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Magnetic interference in a vessel

Eduard

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Hi all,

Rockie pilot here from Barcelona. I'm sailing in a research vessel (full of metal and electronic instrumentation) and willing to take some footage with a Mavic Pro. Most of the vessel locations with enough clearence to take off show magnetic interference warning, but I found a spot, above some plastic bouys, where it "only" shows yellow bars. Just before departuring, I had the chance of doing a small test on the harbour deck, where compass' bars were red, and few seconds after taking off, the drone started to drift laterally. I was lucky enough to put it down quickly and safe. I'm wondering though how risky is to fly from the boat in such conditions. Even if the take off are is more or less free of interference (yellow) I'm afraid it could fly close to a "red" zone as higher decks there full of antenas.

I've been reading some threads about flying from boats, but most of them are related to GPS mode in a moving boat, but I'm just considering to give it a try when the boat is halt, perhaps with a bit of drifting, but quite static.

Thanks in advance for any ideas or suggestions!!

Eduard
 
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Make sure you have a 'Home point set' which will indicate adequate GPS Health, then when you "Check it on the map", check that the orientation of the arrow, is the same as the AC. Good luck.
 
Welcome to Mavic Pilots .
I hope you will find our site helpful and look forward to any input , photo's/video's you might post .
Don't be shy and ask anything if you can't find it by searching . Thumbswayup
 
Hi all,

Rockie pilot here from Barcelona. I'm sailing in a research vessel (full of metal and electronic instrumentation) and willing to take some footage with a Mavic Pro. Most of the vessel locations with enough clearence to take off show magnetic interference warning, but I found a spot, above some plastic bouys, where it "only" shows yellow bars. Just before departuring, I had the chance of doing a small test on the harbour deck, where compass' bars were red, and few seconds after taking off, the drone started to drift laterally. I was lucky enough to put it down quickly and safe. I'm wondering though how risky is to fly from the boat in such conditions. Even if the take off are is more or less free of interference (yellow) I'm afraid it could fly close to a "red" zone as higher decks there full of antenas.

I've been reading some threads about flying from boats, but most of them are related to GPS mode in a moving boat, but I'm just considering to give it a try when the boat is halt, perhaps with a bit of drifting, but quite static.

Thanks in advance for any ideas or suggestions!!

Eduard

It's most likely not the antennas and electronics that will cause problems - it's the ferrous metal structure of the vessel itself distorting the local magnetic field. If you have compass errors at takeoff then you will have the kind of unstable flight that you described. Flying in ATTI mode would be one solution, but the unmodified Mavic Pro does not have that as a flight option.
 
Hi all,

Rockie pilot here from Barcelona. I'm sailing in a research vessel (full of metal and electronic instrumentation) and willing to take some footage with a Mavic Pro. Most of the vessel locations with enough clearence to take off show magnetic interference warning, but I found a spot, above some plastic bouys, where it "only" shows yellow bars. Just before departuring, I had the chance of doing a small test on the harbour deck, where compass' bars were red, and few seconds after taking off, the drone started to drift laterally. I was lucky enough to put it down quickly and safe. I'm wondering though how risky is to fly from the boat in such conditions. Even if the take off are is more or less free of interference (yellow) I'm afraid it could fly close to a "red" zone as higher decks there full of antenas.

I've been reading some threads about flying from boats, but most of them are related to GPS mode in a moving boat, but I'm just considering to give it a try when the boat is halt, perhaps with a bit of drifting, but quite static.

Thanks in advance for any ideas or suggestions!!

Eduard
Howdy from Wyoming @Eduard , welcome to the community, plenty of fine folk and excellent information here.
 
It's most likely not the antennas and electronics that will cause problems - it's the ferrous metal structure of the vessel itself distorting the local magnetic field. If you have compass errors at takeoff then you will have the kind of unstable flight that you described. Flying in ATTI mode would be one solution, but the unmodified Mavic Pro does not have that as a flight option.
When you do the ATTI mod and activate ATTI mode is GPS active on the Mavic for coordinates and showing on the map (but not used for actual positioning)?



Mike
 
When you do the ATTI mod and activate ATTI mode is GPS active on the Mavic for coordinates and showing on the map (but not used for actual positioning)?



Mike

Yes - that's correct. The FC is still receiving and processing the GPS data, but not attempting to hold position or course.
 
Yes - that's correct. The FC is still receiving and processing the GPS data, but not attempting to hold position or course.
Ahh, excellent. That was what was holding me back from making the mod. Thanks!



Mike
 
If you don't mind losing sport mode then I think it's a huge advantage. Or you can always keep sport mode and lose P-GPS.
While I do like having sport mode, to go faster or fight a head wind, I have not needed it much--other than occasionally just for fun. I thought I read the top speed in ATTI mode was similar to Sport. Do you know if that Is true?

My main hesitation to doing the ATTI mod, though, was because I was unsure if you lost GPS altogether when switching to ATTI. While I try to fly LOS there are times when I lose sight for a bit, and rely somewhat on the map to fly closer so I can resume LOS. But thankfully, as you stated, GPS is not lost altogether.

My main reason for wanting to do the ATTI mod is to have a fallback in case I have to contend with a compass error, perhaps combined with a regained loss of GPS signal, where the Mavic might not fly as commanded, yet doesn't switch to ATTI on its own--at least not in time to prevent an incident.

Thanks again.


Mike
 
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It's most likely not the antennas and electronics that will cause problems - it's the ferrous metal structure of the vessel itself distorting the local magnetic field. If you have compass errors at takeoff then you will have the kind of unstable flight that you described. Flying in ATTI mode would be one solution, but the unmodified Mavic Pro does not have that as a flight option.

I'm a bit confused about that. So, ATTI mode doesn't use compass data? I thought GPS and ATTI mode were both using compass that and that the main diff betweenwas was just the use of GPS data. Still don't understand why wrong compass can make it drift even though GPS info didn't change (sorry about my English, not sure if I was clear).

Thanks again to everyone!
 
I'm a bit confused about that. So, ATTI mode doesn't use compass data? I thought GPS and ATTI mode were both using compass that and that the main diff betweenwas was just the use of GPS data. Still don't understand why wrong compass can make it drift even though GPS info didn't change (sorry about my English, not sure if I was clear).

Thanks again to everyone!
While the compass may be active in ATTI, it is not doing anything as far as flying is concerned: you have to do that. In P mode the compass is crucial since without it the Mavic doesn't know which direction it is headed. When the compass fails, or its data is deemed unreliable, the Mavic should switch to ATTI mode on its own. But there have been cases where it has not done so, or not in time to prevent a lost drone. Ergo, having the ability to manually switch to ATTI can be advantageous.

If I were you, Eduard, I would not try to fly from that vessel without being able to manually switch to ATTI. But you of course need to understand that in wind, even slight wind, the Mavic will drift since it will not be holding its own position or course. If you have not flown in ATTI you might need some practice with that to understand how to deal with it (in my opinion, it is not that hard).

Another thing, and Sar can hopefully chime in if this is not practical, is taking off in ATTI, ascending above the vessel to clear any magnetic interference, then switching back to P mode and wait till home point is set. Before landing you can switch back to ATTI.



Mike
 
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While the compass may be active in ATTI, it is not doing anything as far as flying is concerned: you have to do that. In P mode the compass is crucial since without it the Mavic doesn't know which direction it is headed. When the compass fails, or its data is deemed unreliable, the Mavic should switch to ATTI mode on its own. But there have been cases where it has not done so, or not in time to prevent a lost drone. Ergo, having the ability to manually switch to ATTI can be advantageous.

If I were you, Eduard, I would not try to fly from that vessel without being able to manually switch to ATTI. But you of course need to understand that in wind, even slight wind, the Mavic will drift since it will not be holding its own position or course. If you have not flown in ATTI you might need some practice with that to understand how to deal with it (in my opinion, it is not that hard).

Another thing, and Sar can hopefully chime in if this is not practical, is taking off in ATTI, ascending above the vessel to clear any magnetic interference, then switching back to P mode and wait till home point is set. Before landing you can switch back to ATTI.



Mike

Mike, thanks a lot for the info! I've flown in ATTI mode a couple of times with a DJI Inspire, so I might try that. The question now is how to convert the Sport mode switch to an ATTI one. Any recommendation or instructions to follow on that sense? Also, do you know if that modification could affect my DJI Care Refresh?

Thanks again in advance!
 
I'm a bit confused about that. So, ATTI mode doesn't use compass data? I thought GPS and ATTI mode were both using compass that and that the main diff betweenwas was just the use of GPS data. Still don't understand why wrong compass can make it drift even though GPS info didn't change (sorry about my English, not sure if I was clear).

Thanks again to everyone!

In ATTI mode the FC only stabilizes attitude (pitch, roll and yaw) and altitude. It doesn't need compass or GPS data to do that. It might use magnetometer data to counter rate gyro drift, but it wouldn't need to trust the yaw value to do that. And stable ATTI flight has been demonstrated with a P2 after the compass was removed, so not essential.

While the compass may be active in ATTI, it is not doing anything as far as flying is concerned: you have to do that. In P mode the compass is crucial since without it the Mavic doesn't know which direction it is headed. When the compass fails, or its data is deemed unreliable, the Mavic should switch to ATTI mode on its own. But there have been cases where it has not done so, or not in time to prevent a lost drone. Ergo, having the ability to manually switch to ATTI can be advantageous.

If I were you, Eduard, I would not try to fly from that vessel without being able to manually switch to ATTI. But you of course need to understand that in wind, even slight wind, the Mavic will drift since it will not be holding its own position or course. If you have not flown in ATTI you might need some practice with that to understand how to deal with it (in my opinion, it is not that hard).

Another thing, and Sar can hopefully chime in if this is not practical, is taking off in ATTI, ascending above the vessel to clear any magnetic interference, then switching back to P mode and wait till home point is set. Before landing you can switch back to ATTI.



Mike

I'm not sure about taking off in ATTI and then switching to P-GPS. At some point the yaw value has to be initialized for P-GPS to work. Normally that happens at startup, so I'm not sure that starting in ATTI will make any difference and I don't know what effects might occur switching in to P-GPS later if yaw was initialized incorrectly. That sounds like it needs an experiment.
 
Mike, thanks a lot for the info! I've flown in ATTI mode a couple of times with a DJI Inspire, so I might try that. The question now is how to convert the Sport mode switch to an ATTI one. Any recommendation or instructions to follow on that sense? Also, do you know if that modification could affect my DJI Care Refresh?

Thanks again in advance!

I don't know if that modification is possible with recent firmware and DJI Assistant, under which it's been reported not possible to switch on developer tools. I'm running older firmware and an earlier version of the Assistant software. Others may be more up to date with information on this.
 
most of the time I fly my mavic pro from a boat, I have had a warning of magnetic interference, I always take off and move the mavic out of the boat, mavic drift a bit slowly after a few seconds everything returns to normal the warning disappears and I have a normal flight at the time of landing always hand it catch and the warning never returns, and I have never had a single crash always flying on gpsIMG_0185.JPG
 
Hello,
It is a pleasure to welcome you to the Mavic Pilots forum.
I hope that you will be able to use the forum to further your safety knowledge and for the exchange of innovative ideas and as a resource for current developments in Mavic quadcopters.
Enjoy! Thumbswayup
*MAVIC PRO/PLATINUM MANUAL: https://dl.djicdn.com/downloads/mavic/Mavic Pro User Manual V2.0-.pdf
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*GO 4 APP MANUAL: DJI Go 4 Manual

Please post up some of your videos when you get it all figured out.
 
Thanks everyone! Really helping information going on in here, thanks again.

Sar, thats an interesting point and would be nice to experiment what happens taking off in ATTI mode with a wrong compass and then switching to P-GPS. By the way, what version of firmware/Assist are you using?

Lopez, that's a nice boat. How severe is your compass anomaly when taking off? Do you have any issues with the radar, do you switch it off? The thing is the one I'm saliling in is full of electronic equipments and have 2 radars, don't know of that could make a difference. I've been reading a lot today in this forum and found some people having issues when flying from vessels.
 
I read somewhere that someone had problems with the radar in a ship I never had that problem, when taking off mavic drift just a little less than a foot in 4 or 5 seconds so there is plenty of time to maneuver, of course always taking off and landing with the boat out of gear
 
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