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Calibrate or not to Calibrate - What are we supposed to do?
6509 22 2016-11-23
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Homerlovesbeer
lvl.3

Australia
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Hi all,

I've been following these threads for a while now. Something that's really standing out for me are the drones that are crashing, having ATTI/GPS errors and the dreaded spin, all have been calibrated by their owners.

I can't help but think that these issues may have been a result of calibration. The Mavic seems to work nicely, the owners deceide to to a calibration and next thing you know...BOOM.....issues and spinning out of control.

I've had my Mavic a few weeks now and had about 10 successful flights with zero issues. I've upgraded the software, travelled overseas with it (Australia to Bali) and not once have I calibrated. Neither have I experienced any issues, any long IMU locks, GPS locks, etc, it's been flawless out of the box.

Now there is a shed load of conflicting information regarding calibration.

Page 50 of the owners manual states "Only calibrate the compass when the DJI Go app or status indicator prompt you to do so".

Page 23 says Quick Calibration - "Use quick calibration when the DJI Go app notifies that vision sensor calibration is required".

The owners manual doesn't even mention calibrating the control sticks....no mention at all.

Regarding IMU calibration DJI Support says "All our drones are calibrated in the factory, so you don't need to perform calibration out of the box." Do not calibrate "unless there are abnormal flying patterns for the drone."


So what are we supposed to do? To be honest I'm too scared to calibrate now, as issues seem to occur after calibration.

Is is a case of "If it's not broken don't touch it?"
Cheers guys,
Homer



2016-11-23
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Logger
Second Officer
Flight distance : 2883714 ft
Australia
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If it ain't broke don't fix it.
About 80 flights so far. It asked me to calibrate the compass before the first flight and have done nothing else since. Like yours mine has been dragged back and forth across Australia on transcontinental flights half a dozen times. New location just power it up. Wait for the greens and go fly. I was tempted at one point to recalibrate everything due to lack of still image sharpness. But I think it was operator error. Further I was reluctant to reset everything because everything else has worked perfectly & I did not want to open a can of worms.
2016-11-23
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ZeeinBC
lvl.3
Flight distance : 287749 ft
Canada
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I'm waiting on customs clearance for my mavic.  
I've been flying all sorts of quads, and a few different DJI ones.
On most other DJI quads, IMU calibration was something that was done after every upgrade and if the quad was in a new location >100KM away.  Never had an issue.
The problem was if someone screwed up the compass calibration, it would cause issues in flight. That's probably still the case now

I'll do the controller calibration since there seems to be a few controllers that show a 5% bias in one direction that's fixed after a calibration
I'll skip IMU calibration, since it seems with the dual IMU setup, it's not needed unless prompted
I won't do a VPS calibration unless it's randomly detecting objects that are not there
2016-11-23
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rick39
Second Officer
Flight distance : 164354 ft
United Kingdom
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I calibrated everything before my first flight. It's been rock solid and without issue. All calibrations were successful. If I had not calibrated the Mavic and something caused it to crash, I wouldn't know whether it was an inherent calibration issue or not. Having carried out the calibrations meticulously and seen the successful calibration report each time, and then double checked the status of the sensors, I am satisfied with the results. The calibrations made were:
1 IMU
2. Compass
3. Visual positioning system
4. Gimbal
5. Controller

These calibrations were done, where appropriate, on a levelled table top away from any interference, and having removed any metal objects from the area, including and most importantly, my smart watch.
For the people that have had issues with their drone, some will be genuine and I feel really sorry for you guys, but I wouldn't be surprised if the majority could not have been avoided if the aircraft were properly set up. Were ALL calibrations made and checked, or just a compass calibration? Additionally, were the sensor status's checked before and after?
2016-11-24
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Exib
First Officer
Flight distance : 153760 ft
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United Kingdom
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Interesting question, still waiting for Mavic to arrive but I would have done a calibration out of the box (wont do it now though) as I did with my P4 or when I traveled more than 100km away

Would be great if we had some clarification from DJI regarding this
2016-11-24
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clarksbrother
lvl.2
Flight distance : 66824 ft
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United States
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COMPLETELY agree with rick39. Speaking as a (regular aircraft) pilot. When you fly a drone, treat this as if it were an actual aircraft (because, well... it is). You should have a checklist that you run through before each flight.

1) Battery health (controller and Mavic)
2) Has unit been calibrated FULLY? If not, calibrate. Any travel/activities that could cause miscalibration? (i.e. traveling to a different part of the world requires a compass re-calibration due to fluctuations in earth's magnetic field!) Generally, I plan on calibrating the compass/gimbal every time I fly. I check the IMU/controller values BEFORE I fly.
3) Am I well enough to fly (sleep deprived or on medication that could affect my alertness/performance, etc)
4) Is the area safe to fly? Obstacles? Airspace? Hazards to persons? Etc
5) Backup plans - what happens if the drone goes down. Am I going to be able to recover it? Do I know how I'd get there?

That isn't a comprehensive list, but it's some of the biggies. I know this sounds like a lot, but it's not. You can run through that in less than 5 minutes and have the confidence to know that you've prepared yourself to have a successful flight, and once you're up in the air, you can worry about where you're going/what your filming rather than trying to troubleshoot something that could have been addressed on the ground. Have fun, good luck, and safe flying!
2016-11-24
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CptLuke
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Flight distance : 998251 ft
United States
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Logger Posted at 2016-11-24 15:29
If it ain't broke don't fix it.
About 80 flights so far. It asked me to calibrate the compass befor ...

same here , after so many flights no problem at all an so happy with this Drone
2016-11-24
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fansed802632
Second Officer
Flight distance : 1641752 ft
United Kingdom
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clarksbrother Posted at 2016-11-24 13:21
COMPLETELY agree with rick39. Speaking as a (regular aircraft) pilot. When you fly a drone, treat th ...

Agreed. And is this too simple? Facing in the direction the aircraft is pointing, I always check the compass heading before every session and swing around to make sure it "follows" me. In most cases I don't need to recalibrate.
2016-11-24
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Homerlovesbeer
lvl.3

Australia
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Ok I'm a regular pilot as well, commwecial airline pilot.

This whole notion of calibrating the compass just because I've travelled greater than 100km from the last calibration sounds very odd.

I travel massive distances when I fly yet the only time the aircraft compass is recalibrated is generally when a large part of metal is either added/subtracted from the airframe or during normal maintenance.

Airlines don't recalibrate their compass simply because they may have flown a couple of thousand miles from take off.
2016-11-24
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clarksbrother
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Homerlovesbeer Posted at 2016-11-24 10:35
Ok I'm a regular pilot as well, commwecial airline pilot.

This whole notion of calibrating the comp ...

True, but you're not flying less than 400ft off the ground most of the time. Most magnetic interference is caused by the properties of the ground you're flying over which dissipates at the square times distance. Depending on geology, when you're in CLOSE proximity to the ground as you are with a drone, this can have much larger effects than would be observable in an airliner at altitude (or really over 1000 ft). If you happen to take off in a place with higher than average magnetite concentration or is especially iron rich, this can certainly throw compass readings in closer proximity. Another area of unpredictability is over historically volcanically active regions. (example on the Big Island of Hawaii, there are areas of magnetic interference which can even throw compass readings close to ground level by 10°)

2016-11-24
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clarksbrother
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Plus, we're talking about consumer electronics here, not a TSOed piece of equipment. The act of calibration in and of itself is a good check against hardware failure which is much more likely in the case of consumer electronics vs a highly engineered piece of equipment for an airliner.
2016-11-24
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hallmark007
Captain
Flight distance : 6794423 ft
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Ireland
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Just to confuse/ or handy information...

IMU "Inertial measurement unit"
This was not written by me , but was an answer to a question I posed.
As far as I see it, IMU calibration on a level surface updates a table of values the flight controller software uses as a reference for a level stationary hover. From there the craft responds predictably to flight commands.  It also likely measures any sensor noise and thermal drift so that these technical imperfections are accounted for when using IMU sensor data in flight. - this is likely why there must be no vibrations during the calibration process.


Bad IMU calibration could cause drift and attitude issues as the flight controller fights to hold the craft in what it thinks is the correct attitude as opposed to the correct physical attitude.


The IMU usually has 2 types of sensors – angle and acceleration and in turn 3 sensors of each type measuring in the X,Y and Z axis. These sensors can, through vibration, aging, impact etc, drift in their response over time and thus an IMU calibration will establish a new reference for the IMU’s level/stationary state that the flight controller can work with to restore stable flight.


Think of calibration as the bringing back into line the measured craft attitude with the true physical craft attitude.


As to how often an IMU calibration is needed, I wouldn’t like to say; certainly after any impact or if there are suspicions the craft can’t hover in a level attitude in a windless environment. Also after a firmware update is a good opportunity just in case the stored values get corrupted or are incompatible with the later firmware.

I did put this piece together because at least 1 person seemed to have a problem, I think Bad IMU.

Its also good to mention that the IMU is the reason why you are able to shut off the motors using just the throttle down command when on the ground. The IMU reads that the aircraft is unable to move any further, and after three seconds it determines that is has officially landed and can shut off the motors safely.

2016-11-24
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Homerlovesbeer
lvl.3

Australia
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Thanks for the input guys. I've just gone for a fly this morning (burned through all 3 batteries at sunrise at the beach) and noticed when I checked the compass values that one was in the orange.

I moved the Mavic into the middle of the carpark, did a quick compass calibration and went for a fly.

No issues whatsover although when I returned to launch from my original spot one value was orange again so I think the metal fence and chairs nearby were interfering and I probably didn't need to calibrate in the first place.
2016-11-24
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Homerlovesbeer
lvl.3

Australia
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So I suppose that shows that unless the app tells you to calibrate you probably don't need to.
2016-11-24
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Logger
Second Officer
Flight distance : 2883714 ft
Australia
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Homer my Avatar might give a clue as to what I do too    
Since my last post, Mavic & I  flew 3,000km across this country (yet again). I have no doubt when I fire it up, it will all come up good to go, without the need to calibrate anything manually, nor run any cooked up pre-flight procedures. Happy to simply stick with the Manufacturers recommendations.   Invariably if I get the "Strong magnetic interference" or "calibrate compass" message it is because I am tinkering indoors with it. Simply moving outside to a clear area fixes things for me.

So I agree, no need to re-calibrate the compass unless the app tells you and in the first instance consider simply moving the device. Hi Chance the warning message will clear.
2016-11-24
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Homerlovesbeer
lvl.3

Australia
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Haha nice one Logger. Yea I flew several thousand kms to Bali and back with zero issues.

I did enjoy my flying this morning and once batteries all charged up I'll head out again this afternoon again.

All I cam say is the multi charger is a God send
2016-11-24
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Homerlovesbeer
lvl.3

Australia
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Another thing that bothers me...there isn't any way to see how my Mavic will behave when it loses GPS signal. I know it will go to Atti mode but I've been unable to fly in Atti mode. Surely I should be able to fly in Atti mode so I know how my Mavic will behave when I lose GPS?
2016-11-25
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fans814ed400
lvl.1
United States
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Every time I fly it tells me to calibrate it then it tells me that I'm too close to metal what the heck is this
2017-8-27
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Paul_IA
Captain
Flight distance : 4732283 ft
United States
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fans814ed400 Posted at 2017-8-27 12:40
Every time I fly it tells me to calibrate it then it tells me that I'm too close to metal what the heck is this

I find that the compasses on the Mavic are pretty sensitive. I have a metal roof house and I have to be pretty far away from it or I'll get this error. Also check your pockets. Basically remove anything metal from your being and make sure you're away from anything with metal in it.

But once you calibrate, that should be the end of it unless it tells you different. I calibrated once when the big box arrived and haven't done it since.
2017-8-27
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DroneFlying
Captain
Flight distance : 10774613 ft
United States
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fans814ed400 Posted at 2017-8-27 12:40
Every time I fly it tells me to calibrate it then it tells me that I'm too close to metal what the heck is this

Are you getting the message during flight or when your Mavic is still on the ground? If the latter then you're probably seeing it due to the Mavic being near some type of metal, such as the steel that's often embedded in concrete. On the other hand, if you're seeing the message during flight then you may want to upload a DAT file from one of the flights where this occurred so that someone can take a look and try to figure out why it's occurring.
2017-8-27
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Woe
Captain
Flight distance : 4129268 ft
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I stick with the same rules, any new location I do calibration . If I haven't flown the location for awhile calibrate. Over 85 flights no issues,  I've only done one IMU calibration and one vision sensor calibration. Mavic is rock solid.
2017-8-27
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Swedrone
Captain
Flight distance : 10273494 ft
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I haven´t calibrated once since I started flying my Mavic (100 flights +). No problems at all. The Phantom 4 was a different story.
2017-8-28
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george_007
Second Officer
Flight distance : 183045 ft
Sweden
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I only calibrate if the app tells me to which has been.... well, never actually.  Valid both for my Phantom 4 and Mavic Pro. Both flies great.
2017-8-28
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