Hello.
Before I fly the drone, I do a compass calibration if the app asks me to do it.  Yesterday, I did it but I was sitting down on the floor and surrounded by some zinc sheets. When I flew the dron after 500 meters or so, the app asked me a compass calibration on midair.  Sometimes when I moved the drone, the alert dissapears and then after a couple of minutes it appears again.  I read the documentation and it seems I need to do the compass calibration standing up at around 1.5 meters and far from metalic objects.


My MAIN question is if I need to return to home as soon as possible when that message appears or if the alert is not THAT important and I dont need to worry TOO much.

Thanks.

Hi,

Better safe than sorry,   i would return home and perform a compass calibration

If you like   upload your flightlog using this link > https://www.phantomhelp.com/LogViewer/Upload/

or put a cloud-link on here to your flightlog.txt.

cheers
JJB

Return, as compass is very important...if is not calibrated, and your drone loose signal, at Return to Home is a good chance that you will wave your hand for it and see it gone...

Hi, Toonleap. Thanks for reaching out! As already been suggested, please fly back, land the aircraft and perform a quick compass calibration before flying again. Kindly observe the status of the aircraft thru the DJI Fly from time to time as it is crucial in maintaining a safe flight.

Stick a magnet on top of the aircraft, and the only issues you will ever see is toilet bowl effect when hovering, and slight offset in auto panoramic shots.

The compass is not essential, it is just for a bit more precision when using the normal GPS. And in fact drones with Dji's RTK does not have compass since it is unreliable  and they achieve way better position.

djiuser_267jcyL97zif Posted at 1-16 06:11
Stick a magnet on top of the aircraft, and the only issues you will ever see is toilet bowl effect when hovering, and slight offset in auto panoramic shots.

The compass is not essential, it is just for a bit more precision when using the normal GPS. And in fact drones with Dji's RTK does not have compass since it is unreliable  and they achieve way better position.

Such Rubbish , Go learn what a compass does and why you need one flying your drone, I only hope others completely ignore your ridiculous advice. Picture below will confirm just how little you Know.

hallmark007 Posted at 1-18 12:08
Such Rubbish , Go learn what a compass does and why you need one flying your drone, I only hope others completely ignore your ridiculous advice. Picture below will confirm just how little you Know.

[view_image]

Why don't you enlighten us what thr compass is used for?

I guess you have identified some reasons to be used in systems that dont need it (rtk), or need it only for secondary pourposes(in regular gps positioning).

And btw, go see some explanation why systems like rtk exist and how they eliminate compass need to get better realability arownd big industrial metal structures.

djiuser_267jcyL97zif Posted at 1-20 06:42
Why don't you enlighten us what thr compass is used for?

I guess you have identified some reasons to be used in systems that dont need it (rtk), or need it only for secondary pourposes(in regular gps positioning).

First you just lied that Phantom RTK has no compass . This tells me just how ridiculously stupid you are, but how and ever this will be totally wasted on a fool like you.


The compass tells the drone which direction it's facing. The GPS data is used to find the latitude/longitude location.
Bear in mind that in a fluid such as air, Course (path across ground) and Heading (direction nose is pointed) are often different. Only in dead calm conditions would they be the same.
Same as a boat subject to the water currents or a car 'drifting'.

GPS only knows direction if it is moving. Take a handheld GPS and stop. You can turn the GPS and it will only display the proper direction after you start moving again. You need a compass to know what direction you are facing if you aren't moving.


 

The IMU uses the accelerometer and gyroscope to know when the drone turns and calculates its heading based on its rotation and the movement data from gps.

Go read some technical docs about how these systems works. And yes, when rtk module is used, the compass is bypassed, so please stop spreading your basic knowledge.
The compass is not essential for the operation, the drone works fine without such. As I said earlier, there is only slight turn when it is stationary, and that is all. Absolutely no issues to fly without compass.

Straight from the user manual:

Introduction
The D-RTK is a GPS and barometer system specially designed to provide centimeter-level positioning accuracy
for the DJI A3 series flight controllers. Using dual antennas, its heading reference is more accurate than a normal
compass sensor, and it is able to withstand magnetic interference from metal structures.


And in the low entry like the minis, the just use acelerometers to know of it turns. The compas is so unreliable it is used as reference only, small error corrections at most.

I forgive your ignorance. Go fly.

I would defitiely in that situation take the first opertunity to land and calibate the compass.  The mid air compass calibration could be due to large scale interference it a specific area.  

djiuser_267jcyL97zif Posted at 1-21 12:22
Straight from the user manual:

Introduction

I was unable to confirm that the new Mavic's uses RTK natively.  I believe this system requires a standalone module for functionality and at this time I do not believe the Mavic Air2, Mavic Mini and Mini 2 support D-RTK as it is primarily used for professional surveying.   As this is a question for the Mini 2 and support for RTK is not well documented it is confusing for nonprofessional users.

As an aside, D-RTK systems base an initial orientation on a variation of GPS coordinate comparison and derive a heading in degrees as such.  RTK is a great system and I would not be surprised if the lower end Mavic's do not use some functionality.  But at this time DJI has made it abundantly clear that the compass is the primary form for deriving orientation.

I’m confused. Why would you do a compass calibration in my opinion with any metals within 10 feet or at least 5 feet. That just doesn’t make any sense at all.
Near zinc sheets?.
Doug

djiuser_267jcyL97zif Posted at 1-21 12:06
The IMU uses the accelerometer and gyroscope to know when the drone turns and calculates its heading based on its rotation and the movement data from gps.

Go read some technical docs about how these systems works. And yes, when rtk module is used, the compass is bypassed, so please stop spreading your basic knowledge.

You’re a complete idiot who hasn’t a clue, and as someone said bringing rtk into this was ridiculous and shows just how much of a complete idiot you are....go get yourself a book and lie on the beach idiot.

Donut Posted at 1-21 16:36
I’m confused. Why would you do a compass calibration in my opinion with any metals within 10 feet or at least 5 feet. That just doesn’t make any sense at all.
Near zinc sheets?.
Doug

At that time, I did a compass callibration near zinc sheets lying about 5 feet. The app said the compass calibration was sucessful so I didnt mind at the time. Once I was on the air and about 500 meters or so, the app sent me that compass calibration required even when I did the calibration on the ground and was sucessful.

Very weird indeed Doug.

hallmark007 Posted at 1-21 16:53
You’re a complete idiot who hasn’t a clue, and as someone said bringing rtk into this was ridiculous and shows just how much of a complete idiot you are....go get yourself a book and lie on the beach idiot.

You can insult me as much as you like, but that does not change the fact the drone does not need the compass for its return to home, stable flught or any other major functions.

djiuser_267jcyL97zif Posted at 1-23 00:48
You can insult me as much as you like, but that does not change the fact the drone does not need the compass for its return to home, stable flught or any other major functions.

You’re 100% wrong and continually giving out bad information.Dji drones can fly without GPS but not Compass, why do you think drone drops gps in favour of compass when there is conflict between Compass and IMU. Quit giving ridiculous information...

You know if you guys keep this up you’re going to force me to glue a magnet to a Spark in the name of science (Spark is my husbands so what do I care). Smiley face.

djiuser_267jcyL97zif Posted at 1-23 00:48
You can insult me as much as you like, but that does not change the fact the drone does not need the compass for its return to home, stable flught or any other major functions.

I agree that RTH is based on GPS.  The compass would not be needed for the process.

Don't know much about drones as I'm new but I know for a fact a drone should not need a compass to head home.

Don't people remember the very 1st GPS systems portable Bluetooth devices?

Technically only a GPS is needed to reach any destination.

JohnLietzke Posted at 1-23 13:24
I agree that RTH is based on GPS.  The compass would not be needed for the process.

i read and cannot believe what kind of stupidity people on this forum come up with...if the compass is not needed why it is so important to calibrate it? why dji explicitly states to calibrate before take off and make sure it is accurate?? if you don't need it then please make sure you calibrate next to a magnet, then take off and grab the results. it will be quite entertaining story and a good lesson for you.

djiuser_hJmrJuQGB6Sn Posted at 1-23 13:52
Don't know much about drones as I'm new but I know for a fact a drone should not need a compass to head home.

Don't people remember the very 1st GPS systems portable Bluetooth devices?

How Does RTH Work?

A DJI drone will set its takeoff position as the Home Point when it receives four GPS signals or more. The drone will continuously analyze real-time GPS coordinates and use a compass to assist its return flight. Anything that interferes with the Home Point position,” GPS, or compass can affect the RTH function.”

In order to ensure your drone returns to the Home Point safely, please fly it in an open area free of interference, and remember to refresh the Home Point before any flight.*



*Please note that urban areas with lots of tall buildings can interfere with GPS signals. Magnetic fields, high voltage cables, and structures made from metal can also interfere with the compass.

Above an a short draft from Dji on their website, full article in link to dji site below....

https://store.dji.com/guides/ret ... have-drone-feature/

djiuser_267jcyL97zif Posted at 1-23 00:48
You can insult me as much as you like, but that does not change the fact the drone does not need the compass for its return to home, stable flught or any other major functions.

dude, i am literally ashamed you are so ignorant and on top of that from my country...to say the compass is not needed nor used in the minis as it is unreliable is beyond stupidity. you can try flying with incorrect compass heading and tell us how it feels and ends...though i doubt it will be happy ending. not to mention you might not be able to take off if compass is not calibrated. so much for an unneeded piece of unreliable tech...and the simplest example...in atti mode without gps how exactly do you imagine drone controls will look like???enlighten us please

JohnLietzke Posted at 1-23 13:24
I agree that RTH is based on GPS.  The compass would not be needed for the process.

GPS signal is necessary but not sufficient for your drone to return to home safely. Your drone's compass also needs to be relatively free from interference. GPS only determines the drone's location; the compass determines its orientation. If you initiate RTH, your aircraft will turn its head and fly back to the Home Point. But if it doesn't know which way to turn, it may end up flying somewhere else.

Check out djis article above..post 22

Lisa3 AKA Karen Posted at 1-23 09:36
You know if you guys keep this up you’re going to force me to glue a magnet to a Spark in the name of science (Spark is my husbands so what do I care). Smiley face.

You dont need to put a magnet on anything, yes it may cause drone to TBE, But it may also cause conflict Between IMU and Compass and your Drone in this circumstance is designed to drop GPS in favour of Compass because dji drones can fly without GPS but not without Compass. We all know that they’re drones out there that dont use compass IE Skydio, but dji drones including all new drones are equipped with 1,2, or 3 compasses and they are not there for fun ;+)’’’”””

hallmark007 Posted at 1-23 14:41
GPS signal is necessary but not sufficient for your drone to return to home safely. Your drone's compass also needs to be relatively free from interference. GPS only determines the drone's location; the compass determines its orientation. If you initiate RTH, your aircraft will turn its head and fly back to the Home Point. But if it doesn't know which way to turn, it may end up flying somewhere else.

Check out djis article above..post 22

Based on your DJI documentation I just went to the park and conducted a test.

I have an 80lbs magnet that I set to the west of the drone about 2ft away.   Then did a compass calibration. The drones heading was about 290 degrees when facing north which should be 0. I used the compass on my phone to get  as close to north when facing the drone to look at the orientation radar.

I then flew a little over 500ft out and hit the RTH button.  After the Mavic Air 2 turned and began to fly it corrected itself after about 20ft to the most direct line to the HomePoint and flew right to it and landed.

I think the compass is used as a fixed number for the GPS angle in a 360 degree plane to compare from to ensure accuracy.

The inaccurate compass heading had no bearing on the accuracy of the RTH.

I do think that if interference to the compass was experienced in the air that this may affect RTH.

sbonev Posted at 1-23 14:32
i read and cannot believe what kind of stupidity people on this forum come up with...if the compass is not needed why it is so important to calibrate it? why dji explicitly states to calibrate before take off and make sure it is accurate?? if you don't need it then please make sure you calibrate next to a magnet, then take off and grab the results. it will be quite entertaining story and a good lesson for you.

I just tried calibrating it next to a magnet. Have you?  

JohnLietzke Posted at 1-23 16:27
Based on your DJI documentation I just went to the park and conducted a test.

I have an 80lbs magnet that I set to the west of the drone about 2ft away.   Then did a compass calibration. The drones heading was about 290 degrees when facing north which should be 0. I used the compass on my phone to get  as close to north when facing the drone to look at the orientation radar.

Kudos to you for doing an actual test.

Very interesting, do you think it flew in the wrong direction, realized the compass must be off based on gps reading then disregarded the compass and used just the gps?

Did you get a warning to calibrate the compass during or after it returned home?

Lisa3 AKA Karen Posted at 1-23 17:37
Kudos to you for doing an actual test.

Very interesting, do you think it flew in the wrong direction, realized the compass must be off based on gps reading then disregarded the compass and used just the gps?

Lisa AKA Karen,

It was hard to tell how errant the initial RTH heading was from the HomePoint trajectory.  It was not much but it did appear too slightly correct on the screen.  There were some 5-8mph wind gusts, so that could have been why it corrected.  I can only estimate, but I would say it curved about 10-15° if that.

I have no idea what went on with GPS to Compass interaction.  I would assume that once the magnetic interference dissipated that the fixed compass heading with the -70° inaccuracy from my magnet experiment remained as the orientation indicator showed the drone at an angle even when it was flying straight out at greater than 200ft.

From my understanding once a digital Hale Affect compass is calibrated it holds the True North degree angle until it is recalibrated.  In this case an incorrect one.

My best assumption from having written a mapping application for IOS is that Mavic Air 2 is capable after movement to derive a bearing heading from GPS Coordinate comparison.  The caveat, is the difference in GPS coordinates.  Without 2 points that are .5-10m apart I do know if the Mavic Air 2 would have initially generated a somewhat accurate heading with the compass so misaligned from north.

I never got a compass calibration warning.  And it took two calibrations to return the compass to a True North.

hallmark007 Posted at 1-23 14:36
How Does RTH Work?

A DJI drone will set its takeoff position as the Home Point when it receives four GPS signals or more. The drone will continuously analyze real-time GPS coordinates and use a compass to assist its return flight. Anything that interferes with the Home Point position,” GPS, or compass can affect the RTH function.”

Which was my point in my previous post.

I only ever had issues with the very 1st iteration of GPS losing signal near built up city's with sat navs.

All it needs is cooordinates with Glonass and Galleleio imo it's far more reliable with a good fix of sats than a compass that can't be calibrated near metal, Can't be flown near metal or powerlines or flies in some random direction because of interference with the compass.

I know they're 2 different techs and a compass is for heading but there are drones out there without a compass.

I'm really not sure what the doubters don't understand about GPS being quite accurate especially with latest GPS tech.

sbonev Posted at 1-23 14:40
dude, i am literally ashamed you are so ignorant and on top of that from my country...to say the compass is not needed nor used in the minis as it is unreliable is beyond stupidity. you can try flying with incorrect compass heading and tell us how it feels and ends...though i doubt it will be happy ending. not to mention you might not be able to take off if compass is not calibrated. so much for an unneeded piece of unreliable tech...and the simplest example...in atti mode without gps how exactly do you imagine drone controls will look like???enlighten us please

It's not needed lol, There is directional tech out there without the need for a compass.

hallmark007 Posted at 1-23 09:24
You’re 100% wrong and continually giving out bad information.Dji drones can fly without GPS but not Compass, why do you think drone drops gps in favour of compass when there is conflict between Compass and IMU. Quit giving ridiculous information...

Just because DJI decided to incorporate in their software not to allow take off without a calibrated compass does not mean a device needs a compass that's because DJI decided that way it's nothing to do with the products useability.

JohnLietzke Posted at 1-23 16:29
I just tried calibrating it next to a magnet. Have you?

i am smarter than that to try stupid things just to prove somebody online how stupid their idea is...

djiuser_hJmrJuQGB6Sn Posted at 1-23 22:13
It's not needed lol, There is directional tech out there without the need for a compass.

ok the simple fact that there is tech that does not need a compass does not mean that the one in the mini is there just for the sake of one more software requirement step before flight and out of dji's whim.

your example being like there are watches without battery also...so what does that help you with your drone???

I’m stealing this and using it as my signature on another forum, it’s fantastic.

“ i am smarter than that to try stupid things just to prove somebody online how stupid their idea is..”

sbonev Posted at 1-24 01:41
ok the simple fact that there is tech that does not need a compass does not mean that the one in the mini is there just for the sake of one more software requirement step before flight and out of dji's whim.

your example being like there are watches without battery also...so what does that help you with your drone???

There are some facts about how the system works, and also 2 people that only do insults in this thread.

If you don't want to be assamed for your own country the make an apology for your own posts.

djiuser_267jcyL97zif Posted at 1-24 05:10
There are some facts about how the system works, and also 2 people that only do insults in this thread.

If you don't want to be assamed for your own country the make an apology for your own posts.

i am not ashamed of my country, but of your ignorance...big difference that proves you just play with words and have little facts to support your claims. Where are your facts how system works and that the compass is not essential for the mini/mini 2. where are your facts that compass is bypassed and not relevant for flying?

Holy smokes, entire countries are ashamed by a post on a DJI forum?

Anyway, does anyone know with absolute certainty the role of the compass on the drone in question (I’m actually more interested in how the IMU and compass work rather than how they are used but that’s for another day)?

100%, not I think, it should, it might, sort of, possibly, kind of, maybe.

Lisa3 AKA Karen Posted at 1-24 06:28
Holy smokes, entire countries are ashamed by a post on a DJI forum?

Anyway, does anyone know with absolute certainty the role of the compass on the drone in question (I’m actually more interested in how the IMU and compass work rather than how they are used but that’s for another day)?

Here plenty of reading for you.

The best way I can explain this is. If you put your Aircraft on the ground in normal circumstances, start it up, then lift it up and turn it 90 degrees to the right both your compass heading and IMU will both move together 90 degrees and no problems.
If you put your Aircraft on the ground and there is magnetic interference only the heading of your compass will change, your aircraft will still take off. But when it clears magnetic interference compass will then move to correct heading which you would think was great. But No, what happens is IMU is then conflicted and confused because of this sudden movement by compass, so you receive IMU exceptional heading warning, your aircraft cannot deal with data conflict so decides to switch to Atti mode dropping gps in favour of compass simply because aircraft can fly without gps but not compass.


The main function of gyroscope technology is to improve the drones flight capabilities.  The drone’s hardware, software and algorithms work together to improve all aspects of the flight including hovering perfectly still or taking steep angled turns.  A drone with six axis gimbal feeds information to the IMU and flight controller to vastly improve the flight capabilities.

The gyroscope needs to work almost instantly to the forces moving against the drone (gravity, wind etc) to keep it stabilized.  The gyroscope provides essential navigational information to the central flight control systems.

In the vast majority of drones, the gyroscope is encompassed or integrated within the IMU (Inertial Measurement Unit).  The drone IMU, along with  satellite positioning (GPS and GLONASS) are also components of the flight controller system.

An inertial measurement unit works by detecting the current rate of acceleration using one or more accelerometers. The IMU detects changes in rotational attributes like pitch, roll and yaw using one or more gyroscopes.  Some IMU on drones include a magnetometer, mostly to assist calibration against orientation drift.
On board processors continually calculate the drones current position. First, it integrates the sensed acceleration, together with an estimate of gravity, to calculate the current velocity. Then it integrates the velocity to calculate the current position.
To fly in any direction, the flight controller gathers the IMU data on present positioning, then sends new data to the motor electronic speed controllers (ESC). These electronic speed controllers signal to the motors the level of thrust and speed required for the quadcopter to fly or hover.
How a takes off and flies is fascinating technology.  In another article entitled “How A Quadcopter Flies” we explain nice and simply how a drone can take off, hover, fly in any direction and land by adjusting its motor and propeller directions.  The article includes some very informative videos.

djiuser_hJmrJuQGB6Sn Posted at 1-23 22:15
Just because DJI decided to incorporate in their software not to allow take off without a calibrated compass does not mean a device needs a compass that's because DJI decided that way it's nothing to do with the products useability.

Read what it says before you continue to spew false and wrong information. 1 I never said dji disabled drone and this is the reason they installed a compass in their drones. That would be pretty stupid. But i clearly explained why dji drones use compass.