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curious1
04-12-2007, 07:16 AM
I would like to conceal Ping))) in a fixed position as descretely as possible to sense an approaching object. BS2 outputs would vary depending on distance.
Can it operate through anything like very loosely knit fabric or does the emmiter and receiver·have to be totally unobstructed ?

Chris Savage
04-12-2007, 10:01 AM
Hello,

Anything shrouding the transducers will adversely affect the performance. If you’re trying to conceal it remember there is a bright flashing LED during normal operation. Also bear in mind that if you’re trying to detect people we don’t make good reflectors of ultrasonic sound. Clothing and skin tend to absorb the pulses rather than reflect them so you will no doubt get unreliable readings. Take care.

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Chris Savage
Parallax Tech Support

curious1
04-12-2007, 10:45 AM
The PIR sensor may be a better choice but......it would only sense the presense of a moving object, no distance.
I read all I could find about the PIR sensor and there is no mention of it's field of view. Range is about 20'.
·Can the field of view be narrowed with an extension tube or blinders ? (like on a draught horse)
If so, several could be mounted on adjacent walls of a room, and if they didn't overlap, (much) ·it would create a grid.····Any moving object in this space would trigger one sensor on each wall. This would give the stamp an X Y coordinate which outputs could be programmed for whatever function necessary. For instance tracking or panning with a camera or whatever.
This is my basic plan, not out of necessity, just for a learning experience.
If there is a more practical approach or if someone has been there and done that, I'd appreciate the input.
Thanks Chris,
Thanks all,
RC

Chris Savage
04-13-2007, 01:06 AM
RC,

I believe Vern on the forums here has demonstrated using PVC pipe to obscure the FOV of the PING))). You certainly can use it to do that. Take care.

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Chris Savage
Parallax Tech Support

curious1
04-13-2007, 01:38 AM
I searched Vern's posts, didn't see anything on PIR.

Thanks for the input. I tried to attach a photo of preliminary set-up using·4 tactile switches to simulate 4 PIR's,2 on adjacent walls. Output is to enable, step and dir. of motor driver. There will be 4 on each wall creating 16 target zones. Im working on the code. It·will pan in one dir, wont come back. I think I need a pulse generator or some way to have the BS2 keep track of where the motor is so it will know which way to go next.

Thanks Chris,

RC

curious1
04-13-2007, 01:47 AM
one quick thought, (imagine that) Would it be possible to mount 3 PIR's with tubes side by side angled slightly away from each other so the target would only trigger one ? LEFT CENTER RIGHT
So if right =1
Pan right until right=0, center=1
and vice versa.
Less hardware, simpler code.

Chris Savage
04-13-2007, 05:34 AM
Sorry, maybe I had the wrong person...Try this link...It's the one I was thinking of and I found it on Google by typing Parallax PIR PVC.

http://www.scary-terry.com/itw/pirsensor/pirsensor.htm

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Chris Savage
Parallax Tech Support

curious1
04-13-2007, 12:35 PM
It looks as though the PIR sensor is meant to be stationary and even takes a little while to settle in. Doesn't look like you could pan or scan with it. If it senses motion, and it was moving , everything would be moving relative to it.
Can anyone confirm....?
RC

kelvin james
04-13-2007, 02:10 PM
Although a little on the pricey side, the thermal array sensors are pretty cool, even have a servo interface. Not sure of the maximum range.


http://www.acroname.com/robotics/parts/R255-TPA81.html (http://<br>http://www.acroname.com/robotics/parts/R255-TPA81.html)

Chris Savage
04-14-2007, 05:58 AM
Confirmed…PIR sensors are definitely not meant to be moved. They stay still and wait for a sudden change in the PIR pattern within their field of view.

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Chris Savage
Parallax Tech Support