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Re: Question: Human detection

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  • jeffhoron
    Objects emit infrared radiation in proportion to temperature. See: http://imagers.gsfc.nasa.gov/ems/infrared.html Scroll down to How can we see using the
    Message 1 of 7 , Feb 3, 2006
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      Objects emit infrared radiation in proportion to temperature. See:

      http://imagers.gsfc.nasa.gov/ems/infrared.html

      Scroll down to "How can we "see" using the Infrared?"

      The item I linked to is intended to detect people. I suspect that
      two could be used to (crudely) follow a person. Or if someone was
      feeling bold they might take out the infrared sensors or purchase
      some other very sensitive IR photosensors and use them in a
      differentiating circuit.



      --- In beam@yahoogroups.com, Boštjan Jerko <bojerko@...> wrote:
      >
      > This is an IR and not body heat detector.
      >
      > B.
      >
      > On 2/3/06, jeffhoron <jeffhoron@...> wrote:
      > >
      > > How about hacking one of these:
      > >
      > > http://www.goldmine-elec-products.com/prodinfo.asp?
      > > number=G4567&variation=&aitem=17&mitem=24
      > >
      > >
      > > --- In beam@yahoogroups.com, "darthjder" <b6ol@> wrote:
      > > >
      > > > Does anyone have any ideas on what kind of component to use in
      an
      > > IR
      > > > heat sensing application, particularly for detecting human body
      > > heat?
      > > >
      > > > So far I've got circuits that are sensitive mostly to IR light
      than
      > > > heat. (Phototransistor-based: trying to use Radioshack parts
      only)
      > > And
      > > > it looks like RS has canceled thermistors.
      > > >
      > > > The goal is to make anything that detects people (A stalker-
      bot,
      > > since
      > > > a robot following a person can be seen as both hostile or
      friendly;
      > > > That, and the idea of replicating the Mechanical Hound's
      behavior
      > > > sounds cool), even while the robot is running. E-field
      detectors I
      > > > know have been tried, but antennae are a bit of a hassle.
      > > >
      > > > Just want to see what else is reliable besides sound: It's
      hard to
      > > be
      > > > "sonitropic", since one has to be sensitive (So the robot can
      find
      > > > differences in both ears) while not being vulnerable to any
      noise
      > > in
      > > > the circuit.
      > > >
      > > > Idea: Use an opamp neuron network, then use the BEAMsonics
      front-
      > > end
      > > > to create a signal the varies the threshold of the opamp.
      > > Advantages
      > > > to this are the availability of parts (Opamps are available at
      > > > Radioshack) and the fact it speeds up neuron networks instead
      of
      > > > slowing them down. (When a loud sound is made, it would be
      best for
      > > > the robot to behave in an animal-like manner and jump, not
      lock up
      > > and
      > > > hibernate.)
      > > >
      > > > Any better ideas? Preferably ones that don't require the human
      > > being
      > > > to be lit up in a radiant flame just so the robot can seek the
      > > light
      > > > of the firey glow on his/her head?
      > > >
      > >
      > >
      > >
      > >
      > >
      > >
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    • WilliamChops Westfield
      ... Hmm. contact-less thermometers are becoming relatively affordable, and might provide a much more directional sensor than the passive IR detectors like the
      Message 2 of 7 , Feb 3, 2006
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        On Feb 3, 2006, at 7:32 PM, jeffhoron wrote:

        > Objects emit infrared radiation in proportion to temperature.

        Hmm. contact-less thermometers are becoming relatively affordable,
        and might provide a much more directional sensor than the passive
        IR detectors like the one you reference (which are pretty much
        designed NOT to be directional.)

        http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91778

        BillW
      • jeffhoron
        Interesting idea. That s the lowest-cost non-contact thermometer I ve seen with a decent (8:1) distance to spot (measured area size) ratio. I suppose it
        Message 3 of 7 , Feb 4, 2006
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          Interesting idea. That's the lowest-cost non-contact thermometer
          I've seen with a decent (8:1) distance to spot (measured area size)
          ratio. I suppose it depends on Darthjder's intended application, so
          Darthjder please tell us if we're headed down the path you wanted to
          go. Two PIR sensors could provide left/right/straight ahead info
          similar to a simple photovore for $11. Maybe some blinders would
          help. I could also imagine one non-contact thermometer being used
          to sweep for a person in a sort of head / rider configuration or
          multiple units being used to zero in on things in the right
          temperature range, but that could get expensive. As a bonus, the
          targeting laser(s) could really freak people out, and being class II
          they are relatively safe.




          --- In beam@yahoogroups.com, William "Chops" Westfield <westfw@...>
          wrote:
          >
          > On Feb 3, 2006, at 7:32 PM, jeffhoron wrote:
          >
          > > Objects emit infrared radiation in proportion to temperature.
          >
          > Hmm. contact-less thermometers are becoming relatively affordable,
          > and might provide a much more directional sensor than the passive
          > IR detectors like the one you reference (which are pretty much
          > designed NOT to be directional.)
          >
          > http://www.harborfreight.com/cpi/ctaf/displayitem.taf?
          Itemnumber=91778
          >
          > BillW
          >
        • darthjder
          Thanks guys! Woah, these are good ideas. Using PIR sensors in a photovore... Actually, since we re looking for humans here, we can lessen the robots confusion
          Message 4 of 7 , Feb 5, 2006
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            Thanks guys! Woah, these are good ideas.

            Using PIR sensors in a photovore... Actually, since we're looking for
            humans here, we can lessen the robots confusion (deciding whether to
            target a candle or a human) by measuring sudden changes in heat rather
            than heat itself. (The candle stays still most of the time. The human
            being's heat moves around alot.) This also makes the robot harder to
            fool: If a human to run past a large heat source, the robot wouldn't
            go to the heat source, but to the running human. The basics of the
            BEAMsonics circuit and Robinson's Hider hearing cicuit provide a good
            example for detecting changes in readings.

            The mention of a laser puts an idea into one's head: What if the robot
            puts out a screen of 4 beams in front. 4 corresponding recievers check
            if any of the laser beams begins to vary in reflection (That is, the
            human freaks out and starts moving, which changes the reading on the
            reciever). The robot then charges towards the human based on this
            information.

            A bit pricey, though. It would be cheaper to use mirrors surrounding
            an IR LED to create the beam. The mirrors could be implemented with a
            reflective metal tube and a reflective metal cone put on top of the
            LED. A similar system, using two beams on each side of a robot's head,
            could be used to create fleeing behavior for grazing robots in an RJP.
            Or, like Jeffhoron suggests, we can mount the beam-sweep system on a
            head! Heh.

            All this talk about human tracking makes it seem like we should have
            seen a human-tracking head by now... Especially from the guys who did
            military-type work with Mark Tilden.

            --- In beam@yahoogroups.com, "jeffhoron" <jeffhoron@...> wrote:
            >
            > Interesting idea. That's the lowest-cost non-contact thermometer
            > I've seen with a decent (8:1) distance to spot (measured area size)
            > ratio. I suppose it depends on Darthjder's intended application, so
            > Darthjder please tell us if we're headed down the path you wanted to
            > go. Two PIR sensors could provide left/right/straight ahead info
            > similar to a simple photovore for $11. Maybe some blinders would
            > help. I could also imagine one non-contact thermometer being used
            > to sweep for a person in a sort of head / rider configuration or
            > multiple units being used to zero in on things in the right
            > temperature range, but that could get expensive. As a bonus, the
            > targeting laser(s) could really freak people out, and being class II
            > they are relatively safe.
            >
            >
            >
            >
            > --- In beam@yahoogroups.com, William "Chops" Westfield <westfw@>
            > wrote:
            > >
            > > On Feb 3, 2006, at 7:32 PM, jeffhoron wrote:
            > >
            > > > Objects emit infrared radiation in proportion to temperature.
            > >
            > > Hmm. contact-less thermometers are becoming relatively affordable,
            > > and might provide a much more directional sensor than the passive
            > > IR detectors like the one you reference (which are pretty much
            > > designed NOT to be directional.)
            > >
            > > http://www.harborfreight.com/cpi/ctaf/displayitem.taf?
            > Itemnumber=91778
            > >
            > > BillW
            > >
            >
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