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The Little Motor that Should Have

A project log for Drone Swarm

Drones of varying complexity swarm an area, forming a distributed sensor and actuator network.

les-hallLes Hall 03/30/2015 at 18:166 Comments

The thing pictured above was an attempt at a "motor" that I created on my printer. It has three pairs of magnets gripping three fan blades in a rotor and a coil wound around a stator. The motor doesn't run, of course, because I didn't pay homage to the right hand rule before building it, and I shamelessly (or perhaps shamefully lol) post it here for your enjoyment as an example of yet another idea that didn't quite make it in prime time. That's OK though, because if you look closely you'll see that I figured out some cool stuff, like how to wind a coil on a form (and how to make that form in the first place), how to get magnets to stay put by having them grip each other in pairs, and how to make moving parts fit together in a single print.

So there was experience gained and lessons learned on this effort also (and iI did do it from thought to failed test in one day) as in my previous work. Don't worry, I'll stop shooting arrows all over the place and hit the dang target if not the bull's eye pretty soon, just you wait and see.

I thought for some reason i'd make a boat propeller for my water craft drones. I have a bit of a notion to combine the moving part with the engine when possible, so that led to the magnetized propeller concept. It would be cool if you could have just a magnet or iron core thingie in the water and all the coils and electrical what-not on the dry boat hull (suppoedly dry!).

The easy way to fix this debacle is to turn it into a stepper motor, which I have built before like this. I can just arrange some coils radially and set those magnets in radially also and with the right control setup using an ATtiny95 mocrocontroller chip and an L293D motor driver chip just zap those coils in the right way and the thing will move, I've done it before. It just requires a core to make it work properly so the ciols would need a magnetic core each and that should do it.

I think I'll redesign this motor that way. More to follow...

Les

Discussions

frankstripod wrote 03/31/2015 at 05:02 point

I like this! It reminds me of something I would do, but to chicken to try or admit to. Made my day, thank you :)

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Les Hall wrote 03/31/2015 at 05:15 point

Haha yeah, if we can't laugh at ourselves then who can we laugh at?  Or something like that...

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Eric Hertz wrote 03/31/2015 at 04:23 point

If I understand correctly, you're trying to make a sort of "floating-core" motor, where there's actually no need for a shaft, bearings, etc...?

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Les Hall wrote 03/31/2015 at 05:18 point

Yes, the "fins" in this design are just placeholders for a proper three-bladed propeller inside of a circle that is entrapped by a mount with coils in it.  The coils are potted and dry in the boat (or hopefully dry) while the stator spins in contact with the water and has magnets, core pieces, and 3d print plastic.  That's the notion anyway.  

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Eric Hertz wrote 03/31/2015 at 06:50 point

I dig it... I don't think I've ever seen a motor like that. Hope it works! One thought, it might be hard to keep it centered without some sort of feedback system... but I imagine the reduction in friction of such a device might be significantly more efficient, even with a feedback system.

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Les Hall wrote 03/31/2015 at 07:27 point

could be, i dunno.  I'm thinking a stepper motor configuration would work mostly because that's what i know how to make and drive with digital signals from a processor.  Stuff like squirrel cage motors and what not are out of my league.  

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