Let's Make Robots!

m&m sorter #3

Sorts m&m's by color
DeltaRobot-0.02.zip3.44 KB

Videos: http://www.youtube.com/watch?v=Pbb9GOWaL4g and http://www.youtube.com/watch?v=mPakG8p3MHE

Update: Added schematic for the vacuum system

Code word were: CHEAP!

Cheapest RC servos I could get, Cheapest Arduino, almost. Straws from mc donalds, icecream sticks, rubber bands, Lots of scrapped stuff just waiting to be used in the workshop. Solenoids in the valves were from old tapedrives, and the valves them selfs were from old bicycle tubes. Vacuum and pressure comes from an old aquarium pump, reshaped to make vacuum too.

The dark disk is a sun shade, had to add that before filming outside, othervise color detection made too many mistakes.

"Exploded view" of lower arm:

"Exploded view" of lower arm

Lower arm:

Lower arm

Lower arm about to be connected to bolt on upper arm

Lower arm about to be connected to bolt on upper arm

Lower arm and the moving platform:

Lower arm and the moving platform


Two valves, the lower one disassembled

The pin visible at the end of the yellow tube pin of the bicycle valve. The brass tobe above goes over the pin. Since the pressure uses in the robot is low, +/- 0.15 bar, I could go with these simple home made solenoid valves.

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Thank you very much for the photos and description . They explain a lot . I love the use of common and cheap materials .

How did you make the color detector?

At the buttom of the small black tube you see, there is a RGB LED and a phototransistor, both facing updards. Whan a m&m is placed, and the lid is over, I make 4 readings. First a dark one to get an offset, and then a reading with each color on.

In the arduino code I then compare the readings with a table and pick the color from the table row with least error.

The phototransistor i picked is definitely not correct, its tuned for the IR band, but it works ok anyway, and its fast!

I have a transistor between the phototransisitor and the arduino analog input, just to make the arduino look into a ~10kohm impedance, and not the ~1Mohm from the phototransistor<->resistor chain. A simple grounded collector IIRC.

Just love your Delta robot! Amazing stuff and I have to have a go on a Delta myself some day. I had a go at a ‘Perler Beads Sorter’ earlier but gave up. http://letsmakerobots.com/node/18124
I might have another go at it…

Ahhh, I sense a challenge there. But at a size of 5x5mm, and even with a hole in, it's not a job for my vacuum sucker. The m&m's I have toyed with are 14x7mm, and does not clog as easy as your tube beads.

Still, my dispenser mechanism, took quite some time to get right.

Cool.  Is the color detector unit a purchased item of did you make it yourself?

Home made. tri-color LED and a phototransistor.