Taste the rainbow one color at a time with this sorting machine

What’s better than a mouthful of Skittles, right? When it comes to various-colored candies, such as Skittles and Starburst, there’s always those one or two flavors you’re secretly wishing are heavily favored inside the pack. It would seem that many of us tend to love the red, tolerate the orange, and simply leave behind the yellow. Well, a group of Cornell engineering students recently devised a final project that will surely solve that quandary.

With their ECE4760 class coming to an end, the Maker trio devised an ATmega1284 powered Skittle-sorting miniature factory that actually bags and seals same-colored candies into little pouches of flavor. Problem solved!

How it works is relatively simple. The Skittles are loaded into a plastic funnel at the top, where they are fed through a color-detection module one candy at a time — either automatically or manually. Red, green, blue and white light are reflected off the Skittle, while the color is deciphered using an RGB LED and OPT101 photodiode driven by an ATmega1284.

“The LED is directed onto the Skittle with a small light block between it and the photodiode. As light hits the Skittle, certain wavelengths are reflected. The wavelength of the Skittle’s color is reflected most strongly. For example, shining a green light onto the green Skittle will reflect more light than shining a green light onto a red Skittle.”

Once a color is detected, a solenoid shoots the Skittle down a cardboard ramp which leads the piece of candy through a hole and into its appropriate bag. The ramp’s position is controlled by a servo and changes depending on the color. Once a bag has reached its preconfigured capacity, the packaging wheel rotates through a heat sealer to seal and cut the pouch.

“We chose this project because we liked the multidisciplinary approach it required. There were challenging elements from both an electrical and manufacturing engineering perspective. We needed accurate color sensing, precise servo control, and repeatable timing to ensure the Skittles would sort correctly. In addition, we had to build a mechanical structure capable of passing a single Skittle within fairly strict tolerances. As an added benefit, we acknowledge that many people have Skittle flavor preferences which our mini-factory caters to,” the team writes.

Watch it in action below!

Candy lovers interested in learning more can hurry over to the team’s official project page here. Meanwhile, you may also enjoy this Atmel | SMART SAM D21 based Skittles sorter which was recently on display this year at Electronica.