Compass data error w/screenshot

[MavProPlat1968]

Crashed my MPP and got it back up and going with a gimbal ribbon cable. Took it out for a test flight this evening and I flew it out about 2000 feet and hit RTH, done everything it should. When it got back as it hovered preparing to land I got the error that is in the screenshot. So I connected to my pc and calibrated the vision sensors and tried it again...same results. I tried it several time and got the same error at the same exact point in landing. Any ideas. Oh and I also got a “strong wireless interference “ warning when I launched...also, the compass calibrates fine..

 

[Thomas B]

Don’t think this is related to vision sensors. In the screenshot the compass in the inset lower right is 45 degrees different than the compass inset lower left. Try calibrating the compass in a nonmetallic area. Try to do both of the MPP compasses. If that doesn’t fix it you may need to fly in a different location.

 

[MavProPlat1968]

Don’t think this is related to vision sensors. In the screenshot the compass in the inset lower right is 45 degrees different than the compass inset lower left. Try calibrating the compass in a nonmetallic area. Try to do bth of the MPP compasses. If that doesn’t fix it you may need to fly in a different location.

Nice catch...I didn’t even notice that.

 

[Thomas B]

Nice catch...I didn’t even notice that.

Try and post results please. It’s how we all learn.

 

[MavProPlat1968]

Try and post results please. It’s how we all learn.

Will do

 

[Meta4]

I got the error that is in the screenshot.
So I connected to my pc and calibrated the vision sensors and tried it again...same results.

The vision sensors won't do anything to fix a problem with the compass data.

 

[MavProPlat1968]

Don’t think this is related to vision sensors. In the screenshot the compass in the inset lower right is 45 degrees different than the compass inset lower left. Try calibrating the compass in a nonmetallic area. Try to do both of the MPP compasses. If that doesn’t fix it you may need to fly in a different location.

Does it not calibrate both compasses at the same time?

 

[Meta4]

Does it not calibrate both compasses at the same time?

Compass calibration calibrates both compasses - there wouldn't be much point in doing it separately.

Compass calibration doesn't actually do anything to the compass.
It just identifies and measures the magnetic fields that are part of the drone so they can be ignored.

 

[MavProPlat1968]

Compass calibration calibrates both compasses - there wouldn't be much point in doing it separately.

Compass calibration doesn't actually do anything to the compass.
It just identifies and measures the magnetic fields that are part of the drone so they can be ignored.

I'm getting a Compass Redundency switch error now while trying to calibrate.

 

[sar104]

Don’t think this is related to vision sensors. In the screenshot the compass in the inset lower right is 45 degrees different than the compass inset lower left. Try calibrating the compass in a nonmetallic area. Try to do both of the MPP compasses. If that doesn’t fix it you may need to fly in a different location.

That's not correct - the video feed, map and radar are all consistent. The aircraft is facing southwest.

 

[Thomas B]

That's not correct - the video feed, map and radar are all consistent. The aircraft is facing southwest.

Ok, but why are the arrows in the two fields I referenced different?

 

[sar104]

Ok, but why are the arrows in the two fields I referenced different?

You are ignoring the north reference in the radar display on the left, which is 90° counterclockwise. That's because the operator is facing east, or at least the mobile device compass thinks it is facing east. Relative to the (different) north references in the map and radar, the heading is the same, and the map is consistent with the video feed.

 

[sar104]

I'm getting a Compass Redundency switch error now while trying to calibrate.

You need to look at (or post here) the mobile device DAT file for that flight. That contains the raw magnetometer data for both compasses and the event stream log from the FC.

 

[MavProPlat1968]

You need to look at (or post here) the mobile device DAT file for that flight. That contains the raw magnetometer data for both compasses and the event stream log from the FC.

Could you explain to me where to get those and I will gladly post them. Never done that before.

 

[sar104]

Could you explain to me where to get those and I will gladly post them. Never done that before.

Unless the DAT file is obvious, take a look at the txt log first:

TXT log: DJI Flight Log Viewer | Phantom Help

That will tell you the DAT file index number, which should make it easier to find:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[MavProPlat1968]

Unless the DAT file is obvious, take a look at the txt log first:

TXT log: DJI Flight Log Viewer | Phantom Help

That will tell you the DAT file index number, which should make it easier to find:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

I think this is what your looking for @sar104 if not let me know. Like I said, I only get that error just at the point it is about to start its decent from RTH.

 

[MavProPlat1968]

You are ignoring the north reference in the radar display on the left, which is 90° counterclockwise. That's because the operator is facing east, or at least the mobile device compass thinks it is facing east. Relative to the (different) north references in the map and radar, the heading is the same, and the map is consistent with the video feed.

I was indeed facing east

 

[Thomas B]

Very interested to see the data interpretation.

 

[sar104]

That does appear to be the flight, although it is a rather strange DAT file. DatCon doesn't note it as a flight - it doesn't have the usual motor start marker. Anyway - I'd forgotten that the MPP mobile device DAT files don't show both compass datasets - that requires the aircraft DAT file. On the other hand there are some obvious issues. Looking at the mag_mod value (the square root of the sum of the squares of the field components which equals the magnetic field strength) you see the following:



Obviously the earth's magnetic field strength shouldn't appear to vary depending on the orientation of the aircraft. That strongly suggests that the compasses are not properly calibrated, and that some magnetic field due to the aircraft itself is being added to the measured field.

 

[MavProPlat1968]

That does appear to be the flight, although it is a rather strange DAT file. DatCon doesn't note it as a flight - it doesn't have the usual motor start marker. Anyway - I'd forgotten that the MPP mobile device DAT files don't show both compass datasets - that requires the aircraft DAT file. On the other hand there are some obvious issues. Looking at the mag_mod value (the square root of the sum of the squares of the field components which equals the magnetic field strength) you see the following:

View attachment 71172

Obviously the earth's magnetic field strength shouldn't appear to vary depending on the orientation of the aircraft. That strongly suggests that the compasses are not properly calibrated, and that some magnetic field due to the aircraft itself is being added to the measured field.

At this point all this stuff is new to me, so if I’m being honest I really don’t have a clue what all that means, but it doesnt look real good. Could this be a damaged compass from my crash? And this may sound like a dumb question to you, but when I took the drone apart to replace the gimbal ribbon cable, I put all of the small screws in one of those magnetic bowls so I wouldn’t lose them. When putting them back in they were magnetic because they were sticking to my non magnetic screw driver. Could that be an issue?