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Topic: Magnetic Levitation (Read 10890 times) previous topic - next topic

simon.monk

Arduino-based magnetic levitation from my book 15 Dangerously Mad Projects for the Evil Genius (http://www.dangerouslymad.com)

http://www.youtube.com/watch?v=WiUng4zF9_M
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I write books about Arduino and Electronics: http://simonmonk.org

liuzengqiang

Nice but how is arduino incorporated it this?
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter

CrossRoads

Is partially explained here
http://www.dangerouslymad.com/projects/chapter-13-levitation-machine
and in browsing the code. No circuit diagram.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

simon.monk

Quote
Nice but how is arduino incorporated it this?


The Arduino controls the power to the electromagnet, position is detected with an IR LED / phototransistor pair.

You can't do simple on / off power control when it crosses the beam, you have to take the velocity of the object being levitated into account, or it rapidly becomes unstable and falls off.

The sketch can be downloaded from the page for that project on the website (http://www.dangerouslymad.com)
--
I write books about Arduino and Electronics: http://simonmonk.org

mowcius

Have you tried this with a linear hall effect sensor?
That seems to be the way to go as you don't need anything around the sides of the device.

simon.monk

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Have you tried this with a linear hall effect sensor?


No, I did read up on that as an option but was more confident of getting the optical version working. It probably isn't any harder, but I had to start somewhere!

I have plans for a version 2 which could use the hall effect sensor, but would have a much bigger electromagnet! I'd like to be able to suspend a set of 'planet balls' I have of various sizes - Jupiter's about 5 inches in dimeter and would look pretty cool.
--
I write books about Arduino and Electronics: http://simonmonk.org

liuzengqiang


Quote
Have you tried this with a linear hall effect sensor?


No, I did read up on that as an option but was more confident of getting the optical version working. It probably isn't any harder, but I had to start somewhere!

I have plans for a version 2 which could use the hall effect sensor, but would have a much bigger electromagnet! I'd like to be able to suspend a set of 'planet balls' I have of various sizes - Jupiter's about 5 inches in dimeter and would look pretty cool.


Nice. You can set them spinning freely too.
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter

simon.monk

I have no idea how to accomplish it, but it would be great if some kind of motor effect could be induced to impart a small spin force to the spheres, without having to set them spinning by hand.

They do spin for quite a while, when set going, but eventually slow down.

Ideas anyone?

It would certainly make a great installation on the ceiling. The ceiling lamp could be disguised as the sun!
--
I write books about Arduino and Electronics: http://simonmonk.org

mowcius

Hmm, apart from having a ball which isn't perfectly smooth and blowing air lightly across one side (due to limited resistance it shouldn't take much to set it going), no. Or even a ball which looks smooth, try blowing air over one side (maybe ducted from a fan so you don't turn purple) and see if it gets it moving.


simon.monk

Quote
blowing air lightly across one side


That's possible.

I was hoping for an electrical solution.

What would be most impressive (but quite likely impossible) would be 2 axis control of the levitated item. so you could control spin and tilt it remotely.

Maybe one of those tiny toothbrush motors with an eccentric weight powered inductively from the suspension coil?

Or fine control of the coil to drop the item faster than it raises it and have tiny fins. A bit like if you lie on your back in a swimming pool and propel yourself by doing fast stoke one way, then very slow stroke the other.
--
I write books about Arduino and Electronics: http://simonmonk.org

mowcius

Quote
Maybe one of those tiny toothbrush motors with an eccentric weight powered inductively from the suspension coil?

It would mess up the balance of the ball though and inductive power for a multiple-axis-spinning object would be very tricky.

I kinda wish I had an electromagnet here to try this now (and yes I know I could make one - possibly)

liuzengqiang

I thought it will just spin freely if you touch it with a gentle pluck. You can't control this degree of freedom with the coil since the coil is symmetric (cross fingers) all way around  except for up and down.
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter

mowcius

Well it will spin freely but as said, will slow down due to the surface not being 'perfectly smooth' and air currents will also affect it.

liuzengqiang

If you attach a mirror shard on the ball and use a photo gate, you may be able to find its rotational speed thus characterize the slowing down since I expect the ball will make tens of turns before stopping. I am thinking the resistive factor goes with square of the rotational speed, as a result of quadratic air drag, like when the ball is tossed in the air. Would be nice to check that assumption. I am totally making it up with marginal facts.  :smiley-roll-sweat:
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter

mowcius

Well as there will then be a greater mass in one place due to the mirror shard, won't that end just want to face downwards all the time so then it won't spin as freely?

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