Mavic 2 Pro strange crash

[Peio64270]

Hello,
I recently bought a second hand Mavic 2 Pro with the idea to replace my Air 2S that I found disappointing with Litchi waypoints missions.
After having calibrated IMU and compass, I decided to realize a short test-mission in my neighbourhood in order to compare flight capacities, photos and films shot respectively by my old Mavic Pro (Jan. 2017) and by this Mavic 2 Pro.
I used first the Mavic Pro and the mission went pefectly (nice weather, no wind, short distance low speed). Then I sent the Mavic 2 on the same mission with the same success till almost at the end, when the drone passed close to a tower of an old castle and stopped, then flying very slowly in direction of this tower.
I could well observed it since I was located some 80m from this tower and it was flying so slowly that it looked immobile. But the video showed without any doubt that it was approaching dangerously the tower. At the last moment, I pushed the right stick back without any effect (at 4m 31.4s in PhantomHelp) and it hit the stones a fraction of second later, broke two propellers and fell to the ground roughly 20m down. Apart propellers, damages are limited to to the left landing gear front leg.
I have no explanation for this strange behaviour and there is no error message in the log if I believe PhantomHelp :


DJI Flight Log Viewer - PhantomHelp.com

However the only message strangely displays "decollage en cours" ("Take off started") while the drone has crashed some seconds earlier (at 44m 42.2s).
Also, just before the stop, I remark that the Mavic 2 deviated from its trajectory, if I compare to what did the Mavic 1 some minutes earlier (sea attached screeshots taken from CSVview, yellow arrow).
Could this be due to the setting sun ? Both drones were at this moment flying backward in direction of the sunset and only the Mavic 2 has back sensors for O.A. I already had this problem with my Mavic 1 while the drone was flying forward in direction of the sun. The drone stopped suddenly during the mission and I had great difficulties to resume the situation.
Thanks in advance for your help because I lost confidence in this drone.

Mission here : Mission Hub - Litchi

 

[Yorkshire_Pud]

Can you post the logfrom the Mavic pro as well. The GPS count in the M2P seem rather low, the Mavic Pro's log might be a useful comparison.

 

[GFields]

Hello,
I recently bought a second hand Mavic 2 Pro with the idea to replace my Air 2S that I found disappointing with Litchi waypoints missions.
After having calibrated IMU and compass, I decided to realize a short test-mission in my neighbourhood in order to compare flight capacities, photos and films shot respectively by my old Mavic Pro (Jan. 2017) and by this Mavic 2 Pro.
I used first the Mavic Pro and the mission went pefectly (nice weather, no wind, short distance low speed). Then I sent the Mavic 2 on the same mission with the same success till almost at the end, when the drone passed close to a tower of an old castle and stopped, then flying very slowly in direction of this tower.
I could well observed it since I was located some 80m from this tower and it was flying so slowly that it looked immobile. But the video showed without any doubt that it was approaching dangerously the tower. At the last moment, I pushed the right stick back without any effect (at 4m 31.4s in PhantomHelp) and it hit the stones a fraction of second later, broke two propellers and fell to the ground roughly 20m down. Apart propellers, damages are limited to to the left landing gear front leg.
I have no explanation for this strange behaviour and there is no error message in the log if I believe PhantomHelp :


DJI Flight Log Viewer - PhantomHelp.com

However the only message strangely displays "decollage en cours" ("Take off started") while the drone has crashed some seconds earlier (at 44m 42.2s).
Also, just before the stop, I remark that the Mavic 2 deviated from its trajectory, if I compare to what did the Mavic 1 some minutes earlier (sea attached screeshots taken from CSVview, yellow arrow).
Could this be due to the setting sun ? Both drones were at this moment flying backward in direction of the sunset and only the Mavic 2 has back sensors for O.A. I already had this problem with my Mavic 1 while the drone was flying forward in direction of the sun. The drone stopped suddenly during the mission and I had great difficulties to resume the situation.
Thanks in advance for your help because I lost confidence in this drone.

Mission here : Mission Hub - Litchi
View attachment 124810

Thanks for creating your thread in the Mavic Forum. I removed the one you posed in the Phantom Forum @Meta4 or @sar104 can help you with this

 

[Dronecation]

Hello,
I recently bought a second hand Mavic 2 Pro with the idea to replace my Air 2S that I found disappointing with Litchi waypoints missions.
After having calibrated IMU and compass, I decided to realize a short test-mission in my neighbourhood in order to compare flight capacities, photos and films shot respectively by my old Mavic Pro (Jan. 2017) and by this Mavic 2 Pro.
I used first the Mavic Pro and the mission went pefectly (nice weather, no wind, short distance low speed). Then I sent the Mavic 2 on the same mission with the same success till almost at the end, when the drone passed close to a tower of an old castle and stopped, then flying very slowly in direction of this tower.
I could well observed it since I was located some 80m from this tower and it was flying so slowly that it looked immobile. But the video showed without any doubt that it was approaching dangerously the tower. At the last moment, I pushed the right stick back without any effect (at 4m 31.4s in PhantomHelp) and it hit the stones a fraction of second later, broke two propellers and fell to the ground roughly 20m down. Apart propellers, damages are limited to to the left landing gear front leg.
I have no explanation for this strange behaviour and there is no error message in the log if I believe PhantomHelp :


DJI Flight Log Viewer - PhantomHelp.com

However the only message strangely displays "decollage en cours" ("Take off started") while the drone has crashed some seconds earlier (at 44m 42.2s).
Also, just before the stop, I remark that the Mavic 2 deviated from its trajectory, if I compare to what did the Mavic 1 some minutes earlier (sea attached screeshots taken from CSVview, yellow arrow).
Could this be due to the setting sun ? Both drones were at this moment flying backward in direction of the sunset and only the Mavic 2 has back sensors for O.A. I already had this problem with my Mavic 1 while the drone was flying forward in direction of the sun. The drone stopped suddenly during the mission and I had great difficulties to resume the situation.
Thanks in advance for your help because I lost confidence in this drone.

Mission here : Mission Hub - Litchi
View attachment 124810

Possible GPS interference from the tower?

 

[Peio64270]

Can you post the logfrom the Mavic pro as well. The GPS count in the M2P seem rather low, the Mavic Pro's log might be a useful comparison.

Yes. This is the PhantomHelp report :

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

My Mavic 1 was modded and can receive Gallileo in addition to the common GPS+Glonass. This could explain the higher number of satellites received by this drone as compared to the Mavic 2 Pro.
At 4m 30s in the Mavic 2 log, I am not too surprised by the decrease in satellites number because after this moment the drone was touching the castle tower and then, falling all along the wall. (DJI Flight Log Viewer - PhantomHelp.com)

 

[Peio64270]

Possible GPS interference from the tower?

Why not with the older Mavic 1 ?

 

[ftcros]

Possibly a loss of signal from the RC coupled with RTH being set to 'hover'? The drone then 'drifted' in the wind?

 

[Cymruflyer]

Possible GPS interference from the tower?

GPS comes from 12,400 miles above the earth and would have no bearing on a land based tower or tall building, if the rest of the area was visible to the sky.

 

[ftcros]

GPS comes from 10,000+ miles above the earth and would have no bearing on a land based tower or tall building, if the rest of the area was visible to the sky.

I do not think it involved GPS. Interference between the Remote Controller and the Drone usually results in the drone drifting or flying aimlessly or without guidance. GPS will not lock it in a 'hover' and, until RTH is established with the help of GPS, the drone just flies aimlessly. VLOS might have happened at the far end of the fortress? The altitude flown seems to have been 50 ft. Were you able to see the drone at all times at that altitude. Your RC-Drone signal is visual-line-of-sight with some help from reflective surfaces. If the signal became obstructed the RTH would initiate and the RTH altitude,etc, would take time to initiate a return. If the signal returned at the point you saw it again at the corner tower perhaps the confusion took over and the drone became a 'fly-away'. I've lost my Mavic 3 due to RF interference in visual control at 50' from where I was standing. I confirmed this with the data from the RC Pro.

 

[Yorkshire_Pud]

In both logs the GPS health/level is listed as 0, zero, I do not know if this is a quirk of these logs being Litchi logs. I am on the wrong computer to check my own Litchi flights for comparison but certainly I think the satellite count in the M2P log is low. Whether or not, around the tower, it is low enough to trigger ATTI mode I do not know but the log does not seem to indicate the it does. The drone appears to have been above VPS range.

With regards to no response to the reverse stick command, two thoughts occur to me.
1) Have you checked the sticks' calibration?
2) Do horizontal movement stick commands have any effect whilst in "waypoints" flight mode? I have not flown a Litchi waypoints flight so do not know.

Really this nerds needs the attention of @sar104 @slup or @Meta4.

 

[Meta4]

In both logs the GPS health/level is listed as 0, zero, I do not know if this is a quirk of these logs being Litchi logs.

That appears to be a glitch in the Litchi log, as the drone recorded a home point and was constantly recording distance from the home point.
With GPS Reliability of zero, neither is possible.

 

[sar104]

Really this nerds the attention of @sar104 @slup or @Meta4.

Are you saying I'm a nerd?

 

[Yorkshire_Pud]

Are you saying I'm a nerd?

oops certainly not, typo or MacBook auto correction mistake, corrected.

 

[sar104]

oops certainly not, typo or MacBook auto correction mistake, corrected.

Just kidding, and not a problem as I clearly am one. Just not used to being called on it. Except perhaps by Siri.

 

[Yorkshire_Pud]

Cough lol

 

[Dronecation]

GPS comes from 12,400 miles above the earth and would have no bearing on a land based tower or tall building, if the rest of the area was visible to the sky.

True, but I was thinking in terms of it being a metallic tower [not certain exactly what kind of tower it is] but metal structures or buildings can reflect electromagnetic waves causing issues.

 

[Peio64270]

Possibly a loss of signal from the RC coupled with RTH being set to 'hover'? The drone then 'drifted' in the wind?

This is a Mavic2. Loss of signal does not stop the mission instead this is specified in settup. And this is not the case. Further, I was 80m frm the drone and I could see it easily.

 

[Peio64270]

I do not think it involved GPS. Interference between the Remote Controller and the Drone usually results in the drone drifting or flying aimlessly or without guidance. GPS will not lock it in a 'hover' and, until RTH is established with the help of GPS, the drone just flies aimlessly. VLOS might have happened at the far end of the fortress? The altitude flown seems to have been 50 ft. Were you able to see the drone at all times at that altitude. Your RC-Drone signal is visual-line-of-sight with some help from reflective surfaces. If the signal became obstructed the RTH would initiate and the RTH altitude,etc, would take time to initiate a return. If the signal returned at the point you saw it again at the corner tower perhaps the confusion took over and the drone became a 'fly-away'. I've lost my Mavic 3 due to RF interference in visual control at 50' from where I was standing. I confirmed this with the data from the RC Pro.

As I said, I was about 80m from the drone and I could see it. Also, I received an excellent video feed on my device that allowed me to see the Mavic approaching very slowly but dangerously the tower (by visual sight, the movement was too slow to be detected, look at the log : 0.3 kmh). The log published above does not indicate any connection loss nor RTH and even no change in the mode of flight. The drone stays on "Waypoints" till I try to act on the right joystick (without any effect) some tenth of seconds before the contact, at 4m 31.4s.

 

[Peio64270]

In both logs the GPS health/level is listed as 0, zero, I do not know if this is a quirk of these logs being Litchi logs. I am on the wrong computer to check my own Litchi flights for comparison but certainly I think the satellite count in the M2P log is low. Whether or not, around the tower, it is low enough to trigger ATTI mode I do not know but the log does not seem to indicate the it does. The drone appears to have been above VPS range.

With regards to no response to the reverse stick command, two thoughts occur to me.
1) Have you checked the sticks' calibration?
2) Do horizontal movement stick commands have any effect whilst in "waypoints" flight mode? I have not flown a Litchi waypoints flight so do not know.

Really this nerds needs the attention of @sar104 @slup or @Meta4.

Very close to the tower (just before contact), GPS count is decreasing from 14 to 10, according to the log file. This is low as to compare to the Mavic 1 (20 satellites instead of 14) but as I said, My Mavic 1 receive Gallileo, not the Mavic 2.
Yes, acting on the right joystick is normally effective during a mission (you can set the mission speed to zero and fly it by acting manually on the right joystick). Speed changes as well as gimbal pitch are transmitted live by the RC during a Litchi mission and acting on the right stick overcome what was registered in the mission settings.

 

[Peio64270]

@sar104

What do you think about this strange accident ?
Could it be the setting sun wrongly recorded by the rear camera as an obstacle that stopped the Mavic 2 ?
I had in two occasion the Mavic 1 stopped during missions by the rising or setting sun right in front of the drone. But this was in open space and I can't say whether the stopped drone drifted or not by some metters at this moment.
Anyway, the front sensors should have recorded the very close proximity of the tower and they didn't, apparently.