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I need some help to creat a securety Boe-Bot with the PIR sensor and program it — Parallax Forums

I need some help to creat a securety Boe-Bot with the PIR sensor and program it

BlindmonkBlindmonk Posts: 12
edited 2007-02-13 18:59 in BASIC Stamp
I have little experience with the Boe-Bot and I am trying to create it to control an area and when body heat is detected then the PIR sensor will trip a speaker to alert me. I was wondering if the PIR sensor from the Parallax inc. can be used to detect body heat while the Boe-Bot is moving? If any one has any helpful programs that I might be able to use or any advise on how to go about starting this please let me know.

Thank you,

Comments

  • FranklinFranklin Posts: 4,747
    edited 2007-02-11 18:05
    The PIR will detect the movement of a heat source in relation to the sensor. If the sensor is moving and the source is not that will trigger the sensor. If you can live with that this will work. You could also just put sensors in the area like a regular alarm system if it important.

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    - Stephen
  • BlindmonkBlindmonk Posts: 12
    edited 2007-02-11 23:03
    So what your saying is that if the Boe-Bot is moving around on the floor and there is any type of heat withing 20feet it will go off? I was hoping to be able to detect a human presence as the Boe-Bot moves around, will the PIR sensor work in that case? I don't seem to fully understand what your saying I am sorry, are you saying that if the Boe-Bot is moving and there is any type of heat moving of still it will go off?
  • FranklinFranklin Posts: 4,747
    edited 2007-02-11 23:42
    The pir detects movement in relation to itself. It does not matter to the pir if it is stationary and the heat source is moving or if the pir is moving and the heat source is stationary.

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    - Stephen
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-02-12 06:13
    The PIR won’t work properly when moving as the heat patterns will be in a constant state of change. It would more than likely continuously trigger. These devices are designed for stationary use. Take care.

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    Chris Savage
    Parallax Tech Support
  • bryan costanichbryan costanich Posts: 29
    edited 2007-02-12 22:19
    Blindmonk,

    think of it this way, the heat sensor detects a change in heat patters, right? so if it were stationary, and the heat source (a person or a fireplace) moved, then the heat pattern would change, yes? now, imagine the heat source being stationary and your sensor moving (on your r0b0t). when the sensor moved, the pattern would change. it's about relativity.
  • BlindmonkBlindmonk Posts: 12
    edited 2007-02-13 15:44
    Alright I understand now, what would be the best thing to use if I wanted to detect anytype of movement with the robot?· Is there any way to allow the robot to follow the heat pattern (ie go towards the heat)?·
  • Mike GreenMike Green Posts: 23,101
    edited 2007-02-13 16:00
    A PIR sensor is really not designed to locate a heat source in a space. It's designed to identify relatively rapid changes in the heat level in an area. Have you looked at the CMUcam? It's designed to track an object in a visual space. You could use a PIR sensor while the BOE-BOT is "sitting there". Once the PIR sensor triggered, you could use a CMUcam to look for movement and track that.

    There are expensive far-infrared cameras that can be used for tracking "heat". Most CCD cameras will detect infrared, but that's near-infrared, interesting for photos, but won't help you for tracking "heat".
  • LSBLSB Posts: 175
    edited 2007-02-13 17:07
    Is it feasible to have the BOE-bot pause while taking the reading? Say, move 5 feet... or 5 inches... then stop to take the reading?
  • BlindmonkBlindmonk Posts: 12
    edited 2007-02-13 17:16
    If I was to still use the PIR sensor and pause it every 20 inches wouldn't it still take a reading when it is moving for those few seconds? I thought about it and I do like the idea of using the CMUcam, and maybie if I was to have the Boe-Bot in one spot in a room and then when a heat source is detected then it would trigger the CMUcam and follow the source. Thanks for all your input so far it has been very helpfull.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-02-13 18:51
    There is a settling time for the PIR sensor to adjust to new IR patterns. During this time there can be false triggering. So your BOE-Bot would have to be still for up to 30 seconds or more to ensure no false triggering.

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    Chris Savage
    Parallax Tech Support
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2007-02-13 18:59
    Blindmonk -

    A PIR is not the only method of detecting an infrared heat source. Here is a simple, (relatively) long distance infrared detector you can make yourself, with just a few spare parts.

    Take an old flashlight that no longer works, or buy a flashlight at the dollar store, and carefully remove the parabolic reflector from inside the lens end. Pick up an I/R photo-transistor and a few fine pieces of heat shrink tubing. Solder longer leads onto the I/R photos-transistor. Insulate the leads from one another using the heat shrink tubing.

    Carefully drill one (or more) small holes towards the narow end of the parabolic reflector about 2/3rds of the way in, so that the leads of the I/R photo-transistor can pass through. You should be able to center the I/R photo-transistor in the center of the reflector.

    Make a firm mounting for the reflector assembly perhaps using a hose clamp to gentrly grab the outside of the large end of the parabolic reflector. Don't tighten anything so tight that it can't be adjusted at this point.

    One of the many analog circuity genuises on here can tell you how to hook this up, and can perhaps indicate whether a small amplifier (op-amp maybe) will be necessary to condition the signal before it goes to a Stamp pin.

    Test it out, and make any adjustments you need to. A dab of glue on the outside of the parabolic reflector where each of the extended leads comes through is all you need to keep it centered. Just make sure the transistor is center-aligned before the glue dries.

    If you can't envision what I'm saying here, let me know, and I'll try to make a rudimentary drawing for you, since I'm NO artist! smile.gif

    As a kid, 50 years ago, I won second prize in a science fair for a similar system which was a "match detector" which would operate from almost 10 feet away. This was LONG before the decent electronics devices we have today.

    Regards,

    Bruce Bates

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