Simple and Reliable Metering Solutions for Sorting M&Ms in Kinetic Sculptures

[Involute]

I make computer-controlled kinetic sculpture (http://www.youtube.com/watch?v=oFNG-sxLnM8" one of my pieces). I'm working on a piece that will sort M&Ms by color. I've got the color ID and sorting parts under control, but I'm having trouble coming up with a simple and reliable mechanism for metering them individually out of the hopper and over the color sensor (which looks up at the bottom of each M&M).

My latest approach has been to use an http://upload.wikimedia.org/wikipedia/commons/7/7a/Internal_Geneva_wheel_ani.gif" with holes around the perimeter. Attached is a sketch of an early design. From a practical standpoint, the current version is identical. The problem is occasionally an M&M fragment gets in the hole and prevents a whole M&M from sitting flat, causing it to jam when the wheel tries to drive it under the triangular shaped diverter you can see in the sketch (see the other attachment). While I'm trying to fix this, I thought I'd reach out to the community and see if anyone has a better idea. I'm not wedded to the Geneva wheel approach, so don't feel you have to stick with that. All I ask is that it be simple and reliable.

Thanks for your help.

 

[Space_Cowboy]

If your problem is bits and fragments of M&M's, you could shake your M&M's over a simple sieve before passing them through your hopper. The sieve holes should be just under the diameter of the M&M's so that any fragments will fall through but the whole pieces will pass.