Rhymes With "Biscuit": P1-powered rolling-ball sculpture
mpark
Posts: 1,305
This is a piece I've been working on for too long; I'm hoping I can declare it done now: 3:30 YouTube video
In a typical rolling-ball sculpture, the balls are raised by some mechanism and then they roll down various interesting routes. Rhymes With 'Biscuit" is a little different in that the balls roll around and round without going up or down (very much).
There's a P1 inside controlling five servos. Hope you like it!
Comments
Rhymes With "Biscuit" , and very Artistic!
Congratulations on a wonderful achievement.
Super impressive; gifted me a big smile to lift the start of the day !
Excellent! I couldn't quite correlate the servo noise with anything on the model until you zoomed in on the track switch, and then kept getting a little nervous hoping it wouldn't lose sequence but it never did. Really cool display!
Cheers,
Jesse
That's really cool! Still trying to decipher the name, though.
Doc
Hi, that is nice!
If You like, you could share a little bit, how it is done. For example I would like to know, how you detect the position of the balls. :-)
Christof
That has crossed my mind too but maybe it's not necessary... I'm still thinking about it.
Thanks for the nice comments!
Well, to let you in on a little secret, RWB has no idea where the balls are. It's completely open-loop. The up-and-down movements of the four track segments produce a kind of traveling wave. If you start a ball at the right time with the right speed, it will catch the wave and be propelled. It's even self-correcting (to a point): a ball that's a little behind the wave gets accelerated, a ball that's ahead gets slowed down.
In the 1- and 3-ball cases, there's never more than one ball on a track segment and the system can be very stable. When five balls are in play, however, each segment will have two balls at some times, which makes things trickier. I did some simulations and was pretty optimistic, but I was still amazed to actually see five balls working in real life!
There's a bunch of parameters to tune the thing, so there's a Parallax wireless card inside so I can tweak numbers via a web interface.
Happy to answer any more questions.
Great!
Do you really need the switch in the middle?
I expect the balls keep rolling in there directions.
Or is the track-width who is making mechanical noise
My first prototype did not have a switch (https://youtu.be/PTdX74ys4gQ), so I could have (and probably should have) avoided the complications of adding a switch, but where's the fun in that?
Lemniscate
(It's been a week and a half now and nobody else seems to have guessed yet, unless I missed something on a Live Forum.)
Yes, finally! Well done, @Electrodude!