Jan 19, 2008

NXT Gumball Sorter


Elegantly-designed. (The action starts forty seconds into the video).

6 comments:

CATpit contractor said...

The "gate" mechanism this uses is a very good way of getting one gumball at a time, plus it saves on the number of motors used. I eagerly await for somebody to start sorting soccer balls, basketballs, and Zamor spheres using a similar mechanism :0)

Matthias Paul Scholz said...

Would be nice to see in detail how the "gate mechanism" avoids two balls escaping from the balls' store at one time.

Who is the author of the robot?

Brian Davis said...

Sorting Zamor spheres is easy - they are slightly larger, and I've built tracks that sort them 100% (smaller soccer and basketballs fall through, while Zamors roll over). Distinguishing soccer balls from basketballs is much harder with the light sensor, as the soccer balls have a variety of "colors" (they will register as black, white, or some shade of grey, depending on where the line is under the sensor), although with the Hitechnic color sensor it might be easier.

The only reliable way I've seen was originated by the SMART group in Washington state, and involves the brilliant idea of spinning the balls under the sensor, looking for changes in the readings - basketballs are fairly uniform, while soccer balls (*most* of the time) will have a non-uniform reflection (as black lines or white regions rotate under the sensor). I believe it was Dave Shilling and/or Gus Jansen who came up with this method, and it's the only one I've gotten to reliably work.

As to the gate, yes, that is nice. I'd guess the upstream side ends up being a "chamber" or "liftpad" that is only one gumball wide. If there are two (or more likely many more) in line, when that lift pad goes up it only pushes the first gumball in the chain upwards, like the ball release mechanism on my Digicomp II model.

It's a really well-done, elegant example of a robot. The other thing I find fascinating is how it's accumulated over *one million hits* in just a week on YouTube! That in itself is an unheard of hit rate for something with the tags "lego nxt"!!

--
Brian Davis

222doc said...

wow thats all the tags he used? not sure how to check tags used? you are right that is unheard of, and makes it the top viewed of all time for a lego project. guess people love gum!!

Matthias Paul Scholz said...

>The other thing I find fascinating >is how it's accumulated over *one >million hits* in just a week on >YouTube!

Yes, though it's a nice robot, that's rather ... hm ... surprising.
Considering the usual hit rates even very spectacular LEGO robots get on YouTube (the topic is a somewhat particular part of the universe, after all), it's hard to imagine that in fact so many different people watched the video in such a short time.

lajeesh said...

I saw your comments regarding the project done by you (gumball sorter). As a mechatronics student I got inspired from your work , and Im interested in doing some projects of my own related to yours . I kindly request you to pass some information regarding the sensor used in it. It will be really helpful for me ,if you kindly do the needful.

Thank you
Lajeesh.A

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