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Automatic Pet Door... — Parallax Forums

Automatic Pet Door...

idleupidleup Posts: 46
edited 2005-10-23 15:51 in General Discussion
Has anyone created an automatic pet door with a stamp? I am looking for one and all the ones on the market are either electromagnetic or infra-red and they both have bad reviews for the cat having to be right up against the sensor or it wont work. I am not sure why there hasnt been someone who creates an RF solution that works off proximity, or maybe there is a better way to detect proximity?

Anyway, I am thinking of building it. I want something that can detect the cat from about 2 feet away and unlock the cat door. Seems like a simple stamp project, but not sure hwo to do the sensor part...

- Matt

Comments

  • Tom WalkerTom Walker Posts: 509
    edited 2005-10-20 13:03
    idleup,
    This topic has passed through these halls before. My approach would be a combination of RFID technology, some other "body-sensing" technology, and training. Some type of "tunnel" setup would put the pet-attached RFID tag close to the sensor. Initially triggering on some other sensor (ultrasonic, IR, step-trigger, anything which would not require entrance into the "tunnel") would train the animal that the "tunnel" and opening pet door are "good" things. You may have to put up with some unauthorized visitors to start with, but I would think that, with sensors placed appropriately close tothe entrance of the "tunnel", transitioning to the RFID-only activation should be relatively quick.

    HTH

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  • idleupidleup Posts: 46
    edited 2005-10-22 21:58
    I was looking at the RFID reading that Parallax sells and noticed that it must be within 4". Is there anything out there that can go up to 2 feet? accourding to some RFID websites I was looking at there are some that go up to 20' and are passive but I cannot actually find them. I also want something that is electronics level to make your own circuit and many searches bring up completed products (from Symbol or Intermec).

    The other problem is the size of the Transponder. The Parallax one is almost 3 inches (much to large for a cats collar), are there any other that would work?

    - Matt
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-10-23 00:01
    idleup said...

    ·I also want something that is electronics level to make your own circuit and many searches bring up completed products (from Symbol or Intermec).

    - Matt

    The most commonly used is the one availible at http://www.expresspcb.com/·its good but the file it outputs will be taken only by them. The other is Eagle at http://www.cadsoft.de·which outputs to Gerber which is standard for the industry, but has a steeper learning curve. There are many others, but these two are the most used because they work well and·both are free.

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  • Kevin WoodKevin Wood Posts: 1,266
    edited 2005-10-23 04:54
    I think that Matt meant that he was looking for the discrete components to build his own RFID circuit, but his searches only resulted in manufactured RFID systems.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-10-23 05:25
    Gothca, sorry for the misunderstanding. In that case·http://www.ti.com/tiris/default.htm·and http://www.atmel.com/products/RFID/

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  • Mr.EdMr.Ed Posts: 35
    edited 2005-10-23 13:45
    Hi there,

    I have a similar project going on (see previous posts from me). But in my case, i want to use the chip that is allready inserted under the skin of my 3 cats. In that case one would need an ISO 11784/11785 FDX-B compatible reader. It works, as stated, with full duplex on 124KHz/134KHz.

    I have such a reader, but it's far too small to be sensitive enough. You really have to "stick and rub" it onto the back of the cat to get a reading. The chip is located near the neck, between the shoulderblades, slightly·towards the lefthand side. My plan would be to get a large antenna wich would have a round·shape to fit around the tubular design of the cat door. This way one would get a reading from all the transponders in all cases·(because transponders have a slightly varying·position per animal).

    I know that farmers use this on cattle. They let cows swollow a transponder where it sits (and stays) in its stomach. They use large gate-like antennas and get readings from 1m/3Ft or more.

    Sofar i have been unsuccesfull in obtaining the right (and affordable) antenna to use in this project. In other words, the project is on ice for now. I hope to finish it in near future though.

    Good luck with it...smilewinkgrin.gif
    Ed.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-10-23 15:51
    Mr.Ed said...
    Sofar i have been unsuccesfull in obtaining the right (and affordable) antenna to use in this project. In other words, the project is on ice for now. I hope to finish it in near future though.

    Good luck with it...smilewinkgrin.gif
    Ed.

    Youve hit the nail on the head, affordable is the operative word. Most of the cheap readers assume you will be able to place the ID in extremely close proximity, use in distance sensing requires a well designed antenna, which is a black art, complicated by the fact that RFID uses the radio waves to both communicate and supply power to the transponder, so optimizing the antenna just for signal strength may not be sufficient. The majority of antennas Ive seen capable of distance sensing start in the mid 100's and go into the thousands, just for the antenna! It may be simpler to have a standard low power RF transmitter combined with a proximity device so that when both are present the mechanism is activated.

    The other thread is here: http://forums.parallax.com/showthread.php?p=524783·three pages of good info.

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    Post Edited (Paul Baker) : 10/23/2005 3:55:11 PM GMT
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