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Line detector that works on grass? — Parallax Forums

Line detector that works on grass?

bulkheadbulkhead Posts: 405
edited 2006-07-10 01:23 in Robotics
I doubt a simple led/phototransistor combo could detect a white painted line on grass in sunlight, so what other options are there? Would it work if I somehow shielded out the ambient sunlight and had my own light source? Anyone do this before?

Comments

  • Matt WhiteMatt White Posts: 60
    edited 2006-07-09 15:42
    Well... there's probably several factors here (length of the grass, health of the vegitation (green or brown), shade/sunlight, etc.). I would emagine that the TAOS color sensor would work well. It reads values in RGB. Grass being green if you painted a white you should be able to tell the difference, its a pretty sensitive sensor. If the you are over unpainted grass your green value would increase while your red and blue values decrease. If you are over a white line the green value would decrease and your red and blue values would increase. As long as the grass in your yard doesn't inhibit the robots ability to make course adjustments while moving forward.

    Matt
  • A.C. fishingA.C. fishing Posts: 262
    edited 2006-07-09 15:55
    A CMU cam would work

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    Somebody said...
    -Never Underestimate the power of human stupidity.
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  • bulkheadbulkhead Posts: 405
    edited 2006-07-09 22:53
    Well, I am trying to find the simplest solution. Just something that would return a 0 or 1 for line or no line. What I am worried about is that since the sensor is on the move, it's own shadow and the sun's angle would affect it. If the sensor is detecting its own shadow, the values would change as well. Is there any simple way to use a CMU cam without connecting it to a computer?
  • Matt WhiteMatt White Posts: 60
    edited 2006-07-10 01:23
    Well with the TAOS sensor I think the values would change in relation·to each other.· White painted grass·should return values all near each other for RGB, or.. you'll have substantially more green than anything else when over the grass.· Regarding shadows... I'd just put a hood over the sensor as it will create its own white light to read the sensor values (there's two ultra bright white LED's on the sides of the·apature).· As far as returning a 0 or 1, its usually not that simple.· Even if you use a standard CdS its voltage is analog and has to be processed by an ADC or some other RC type circuit.

    Matt

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