Human detection

Ugha

I want to design a bot that locks onto an object with IR (or perhaps ping)
then senses if its human or not.

Is there any way to do this? I had high hopes for the PIR sensor but it seems
it only detects movement.

Anyone know if the movement is only in the human temp range or is it any
movement?

Oh... also... will an IR LED throw off the PIR sensor?

LilDi

PIR sensors detect thermal infrared signatures only. Any object that emits thermal IR and moving will trigger the PIR (within the range limits of the PIR). IR LEDs will not interfere with PIRs.
Reflective IR is between 0.7 and 3 micrometers.
Thermal IR is betwene 3 and 14 micrometers.
Humans emit between 8.6 and 9.6 micrometers.

Ugha

Is there a way to tune or filter the PIR detector so it can only pick up the human range then?

Also... would an object in front of the PIR detector affect it's "sight"? For example, a thin
piece of felt or paper a half inch or so in front of the detector.

My idea is possibly using IR leds to "lock on" to a stationary target then sweep the PIR left
and right to simulate movement enough to trigger it if its human-range.

Does anyone know of a better way to detect humans?

stevenmess2004

Try getting the filter out of a security PIR detector. Don't know what wavelength they work with but it should be somewhere around what you want.

Franklin

That would depend on how you define "Human" to your program.

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- Stephen

Ugha

Human would be defined as a stationary or near-stationary object that either meets the normal human temp range... or in some
other way senses that a person is not a lifeless object.

I considered using some kind of skin tone identifying process, but the RGB color sorter on the parallax site only works at about
a 1" distance. And it's a little expensive.

I'd need something that'd work from about a foot away.

As far as I can tell... PIR is my only hope.

Stevenmess2004: I have one I tried to rip apart, its even less sensitive than the parallax PIR.

Dgswaner

I think a combination of sensors will yield the best luck. perhaps a PIR sensor to sense movement, then the bot knows which way to look for a possible human, using roborealm. a simple cam could detect skin tones, use an IR thermal array like the Devantech Thermal Array Sensor, to make sure that the skin tone has a heat signature, and then a ping sensor to judge distance, roborealm could help judge distance/dorection also. should work well as long as you don't have any skin colored coffee mugs sitting around!

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"A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

DGSwaner

Bruce Bates

Folks -

The term "skin tones" has been used more than once in this thread. That is not one singular color. Like M&M's we humans come in many different colors, thus using "skin tones" would be a bit difficult, if not impossible.

The I/R heat emission signature is fine, but I'm not sure we all would "look" the same there either. So too, clothing will alter the I/R heat emission signature to one degree or another.

Franklin (Stephen) said it all above, when he stated:

"That would depend on how you define "Human" to your program."

There is a good deal more to that statement than may meet the eye!

Regards,

Bruce Bates

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"Genius is one percent inspiration and ninety-nine percent perspiration."

Thomas Alva Edison

quickster47

You may want to invest in this TPA81 - 8x1 Thermopile array. I have one and for picking out humans, it just can't be beat.

http://www.robot-electronics.co.uk/acatalog/Thermal_Array_Sensor.html

Carl

Zoot

Here's a link to a video of a HexCrawler using the Devantech themopile array to follow a human:

The page with video: share.crustcrawler.com/NorrisLabs/FollowMeHexCrawler/FollowMe.htm

Project description: http://forums.parallax.com/showthread.php?p=615077

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When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php

LilDi

Ugha,
·· To answere your question. A Thermal IR filter is available but very expensive. There is a PIR sensor that has a built in filter that targets the human IR range and filter out other thermal IR. (Eltec 442-3)
http://www.acroname.com/robotics/parts/R1-442-3.html

Placing a loosely woven cloth in front of the PIR is possible with some IR attenuation. Experimentation will be needed with the type of cloth. There is a product called Poly IR-4 and Poly IR-9. Its a plastic material that passes thermal IR and looks black to the naked eye.
http://www.fresneltech.com/pdf/POLYIR.pdf

Post Edited (LilDi) : 2/14/2008 4:48:00 PM GMT

Dgswaner

skin tones don't refer to one color.... and I'd suggest the don't knock it till you try it approach for me the stock skin tones filter for roborealm worked great (working on a USB missile launcher sentry). I don't have a multi racial family so I can't say how it works across races but for a little white guy and his family it works well. well enough in fact that it could almost be used by it's self as a "human detector"


They Demo is free and you can use pictures to test filters. you might want to try it and see how it works for you and your environment.


Added Photo examples.

The one of my daughter is using:
Gaussian blur
Skin filter
RGBfilter Red
and center of Gravity.

I zoomed in on the output image so you could see the box and read the text, the X and Y are variables that can be used to control servos, make calculations what ever you can think up.

the photo of lots of people is just the stock skin filter,

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"A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

DGSwaner

Post Edited (Dgswaner) : 2/19/2008 4:02:44 PM GMT