Insight on my Fly Away? - HealthyDrone & YT Link

Wow that wild to see the real time playback when it strikes the building, I don't know how it didn't plummet to the ground.

Edit: I take that back, it did plummet, some how it had enough room to recover.
 
Seems like there was a problem with the compass that caused the P3 to switch to ATTI mode.
upload_2016-5-13_14-17-40.png

When the P3 starts to gain altitude magMod changes without any change in direction.

As the magMod is falling off the P3 decides there is a COMPASS_ERROR_LARGE and switches to ATTI mode.
upload_2016-5-13_14-32-16.png

The COMPASS_ERROR_LARGE occurs at 4.028. At this time the P3 switches to ATTI which had been in GPS_ATTI.

I know this has been described as fly away. Is it possible that it's actually a drift away? I know that the P3 reached 20 M/sec but the speed increased with altitude.
upload_2016-5-13_14-48-56.png


At about 15 seconds the P3 couldn't hear the RC for much of the rest of the flight.
upload_2016-5-13_14-53-2.png

2 is P, 1 is A , 0 is F and 4 is "remote control switched off" which really means the P3 can't hear the RC.
 
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I know this has been described as fly away. Is it possible that it's actually a drift away? I know that the P3 reached 20 M/sec but the speed increased with altitude.

That may be possible, although the first spike in speed (0:54 Run Time) when I initially realized something was wrong, the drone was at a steady altitude, but traveled at 74 kmh (45 mph) with out any added input from the controller and just drift alone. There was really next to no wind this morning. I know its normal to experience some drift in atti mode when there is no noticeable wind, but I haven't had it shoot off the way it did this morning.

I got a RMA, fingers crossed that it's covered.

Thanks for the analysis everyone! I think I have learned more in one day about the workings of my drone due to this than I have flying it over the past few months.
 
That may be possible, although the first spike in speed (0:54 Run Time) when I initially realized something was wrong, the drone was at a steady altitude, but traveled at 74 kmh (45 mph) with out any added input from the controller and just drift alone. There was really next to no wind this morning. I know its normal to experience some drift in atti mode when there is no noticeable wind, but I haven't had it shoot off the way it did this morning.

I got a RMA, fingers crossed that it's covered.

Thanks for the analysis everyone! I think I have learned more in one day about the workings of my drone due to this than I have flying it over the past few months.
Since you have a P3 Standard there is no motor speed or load data. But there is motor commanded data
upload_2016-5-13_15-31-6.png

This shows that up until about 18 seconds the P3 was trying to hover more than go somewhere. After that the back motors start getting faster.
 
The strange thing if wind (that would be a heavy gust) is the RC lost. Could low RC battery be the cause? Was it fully charged?
Are there any log files showing RC battery data? I hadn't realised this is a P3 standard which explains the motor graphs.
 
The strange thing if wind (that would be a heavy gust) is the RC lost. Could low RC battery be the cause? Was it fully charged?
Are there any log files showing RC battery data? I hadn't realised this is a P3 standard which explains the motor graphs.

The controller was and still is at 3 out of 4 lights for the charge indicator.
 
@Luap and I've been looking at this further.

The yaw field in the .DAT is a result of a flight controller computation. It's a prediction based on the compass magnetometers, the gyroscopes, and probably some other inputs. To look at yaw based just on the compass magnetometers a derived field called magYaw was implemented in DatCon. (Actually, magYaw was resurrected from an earlier version of DatCon). magYaw is computed in DatCon; it's not a field that exists in the .DAT. That DatCon version can be obtained by looking at GUI Version of DatConverter
upload_2016-5-15_7-9-43.png

This graph plots yaw and magYaw in the first part of the flight. Initially, magYaw has a value of 132 but the P3 is facing about -90 (this can be seen from @Krum04 's video). Yaw's value has been set close to the magYaw value by the flight controller. At about 3 secs magYaw begins to change to the correct value (increasing to +180, passing through 180, and then decreasing from -180). Yaw doesn't change because there has been no gyro input saying the P3 is turning. It is precisely this time that COMPASS_ERROR_LARGE is seen and the flyCState switches from GPS to ATTI. It's ironic that COMPASS_ERROR_LARGE is signaled because the compass has gone from incorrect to correct.


@Krum04 if you find yourself at the launch site and you're interested could you take some measurements please. Place the P3 in the same location and heading. Then rotate 90 degrees, wait 15 seconds, rotate 90 degrees, wait 15 seconds,.... No need to start the motors. Then Dropbox the .DAT.
 
I think @Krum04 is right. It wasn't a drift away it was fly away. In brief the P3 lost connection and initiated RTH 3 seconds later. But the yaw was still incorrect so it flew in the wrong direction.
upload_2016-5-15_11-5-39.png

Not shown is the connection to the RC was lost at 15 seconds. 3 seconds later at time 18 seconds RTH is initiated (grey line goes to 15). Yaw (blue line) is at -138 and needs to be at -78, the direction of home. The P3 turns clockwise so that yaw becomes -78. However, the real heading at this point is shown by magYaw to be 42. This is consistent with both @Krum04 's video and @Luap 's Dashware video.
 
From the video, this looks like classic TBE caused by what I suspect is a bad calibration. The initial pattern is a large circle. The camera horizon begins to drift right at the same time which is another symptom.

It's hard to explain why this didn't happen on the first flight but I know that often the bad calibration fly away won't always happen. There will be a heading that triggers it.
 
From the video, this looks like classic TBE caused by what I suspect is a bad calibration. The initial pattern is a large circle. The camera horizon begins to drift right at the same time which is another symptom.

It's hard to explain why this didn't happen on the first flight but I know that often the bad calibration fly away won't always happen. There will be a heading that triggers it.
I don't know about classic TBE in general. But, in this particular flight the "flyaway" was triggered when RTH was initiated and the yaw value was incorrect. Before launch the compass was incorrect. Shortly after launch the compass started having the right value but yaw didn't change to reflect the correct compass value. Yaw is a calculation done by the flight controller and was incorrect when RTH was initiated. Take a look at the post right before your post.
 
TBE is a symptom of compass / GPS disagreement:
  • FC computes a bearing from current GPS position to desired GPS position.
  • Phantom attempts to fly on that heading using the compass.
  • Phantom actually flies a different heading because the compass data is off.
  • FC finds itself in the wrong place and recalculates a new bearing to target.
  • Phantom continues to miss the target forming an arc in the process.
  • Depending on the margin of error and speed, the amount of error increases or decreases.
I suspect a bad compass calibration can be localized to only part of the compass range. This is why some people get away with bad calibrations. It's only when they point in the direction where the calibration went awry that the effect is noticed.
 
Having read through this thread, this is all too similar to what happened to me last night. I apologize if it’s more appropriate to start a new thread, but because of the similarities I thought I would reply here.

After 25 hours of flight time and hundreds of flight with no issue, i've started to have issues in the last month. Mainly loosing satellite signal for what seems like no reason. Last night, after flying in an open field with concrete grain elevators near it, a place i've flown many many times, the drone went rogue. It all of a sudden picked up speed and flew to the right and crashed into one of the grain elevators a couple hundred feet away. The last recorded speed was 52MPH without any help from the controller. The wind was around 5MPH, if that. Unfortunately, I don't think i'll be able to recover the data off the aircraft since its in pretty rough shape and the camera mount is no longer attached.

I do have a capture of the DJI app(sorry for the overlay) that shows around the 3:42 mark I loose satellite signal at 177feet while barely moving, maybe 2mph. The drone then immediately begins to take off on it’s own and picks up enough speed to make it all the way to at least 52mph, which was the last recorded speed before it went crashing into the wall of a grain elevator.
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Although it did say satellite signal loss, healthy drones shows no issue with GPS. At crash time there was 15+ satellites.

This isn’t the first time i’ve experienced issues, a couple weeks ago I also had a similar issue. When loosing signal the gimbal dropped abruptly and the aircraft tilted. I was able to recover and finish out the flight without issue. Here is video with overlayed data:
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Related or not, here is a video of the drone taking off on it’s own while sitting on the ground with no controller help.
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Curious to hear anyones thoughts!
 
Update: I sent my drone in to DJI. They covered the shipping there and back. When they first received it, I was informed by the phone support that based on the flight data, the repair would be out of warranty to the tune of $260.
They said they could have a rep call me back to go through the flight data and explain why, but I would have to wait 5-10 days. I was told this on June 3rd.

I just got a tracking number today with a status update that my repairs were now covered under warranty. I am super happy to have it coming back. Summer is in full swing and not having my drone this past month has been killing me haha.

Thanks everyone for the analysis. I am going to pay extra attention to my compass status regardless of calibration from now on.
 
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Update to my post as well:

They also covered mine under warranty after reviewing flight logs. They received it on May 28th and today I was told its on its way back. It took about 7 days for them to review flight logs and warranty the work after they asked me for them
 

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