Light vs Dark Tile Sensing

Discussion in 'The Projects Forum' started by D. Haaland, Jan 11, 2011.

  1. D. Haaland

    Thread Starter New Member

    Jan 11, 2011
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    0
    Hello,

    I'm trying to build a circuit that can differentiate between light and dark tiles. I was thinking of using an LED/Light sensor combination. I want to be able to detect from far away (10cm) and also as close as (.5cm). It can be a different sensor for each distance.

    I found this photodiode, http://ca.mouser.com/ProductDetail/Avago-Technologies/APDS-9301-020/?qs=t8w9rvwJwK8OBnnCABHlZw==, and would couple it with a 640 nm light source (blue).

    The idea would be to shine the light and detect the amount relfected from the surface. Ideally, the amount refelcted off the light surface would be measurably higher than the dark surface.

    Before I move forward, does this seem to be a viable solution? Alternatively, does anyone know of any other components / methods that were successful in similar applications?

    Thanks
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
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    Using a camera to do strong contrast differentiation is rather easy these days. There are many projects available to help.

    Even the LEGO Mindstorm kits can to it. They have a little camera that can be used in line following and object avoidance. Even basic object recognition.

    You didn't mention your control source, be it a microController (Which type?) or a PC.
     
  3. #12

    Expert

    Nov 30, 2010
    16,313
    6,817
    You had me going for a minute. I was thinking you can sense light or dark way simpler than using a computer. Then I see the datasheet. Yep. It's a sensor for use with a computer of some sort.

    Carry on.
     
  4. D. Haaland

    Thread Starter New Member

    Jan 11, 2011
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    I'll be creating the device using a PIC mcu to control the system, most like in a 40 pin DIP configuation.

    Unfortunately, the camera solution would be too large and expensive for the purposes of this project and while I have the Lego kit, I'd like to have more control over the operation of the machine...
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
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    I was only suggesting that the technology has been "well done" by now, and would likely be easier to impliment then you think.

    Here is some info I came across while searching around on your problem:

    This is a color sensing with phoro resistor:
    http://www.societyofrobots.com/sensors_color.shtml

    Here is an AtMEGA8 with a few dollar camera that can track multiple colors at once at 30fps.

    Much less expensive than you think:
    http://www.elektronika.ba/742/robot-vision-with-atmega8-and-color-camera/
     
    Last edited: Jan 11, 2011
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