Automatic Color Detection

[KLOZ] submitted his final project from college. Rather than an expensive CCD camera, he used a set of colored resistors LEDs and a light dependent resistor (I’m assuming he means a photo resistor) to determine the color of a product (m&ms). He used the carriage from an old HP inkjet, a custom cnc cut wheel to separate and deliver the m&ms and a Parallax propeller micro controller board to tie it all together. Now he can hog all the green ones for himself.

Update: Yes, I’m an idiot. I did mean colored LEDs. People who caught me will get an email – I’ve got something for ya.

Check out the sorting demo video after the break

15 thoughts on “Automatic Color Detection

  1. I don’t know about you but I can make coloured resistors… it just depends on what shade of brown you want and how much current you’re willing to send through them. :-)

  2. damnit, I noticed that before the change, too, but I thought ‘meh, he means LEDs’…


    neat hack though — I’m amazed at how fast the thing is. Seems that he indexed the carrier to the right edge of the track, since if you look closely it returns all the way to the edge before moving out to deposit an M&M. If he figured out how to use relative positioning, it could be even faster…
    though then you might get some cumulative errors.

  3. will o\\\’brian, i wonder if i get a sticker for seeing that one lol. nice job by the way looking forward to doing this pretty soon as my final for electronics class.

  4. you can do it backwards with 1 white led and some LDRs with coloured filters on them.

    and is photo resistor another name for light dependent resistor or are you thinking of something different because they are LDRs

  5. so this thing actually takes about 4 and a half minutes to completely sort a bag of M&M’s ? the one in my class only takes about 2 minutes to sort 2 (measured) cups of colored erasers.

  6. The main factor with speed is the time it takes for the LDR to reach a stable resistance. In my project this is about 1/4 second. It could be less, I never made mesurments. just figured leaving it at 1/4 would be safe. And Yes I could have used multiple LDR’s with COlor filters, but the main problem with that would be the fact that I would need more then one ADC chip, at $4 a pop that would throw off my cost savings. And not to mention using more of my 32 pins on my Propeller board.

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