Discussions

Compass offsets always above 400+

Posted by Lester on November 28, 2013 at 6:15pm

I need some advice please.

I've got the APM 2.6 with an external compass and the offsets are always >400 on all axis (X,Y,Z) no matter where I place it on the frame, away from metals and close to metals. I've done the live calibration at least 20 times now in every position I've tried the offset readings are all extremely high. I get even higher readings when it is closer to the metal parts of the quad.

Is my compass faulty? I may have left a magnetized screwdriver head close to the compass when I was initially assembling it. Is this permanently throwing the compass readings off? Is there a fix for this?

Thanks,

Lester

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26, apm, compass, external, high, offsets

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Replies

Moderator

Graham Dyer December 28, 2014 at 10:28pm

This thread is 10 months old, the OP hasn't been active since March, I think we can let it go.
Stuart Brookes December 27, 2014 at 1:09am

Have you tried in a different location? Maybe you have some local magnetic anomaly? Are you doing indoors ina building with iron girders or reinforced concrete? I don't know if these could make the offsets that high, but I have seen it affect the quality of calibration.
- Paul Vang > Stuart Brookes December 28, 2014 at 2:52pm
  
  so i found the issue. yes i am inside and i have a metal object to hold my GPS so its getting in the way of a good gps lock.
  - Greg > Paul Vang December 28, 2014 at 9:32pm
    
    Paul,
    
    What are you replying about? The OP was asking about a compass.
Paul Vang December 26, 2014 at 3:40pm

could it be the internal compass. did you disable the internal compass? or calibrate the internal compass?
Tommy Larsen February 23, 2014 at 12:53am

I have the same problem. The strange thing is that even when i verify that i use external compass, the only way to make the "quad" on the map in MP is to rotate the APM. When i only rotate the GPS/Compass, it doesn't move in MP map.
Ted Weerts February 23, 2014 at 12:20am

you could try putting a grounded plane underneath your compass. or over/on top of your power distribution. Either way, shield the compass from the noise.

any metal should work: copper, alu, steel. the trick is to wire it to your ground. This type of shielding is good for high frequency, fast fields like the power distribution but ineffective against low frequency, or slowly changing fields.

http://en.wikipedia.org/wiki/Electromagnetic_shielding

also: are you doing your calibration inside? like at your computer? i found that inside at my desk produced extremely out of range offsets, but simply going outside with a laptop brought them back down to normal values.
hal February 21, 2014 at 7:07pm

Screws can magnetize. You may have accidentally magnatized one of them during assembly near the gps/compass module.
- John Fressinet > hal February 22, 2014 at 4:16am
  
  I have the same issue with my brand new Pixhawk.
  
  What can we do ?
  - Andres > John Fressinet February 22, 2014 at 10:10pm
    
    what i did is to write 10% of the gains and i'm getting to arm, though it is not flying smooth as it should, in fact it toilet bowls heaps. I did that just to verified that there wasn't anything else wrong with the pixhawk, so now in trying to get a GPS module with built in compass and see if that solves the problem...