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Topic: best way to detect a human head over a pi||ow (Read 1 time) previous topic - next topic

sarach

It's easy to detect a human head over a pillow. Just use the weight, if it detects the weight, the human head over a pillow.

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polymorph

Quote
What does your second, grounded, piece of foil bring to the party please?


Capacitance is being measured between the Receive pin and ground. Your body is coupled capacitively to ground. The extra sheet of metal connected to ground increases the capacitive coupling of your body to ground, increasing the reading and therefore sensitivity. Also, if the Arduino is not actually grounded (which is almost certainly the case), then you are really measuring just the capacitance from the Receive pin to the Arduino common.
Steve Greenfield AE7HD
CET Consumer Electronics and Computer
Please don't read your attitudes into my messages

polymorph

Conductive fabric is a great idea, but you -don't- put it in the pillow. Put it below.
Steve Greenfield AE7HD
CET Consumer Electronics and Computer
Please don't read your attitudes into my messages

SirNickity

Ah man, it just occurred to me:  Could've suggested a drool detector!   :smiley-yell:

123Splat

Fergit the foil,  Bear trap under the pillow.  No head on the pillow, no detection.  Head hits the pillow, Bear trap closes, crushing pillow and head causing scream.  Sound detector picks up sound energy from scream and fires detection circuit... No need to worry about whether or not subject is awake or asleep, They will be awake (for a short time) after the detection. Discrimination between feet and head,,, Does it matter?  Discrimination between head and cat,,,, Oops,  Oh, well........

Sorry, couldn't help it.

I vote for the capacitance sensor.  However there might be some issue with comfort suing PCB's for sensor plates.

JimboZA

If using the bear trap approach, it will need re-setting after each deployment, which is a bit of a pita to do manually. I'd add a huge servo to the trap, and on command from a timer after deployment, the servo will open the jaws thus resetting the trap for the next victim subject. You might consider some kind of ejector to remove the previous victim subject.
No PMs for help please. Not active on this forum any more.

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