APM 2.6 external compass making a difference


Last month, we had the opportunity to setup an APM 2.6 for a candidate, i.e. this baby will be shipped away after field test. We received one of those revised board that has no onboard compass, where the compass can be placed away from power and motor sources as far as possible to avoid magnetic interference. On this build, we decided to keep it simple, mount the compass/gps on the side bay, as shown on the picture, and the “compassmot” result was at an acceptable range 24% on the first run, so we just left it since then.  We average about 10 or more satellites, so we are getting good signal here.


We are pleased with how this external compass can significantly reduce magnetic interference; the loiter is good. We accepted the default PID values, with one exception, we adjusted the Loiter PID P to 0.5 (from 1.0) to reduce aggressiveness as recommended for this release.  The build time was reduced by half.


Thanks 3DR!




APM 2.6. Filmed with APM gimbal Keychain Camera #16 Lens D and with the default PID, out of the box DJI motor and propellers.

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3D Robotics
Comment by Chris Anderson on November 29, 2013 at 4:25pm

Glad to hear it! We're going to be releasing a mast for that GPS/compass next month, so that will make your future builds easier. 

Comment by Alex on November 29, 2013 at 5:39pm

As I can see APM very soon will be looks like Naza

Comment by Rick on November 29, 2013 at 8:03pm

It would be best to have the GPS higher than the APM.  Don't want to degrade the already weak GPS signals by having the GPS in the shadow of the rest of the 'copter.

Comment by noeL on November 29, 2013 at 8:48pm
Thanks Chris, more builds to come, that one went to the city manager.
Comment by cirilo on November 30, 2013 at 6:32am

Went from 54% to 10% with external mag too. 

Comment by Balloon on November 30, 2013 at 8:23am

I have setup same DJI and I can Compassmotor from 24% to 1-2% only. 

Comment by Oliver on November 30, 2013 at 4:10pm

I have my compass on a mast, about three and a half inches above the board (and slightly below the GPS so as not to obstruct that). My concern in having it closer to the board is the possibility of the mag field there changing during or between flights. My presumption is that you want not only a low figure, but also a consistent one. Is that being overly cautious?

Comment by Andrew Chapman on December 1, 2013 at 1:13am

I just noticed Foxtech have some neat looking folding GPS masts:


Comment by Cory Hill on December 2, 2013 at 12:03pm

Looking forward to getting a proper mast for my 3DR uBlox as well.  In a pinch, you can pick up some balsa wood square dowel from a hobby shop and make a nice light one for testing.  Obviously not a good permanent setup, but great for testing and easy flights.

Comment by Bill Isenberger on February 15, 2014 at 7:22am

Chris, any news on the mast for the GPS/compass? Haven't seen it show up in the store yet.


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