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how to program a IR sensor ??

Former Member

i need a tutorial to program an IR sensor (not ic) for differentiating colors ..for my line-following bot

  • Personally I wouldn`t bother with IR for Colors, a simple Cadmium Disulphide photo resistor will do the job for you much easier.

    although it Will be possible with IR, you Will get strange readings from different inks, that Look to be the same color to the naked eye, for instance Plants (yes the green growing things) will look perfectly White in IR and not Green at all.

    so use something that responds in the Visible spectrum.

    then it`s a case of outputting this sensor reading to an analog port of some description and using a Bounce-Back light to measure the reflectivity of the ink surface.

    red will reflect red and give a high reading, but green will not reflect it and so it`ll give a low reading.

    color opposites will be red-green, yellow-blue etc...

    you`ll need to iluminate the line for the robot to follow anyway, so using an RGB LED will be a good choice.

    the s/ware is fairly simple, light up Red and take a reading, then the same for Green, and then Blue, which ever gives the best reading is likely to be the color it`s seeing.

    hope that helps a little image

  • I agree with YT2095, an IR sensor will not readily do what you want.

    If you want your line following robot to switch to different colored lines, you might want to just go to different line widths.  These will be easier to determine with simple sensors and software.

    To do color discrimination, you need to include spectral filters and a good full color illuminator.

    One simple way to achieve a color discriminator circuit, would be to use a white light illumination source and pass the resulting image through a set of Dicloric (not sure about this spelling) filters.  These would give you a blue, red and green signal that you could pass to inexpensive lead sulfite light sensors.  You can get the filters from surplus stores.  They were used in the early TV cameras to get RGB images to combine for color television.

    To do this level of spectral discrimination in IR, you need specialized filters, which are very expensive.

     

    Hopefully this post can help you decide what approach might work for your application.  If you tell us more about what you want to do, we could probably give you some better suggestions.

     

    DAB

  • Most line following robots only track a black line on a white floor, or a white line on a black floor.

    This can easily be done using IR transistors and LED's (the standard for most line following robots).

     

    I have an example here: http://buildsmartrobots.ning.com/profiles/blogs/build-launchbot-a-c-programmable-debuggable-16bit-robot-for-only-

     

    There is a schematic and pictures of the board.  you can see the robot in action here

     

    The code was written for the TI Launchpad and can be found here: http://api.ning.com/files/Yocy2J8IGbgNKxiBk5stCtFlPcC8LadZLT096Ldd-btd*FycNB0h1UHfzgYGheiCTnsWEkKr2ZhqmHq3K2KAQWoPKK2bsIFb/EMGRobotics_LaunchBot.zip