I was just thinking of the possibilities if you could scale this thing up! This would be fun if you could scale it all the way up for a person. Then sell it to the Tomato juice company V8 for a witty commercial. :)

I am just wondering if it is possible to get the accuracy tight enough to stabilize the pencils so that the motion is not as erratic.

I imagine you would need finer control over the servos? Then again I am not exactly an engineer.

If you could manage to get this thing scaled DOWN and accurate/quiet enough with cheap enough parts this thing would make an amazing desk toy in the future.

Masta Squidge, the erratic behavior is because the function is oscillating. It needs a PID algorithm.

hmm.. inverted pendulum in 2 axes.

If the system is tuned well, the pen would appear standing straight up, almost without visible movement.

If it was driven with voice coils like the head in a HDD it would be quiet and quick enough to seem motionless, maybe the lens positioners from a couple old cdrom drives could be hacked?

Not two “ordinary” cameras… The “cameras” described in the linked web page are analog “retinas” that detect and report contrast changes of changed pixels only, at up to hundreds of “frames” per second, giving a small enough quantity of output data to be processed with only a small processing load. That is what allows detection speed fast enough to balance a pencil, which is too small for a human to balance.

I think the erratic movement makes for a neat display of how it works. I dont know if the prosesor is just to slow or if its just bad math or just done on purpose but its much more interesting to watch than something perfectly balanced.
Nice Work.

@robwentworth

i know loads of jugglers who can balance itens smaller than a pencil on their nose. teaspoons are quite popular. but i have seen a few people balancing cigarettes and once

there even one guy who balances a juggling club on the top of his head, where he can’t actualy see it!!

i read an article in Cascade (the european jugglers journal) a few years back that explained that the movements that a juggler makes are actually faster than the ammount of time it takes for the the brain to comunicate with the muscles. the cited a principle called “dynamic noise” that was apparently also used in the design of aircraft wings. apparently just adding a small random wiggle makes the whole system more stable.

2psuedonymous:
> A random, even if smaller, unpredictable noise is much harder to compensate for.
I think we can use it as RNG in cryptography :-)

i also guess that it’s possible to make it more stable using proper algorithms. but if it was 100% stable it would look like any other pencil holder, so the motion is cool – almost like lava lamp :-)

a 10 cent pencil will cost 15$ a month to run :P