Hall Effect sensors...

[David Halliday (Volt Computer)]

The VR system was Polemus but a search on AltaVista only turned up 14
entries, one of which was for a VR product.  Polemus has gone out of
business and I guess they aren't in the news that much anymore...
Sigh...  A search on Jaron Lanier turned up more entries for his music
than for his VR work...

I don't know how the Polemus systems worked but I do know that they were
experimenting with Ultrasonic positioning systems in 3D space - there
were several towers with pulse generators on them ( it was actually a
little spark gap - very clever idea )  The position of the spark gaps
were known, their spark was triggered by a computer and the noise of the
spark was received by a microphone on the unit being tracked.  BY
measuring the time delay between the two, the distance from that spark
could be determined and when this was integrated with the other towers
data, position in 3D space was established to an inch or so.

There were some tracking units that were tethered - an articulated rod
would extend out from the unit and the other end was mounted on a fixed
platform.  Optical encoders on each joint of the rod would record
movement and a little bit of trig would get the absolute position of the
unit.


The Power Glove is much sought after!  Good deal!!! <grin>
It works with a resistive strain gauge in the back cover of the glove.
Check these sites out for an interface.

http://www.cms.dmu.ac.uk/People/cph/menelli.html
http://www.rsol.com/pg/index.html

This would be an interesting source of control voltages for panning or
filter control ( point for frequency and make a fist for resonance... )



> -----Original Message-----
> From:	The Dark force of dance [SMTP:batzman at dove.mtx.net.au]
> Sent:	Thursday, September 18, 1997 11:34 PM
> To:	David Halliday (Volt Computer); 'synth-diy at horus.sara.nl'
> Subject:	RE: Hall Effect sensors...
> 
> Y-ellow.
> At 04:49 PM 9/18/97 -0700, David Halliday (Volt Computer) wrote:
> 
> >The sensor I am looking forward to playing with is the gyro sensor -
> >they are making very tiny gyroscopes for use in position sensors.  I
> >remember seeing one company selling a dual axis unit for around $120.
> >This one was especially clever in that the gyro was a rapidly
> rotating
> >thin plastic disk with a conductive coating.  There were capacitive
> >sensors mounted close to the surface and the signal was generated by
> the
> >deformation of the disk as the whole unit was moved.  It would give
> both
> >position and rate of change.
> 
> Wowa. What a wicked device. What about using a pleamus (SP?) You know
> the
> little devices they use for sensing positions in VR systems. I have no
> real
> idea how these little boxes work but I happened to acquire an old
> power-glove thing. I dunno, Nintendo or Matel or something. Can't
> remember
> off hand. I stuck it in a draw inside and haven't looked at it yet.
> For all
> I know it probably dosn't use a real pleamus. (SP?) But it's got these
> three
> gizmos on the end of a stick which are obviously either sensors or
> emitters
> of some kind to work in conjunction with the glove. I'm told these
> glove
> things are 'to-die-for' in the home-brew VR community but I just
> happened to
> pick it up in a lot from an auction for a few bucks. I was actually
> only
> interested in the two old C64s in there. So I could rip the SID chips
> out of
> 'em. But I'd thought this glove thing might make a good controller at
> some
> stage.
> 
> Hey perhaps I could drive my new digitally controlled mixer with it?
> More
> stupid ideas to come. Just you wait. :)
> 
> Be absolutely ICebox.
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