Drifting / Magnetic Interference? (a.k.a. I need some pre-flight checks!)

[JoeSoap76]

Hi,

I was flying my M2Z yesterday and found I had quite significant sideways 'drift' at times. It was particularly bad when I was near this old church. I took off from the grass in the middle of the ruined outline of walls on the left and really had to work to keep it in place.



At the time I put it down to the wind, but whilst it wasn't still it wasn't blowing a gale either and the drone handled fine once it was up at the height in the picture. Thinking back on it I realised that I turned the drone on inside the grounds and had to calibrate the compass... and I did that on that gravel path leading towards the gate, near to the building and surrounded by gravestones.

So, I'm new to this. I've read that magnetic interference can be a problem, but would it account for fairly severe sideways drift like this? I guess big old stones like this might be a particular source and calibrating close by was a bit stupid. Live and learn.

I won't get a chance to recalibrate in an open space for a day or two... just a bit worried that I'm jumping to conclusions and it's going to be something more mechanical.

 

[Speedmeister]

The Mavic will fight to keep its position hold even if it has to hover in an angle. I do a hover test at a height beyond VPS range to test GPS hold before actually flying. This is also the best time, imo, to resave homepoint as an extra precaution when there is a good chance auto RTH might kick in during my flights. I only do compass calibration when my hover test fails.

 

[JoeSoap76]

I was thinking that if this does turn out to be magnetic interference I will have learned to not panic every time the app tells me to recalibrate the compass, but to look about and ask 'why?' before doing anything.

I was also thinking that I should probably come up with a set of pre-flight tests to make sure everything is working well. So thanks for the advice, that's definitely going on my list

 

[Simmo]

Did the app tell you "home point has been recorded, please chack it on the map.."????

 

[JoeSoap76]

Did the app tell you "home point has been recorded, please chack it on the map.."????

Embarrassingly, I really can't remember... we were driving home from a holiday and my wife was waiting in the car for me to make a "quick stop" to try the drone. I think I may have been in too much of a hurry here.

 

[sar104]

You have provided far too little information to determine what happened on that flight. You would need to check the flight logs.

The best pre-flight check to ensure that there is no significant magnetic interference at takeoff is to look at the aircraft orientation arrow on the GO app - it should be pointing in the same direction on the map that the aircraft is actually facing.

 

[SteveCA]

You have provided far too little information to determine what happened on that flight. You would need to check the flight logs.

The best pre-flight check to ensure that there is no significant magnetic interference at takeoff is to look at the aircraft orientation arrow on the GO app - it should be pointing in the same direction on the map that the aircraft is actually facing.

on some flights I’ve noticed that the compass orientation arrow is correct relative to north pointer but the orientation arrow is completely wrong relative to my controller/phone. I am on the compass window not the map window. It is totally random. Any ideas on the cause?

 

[sar104]

on some flights I’ve noticed that the compass orientation arrow is correct relative to north pointer but the orientation arrow is completely wrong relative to my controller/phone. I am on the compass window not the map window. It is totally random. Any ideas on the cause?

I've seen a few reports of that. I've no idea what is causing it though.

 

[DanMan32]

Device compasses often drift. Whenever I look on Go map/radar or use a compass app, I have to do the figure 8 wrist movement. Not much though.

But even if your device compass is off, actual drone heading relative to actual north should show same on radar's north.

 

[SteveCA]

Device compasses often drift. Whenever I look on Go map/radar or use a compass app, I have to do the figure 8 wrist movement. Not much though.

But even if your device compass is off, actual drone heading relative to actual north should show same on radar's north.

I think you nailed it. I have noticed that it doesnt appear to happen if I calibrate my phones compass before flying.

 

[Meta4]

and the drone handled fine once it was up at the height in the picture.

There's your smoking gun
It's likely that the issue had nothing to do with your compass but was the VPS having trouble finding a strong pattern or texture to lock on to on the ground.
In a situation like that, try disabling the VPS or flying higher than VPS range and see if that changes things.

 

[DanMan32]

When I was testing for possible IMU/compass issues by flying out and in along my driveway, it was drifting right. The replacement did the same thing.
It occurred to me VPS may be causing the drift and not any IMU/compass issues. Seemed to fly straight once in the air.
I think I'll just turn VPS off for a while.