The guys over at opendroid have announced that they have released a new version of their of the EPM, Electro Permanent Magnet. It looks like a neat solution for UAV cargo gripping. Best of all its a totaly open source project.
The video below explains the operating principle but you can build your own one buy visiting the opengrab wiki here - https://code.google.com/p/opengrab/wiki/Assembly
Some of the improvements over the previous Electro Permanent Magnet include:
- Supported are RC PWM and Can Bus with the Can Aerospace daughter card. The EPM has an onboard PIC12F MCU with an in circuit programming header to allow easy re-flashing.
- Even lower power consumption; 400mA for 400ms at 5V per cycle or 800mJ.
- On board tactile push button: Allows toggle testing the EPM on/off having only the power connected
- Cycle time: The Cycle time is 400ms or 2.5Htz. This solves the problem when the EPM is turned on and the target does not make perfect contact, the majority of the energy is used to move the target into place rather than realign the magnetic domains, resulting in a much reduced holding force. With the fast cycle time one can turn the EPM on a few times in a row to make sure proper contact has been made.
- Full bridge Thyrisotor drive circuit increases efficiency and reduces capacitor size .
- Reduced magnetic interference allows mounting within 5cm of a magnetometer (please test it with your application)
- Lighter- mass has been reduced to 47grams.
You can find the schematics here - https://upverter.com/eda/#designId=5466622af0d942e4
and the code here - https://github.com/ctech4285/EPM_688_V2
And you can buy one here - http://nicadrone.com/index.php?id_product=13&controller=product