Lost Mavic after loss of connection

[Dave A]

It would seem that DJI have programmed it to ask after 30 days.
No-one has come up with a good reason for them to do this.
Distance from anywhere is irrelevant to compass calibration and time since recalibration should also be.
My P4 pro has never had anything calibrated and has had almost two years of hard professional work over large distances.
It still flies as well as the day it came out of the box.

Although this has gotten off the OP's main subject I would have to agree with Meta4. The drone will tell you if it needs calibration. My MPP has never asked me to calibrate the compass or IMU and I have never done one. Since for a year it has flown great right out of the box why would I mess with it. If the compass is working and there has been no warning in the app to calibrate it then you can't make a working compass work better. I'm no expert, far from it, but seems to make sense to me.

 

[sar104]

Although this has gotten off the OP's main subject I would have to agree with Meta4. The drone will tell you if it needs calibration. My MPP has never asked me to calibrate the compass or IMU and I have never done one. Since for a year it has flown great right out of the box why would I mess with it. If the compass is working and there has been no warning in the app to calibrate it then you can't make a working compass work better. I'm no expert, far from it, but seems to make sense to me.

Prior to the Mavic 2 the only trigger to recalibrate the compass appeared to be if the FC detected problems with the magnetometer readings, certainly in terms of absolute values and likely if it saw unexpected variations with rotation. That mostly worked fine.

The Mavic 2 has firmware that requests calibration every 30 days, although some units are apparently immune because they have a "last calibrated" date far in the future. Why they suddenly decided to incorporate that on just this model is not clear.

 

[Oli34]

There is something not right about this. The .txt log you submitted only has 141.8 secs of data. Their analysis shows data at 168 secs. Did you submit the tablet .DAT to DJI?

DJI was given the DAT FILE. However, the time that they claim that the battery ‘popped out’ was when the drone was not in the air. The aircraft was hovering at time of disappearance so I’m not sure why the batt would dislodge then

 

[rfc]

Op, Have you been able to get down to the beach to take a closer look?

 

[BudWalker]

DJI was given the DAT FILE. However, the time that they claim that the battery ‘popped out’ was when the drone was not in the air. The aircraft was hovering at time of disappearance so I’m not sure why the batt would dislodge then

Could you provide the .DAT then? There is a small chance that it will yield something useful. It might be small enough that you can change the file extension to .txt and attach it to a post. Otherwise you'll need to use something like Dropbox or GoogleDrive.

 

[Oli34]

Could you provide the .DAT then? There is a small chance that it will yield something useful. It might be small enough that you can change the file extension to .txt and attach it to a post. Otherwise you'll need to use something like Dropbox or GoogleDrive.

Dropbox - dji flight records - Simplify your life

Dropbox - videoCache - Simplify your life

 

[SpinItUp]

Satellites intercepting drones now?

According to that DAT file your searching in the wrong part of the cosmos

 

[Meta4]

Satellites intercepting drones now?
View attachment 51489

That just looks like a zero record rather than an actual flight record
You'll note it starts at 0.000 N 0.000 E

 

[Photo Booth]

And yet another Mavic 2 that apparently fell out of the sky due to battery disconnect.

Considering the number of Mavic 2 Pros that are getting flown already, these battery disconnect issues are a tiny percentage. But, still, I don't recall reading about this many apparent battery disconnect issues with the original Mavic. I haven't handled a Mavic 2 but it sure seems like there is some sort of design problem with regard to how the battery is secured to the aircraft.

Mark

 

[sar104]

And yet another Mavic 2 that apparently fell out of the sky due to battery disconnect.

Considering the number of Mavic 2 Pros that are getting flown already, these battery disconnect issues are a tiny percentage. But, still, I don't recall reading about this many apparent battery disconnect issues with the original Mavic. I haven't handled a Mavic 2 but it sure seems like there is some sort of design problem with regard to how the battery is secured to the aircraft.

Mark

Agreed - I recall very few battery disconnects with the Mavic Pro. Comparing my MP to my M2P, the battery is easier to install in the M2P, but I can see how one might leave one side unlatched. The M2 clearly has some kind of battery detection system since it writes the variable "battery_info:Batpresent" to the DAT file.

 

[Photo Booth]

The bigger question is... Are some of these Mavic 2 Pro batteries becoming unlatched even though the battery was installed correctly by the pilot? Is the latching mechanism itself a "defective" design?

Mark

 

[sar104]

The bigger question is... Are some of these Mavic 2 Pro batteries becoming unlatched even though the battery was installed correctly by the pilot? Is the latching mechanism itself a "defective" design?

Mark

Is there a reason to suspect that?

 

[Photo Booth]

Is there a reason to suspect that?

Not really. But the alternative narrative is that a higher percentage of Mavic 2 Pro owners don't understand how to snap a battery in place fully and correctly (compared to original Mavic Pro owners).

Mark

 

[sar104]

Not really. But the alternative narrative is that a higher percentage of Mavic 2 Pro owners don't understand how to snap a battery in place fully and correctly (compared to original Mavic Pro owners).

Mark

Or just that it is easier on the M2 not to fully latch it.

 

[Photo Booth]

Or just that it is easier on the M2 not to fully latch it.

That's what I meant by a "defective" design. Keeping the battery in place is kinda important on a drone. If it's easier to fail to fully latch then it's due to a design change (compared to original Mavic).

I've not handled a Mavic 2 yet so guys that own both would certainly know better. But on my Mavic Pro the battery is a tight fit. You have to give it a certain amount of force to get it to fully latch but BEFORE it is fully latched it doesn't appear to be viable for flight. In other words, you have to latch it fully with some bit of pressure to fully seat it or it's not connected at all. Then it takes a bit of a tug to remove it. If the Mavic 2 slides in easier and is easier to remove, perhaps that was a mistake on DJI's part?

Mark

 

[Zmaj1701]

Thank you.
Although I sent the data via the app DJI wat me to go to iTunes and use drop box which I’m doing.

I was looking at the drone but then the controller bleeped saying loss of connection. I looked down at the controller to see what was going on. After looking bask at the drone it had vanished...

What I really do not understand in the whole story, if the signal is lost (I have tried it many times) the aircraft should return to the place where it take off in first place. So it is in setup by me: return to home if the signal is lost -> rth is 90 m (200 ft cca) -> before flight allways set current home position, and more important if I am 50 km away from last calibration of my compas position, allways calibrate compas on current position, after that I go fly! This four things prevent that situation which happened to you, that the drone just flyaway! Sorry about that, but I do not think this would have happened that this was all set...my prediction. Many things can affect the signal quality, it is not necessary that it is always the distance. Unless your dron was hacked by somebody else...

 

[BJR981S]

Prior to the Mavic 2 the only trigger to recalibrate the compass appeared to be if the FC detected problems with the magnetometer readings, certainly in terms of absolute values and likely if it saw unexpected variations with rotation. That mostly worked fine.

The Mavic 2 has firmware that requests calibration every 30 days, although some units are apparently immune because they have a "last calibrated" date far in the future. Why they suddenly decided to incorporate that on just this model is not clear.

I suspect that they have done this is people like Meta4 are spruiking misinformation about compass calibrations. Those of us that have been in this hobby for a long time, particular those of us with electroniscs degrees and have experience with Autopilots using magnetometers, understand a lot better than the self taught recent hobbyist of DJI only products.

As I said I suspect DJI Are fixing this problem by enforcing regular compass calibrations. On the pro it had dual compasses so you could get away with a degree of error. On the M2 only 1 compass so its more critical.

The alert that is generated by the app and does so when excessive compass interference is detected. It neither alerts for low level magnetic anomalies introduced by the drone itself. Or for significant magnetic anomalies in the area of flight that you may encounter.

The motors on these drones are magnetic they pulse magnetic fields.. They will magnetise the iron based components in the drone over time. Unless you degauss the drone regularly you should calibrate the compass regularly. Particular when moving to a new flight location that may have localised significant magnetic anomalies.

Calibration also calibrates the deviation angle of true north from magnetic north based on your calibration location.

I would not recommend regular calibrations of the IMU, only the Compass.

 

[sar104]

That's what I meant by a "defective" design. Keeping the battery in place is kinda important on a drone. If it's easier to fail to fully latch then it's due to a design change (compared to original Mavic).

I've not handled a Mavic 2 yet so guys that own both would certainly know better. But on my Mavic Pro the battery is a tight fit. You have to give it a certain amount of force to get it to fully latch but BEFORE it is fully latched it doesn't appear to be viable for flight. In other words, you have to latch it fully with some bit of pressure to fully seat it or it's not connected at all. Then it takes a bit of a tug to remove it. If the Mavic 2 slides in easier and is easier to remove, perhaps that was a mistake on DJI's part?

Mark

The M2 battery slides in more smoothly, so in that sense it is easier to install properly. I don't know whether that make it more likely for someone not to latch it correctly. On mine I found that it is possible not to engage both latches, but only by not positively pushing it into place. I'm not sure that a smoother fit should be characterized as a design fault.

 

[sar104]

I suspect that they have done this is people like Meta4 are spruiking misinformation about compass calibrations. Those of us that have been in this hobby for a long time, particular those of us with electroniscs degrees and have experience with Autopilots using magnetometers, understand a lot better than the self taught recent hobbyist of DJI only products.

As I said I suspect DJI Are fixing this problem by enforcing regular compass calibrations. On the pro it had dual compasses so you could get away with a degree of error. On the M2 only 1 compass so its more critical.

The alert that is generated by the app and does so when excessive compass interference is detected. It neither alerts for low level magnetic anomalies introduced by the drone itself. Or for significant magnetic anomalies in the area of flight that you may encounter.

The motors on these drones are magnetic they pulse magnetic fields.. They will magnetise the iron based components in the drone over time. Unless you degauss the drone regularly you should calibrate the compass regularly. Particular when moving to a new flight location that may have localised significant magnetic anomalies.

Calibration also calibrates the deviation angle of true north from magnetic north based on your calibration location.

I would not recommend regular calibrations of the IMU, only the Compass.

Actually I'm not sure that you really understand the sensor technology in these aircraft at all. In the many logs that I've looked at related to compass issues, lack of calibration has possibly arisen once as a cause. And many users have been flying the Phantom and Mavic aircraft for years without recalibration, and the log data do not indicate any problems. If you had ever looked at these data yourself you would know that.

And so, while regular calibration should not cause any problems itself, it certainly isn't necessary, which is why, presumably, DJI guidance for many of their models has been to calibrate only when the FC requests it. That fact, alone, should tell you that arguing that DJI knows best, even though they have never explained their intermittent "recalibrate if you move location" or "recalibrate regularly" strategy, is not logical.

"The alert that is generated by the app and does so when excessive compass interference is detected. It neither alerts for low level magnetic anomalies introduced by the drone itself. Or for significant magnetic anomalies in the area of flight that you may encounter."​

What on earth is that statement supposed to mean? So it detects magnetic interference, but not interference due to the drone and not interference where you are flying? What, exactly, does that leave for it to detect?

And then the old nonsense again about calibration correcting for deviation or local magnetic anomalies. It's completely, trivially obvious that it cannot do that. True north is an arbitrary direction - it cannot measure or detect true north. Deviation is computed based on a global magnetic model, not measured. Even a cursory literature search would confirm that.

I'm afraid that once again it is you propagating disinformation, not @Meta4.

 

[dbyantis]

After checking that the aircraft was safe to fly, I took off from a carpark that over looked Polzeath (Cornwall UK). The signal was excellent when I started to take photos and videos of the sunset when suddenly the remote said connection lost. I then immediately pressed return to home but the drone didn’t respond. I ran to the cliff edge as it was Lowtide I went onto the beach to search for the drone at its last known location . I searched everywhere for an hour, and had the controller on at all time. I asked people on the beach if I had seen the drone but no one had. I had taken all precautions and always kept the drone in line of sight as instructed by the app.

I’ve sent data to DJI. I’m hoping for a claim on the warranty as I was very close to the drone given it’s meant to have a huge range.

What do you guys think about this case?

Was there metal in the car park? Compass may have been compromised.