Electro Permanent Magnet Cargo Gripper got a lot better!


Hello all,

we made some good progress and pushed out version 2.5, (actually it has been shipping for a few weeks)

The main change is that we only use Alnico magnets now and instead of magnetizing those fully in either direction go from full magnetization to completely demagnetize.

The advantage is a reduced air gab and shorter magnetic path length resulting in improved holding force.

It was a little tricky to find the ‘0’ point, or just how much of an external magnetic field needs to be applied to demagnetized the magnets but not more. Eventually we found a solution, magnetize them in alternative directions repeatedly while decreasing the amplitude of the field. This all happens in less than 1 second.


Git repository for Parts Drawing PCB Masks Pic12F source code


Schematics and PCB files 


Views: 3030

Comment by Randy on April 8, 2015 at 10:20pm

I love the EPM.  So now it's still small but waay stronger than the previous version, nice!

Comment by eUGENE on April 9, 2015 at 12:19am

I love the EPM too. But unfortunately Nicaragua so far away from me for shipping :)

Comment by Euan Ramsay on April 9, 2015 at 12:20am

This is it in action; unfortunately wasn't able to fully fly it in full auto mode, but it's definitely stronger. And it still works on auto missions. This payload has flown, and basic flights can be performed.

The laws of physics still apply unfortunately, particularly the ones to do with momentum, force, inertia and gravity, so the full 8kg can't be exploited in the air with one magnet. Carefully payload packaging and smooth flight characteristics are essential to get good performance. If you have any slop between the plate and the payload, it will exert lateral pull forces on the plate, causing separation. This payload is 4.5kg.

I'll be adapting my existing loader frame to accommodate the new units, so the full 8-10kg can be carried and deployed safely, and to allow a more aggressive flight envelope.

Comment by Joshua on April 9, 2015 at 12:59am

Is there any limitation as to how closely you could place adjacent grippers (if you had a desire to carry a larger payload)?

Comment by Euan Ramsay on April 9, 2015 at 1:40am

None that I've seen. But I've yet to test with 4 x version 2.5. Version 2.0 was no problem. Even the magfield intrusions weren't that bad.

Comment by Euan Ramsay on April 9, 2015 at 1:49am

I would recommend as much separation as possible for other reasons - the wider the platform, the less chance there is that a lateral acceleration will dislodge the payload.

Comment by Romain Grave on April 9, 2015 at 2:28am

This is indeed a great improvement!

Comment by Leo Hogg on April 9, 2015 at 3:22am

Fantastic! What is the best way to buy this in Europe?

Comment by Drone-University.com on April 9, 2015 at 5:47am

Out of curiosity, have you tried to graph mag_field when you are actioning your system ? Thx

Comment by Andreas Jochum on April 9, 2015 at 8:28am

@Hogg, by it from NicaDrone.com


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