Can't get the compass to work on APM 2

I have just received my new APM 2 and I was all excited about it. I had my plane ready to mount it.

Before mounting the APM I thought let me do the Compass declination and calibration before I fit it.

I can't get the compass to reliably work.

I connect via USB and set the compass to enable, then I do the turning of all axes after I set my home declination. The strange thing is that I get new values every time I do this and all of them are of by a bit...some more some less when looking at the HUD.

Once I disconnect from the Planner and then reconnect the compass is set to "DISABLE" and will show North.

What am I doing wrong?

I am using Mission Planner 1.1.96 and Arduplane 2.40. The APM has not yet been powered by anything but the USB cable.

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  • Hi Guys,

    I have this problem with the compass not working on my new APM 2. Now I have tried something else.

    I loaded Arducopter 2.6 and I am amazed that the compass is working perfectly. I have calibrated it and it took my location and heading first time every time.

    What's up with the Arduplane verson 2.4?

    How can I revert back to version 2.34?

  • From The NamPilot..

    Hello Andreas,

    Joe here from Swakopmund.

    Its nice to have the compass, but you do not need it at all. Our UAV flies well within GPS track error, and to verufy our autopilot we have flown a Septentrio Tri-antenna GPS , the PolaRX2, which give centemetric position accuracy and sub degree pitch and roll accuracies - we are within 1meter of track on straight legs with wind less than 4m/s. Compass is usefull for auto-launch while ground speeds are less than the GPS speed detect point - about 4 or so m/s, but NOT needed. The only 'usefull' application for compass is a sort of robust nav mode, where GPS is lost and you try fly ( for a short while) on dead reckoning, ie intepolated position and compass heading. But a compass giving 2 or 3 degree accuracy, with a plane 5km away will result in missing the destination anyway. So, do not stress about the compass. The magnetometer is on of the most difficult sensors to calibrate and temperature compensate.

    On another issue however, 

    I have been following your discussion since you lost your plane, and am rather concerned about the way you are going about flying, the safety aspects, etc. Your discussion were read by Mr Kangootuie at DCA and he forwarded such to me for my comment. 

    You may remember your visit to my place in Swakop and so are aware of what we are doing here in trying to establish a UAV process within Namibia. We are in close discussion with the Civil Aviation Authorities (DCA) to try and establish some means whereby we can have their blessing in flying UAV's. This is needed since we need to be able to obtain insurance, and to be covered in the event of an incident. UAV operation is not covered by the RC rules here, nor any other rules, so I believe it is up to the UAV operator to be extra vigilant of where and what he is doing. Flying an untested and unproven system beyond visual range, in fog, with no understanding of the effects of moisture ( and as you were at the coast you say) salt fog, the worst, is really looking for trouble. The electronics is not conformally coated or protected in any way from these effects. Telemetry range is hugely reduced in fog.  

    All we need is on bad incident and the easiest way for DCA to regulate the use of UAV's in Namibia is to outlaw them. This is a very small economy, with no country benefit of income from UAV's, so it will be no loss to them at all.

    But the people who are trying hard to establish a method and system here will suffer greatly! We have 5 aircraft with the Minestry of Environment, flying IR cameras for antipoaching, we have trained pilots operating them, with RC backup. The planes are fitted with secondary GPS and telemetry as backup, with the secondary telemetry able to terminate the plane as well.   As, in this country, no civilian aircraft may fly below 1000meters AGL over national parks, we are somewhat covered within the parks, and do not fly above 150m AGL. Outside of the parks we register a NOTAM ( Notice to Airmen) with DCA before the flight, giving where and when we fly, and notify when done. You may think this is overboard, but since there are no regulations in place yet, we feel the need to cover ourselves as best as possible. We also have a handful of of small electrics flying with land surveyers ( take a look at SurVoyeur on this site), and hammer these aspects into these people as users, as well.

    I am not advocating a beaurocratic cumbersome process each time you want to go do a test flight, etc, but for such events, do it far from anyone, keep it in visual range, and if in any doubt of the system, have a backup mode - RC Radio with manual flight mode, etc. If you are going to fly in 'difficult' areas, please play it safe...

    Lets do our best to keep the use of UAV's safe and that will ensure that DCA continues to progress favourably with regard to the usage of such.

    Good luck with your autopilot endeavors!


  • 3D Robotics

    You can go into the CLI and try the test/compass test. That will show you raw data.

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