Hello all,

I just finished up the instructions let me know what you guy think!

click this link if you don't like the formatting :)

http://planner.ardupilot.com/wiki/common-electro-permanent-magnet-gripper-v2-x/

 (EPM) Electro Permanent Magnet Gripper V2.X

The EPM688-V2.X is an Electro Permanent Magnet, combining the advantages of electro and permanent magnets.
This Device comes with integrated electronics that can be operated with 5V PWM signal common on RC electronics.
The device is designed to hold 1kg of cargo. It is the user’s responsibility to verify that this can be achieved in each
particular case.

Improvements:

Supported are RC PWM and CanBus with the CanAerospace daughter card. The EPM has an onboard PIC12F MCU with an in circuit programming header to allow easy reflashing.

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

Links / resources:

Datasheet

Purchase

Git repository for Parts Drawing PCB Masks Pic12F source code

PDF Drawing

Shematics and PCB files

User Group (Help)

What is an electro permanent magnet?

• The Electro Permanent Magnet gripper safely holds on to a cargo payload using permanent magnets without consuming power.
  • The EPM releases that load when desired by delivering a short pulse to an electro-magnet accomplishing short term field reversal.
  • The safe cargo payload for a multicopter EPM is normally up to about 1kg with the magnets actually providing 7kg holding power.
  • An appropriate iron or steel plate needs to be incorporated into the top of the cargo payload.
• The EPM Cargo gripper EPM-688-5 V2.X  from http://NicaDrone.com is now supported by APM:Copter release.
• Check out this paper by Ara Nerses Knaian -: http://opengrab.googlecode.com/files/Electropermanent_Magnets_Knaia…
  • Or watch the completed kickstarter project videos  that go over the working principle.
  • http://www.kickstarter.com/projects/412473553/opengrab-open-hardwar…

How to setup Manual RC control:

Seems to be broken on APM:Copter as of Feb 27 2014

Set RCXX_FUNCTION (i.e. RC6_FUNCTION) parameter

Now setup your RC control to produce 3 PWM singals on the selected APM RC input;

1150ms for off,

1500ms for do nothing

1925ms for on

How to setup manual control RC receiver

Connect the EPM directly to the RC receiver and setup a 3 position switch or anything that produces 3 different PWM signals on the RC transmitter and your done!

1150ms for off,

1500ms for do nothing

1925ms for on

How To Setup A Mission:

The traditional way to control a PWM output only works as part of a mission (i.e. AUTO mode).  Follow these instructions:

• Connect your APM to the mission planner
• On the Config/Tuning > Full Parameter List page, ensure that the RCXX_FUNCTION is set to zero for the servo (i.e. RC10_FUNCTION if the servo is connected to A10 on the left side of the APM).
• Press the Write Params button

• Create the mission you wish to fly and add a DO_SET_SERVO command and include the servo number (i.e. “10″) in the “Ser No” field and the PWM value, keep in mind if you constantly give the on command it will constantly turn on.1150ms for off,1500ms for do nothing1925ms for on

Note that the DO_SET_SERVO command is a “do command” meaning that it can only be run between waypoints so it must not be the first or last command in the mission.  It will be executed immediately after the waypoint that precedes it.

On the Mission Planner’s Flight Data screen, there is a Servo tab that will allow servos to be moved in future versions of APM:Copter, Plane and Rover but it is currently not functioning.

Electrical Setup General:

• Magnetic interference has been reduced and mounting it with a minimum distance of 10cm of the magnetometer works fine. Mounting it closer is only recommended after testing magfield: Mission Planner->tuning->magfield->turn EPM on and off: Deviations over 30% interference (if it’s sustained) will make vehicles start circling but 10% should be fine.

• Current draw is 600mA with sharp rise, do not connect it to the analog output rail of the APM2, connect directly to the main 5V power rail and make sure the BEC can keep VCC stable to avoid brownouts. There is a 400mV drop in VCC when using the 20A 3DRobotics ECS on-board BEC
• When using a separate BEC or power source connect the ground to the PWM source ground.

Electrical Setup RC Receiver:

Cable Color codes:

• Yellow: PWM
• Black: Ground/Gnd/Negative
• Red:   VCC/Positive

Electrical Setup APM aux channel (Mission Control / RC Pass-thru)

Servo outputs from RC5-RC8 can be used if they are available or AN10 or AN11.  Note If that the power supply of the EPM is connect to the main servo rail and not to the AN power rail. Again make sure that the BEC can supply adequate power to avoid brownouts.

Operation:

The on board LED will blink once ever few second if no PWM signal is detected

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.

Introduction EPM V2

Operating principle explained in this video

Improvements:

Supported are RC PWM and CanBus with the CanAerospace daughter card. The EPM has an onboard PIC12F MCU with an in circuit programming header to allow easy reflashing.

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

Links:

Data sheet

Schematic

Source Code / Parts Drawings

User Group / Help

Purchase

Introduction of the CAN daughterboard 

OGCAN is an open hardware CAN bus interface that allows to control OpenGrab EPM and monitor its state via CAN bus or serial CLI. Supported CAN protocols: CANaerospace, UAVCAN (full UAVCAN support comes April 2014).

OGCAN is built on STMicroelectronics STM32F103 MCU running RTOS ChibiOS, implements one CAN bus interface (ISO 11898-2, up to 1 Mbps), one TTL UART for CLI and optional CAN termination resistor (via jumper). OGCAN can be directly connected to EPM via two board-to-board connectors, as shown below.

Supported CAN protocols: CANaerospace, UAVCAN"

Links:

Datahseet

Schematic

Source Code

UserGroup

CANaerospace

UAVCAN

Purchase

Hello,

So last time I went over how we mask PCB's now I am going to show how we etch the boards in 3 minutes flat. Traces down down to 8mil, 1 out of 50 boards might fail.

Here we have part two, let me know what you think!

http://nicadrone.com/index.php?id_cms=19&controller=cms

Hello;

I been getting a lot of emails about how we make our PCBs so finally had some time to post something:

Making PCB for production runs

We are in a 3rd world country so we can't get PCBs/asm'ed in anything under 8-10 weeks so we devolved small scale production process.

The EPM Cargo gripper EPM-688-5 V1.21  from http://NicaDrone.com is now supported by APM:Copter master branch.

Master branch != widely tested! Wait for the 3.2 release if you´re not comfortable with that.

This setup has only been tested by the author.  

All this is open source, check out the resource section at the bottom

What is an electro permanent magnet?

Check out this paper by Ara Nerses Knaian -: http://opengrab.googlecode.com/files/Electropermanent_Magnets_Knaian.pdf

Or watch the completed kickstarter project videos  that go over the working principle

http://www.kickstarter.com/projects/412473553/opengrab-open-hardware-electro-permanent-cargo-gri/widget/video.html

Very cool eh? I thought so...

How to setup:

Get the code: http://dev.ardupilot.com/wiki/where-to-get-the-code/

Open APM_Config.h and un comment line number       35 so your left with

#define EPM_ENABLED           ENABLED             // enable epm cargo gripper costs 500bytes of flash

Build the code: http://dev.ardupilot.com/wiki/building-the-code/

Upload the code: http://dev.ardupilot.com/wiki/load-the-code-ontoapm2x/

Complicated ehh?? If we can justify using an extra 500bytes of flash we could include the code in 3.2 RC1 which is due to come out in a couple of weeks

Connect with Mission Planner

Go to Config/Tuning->Full Parameter List->Find: EPM

Set either Channel 7 or 8 to '19' "EPM", This will allow you to control the EPM with that channel from your RC or Joystick

Set EPM_Enabled to '1', This will enable the EPM

Restart the APM Mission Planner: ->Actions->Preflight Reboot->Do Action

Hardware setup:

Mount the EPM with a minimum distance of 10cm from the magnetometer, make sure to check out the section "Magnetic Interference".

Prepare the cable assembly

Cable Color codes:

Yellow: Signal S_on/S_off

Black: Ground/Gnd/Negative

Red:   VCC/Postivie

The EPM has two redundant Positive and Negative Pins, only one set needs to be connected

The Two Signal have to be connected to A7 And A8 on the APM2.X see APM2_analog_pinout as reference

The Analog output rail has power supply pins next  to the signal pins but it is not recomended to use these pins because the current draw of the EPM during it's 3 second charge cycle exceeds the capacity of what the APM can supply on these pins. You are probably going to blow the onboard fuse or cause random brown outs, creating a flying Schrödinger's Cat.

Mount the EPM:

Connect the cables:

and we are ready to play- hahahaha

Operation:

The EPM688-5 is designed to hold a cargo of 1kg securely and switch on and off effectively with low power consumption. 800mA at 5V for 3S or 3.4J per cycle.

Under the capacitor discharge condition pull either S_on or S_off high  Via RC channel 7 or 8 for 3 seconds and then low. The capacitor is fully charged and the device is ready to cycle. Pulling either S_on or S_off high via Via RC channal 7 or 8, causes the magnetic field to move either in the on or off state.

WEIGHT AND CAPACITY

The complete device will have a mass of about 50 grams, and is capable of holding a mass of 7kg in optimal conditions, in practice it should securely hold 1kg of cargo on a quad.

Magnetic interference:

So the APM uses a compass that is sensitive to the surounding magnetic field. The EPM can produce a sizable field that can interfere with the compass when it is in its on state, without a target metal attached ,if mounted closer then 10cm. Please be carefull since this has not been widely tested.

Resources:

Order The EPM: http://Nicadrone.com

EPM Cargo Gripper Datasheet: http://code.google.com/p/opengrab/wiki/Datasheet

Drawings of parts and models V1.X and 2.X: https://github.com/ctech4285/EPM

Schematics and gerbers: https://upverter.com/eda/#tool=schematic,designId=aee8e8e33e656dad

Ara Nerses Knaian paper: http://opengrab.googlecode.com/files/Electropermanent_Magnets_Knaian.pdf

Original Kickstarter Project: http://www.kickstarter.com/projects/412473553/opengrab-open-hardware-electro-permanent-cargo-gri

Hello,

There has been a lot of support from this community for this project, a lot more than I expected initially. The kickstarter funding periods is set to end in three days. It has been a very interesting ride so far and this is what we already have taken care of:

Importing of Chemicals for PCB fabrication, everything from Iron(|||) chloride to Silkscreen and conformal coding to Electro Nickel Plating stuff has been arrange, and let me tell you it was not easy, you can't just drop of a gallon of Iron(|||) chloride at UPS and ship it to Nicaragua....

The order for the parts that have to be laser cut has been place with a company in China and we expect them to arrive in 20 days

Most equipment has already been ordered and the first batch is due to depart by end of next week. 

Mounting brackets for the R10  from UAir will be 3D printed by shapeways and UAir should have samples very soon. UAir is very helpful and flexible on this, check them out at http://uair.co/r10 . We are on track to make it plug and play for the R10 platform. 

Brackets for easy mounting on Arducopter and most standard frames are also in the works, and there should be no problem integrating it with the APM.

Thank you for the great support and feedback!

Andreas Jochum

Small light Open Source/HW electro-permanent 10kg (ideal) cargo holding magnet for the DIY multicopter drone and robotics communities

I stumbled upon this idea by reading this great article by Travis Deyle about electro-permanent magnets. These magnets are programmed (on off) with a current pulse. No static energy is required. Changing the magnetic field does require energy and is in the hundreds of mJ for our purposes. These electro-permanent magnets are just as strong as Neodymium magnets.

pdf link to the PHD thesis covering this is on the project page

there been a lot of concern of magnetic interfence with the compass, so here is the spiel

there should be no external field since the field lines are closed through the cargo iron in the on state or through the iron in the device itself.
in the prototype the iron goes beyond its saturation, the thickness should 1mm not 0.5mm same goes for the target. looking at the theoretical performance and the prototypes performance about half the field leaks, eg are not going through the metal. i expect the leakage to go down to below 10%.
a laser cut iron cover covering the magnet itself with some distance in the 5mm range,  less 0.1mm thick will absorb the rest of the leakage. we should have a factor of 100 maybe 1000 that we can reduce the external field before one has to invent crazy things. mu metal might give us a few orders of magnitude more, but since its low saturation and some other factors i need to the math to get a quantitative idea on its performance.

long story short simple easy to implement shielding with proper construction should allow one to mount the compass right on top of the magnet

I hope you like my project and am looking forward to some feedback

http://www.kickstarter.com/projects/412473553/opengrab-open-hardware-electro-permanent-cargo-gri

Motor 12mm Tube mount in stainless steel!

What do you guys think?

what parts would you like me to add?