Electromagnet

http://diydrones.com/profiles/blogs/electro-permanent-magnets-for-quadcopters

Imagine a quadcopter hovering above a payload – a can of beans, perhaps. The ‘copter descends onto the payload, activates an electromagnet, and flies away with a hobo’s dinner. Right now, this is a bit of an impossibility. A normal electromagnet that powerful would consume an amazing amount of power, something quads don’t usually have in abundance. With the OpenGrab project, the dream of a remote-controlled skycrane is within reach, thanks to some very clever applications of magnetics. The tech behind the OpenGrab is an electro-permanent magnet, basically an electromagnet you can turn on and off, but doesn’t require any power to stay on. OpenGrab was heavily influenced by a PhD thesis aimed at using these devices for self-assembling buildings. This project had a very successful Kickstarter campaign and has seen some great progress in the project. While beer doesn’t come in steel cans anymore, we can imagine a whole lot of really cool applications for this tech from infuriating electronic puzzles to some very cool remote sensing applications. Filed under: hardware

http://diydrones.com/profiles/blogs/anouncting-epm-v2-electro-permanent-magnet-and-ogcan-can-bus  We are announcing Version 2 of the EPM, Electro Permanent Magnet and the OpenGrab CAN daughterboard (OGCAN). A simple solution for cargo gripping for UAV’s and robots.

http://nicadrone.com/

Zubax
https://docs.zubax.com/opengrab_epm_v3 he NXP LPC11C24 MCU drives a mosfet connected to a transformer in a flyback configuration to charge the main PET capacitors up to 475 V.

A thyristor bridge is used to discharge the capacitor in either direction through the winding inside the AlNiCo material. This results in a short, 20 us 300 A pulse creating a 100 kAm field in the AlNiCo material. This causes the magnetic domains in the AlNiCo magnets to align in a particular orientation to form a magnetic circuit with a ferrous target. More detailed explanation of the operating principle is available on Wikipedia.