Compass error caused by iPad?

[Astro]

hi guys,
Has anyone thought that the magnet in iPads (I assume for the mounting of the external keyboard) has the potential to cause compass error, or at least forced a recalibration?
I've suspected it with my MA a couple of times but have no convincing evidence. I've certainly transported them together but obviously with the power off but never gave it a thought.
In recent days I've tended to keep the controller with iPad away from the MA when powering up. Glenn

 

[Moose1967]

I would think most compass errors are caused by a poor calibration - you may get that it is successful but if you want to be sure go out To a remote spot and calibrate it - solved my compass errors

 

[Bill combs]

hi guys,
Has anyone thought that the magnet in iPads (I assume for the mounting of the external keyboard) has the potential to cause compass error, or at least forced a recalibration?
I've suspected it with my MA a couple of times but have no convincing evidence. I've certainly transported them together but obviously with the power off but never gave it a thought.
In recent days I've tended to keep the controller with iPad away from the MA when powering up. Glenn

i recently purchased a tablet holder for my m2pro it to is new also,i never had to recalibrate this drone before until i started using the ipad,when i use my note 9 no compass issues but everytime i use the tablet app i have to recalibrate

 

[sar104]

i recently purchased a tablet holder for my m2pro it to is new also,i never had to recalibrate this drone before until i started using the ipad,when i use my note 9 no compass issues but everytime i use the tablet app i have to recalibrate

Unless you are using the tablet as a launch pad its magnets are not going to affect the aircraft compass. Something else is going on there.

 

[Olav van Gerven]

Unless you are using the tablet as a launch pad its magnets are not going to affect the aircraft compass. Something else is going on there.

A what? You're not supposed to use the tablet as a launch pad? But that's the only reason I got one!

(I just spilled my coffee over documents, so not to be taken to serious)

 

[Meta4]

I would think most compass errors are caused by a poor calibration - you may get that it is successful but if you want to be sure go out To a remote spot and calibrate it - solved my compass errors

This reflects a misunderstanding of what a compass error is.
It's not a fault with the compass that requires corrective action to fix it.
A compass error is a properly working compass that's warning you of magnetic interference nearby.
Recalibrating the compass won't do anything to solve that.

It would be very uncommon to get a poor compass calibration.
Either the compass calibration is successful or it fails.

 

[sar104]

This reflects a misunderstanding of what a compass error is.
It's not a fault with the compass that requires corrective action to fix it.
A compass error is a properly working compass that's warning you of magnetic interference nearby.
Recalibrating the compass won't do anything to solve that.

It would be very uncommon to get a poor compass calibration.
Either the compass calibration is successful or it fails.

We've seen poor results from compass calibrations when the aircraft field was too large to be corrected for (sometimes without the calibration failing), but the more common issue seems to be that the compass goes out of calibration due to a change in the magnetic field of the aircraft - components added/removed or exposure to strong magnetic fields.

 

[Moose1967]

This reflects a misunderstanding of what a compass error is.
It's not a fault with the compass that requires corrective action to fix it.
A compass error is a properly working compass that's warning you of magnetic interference nearby.
Recalibrating the compass won't do anything to solve that.

It would be very uncommon to get a poor compass calibration.
Either the compass calibration is successful or it fails.

I have to disagree with you Meta4 - these are digital compasses on the drone once the drone is turned on - if you are near metal when you calibrate it, the magnetism of the electric compass will be thrown off thereafter when you fly because it could not properly calibrate the "zero" point

I can recreate my compass errors today just by calibrating near my truck - go try it - I do recommend going to a wide open field to test it and don't fly high - I have two pieces of property 48 acres and 115 acres - I can go to either of them and calibrate beside my vehicle - get an OK for the calibration - then fly and get compass errors - as soon as I walk about 100 feet from the truck and calibrate in a wide open space and then fly from the exact same spot, it will be fine !!

I hardly ever calibrate anymore and when I do I usually walk somewhere where I am 100 percent sure of nothing that can affect the compass.

 

[Meta4]

I have to disagree with you Meta4 - these are digital compasses on the drone once the drone is turned on - if you are near metal when you calibrate it, the magnetism of the electric compass will be thrown off thereafter when you fly because it could not properly calibrate the "zero" point

I'm not sure what you are disagreeing with.
Is the problem you describe due to getting a "bad calibration" or powering up your drone close to your truck?
Why would you calibrate the compass near a big piece of steel like your truck anyway? (not metal, it's only steel that is the issue).

 

[BudWalker]

I have to disagree with you Meta4 - these are digital compasses on the drone once the drone is turned on - if you are near metal when you calibrate it, the magnetism of the electric compass will be thrown off thereafter when you fly because it could not properly calibrate the "zero" point

I can recreate my compass errors today just by calibrating near my truck - go try it - I do recommend going to a wide open field to test it and don't fly high - I have two pieces of property 48 acres and 115 acres - I can go to either of them and calibrate beside my vehicle - get an OK for the calibration - then fly and get compass errors - as soon as I walk about 100 feet from the truck and calibrate in a wide open space and then fly from the exact same spot, it will be fine !!

I hardly ever calibrate anymore and when I do I usually walk somewhere where I am 100 percent sure of nothing that can affect the compass.

After you calibrate near your truck do you then launch from near your truck? That would likely be the cause of any compass errors.

There have been many claims where a calibration was flawed because it was compensating for magnetic effects external to the AC. Most were really claims that someone else had seen this happen. A few, like yours, were pilots claiming to personally observe this. I've not seen a single case where any of these claims have been backed up with actual data.

Would it be possible for you provide some supporting .DAT logs? Ideally 2 .DAT logs
1) A non compass error flight
2) A calibration near the truck followed by a flight launched from the exact same spot as 1)

 

[sar104]

After you calibrate near your truck do you then launch from near your truck? That would likely be the cause of any compass errors.

There have been many claims where a calibration was flawed because it was compensating for magnetic effects external to the AC. Most were really claims that someone else had seen this happen. A few, like yours, were pilots claiming to personally observe this. I've not seen a single case where any of these claims have been backed up with actual data.

Would it be possible for you provide some supporting .DAT logs? Ideally 2 .DAT logs
1) A non compass error flight
2) A calibration near the truck followed by a flight launched from the exact same spot as 1)

What we have seen in DAT files, after calibration, is an IMU yaw - magnetic yaw discrepancy that has a 2π periodic dependence on the yaw value. That indicates that the calibration failed to correct properly for the internal magnetic field of the aircraft.

But, as you point out, that's not the same as a calibration incorrectly reporting success when performed in the presence of an external magnetic field other than the earth's - I don't think I've ever seen that. It's also worth noting that the calibration should work just fine in any steady external magnetic field, provided that it is not so strong that it drowns out the internal magnetic field.

 

[BudWalker]

What we have seen in DAT files, after calibration, is an IMU yaw - magnetic yaw discrepancy that has a 2π periodic dependence on the yaw value. That indicates that the calibration failed to correct properly for the internal magnetic field of the aircraft.
.....

I think you're referring to this thread
Help interpret flight record

Wasn't it ultimately concluded that a 2π periodic Yaw/magYaw error could be explained by the manner in which the pilot handled the AC?

 

[sar104]

I think you're referring to this thread
Help interpret flight record

Wasn't it ultimately concluded that a 2π periodic Yaw/magYaw error could be explained by the manner in which the pilot handled the AC?

In that one - probably yes - but there have been several others, including some that were resolved by using a demagnetizer and recalibrating. If my filing system were better I'd be able to find them quickly but I'll need to do some searching.

 

[BudWalker]

....... If my filing system were better I'd be able to find them quickly but I'll need to do some searching.

 

[BudWalker]

What we have seen in DAT files, after calibration, is an IMU yaw - magnetic yaw discrepancy that has a 2π periodic dependence on the yaw value. That indicates that the calibration failed to correct properly for the internal magnetic field of the aircraft.
......

But, have we seen a case where it can be concluded that the calibration caused the 2π periodic Yaw/magYaw error? No error before the calibration and then error immediately following the calibration.

 

[sar104]

But, have we seen a case where it can be concluded that the calibration caused the 2π periodic Yaw/magYaw error? No error before the calibration and then error immediately following the calibration.

If I recall correctly, there were a couple of those where the compass had been calibrated several times, with no error reported, but the 2π variations continued until after it was demagnetized.

 

[Moose1967]

After you calibrate near your truck do you then launch from near your truck? That would likely be the cause of any compass errors.

There have been many claims where a calibration was flawed because it was compensating for magnetic effects external to the AC. Most were really claims that someone else had seen this happen. A few, like yours, were pilots claiming to personally observe this. I've not seen a single case where any of these claims have been backed up with actual data.

Would it be possible for you provide some supporting .DAT logs? Ideally 2 .DAT logs
1) A non compass error flight
2) A calibration near the truck followed by a flight launched from the exact same spot as 1)

Budwalker - no I do not launch near the truck.

If I get a chance I will re-create the error and save the data files for someone to look at.

We might learn from this.

 

[Bill combs]

Unless you are using the tablet as a launch pad its magnets are not going to affect the aircraft compass. Something else is going on there.

I just test my theory today,I used my galaxy Note 9 first and started the app and rc & m2p no problem I shut it all down swapped it with my ipad 6gen and boom calibrate compass

 

[Meta4]

I just test my theory today,I used my galaxy Note 9 first and started the app and rc & m2p no problem I shut it all down swapped it with my ipad 6gen and boom calibrate compass

How close is the iPad to the drone?

 

[sar104]

I just test my theory today,I used my galaxy Note 9 first and started the app and rc & m2p no problem I shut it all down swapped it with my ipad 6gen and boom calibrate compass

Interesting. To determine exactly what is happening you would need to retrieve the DAT files for those two power up events from the two devices:

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