> the ones that are used to switch the light on on the lawn if a heatsource
> is moving - but then I got to know about BEAM.
>
> Maybe if you choose another, smarter way of detecting sound-direction it
> will work out more easy ... I don't know ... it is an interesting concept,
> definetely.
>
> >I was wondering if anybody is working on an AudioTroph ? I have 3 left over
> >microphones and was wondering if it was possible to get a BEAM bot to follow
> >a certain sound or sound level? If any research or any plans are already out
> >for this please let me know. By the way I created my first semi robot today.
> >Its basicly a motor witha switch and battery but its a start right ?
>
> yep, it definetely is ... if you get the hang of it you will be making nice
> bots quite soon.
>
> Regards
>
> Wouter Brok

--
Chiu-Yuan Fang
chiumanfu@home.com
ICQ=5614919
http://www.geocities.com/SouthBeach/6897/beam2.html

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