Blogs

EMC Shielding for ArduCopter3.0

Posted by Jiro Hattori on June 25, 2013 at 5:40am

The EMC shielding material reduce magnetic interference that is good to ArduCpoter3.0.

Measurement of magnetic interference becomes half by 60micron meter low-loss,high permeability nano-crystalline material.

3689532263?profile=original

Without magnetic shield

3689532249?profile=original

Magnetic shield applied

3689532347?profile=originalMagnetic shield material is Hitachi FINMET low-loss,high permeability nano-crystalline material.

http://www.hitachi-metals.co.jp/e/prod/prod02/p02_03.html

Similar material from 3M™ High Permeability Magnetic Shielding Sheet 1380 will also work.

E-mail me when people leave their comments –
Follow

You need to be a member of diydrones to add comments!

Join diydrones

Comments

  • Tom Mahood June 25, 2013 at 8:30pm

    Mu metal works best when it forms a cylinder around what it is you want to shield (or the converse). It needs to be cylindrical to provide a return for the magnetic flux. It will work somewhat as a flat sheet but it's much less effective. But maybe still good enough to shield an APM.

    Placing some Mu Metal under my APM reduced my magfield value from about 300 to 221. That should be still adequate for the compass to work. In any case my compass WAS still working. At the same time it dropped my compassmot from around 70 to around 30.

    The best way to use Mu Metal is not what I did, shielding the APM. Instead make a cylindrical conduit to pass your power wiring through. Sort of like a shielded electrical cable, but the Mu metal contains magnetic fields rather than RF. Mu metal also doesn't like sharp corners as the magnetic flux doesn't like sharp corners either and will leak out. So a cylinder is the ticket.

  • BluSky1 June 25, 2013 at 7:29pm

    I typically use 3M EMI shielding tape,

  • Gary McCray June 25, 2013 at 7:18pm

    If this works like MU Metal as in TC3's posting it can definitely seriously reduce the Magnetometers sensitivity as well.

    Putting a magnetometer in a Mumetal box pretty much guarantees the magnetometer will not see the Earths magnetic field at all.

    I think you would definitely need to use it only around the DC field emitting parts nad far enough away from the magnetometer so that the damping effect would not be noticeable.

    All things being equal, this might decrease the sensitivity of the magnetometer to the Earths field at about the same rate that it decreased it's sensitivity to the surrounding undesirable magnetic fields, net gain = 0.

    All I'm saying is that this solution can have some downsides and you need to understand that going in.

  • Developer
    Bill Bonney June 25, 2013 at 3:58pm
    @monroe: i have the same concern. This will shield not only the power electronics but the earths mag field from the APM. It makes me think if the earths mag is strongest through the Z axis that we need the mag sensor underneath the MAV and shielded, not above the PDB with the GPS?
  • Developer
    Bill Bonney June 25, 2013 at 3:53pm
    @scott: magnetic field creation is a function of the rate of change in current. The size of cable is irrelevant. The wires thickness only relates to ability to carry current, a thicker wire can support a faaster rate of change in current and a higher mag field. Selecting thinner cable just means a higher chance of cable failure.
  • titeuf007 June 25, 2013 at 1:50pm

    where we can buy it

  • Scott Reid June 25, 2013 at 1:49pm

    Thanks John..  Is it also accurate that undersized DC power cables will generate stronger fields than properly (or over-) sized cables?

  • Developer
    John Arne Birkeland June 25, 2013 at 1:40pm

    Magnetic interference are low frequency (DC) fields. The main source of such noise in a copter then obviously is the DC power cables drawing high currents and the battery. Twisting the DC power cables should help.

    ESC and motor phase wires generate high frequency AC fields, and are to my knowledge not problematic (within reason) for sensors. This is also why a normal conductive material like copper tape will not help. A conductive shield (Faraday cage) will only block AC fields and not a static DC field.

  • Francis Ignacio June 25, 2013 at 1:34pm

    @Scott, All of the above.

  • Scott Reid June 25, 2013 at 1:20pm

    Does anyone know what components actually are responsible for creating most of the magnetic interference?  Is it the DC power cables, ESCs, motor cables, or the motors themselves?    Wondering if it's worth trying to twist DC cabling where possible.

This reply was deleted.