Mavic 2 Pro Flyaway

[kilomikebravo]

Jake: I watched Dylan's clip before I even got my first set of PP filters so after I got my first set, I kept the case away from the drone. Then one day, I put them in the backpack after flying and forgot about them. Freaked out the next time I realized what I had done but, to my surprise, no compass cal request from the aircraft and start up heading was dead on. Left them in the bag (along with others I have added since,) and have flown many times with no issues. Personally, I don't think they affect the aircraft as long as it is not powered up and they're not strong enough to impart a new magnetic field to the aircraft physically. But I ain't no magnetized expert.

 

[JakeBlues]

Jake: I watched Dylan's clip before I even got my first set of PP filters so after I got my first set, I kept the case away from the drone. Then one day, I put them in the backpack after flying and forgot about them. Freaked out the next time I realized what I had done but, to my surprise, no compass cal request from the aircraft and start up heading was dead on. Left them in the bag (along with others I have added since,) and have flown many times with no issues. Personally, I don't think they affect the aircraft as long as it is not powered up and they're not strong enough to impart a new magnetic field to the aircraft physically. But I ain't no magnetized expert.

Hi Kilo

Yeah ... no expert on magnetism either, and you might be in to something that the drone must actually be powered to make an impact.

As I said, our friend who started the thread was almost out of options as to why he had compass issues. It think erring on the side of caution is always the best way to go.

I never transport my drone and PP filters in the same pack... it’s in the case of my GoPro7.

All the best,
Jake

 

[Anterialis]

"Don't get the case too close to the drone, you will have to do a compass calibration".

IMO this is wrong. As long as you remove the cover before taking off, there should be no need to calibrate the compass. It will give you the error when the case is close to the drone as the drone detects a changed magnetic field, but once you remove the case, (maybe after a while..) the magnetic field "returns to normal" so to speak and everything should be ok. I do not believe these tiny magnets will permanently change the magnetic "footprint" of the drone itself and thus there should be no need for a new calibration.

 

[JakeBlues]

"Don't get the case too close to the drone, you will have to do a compass calibration".

IMO this is wrong. As long as you remove the cover before taking off, there should be no need to calibrate the compass. It will give you the error when the case is close to the drone as the drone detects a changed magnetic field, but once you remove the case, (maybe after a while..) the magnetic field "returns to normal" so to speak and everything should be ok. I do not believe these tiny magnets will permanently change the magnetic "footprint" of the drone itself and thus there should be no need for a new calibration.

Hi,

It was kinda demonstrated in the YouTube clip but PEOPLE, if you are happy to place ANY sorts of magnets in front of your drone? Be my guest. IMO, no.

Have a good one.
Jake

 

[Anterialis]

Maybe I misunderstood, English is not my first language.

I was, among other things, referring to “transporting the drone with the magnetic cover in the same bag” issue. I don’t believe this should be a problem as long as you remove the magnets and keep them away from the drone before starting up the drone. The clip demonstrated taking off with a nearby magnet and with the magnet physically on the drone, two things I definitely wouldn’t recommend.. The first example demonstrates (extremely) taking off from an unfit location, similar to eg. concrete with metal bars in it; this creates a disturbed magnetic field and the “compass error” would probably appear. The correct procedure here would be to remove the drone and put it somewhere else, not to recalibrate the compass (although it might say that on the RC).

Am I still misunderstanding? I think we are on the same page actually...

EDIT: I obviously may be wrong here and please let me know if I am, but looking at the video again at about 6:30 ish where he says that you should not place the (magnetic) cover near the drone when changing the filters because “you will have to recalibrate the compass which is a pain”. This is what I believe is wrong. At least in theory this should not be the case. Removing the magnets away from the drone (and maybe give the drone compass a few seconds to adjust) should make it return to normal. Is this not the case in practice? I do however totally agree with “if you can avoid it, do”-principle

 

[paulatkin73]

I don’t believe this should be a problem as long as you remove the magnets and keep them away from the drone before starting up the drone.

in the practical objective reality the compass chip, in case of the M8N GPS the embedded HMC5883L chip may become magnetized and then either will need re calibration, if new offsets are still within acceptable range, or needs to be demagnetized, or, most usually, replaced with a new whole unit.
also, from the personal experience - do not keep your drone overnight on a speaker or a subwoofer, or you will need new compass. in case of a self made drone it is usually only a $40-$50 expense, in case of a mavic probably quite a bit more.

 

[Anterialis]

in the practical objective reality the compass chip, in case of the M8N GPS the embedded HMC5883L chip may become magnetized and then either will need re calibration, if new offsets are still within acceptable range, or needs to be demagnetized, or, most usually, replaced with a new whole unit.
also, from the personal experience - do not keep your drone overnight on a speaker or a subwoofer, or you will need new compass. in case of a self made drone it is usually only a $40-$50 expense, in case of a mavic probably quite a bit more.

Thank you for this educative response.

Am I understanding you correctly that the compass chip (HMC5883L?) can get permanently influenced by smaller ferromagnetic objects like those small case magnets described in the video? Or is this most often a temporal change, if a change occurs at all? If its more of a temporal change in the ferromagnetic state in the internal compass, I would imagine a compass recalibration (while influenced by the magnet) could be hazardous as the compass after takeoff will start drifting (returning to the "normal" state before the magnet induced a change) and after a while become erroneous (and a new calibration needed).

Paulatkin73, what is your opinion on the matter regarding keeping this case (with smaller magnets) in the same bag as the drone?

 

[paulatkin73]

Thank you for this educative response.

Am I understanding you correctly that the compass chip (HMC5883L?) can get permanently influenced by smaller ferromagnetic objects like those small case magnets described in the video? Or is this most often a temporal change, if a change occurs at all? If its more of a temporal change in the ferromagnetic state in the internal compass, I would imagine a compass recalibration (while influenced by the magnet) could be hazardous as the compass after takeoff will start drifting (returning to the "normal" state before the magnet induced a change) and after a while become erroneous (and a new calibration needed).

Paulatkin73, what is your opinion on the matter regarding keeping this case (with smaller magnets) in the same bag as the drone?

Small magnets in case are not stronger than magnets in motors. Unless they are really close to gps puck with compass, it should not matter. I personally would not keep any magnets close to the drone.

I spoke of big magnets like in the trunk of your car - those in big rear speakers woofers. Floor standing speakers. Subwoofer. If chip gets magnetized, it corrupts its readings and to demagnetize you'll need a special electro magnetic tool.

 

[Anterialis]

+1

 

[Trollistika]

Hi guys, new member here since I am in the market for a dji drone. I Read the thread and yeah, odd. But the last post hit me hard. Car speakers do have strong magnets. If you store a drone next to it, it WILL decalibrate the compass. Eventually it will loose it magnetism that it gained and will delve resolve itself. Saying that, If I buy one..... I will DEFINITELY recalibrate after taking it out of my car IF I store it near the speakers.

 

[coliwabl]

Hi guys, new member here since I am in the market for a dji drone. I Read the thread and yeah, odd. But the last post hit me hard. Car speakers do have strong magnets. If you store a drone next to it, it WILL decalibrate the compass. Eventually it will loose it magnetism that it gained and will delve resolve itself. Saying that, If I buy one..... I will DEFINITELY recalibrate after taking it out of my car IF I store it near the speakers.

To be safe, you should re-calibrate before every flight.

 

[Meta4]

To be safe, you should re-calibrate before every flight.

Recalibrating the compass does nothing to make your flight any safer.
Understanding how the Mavic flies (including what compass calibration does) is a much better strategy for ensuring safe flight.

 

[christangey]

Maybe that's true, but I never have.

I have always been under the impression that it was good practice to do so since the last place it was done was, well, China. No different than the recommendation if you travel more than approx 50 miles from the last place it was calibrated, you should calibrate the compass it again.

Ha! If that's the case I'll have to recalibrate every day in the Australian outback!

 

[Boopsi]

Everyone say on compas calibration. No one see that sonar alt. stuck on 7.9m? It's normal on MP2?

 

[ruggb]

I think it is funny. All this argument over compass calibration. IMHO, it is due to the misunderstanding of how these compasses work and why calibration is needed. Here is what I believe supported by Google searches.

The compasses are Hall effect, sensing the Earth,s magnetic fields. They are either 2 or 3 axis. If the instructions call for rotating in 2 directions, it is a 2 axis system. If it requires 3 rotation directions, it is a 3 axis system. Phones and handheld GPS units have 3 axis systems and require rotation in 3 axis.

Drones operate in the air away from magnetic objects and interference (usually). So to calibrate them, you must do it in a similar environment, without interference.

The reason you need to calibrate them has nothing to do with the Earth's magnetic fields or the deviation of them east to west. Calibration does not make them uneffected by local magnetic interference while flying. On the ground or flying interference warnings do not mean your drone needs recalibration, but it may.

Once you calibrate them they are good to go forever, right? WRONG!
Why? Because the purpose of calibration is to normalize the DRONE'S magnetic signature. It has to do with the metal on board the drone.

If you place a screwdrive against a magnet it becomes magnetic. If a drone gets near, or passes thru a magnetic field it picks up some magnetism and changes its on board magnetic environment. Therefore, it will require recalibration. If there were nothing magnetic on a drone, then one calibration would be all it ever needed. But it might be difficult for it to fly without magnetic motors.

Any advice relative to recalibrating when you move a drone from point A to point B has to do with the drone on board magnetic signature changing due to the environment it passed thru going from A to B or the magnetic chalk board you placed it near.

As long as you know your drone's magnetic signature has not changed, then you can forgo recalibration. When you figure out how to determine that, let us all know so we can stop calibrating unnecessarily. Until then, make your decision based on the above facts.

 

[ruggb]

OH, BTW, when calibrating a compass, if you hold the drone or phone in your hand with a watch on your arm or a ring on your finger, the calibration will include those items in the signature. Then you will have to have a real FPV flight. For best calibration do it in the buff.

 

[sar104]

I think it is funny. All this argument over compass calibration. IMHO, it is due to the misunderstanding of how these compasses work and why calibration is needed. Here is what I believe supported by Google searches.

The compasses are Hall effect, sensing the Earth,s magnetic fields. They are either 2 or 3 axis. If the instructions call for rotating in 2 directions, it is a 2 axis system. If it requires 3 rotation directions, it is a 3 axis system. Phones and handheld GPS units have 3 axis systems and require rotation in 3 axis.

Drones operate in the air away from magnetic objects and interference (usually). So to calibrate them, you must do it in a similar environment, without interference.

The reason you need to calibrate them has nothing to do with the Earth's magnetic fields or the deviation of them east to west. Calibration does not make them uneffected by local magnetic interference while flying. On the ground or flying interference warnings do not mean your drone needs recalibration, but it may.

Once you calibrate them they are good to go forever, right? WRONG!
Why? Because the purpose of calibration is to normalize the DRONE'S magnetic signature. It has to do with the metal on board the drone.

If you place a screwdrive against a magnet it becomes magnetic. If a drone gets near, or passes thru a magnetic field it picks up some magnetism and changes its on board magnetic environment. Therefore, it will require recalibration. If there were nothing magnetic on a drone, then one calibration would be all it ever needed. But it might be difficult for it to fly without magnetic motors.

Any advice relative to recalibrating when you move a drone from point A to point B has to do with the drone on board magnetic signature changing due to the environment it passed thru going from A to B or the magnetic chalk board you placed it near.

As long as you know your drone's magnetic signature has not changed, then you can forgo recalibration. When you figure out how to determine that, let us all know so we can stop calibrating unnecessarily. Until then, make your decision based on the above facts.

That's all basically correct, and has been explained many times in many threads. It certainly doesn't hurt to repeat it though.

 

[Meta4]

OH, BTW, when calibrating a compass, if you hold the drone or phone in your hand with a watch on your arm or a ring on your finger, the calibration will include those items in the signature. Then you will have to have a real FPV flight. For best calibration do it in the buff.

You'd have to be wearing a steel ring for it be a concern.
Gold, silver, aluminium, brass, lead and a whole lot of other metals will have zero effect on the compass.

 

[ruggb]

Is that why mine is all rusty!!!!!

 

[FormerMember07122019_2]

My conclusions from this long discussion on the compass.

Magnetic Interference? - move to a different take-off point.

Calibrate Compass? - do the dance.

Check that heading on map matches aircraft orientation before take-off.

Go fly and and avoid big metal objects.

Did I miss anything?