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Discussion in 'General Electronics Discussion' started by Stroller, Oct 16, 2011.

  1. Stroller

    Stroller

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    Oct 16, 2011
    Hi I found this forum through google, I would like to make a system that will fit on a seed drill to detect when the pipes become blocked. The seed is blown down pipes and into the ground, if these pipes become blocked it leaves unplanted ground. Would it be possible to have a light sensor that switches an LED on or off momentarily as the seed passes the sensor, which means that no seed passing or a complete blockage give a steady light? Oh and it needs to be 12v, able to cope with dust and I need 32 of them! Not much really! I hope you can help. Thanks James
     
  2. Externet

    Externet

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    Aug 24, 2009
  3. daddles

    daddles

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    Jun 10, 2011
    I suspect it's not a trivial problem to solve -- you want the thing to work reliably. First, ask yourself if there are commercial detectors that solve the problem reliably on the market for any price. If the answer is yes, then that gives you a clue that the problem might be solvable. If the answer is no, then I'd be a bit concerned, as the technology to do such things has been around for 50-100 years and since there have been millions of farmers who plant things, such a device would be of obvious utility.

    My engineering intuition worries about two problems. First, dust will collect and block optical paths, so that issue will need to be dealt with (it's compounded by electrostatic problems). Second, the detection problem depends on the diameter of the seed in relation to the diameter of the tube it's falling through and the diameter of the detector. It makes intuitive sense that you'd want the optical beam to take up most of the diameter of the tube (I'm imagining a transverse hole with a light on one side and a detector on the other). So then the issue is when a seed passes, it causes a blip in the optical signal; the electronics needs to detect this blip. All of this is doable and has been done thousands of times in other industries, but the devil is in the details and you'll need to sit down and do some experiments.

    A good engineer would also look at other detection methods than just optical. For example, an electrostatic charge could be put on each seed, then that moving charge detected by a sensor. Of course, that opens an engineering can of worms with lots of other things to worry about. How about a mechanical device that is deflected by a passing seed? Some library research would uncover methods that have been used in other areas. Consider contacting some folks on the staff of an agricultural college or your local ag extension.

    If you want more thinking from folks here, you'll have to define the problem better. What's the range of seed diameters, shapes, and masses? How big is the tube they have to fall through? What's the number of seeds per second? Engineering stuff like that...
     
  4. duke37

    duke37

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    726
    Jan 9, 2011
    Some combine harvesters detect grain passing over the sieves with a plate which detects the seed hitting it. A diddy microphone attached to the tube should be able to detect the seed where the tube is curved. The signal will need to be filtered to select the seed signal among the noise.
     
  5. Stroller

    Stroller

    2
    0
    Oct 16, 2011
    Hi

    Thanks for the replies so far, after a bit of digging on the internet and a few inquiries I have found that Dickie-John make a seed blockage sensor.

    http://www.dickey-john.com/product/vigilense-blockag-seed-sensor/

    But at £100 per sensor, at least in the UK it is, it is beyond my budget, hence the desire to have a go at making one. As it says in the website it needs to be able to detect seeds ranging in size from canola to maize/corn. As for flow rate, in wheat, which is my main crop it is about 170gm/minute. As far as I can tell from the website the Dicki-John sensor is fitted in a straight run of pipe so its probably an optical sensor?
    Any sensor fitted would need allow complete air flow as the tubes get blocked very easily, so that rules out any mechanical wheel/flow meter. Any help gratefully received!

    James
     
  6. duke37

    duke37

    5,254
    726
    Jan 9, 2011
    I've Googled 'seed flow monitors' and there are systems based on vibration and optical blocking. Simba Horsch do a drill with optional monitors. It depends on where the blockage is but have you thought about pressure detection?
     
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