P4 active track erratic, falls out of sky

[baane]

I was testing the active track feature and it was acting erratically. The P4 would not hold altitude and would not move horizontallyto follow the subject, it would just rotate in place. Finally, the P4 climbed then dropped from a significant altitude. Luckily a friend was able to catch the P4 so it didn't crash into the ground. I have both flight logs and video of the incident. I am hoping this forum can tell me what happened. I don'tbelieve it was operator error. I have hovered the P4 at low heights since the incident and everything appears to be functioning normally as long as I don't use any of the intelligent flight modes. I am on vacation and would really like to capture so more of the amazing sights but am fearful of another incident occurring without knowing the cause of the first incident.

HealthyDrones.com - Innovative flight data analysis that matters

 

[msinger]

Please upload your TXT flight log here and post a link back here.

 

[baane]

I provided a link to the healthy drones upload of the l9g file in my original post. Here is the phantomhelp link:


Phantom Log Viewer - PhantomHelp.com

 

[baane]

Please upload your TXT flight log here and post a link back here.

Done.

 

[msinger]

After your Phantom started climbing on its own at the end of the flight, it looks like the motors stopped after you had the throttle in the full down position for ~2.5 seconds. That should not happen mid-flight. At that time, the downward sensors were detecting your Phantom was less than 1 foot from the ground. Throughout your log, I'm seeing many other places where the downward sensors were detecting the ground when your Phantom wasn't close to the ground.

Contact DJI support and see what they think about your flight log. I'm assuming you either have a bad piece of hardware or there is a bug in the firmware.

 

[baane]

After your Phantom started climbing on its own at the end of the flight, it looks like the motors stopped after you had the throttle in the full down position for ~2.5 seconds. That should not happen mid-flight. At that time, the downward sensors were detecting your Phantom was less than 1 foot from the ground. Throughout your log, I'm seeing many other places where the downward sensors were detecting the ground when your Phantom wasn't close to the ground.

Contact DJI support and see what they think about your flight log. I'm assuming you either have a bad piece of hardware or there is a bug in the firmware.

Thanks for the response. I assume that this means that I can't fly for the rest of my trip as I don't want to risk a crash.

Also just to note that the motors were still running when my friend caught the P4. I shut them down after he had it in his hands. The video from the P4 shows his clothes moving from the prop wash until I stop the props,

 

[msinger]

Was the altitude just off by 25 feet then? According to your flight log, your Phantom was 25.6 feet in the air when it last logged data. If you landed on top of a hill, then that would explain that altitude difference.

Also just to note that the motors were still running when my friend caught the P4. I shut them down after he had it in his hands.

Got it. My assessment above is partially incorrect then. I was assuming it actually dropped from the sky -- rather than descended in a controlled manner. You had the throttle stick in the full down position at the end of the flight, so perhaps you just commanded it to descend quickly.

 

[baane]

No, your assumption was correct. The P4 was in free fall/uncontrolled descent at the end of the data. My friend literally ran underneath the falling P4 and caught it. The props were still spinning but not providing lift. All of the props were intact. I shut down the motors after he caught the P4. Prior to shutting down the motors I don't believe I was inputting a command to descend as I was watching the P4 ascend uncommanded. May the command you see is me shutting down the motors after my friend caught the P4?

The end point was only a few feet from the takeoff point. Definitely not a 25 feet difference in height between those points.

I don't see the downward sensor data to which you refer in either the downloaded .csv file or the healthydrones.com output. Can you tell me where you are finding it?

 

[baane]

Is there a way to turn off the downward sensors and still fly safely?

Was the altitude just off by 25 feet then? According to your flight log, your Phantom was 25.6 feet in the air when it last logged data. If you landed on top of a hill, then that would explain that altitude difference.


Got it. My assessment above is partially incorrect then. I was assuming it actually dropped from the sky -- rather than descended in a controlled manner. You had the throttle stick in the full down position at the end of the flight, so perhaps you just commanded it to descend quickly.

 

[msinger]

You can turn off the downward sensors in DJI GO.

 

[baane]

Is there a way to turn off the downward sensors and still fly safely?

If I turn off the downward sensors what are the risks/disadvantages of doing so? For example, will auto takeoff and landing still work? Or will the motors shut down in-flight in the throttle is held down too long ( that us, the issue you identified as a potential issue above)?

 

[ems12a]

If I turn off the downward sensors what are the risks/disadvantages of doing so? For example, will auto takeoff and landing still work? Or will the motors shut down in-flight in the throttle is held down too long ( that us, the issue you identified as a potential issue above)?

Auto land will not work with the downward sensors turned off. From what I read you were descending with full throttle and the P4 sensed it was close to the ground and shut off.

You could just descend a bit slower and not give it "full stick" when landing.

 

[schlepprock]

And maybe a nice tip to your brave friend.