I have done quite a few flights on manual mode. Not atti mode. Manual, where if you let go controls drone pretty much just falls down, can flip upside down etc. I have flown all those modes and now it was very first time drone would not listen at all.
Djo Mavic 2 Pro crashes against building in tripod mode
- Thread starter Donvictorio
- Start date
- Status
My M2P has behaved like that when flying between tall buildings which block off a lot of GPS signals leaving only 5 ~ 6 satellites visible. The drone was hovering fine but all of a sudden it flew sideway and backward by itself. I immediately applied corrective control and it responded normally. In the log playback I could see the GPS coordinate of the drone jumped a couple of times so I am convinced that the drone was chasing after erroneous GPS coordinates.
Looking at the data, you were giving it full down on the left stick from 20:46.6 until 23:06.4 which brought the Mavic down from 1400 ft to 94 ft.
At 23:08.8 you gave it aileron and elevator input which slowed the drone to zero and then to a positive velocity in the other direction.
Any change of movement would have been slow because the drone was in Tripod Mode.
As it was at least 260 feet from you, your perception of what was happening is questionable.
If you are comparing with a playback of the flight record, the position showing will be incorrect since that is another thing that requires good GPS.
It's much more likely to simply be a result of having no reliable GPS and flying in atti mode.
See my comment above
The flight data would confirm if this was the case.
Meta4, everything you say makes sense to me and has always been reasonably clear.
Please see the photo.
I was at yellow dot, and that's where I wanted to land (its not the home point) so I was lowering down drone until point 1,subsequently I start slowly proceeding aheas towards me. Approx 30 m in front of me drone suddenly starts to move to left towards building. As I had an excellent visual i immediately applied counter to starboard but when I saw there is no reaction and lateral speed is high, I released all controls and switched to tripod mode at point three. Then I just watched how drone continues until crashes at 4.
The flight environment is very poor for GPS, which the data shows pretty clearly.
Flying there has significant risks.
In summary, I'm not surprised by DJI's finding.
It matches what I see in the recorded flight data.
- Joined
- May 25, 2017
- Messages
- 8,491
- Reactions
- 7,976
- Age
- 61
You had fantastic satellite reception at 500m though, nearly 50m higher than the Petronas Twin Towers, incredible.
Were you trying to use active track up there on the towers ?
No wonder finding satellites was a problem down lower.
www.google.com
Yes DJI made the right call on this, you made some bad decisions.
Did you happen to find your drone pieces ?
Or were they scattered all over someones balcony ?
Were you trying to use active track up there on the towers ?
No wonder finding satellites was a problem down lower.
Google Maps
Find local businesses, view maps and get driving directions in Google Maps.
www.google.com
Yes DJI made the right call on this, you made some bad decisions.
Did you happen to find your drone pieces ?
Or were they scattered all over someones balcony ?
Were you trying to use active track up there on the towers ?
No wonder finding satellites was a problem down lower.
Google Maps
Find local businesses, view maps and get driving directions in Google Maps.
Yes DJI made the right call on this, you made some bad decisions.
Did you happen to find your drone pieces ?
Or were they scattered all over someones balcony ?
You had fantastic satellite reception at 500m though, nearly 50m higher than the Petronas Twin Towers, incredible.
Were you trying to use active track up there on the towers ?
No wonder finding satellites was a problem down lower.
Google Maps
Find local businesses, view maps and get driving directions in Google Maps.
Yes DJI made the right call on this, you made some bad decisions.
Did you happen to find your drone pieces ?
Or were they scattered all over someones balcony ?
Guys, I took off without good gps, fully aware of this. But I would have never said, that drone would be able to make its own movements and not listen to me while still in good range. That's the nut I can't crack.
I do have a great footage, and drone recovered from the building. It didn't hit anyone window, just a decoration panel. It's unusable though.
I understand that good GPS allows the drone to hold position when there are no input from the pilot. I understand that with no GPS the drone totally relies on the inputs from the pilot to control it's movement. Does having some GPS negate all control inputs from the pilot or does the pilot's input override whatever the GPS might attempt to do in controlling the flight of the drone?
If poor GPS is the cause of this crash it would seem that pilot input doesn't negate attempts to control the drone via input from GPS.
If poor GPS is the cause of this crash it would seem that pilot input doesn't negate attempts to control the drone via input from GPS.
Right? I understand erratic movement of drone chasing up incorrect position fix but why not listening to direct command from the pilot
At the end of this flight, the flight controller recognised that the position information it was getting from the GPS receiver was inaccurate and unreliable.
Therefore it assigned a GPS Health value of zero and ignored the GPS data, leaving the drone in atti mode.
So it was a case of having no GPS information rather than having partial GPS information.
GPS was not doing anything to control the drone.
Or to put it more correctly, the flight controller was ignoring, inaccurate and unreliable GPS information.
Having GPS or not having GPS does not negate your joystick inputs.
Poor GPS did not cause the crash.
What the pilot did in an environment where he had no GPS that was the cause.
- Joined
- May 27, 2017
- Messages
- 14,458
- Reactions
- 19,469
- Location
- Los Alamos, NM
- Site
- www.mavicpilots.com
The problem here looks to have been simply marginal positional holding when the number of GNSS satellites dropped to 7 towards the end of the flight. There were no flight issues prior to that in any of the modes:
There were no compass issues - directional control was fine:
But, at the end of the flight there was some loss of fine control when the navHealth dropped to 3. At 1373 seconds there was aileron and elevator input that caused the aircraft to start to move, which it did appropriately:
At 1385 seconds the aircraft was switched from sport to tripod and the control response was reduced accordingly. It continued to respond approximately correctly but the pilot was somewhat fighting the FC, partly because of the mode transition and, probably, poor positional data. That led to some unexpected drift. However, at the end of the flight the aircraft was facing east, and the stick inputs were forwards and right. The aircraft moved east and south, broadly as commanded, and the pilot added no stick inputs to correct that movement:
If that movement led to collision with a building then it appears to have been mostly pilot error.
There were no compass issues - directional control was fine:
But, at the end of the flight there was some loss of fine control when the navHealth dropped to 3. At 1373 seconds there was aileron and elevator input that caused the aircraft to start to move, which it did appropriately:
At 1385 seconds the aircraft was switched from sport to tripod and the control response was reduced accordingly. It continued to respond approximately correctly but the pilot was somewhat fighting the FC, partly because of the mode transition and, probably, poor positional data. That led to some unexpected drift. However, at the end of the flight the aircraft was facing east, and the stick inputs were forwards and right. The aircraft moved east and south, broadly as commanded, and the pilot added no stick inputs to correct that movement:
If that movement led to collision with a building then it appears to have been mostly pilot error.
The data does not support the assertion that the drone failed to respond to joystick input.
That's because data you're referring to is relying on the GPS data which we know was incorrect. You are looking at the velocity graph and say drone followed my response but that's not true. 1380-1385 I applied stick to push drone to right but as you can only see in the video, drone was fast moving to port.
1380-1385 you should see drone moving to left while controller is sending demand to go to right (and slightly ahead) however, this can be seen only in the video, not in the wrong gps data.
- Joined
- May 27, 2017
- Messages
- 14,458
- Reactions
- 19,469
- Location
- Los Alamos, NM
- Site
- www.mavicpilots.com
The GPS data ceased at 1381 seconds, so everything after that is derived from the IMU. If the aircraft was moving left (north) at the end then that isn't consistent with the IMU solution - that may or may not be significant. One question - why did you apply left aileron at 1373 seconds - that's what started the movement to the north?
You mentioned a video - did you post that?
Movie, port side movement starts in 1:28
Please let me know if you can access the video
In 1373 I did apply slight aileron to left to bring drone on top of sidewalk instead of roadlane. My intention was to shift drone around 2-4 meters to left so it's on top of the sidewalk. But I noticed that when drone would not stop moving to port even when I tried to stop it (ie when it was already above the sidewalk). I applied very gentle push as I was in Sport mode, so did it really carefully. However this started movement which never seized
- Joined
- May 27, 2017
- Messages
- 14,458
- Reactions
- 19,469
- Location
- Los Alamos, NM
- Site
- www.mavicpilots.com
That's doesn't appear to be a link to a video despite the URL - all I get is a small png file.
- Joined
- May 27, 2017
- Messages
- 14,458
- Reactions
- 19,469
- Location
- Los Alamos, NM
- Site
- www.mavicpilots.com
Can you post the mobile device DAT file ending FLY095.DAT? I need to see the raw IMU data.
2020_03_09_07_45_41.mp4
drive.google.com
Where do I get the the file you requested, please? Is it in the files from drone or from dji go app?
Can you access this file?
Google Drive: Sign-in
Access Google Drive with a Google account (for personal use) or Google Workspace account (for business use).
drive.google.com
- Joined
- May 27, 2017
- Messages
- 14,458
- Reactions
- 19,469
- Location
- Los Alamos, NM
- Site
- www.mavicpilots.com
2020_03_09_07_45_41.mp4
Where do I get the the file you requested, please? Is it in the files from drone or from dji go app?
Can you access this file?
Google Drive: Sign-in
Access Google Drive with a Google account (for personal use) or Google Workspace account (for business use).drive.google.com
That worked. The instructions to get the DAT file are in the post linked in my signature.
Mobile device DAT files (DJI GO 4 & DJI Fly)
The DAT file naming convention, based on the date and time of the start of the file, is: YY-MM-DD-hr-min-sec_FLYXXX.DAT., where XXX is the flight recorder file index from the HOME_dataRecorderFileIndex field in the txt log.
These are retrieved by the same method as the TXT logs. Under both iOS and Android they are in a subfolder, MCDatFlightRecords, in the folder that contains the TXT logs.
- Status
Similar threads
DJI Drone Deals
1. Mini 2
2. Mini 3 Pro
3. Mini 4 Pro
4. Air 2s
5. Air 3
6. Avata 2
7. Mavic 3 Pro
8. Mavic 3 Classic
2. Mini 3 Pro
3. Mini 4 Pro
4. Air 2s
5. Air 3
6. Avata 2
7. Mavic 3 Pro
8. Mavic 3 Classic
Forum statistics
