I thought compass issues usually caused spinning? I can send a plot of each compass value for each axis, my memory is it was normal...when I get back to my computer I plan to check GPS reception first....
First flight fly away....P3A crash...
- Thread starter TmoneyF
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I thought compass issues usually caused spinning? I can send a plot of each compass value for each axis, my memory is it was normal...when I get back to my computer I plan to check GPS reception first....
Mod indicates issues and seems to be probable cause of the crash (compass )- will post a video soon
Below the video - do watch it up to the very end. Still not 100% sure what the cause is but preliminary findings.
All of this made with @BudWalker tools - Datconvert and Datkml converter. A big thanks to him for bringing these cool converters out!
All of this made with @BudWalker tools - Datconvert and Datkml converter. A big thanks to him for bringing these cool converters out!
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Can you make this a stickie? It's so helpful and I always have trouble finding it with search.
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Cool map at the end @Luap. I will add a couple chats below. For Luap's video you can see the Phantom moving to the right with no control input at 15 sec. Mod is at 1553....then at 18 sec the throttle is pushed all the way down and mod is still 1506 and stable. At around 21 sec after the Phantom has crossed the street the mod starts to go crazy and at 25 sec the CSC is sent. I have locked into when it was drifting at 7 mph with no user inputs. The number of satellites are stable through that time frame.
Here is first chart, it shows control inputs against horizontal velocity. The down throttle is good way to line up to the posted video, it is about the time the Phantom has crossed the street. I then put lines around the period that the Phantom is drifting.
The next chart shows the magmod during this period with velocity to line it up. While it does get messed up later, it doesn't seem any different at the start of the horizontal velocity increase
Here we look at just MagZ
and here is magx and mag y
finally here is the reported longitude and latitude
Here is first chart, it shows control inputs against horizontal velocity. The down throttle is good way to line up to the posted video, it is about the time the Phantom has crossed the street. I then put lines around the period that the Phantom is drifting.
The next chart shows the magmod during this period with velocity to line it up. While it does get messed up later, it doesn't seem any different at the start of the horizontal velocity increase
Here we look at just MagZ
and here is magx and mag y
finally here is the reported longitude and latitude
I can't really say for sure what happened yet....no log messages for compass error or ATTI mode before that. @Tmoney did the drift direction match the wind? The magx and magy keep going a bit after his rudder input, but nothing too crazy....the mod looks fine and the magz for sure...
ianwood
Taco Wrangler
Agreed. There are pretty large compass variations and the characteristic toilet bowl movement.
No the drift for sure did not match the wind. The wind was blowing perpendicular to the machine. It was blowing up the street.
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Incredible work. The amount of data interpretation going on here is outstanding. Is it possible for RF interference to give a CSC command without coming from the transmitter?
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We confirmed the CSC was from the remote, but it was after the Phantom drifted away while TmoneyF was trying to regain control. I have been studying some compass data from other flights and they do not have the pattern in the mod data shown above and below. I looked at the frequency and expected something around 60 HZ to match the powerlines but is was more like 1.36 HZ or .73 sec period...weird....going to try to check the compass calibration next...I think it is also in the data file....
Question does Litchi auto return if you are loose signal and come home? If you set waypoints at a distance what would happen if you lost signal with Litchi. I know with the DJI Go app it would return
Thank you, Nick... great detective work. This is the 4th crash I've seen near a busy street. One member suggested semi trucks with non FAA approved or over powered broadcast on RF which might bombard the phantom. In all four cases the quad refused commands from operator and the quads motors would either allow the craft to characteristically spiral the toilet drain and or fall with a tumble as if the compass is being shaken around different axis.
What does DJI do for folks who's birds crash in these situations?
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What does DJI do for folks who's birds crash in these situations?
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Still investigating but it doesn't look like it totally ignored the RC commands, it just started drifting. Since it didn't give a compass error or indication that it entered ATTI mode, I kind of think DJI would cover it. Also, according to TmoneyF the wind was in a different direction so it seems that it wasn't in ATTI mode anyway...
I took my new phantom 3 pro to a wide open field the first time I flew it last week. No trees, no power lines, no houses and no streets. Look like it hit the power lines and caused it to flip
Here is my last picture, I believe this is where the harmonic first appears in compass mod. This is really close to your takeoff point about 7m (23 feet) up early in your flight, I am able to see it for the rest of the flight. If the compass signal was the issue I am disappointed it didn't show an error and switch to ATTI mode. The amplitude of the harmonic increases as you approach the powerlines which occurs during the drift you did not command. I do not think I would fly at this location again....
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