Has anyone here done much work with proximity sensors?  I am looking to=20
trigger an event when someone stands in front of (or walks past) a=20
specific area in a retail environment.  The sensing must be done from=20
one side only (no beam break methods).

The sensing range would need to be approx 200mm - 1000mm (8" - 40"). =20
The horizontal detection width would need to be approx 500mm (20") at=20
end of the range I guess.  There would be multiple sensors, spaced at=20
approx 600mm - 900mm (24" - 36") intervals.

There is nowhere to mount the sensors apart from near the floor or=20
*maybe* on the wall higher up.  Ideally the sensors need to stand up to=20
a bit of abuse from knocks and maybe a splash from a cleaners mop.

Typical machinery proximity sensors would be easy to mount, but seem to=20
be mostly very short range.  Ambient light can change somewhat so shadow=20
detection would not be suitable I suspect.

I had thought about ultrasonic "range finders" (as used in robotics) but=20
they would probably interact when use this close together.  They also=20
wouldn't stand up to the abuse they'd cop being mounted down low.

I think typical PIRs are going to be too coarse, but maybe there are=20
better ones than what I've seen so far?
David...

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___________________________________________
David Duffy        Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717      Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au
___________________________________________

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