Help with automatic gate design

Discussion in 'The Projects Forum' started by kappi123, Sep 15, 2015.

  1. kappi123

    Thread Starter New Member

    Sep 15, 2015
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    Hi all
    I need help in designing a gate that is to be used for passive wildlife capture.
    Before you ask please watch this video and you will have more of an idea.

    The boma walls are pulled up by a weight (approx 5kg each) in the posts that falls when triggered.
    What I was thinking is to use a pull solenoid on each of the posts to keep the weight in the loaded position.
    Do you guys maybe have any other ideas or would something like this be sufficient?
    http://za.rs-online.com/web/p/tubular-solenoid/4317548/

    The system will be powered by solar, and triggered by a gsm device.
    Will I need any other circuit to run the solenoids?
    Thanks in advance
    Gate.png
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    The solenoid is a good method. A small solar cell could charge up a large capacitor. The energy in the cap would be enough to pull the solenoid.
     
  3. ScottWang

    Moderator

    Aug 23, 2012
    4,855
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    So you are not use the motor with gear to draw the rope, and use the Rotary Solenoids?
     
  4. InspectorGadget

    Active Member

    Nov 5, 2010
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    The solenoid requires 7W continuously to operate to hold the control-line down. Better to use a straight or rotary solenoid to "unhook" the line and let the weight go. That way, your holding is passive and only the trigger is active.

    You could use solar chargers, yes, but better to use a long-shelf-life NiMH and not capacitors, even with the momentary trigger approach.

    Here is a solenoid "catch." Mount it horizontally as pictured. Put a loop in your line and loop it on the end of the catch. Then when you energize it momentarily, the catch pulls in and releases the line.

    http://www.amazon.com/BQLZR-Cabinet-Electric-Assembly-Solenoid/dp/B00L27BLJY

    [​IMG]
     
    kappi123 likes this.
  5. kappi123

    Thread Starter New Member

    Sep 15, 2015
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    Thanks, really like your idea Inspector
     
  6. sirch2

    Well-Known Member

    Jan 21, 2013
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    Yes more than likely depending on the solar/battery combination and the specifics of the GSM device. I would have thought lead-acid batteries where ideal for this kind of project and you may need a circuit to allow the GSM device to power the solenoid and provide protection to the GSM circuit. Do you have a GSM module in mind?
     
  7. kappi123

    Thread Starter New Member

    Sep 15, 2015
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  8. InspectorGadget

    Active Member

    Nov 5, 2010
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    Yes, remember to protect against the back-emf of the solenoid with a big power diode backwards across the coil. Same with a relay coil if you use a relay to drive the solenoid.

    Your GSM-based device doesn't look like a very good idea for triggering these walls. It looks like something you want to do dynamically, in real time, as an animal walks (or runs!) through the area. Neither SMS nor switched-call modes available on that GSM module would be suitable. SMS takes variable numbers of seconds or tens of seconds to go through. Sometimes minutes. Likewise with a straight phone call. Unreliable call setup and connect times.

    You really need some kind of direct-connect radio or real-time mesh network, like maybe Z-wave remote devices if there are battery-powered ones (I mostly know of Z-wave with home power-line devices). Low-voltage Z-wave devices aren't that common (mostly home-power-line oriented) but they can be found:

    http://www.shop.haworldonline.com/F...Interface-Module-Dry-Contact-Relay-112136.htm

    But any wireless low-voltage relay device would work.

    http://www.miniinthebox.com/12v-2-c...-remote-controller-dc28v-ac250v_p1636353.html
     
  9. sirch2

    Well-Known Member

    Jan 21, 2013
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    Does it even need to be wireless? 100m of cable run back to a hide doesn't cost much, then it's just a couple of solenoids, a battery and a switch.
     
  10. kappi123

    Thread Starter New Member

    Sep 15, 2015
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    Yes needs to be wireless in the sence that there is cctv cameras put up at the site and if motion is detected you can log in and see if you want to release the gate- thus you can be more species specific. Mostly put up in very remote locations
     
  11. InspectorGadget

    Active Member

    Nov 5, 2010
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    How many gates do you have, and how coordinated to they have to be with each other or with the animal's movement? I could be wrong about my assumptions about the GSM unit.
     
  12. kappi123

    Thread Starter New Member

    Sep 15, 2015
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    It will mostly just be 1 x 10 meter gate. The rest of the boma is made up of the game capture material and is set already- so it is just the one gate that has to pull up. Animals are given supplementary feed and water in the boma, and when the species that needs to be captured/ moved enters the gate it can be closed as you monitor over cctv.
     
  13. kappi123

    Thread Starter New Member

    Sep 15, 2015
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    Im a veterinarian so this is mostly for wildlife research, and really helps to decrease helicopter costs for darting. Thanks for all the help. Sure we'll get a solution. Just difficult to get certain parts in south africa.
    Will this solenoid work
    http://www.mantech.co.za/ProductInfo.aspx?Item=72M1049
     
  14. InspectorGadget

    Active Member

    Nov 5, 2010
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    Sure; you might need to lengthen the tip through a hole in a bracket so that you can loop the line on the tip when it's protruding through the plate, but when it retracts, it'll pull the line off of it as the tip disappears behind the plate.

    upload_2015-9-18_14-43-1.png
     
  15. InspectorGadget

    Active Member

    Nov 5, 2010
    211
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    So since you have only one gate, and you have some time to react, that GSM module would work for triggering it. You'll probably need some kind of relay to handle the current to the solenoid.
     
  16. kappi123

    Thread Starter New Member

    Sep 15, 2015
    7
    0
    Thanks thought the same. That gsm module has 2 output relays- wont that be sufficient?
     
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