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From: robink@aus.hp.com (Robin Kenny)
Subject: Re: Need Inexpensive object direction sensor
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Message-ID: <1994Aug11.043115.23459@hparc0.aus.hp.com>
Date: Thu, 11 Aug 1994 04:31:15 GMT
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Paul Picot (ppicot@irus.rri.uwo.ca) wrote:
: mlipsky@powergrid.electriciti.com (Mark Lipsky) writes:

: >I am building a project where I need to detect the presence and
: >position of a person standing in front of a sensor.  It does not need
: >to be accurate; I just want to know within say, 5 degrees, where the
: >person is standing in front of my device.  There will be no other
: >objects near the person and the person will be between 2 and 7 feet
: >away.

: If you have a wall or a handrail behind the person, there is a very
: easy solution: mount a series of IR LED's on the wall, pointing toward
: your sensor.  Space them according to your desired resolution: if the
: Simply look for a 'missing' LED (one with a body in front of it)
: -- 
: Paul Picot             | Imaging Research Labs, Robarts Research Inst.
: ppicot@irus.rri.uwo.ca | London, Ontario, Canada

Great idea, Paul. How about the handrail/wall has 3M-brand retro-reflective
tape in a continuous horizontal line? This should be available from 
automotive after-market shops.
The sensor could be spinning (or a mirror periscope feeding the sensor could
be rotating) and the modulated reflection would disappear when viewing
the body. Where the spinning mirror/sensor is viewing would give a direction.
A second mirror a little to the side of the scanner, yet in its field of view
would be aimed 45 degrees offset to provide a parallax sighting.


Robin Kenny - robink@hparc0.aus.hp.com           "New ideas in status quo"
(everything in this message is PERSONAL OPINION ONLY and has no connection
with my work or my employer, the Hewlett-Packard Company Australia)
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