FORCE LANDING ?!

[Mavic_Man504]

from what was mentioned earlier that's not the case

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[Ed209]

couldn't you use a battery/cell tester to see what percentages you're getting per cell?

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That would require opening the battery to isolate individual cells. Not ready to do that with a brand new battery. I wasn't looking closely at voltages in DJI Go while I was flying since I was staying close by and relatively close to the home point.

I did find a few threads on the topic that occurred to P4 pilots. But it had to do with NFZ. While there are some restricted areas in this vicinity, there are no warnings during takeoff so I don't think it would all of a sudden force my Mavic to land. There is a seaplane base out in the bay which I've seen a plane land once. And a heliport.

 

[Steve]

So where you set up the low battery warning levels it doesn't show an overview of the cells in the app?

 

[Ed209]

So where you set up the low battery warning levels it doesn't show an overview of the cells in the app?

DJI Go does display the voltages.

 

[msinger]

Steve, I was only referring to the TXT flight log. DJI GO is not storing the battery data in the log for some reason.

 

[Steve]

Steve, I was only referring to the TXT flight log. DJI GO is not storing the battery data in the log for some reason.

Oh okay lol, I was confused I'm sorry.. I was hoping that it does still pull data from the individual cells.. Kinda had me worried..

 

[BudWalker]

Was flying just now and as I was heading in the broad in DJI Go says "LANDING". Tapping the red X on the screen didn't abort it but I was able to override it similar to fighting autoland in the P3/P4. As soon as I let off the sticks it would go back and say LANDING. I was over water and about 200ft away. Battery was not even close to low yet. I landed shortly thereafter with 39% left.

Without the battery data I couldn't determine the cause. But, maybe what I did find will help someone else determine the cause. The signal SMART_BATTERY.goHome falls to 15 at about the same time the flyCState is set to ForcedLanding.

The ForcedLanding is the teal background. It's not evident, to me at least, why the SMART_BATTERY.goHome falls to 15. It may in fact be the result of flyCState set to ForcedLanding.

 

[Ed209]

Without the battery data I couldn't determine the cause. But, maybe what I did find will help someone else determine the cause. The signal SMART_BATTERY.goHome falls to 15 at about the same time the flyCState is set to ForcedLanding.
View attachment 936
The ForcedLanding is the teal background. It's not evident, to me at least, why the SMART_BATTERY.goHome falls to 15. It may in fact be the result of flyCState set to ForcedLanding.

Bud! Good to see you here. Does SMART_BATTERY.goHome have anything to do with the critical low battery warning or low battery warning. I'm pretty sure they're both set to 15% in DJI Go, I am just too lazy to go into the garage and verify. I could check tomorrow. Thanks for looking. I'm hoping we can figure it out eventually.

Edit: I was nowhere near 15% when the FORCE LANDING event happened though.

 

[msinger]

It's not evident, to me at least, why the SMART_BATTERY.goHome falls to 15. It may in fact be the result of flyCState set to ForcedLanding.

It does get set to 15 on or right after every forced landing in this log. It's an interesting observation, but I'm not sure it's the cause of the forced landing.

When the first forced landing occurred, the battery was at 42% and the voltage was 3.69V (assuming the cells are perfectly balanced). So, it doesn't seem the issue was caused by a low battery.

 

[msinger]

I'm pretty sure they're both set to 15% in DJI Go

Your flight log shows they were set to 30% and 10%.

 

[Ed209]

Your flight log shows they were set to 30% and 10%.

Oh OK I may have changed them for the Mavic to make sure I didn't get carried away. With the P3, I had them turned all the way down due to distance flights.

 

[msinger]

Here's a new flight log with some tweaks to show the available battery data:
https://www.phantomhelp.com/logviewer/NV5TJODFI6ZJIDX633MX

Note: The cell voltage is not the actual cell voltage. I took the total battery voltage and divided it by 3 just to allow the data to be displayed properly in my log viewer.

 

[BudWalker]

It does get set to 15 on or right after every forced landing in this log. It's an interesting observation, but I'm not sure it's the cause of the forced landing.

When the first forced landing occurred, the battery was at 42% and the voltage was 3.69V (assuming the cells are perfectly balanced). So, it doesn't seem the issue was caused by a low battery.

Yeah, I have to agree it's not related to the battery. In my post I alluded to the possibility that the ForcedLanding causes the SMART_BATTERY.goHome to be lowered to 15. With the P3 if SMART_BATTERY.goHome rises above SMART_BATTERY.battery then a GoHome is triggered. Maybe here SMART_BATTERY.goHome is lowered to reduce the possibility of a GoHome whilst in the ForcedLanding state?

In the first two ForcedLandings the change in the SMART_BATTERY.goHome comes after the change to ForcedLanding


There is a lot to learn about what's new with the Mavic.

 

[Ed209]

Closer review of the flight in DJI Go showing stick inputs shows that I had 100% left stick down during the first 2 events at 11:27:17 and 11:35:09. I was descending to bring it down at that point. It's like it started the auto land nanny feature only I wasn't hovering a few feet off the ground; I was 95ft and 91ft respectively. The 3rd one was my doing at 12:19:03, 5.2ft off the ground.

 

[TheLightSpeed!]

Ed209 you can adjust the gimbal horizon both in flight and on the ground. Select the HD camera in the settings and select manual gimbal Adjustments just like the P3 and P4


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[Ed209]

Ed209 you can adjust the gimbal horizon both in flight and on the ground. Select the HD camera in the settings and select manual gimbal Adjustments just like the P3 and P4


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Thanks. I'll give that a shot. I remember with the P3 you could do the gimbal auto calibration while in flight and that usually fixed the issue. I haven't had to do it in so long but maybe the manual gimbal adjustment will fix that problem.

 

[scooot]

Hi,
For seasoned pilots like the op this must be a worry but for newbies like me investing a £1000 it's terrifying.
In theory you could lose your drone on your maiden flight with a issue like this.with the knowledge of the more advanced members and feedback from mavic owners I hope these issues quickly get resolved.

Scott


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[msinger]

Closer review of the flight in DJI Go showing stick inputs shows that I had 100% left stick down during the first 2 events at 11:27:17 and 11:35:09. I was descending to bring it down at that point. It's like it started the auto land nanny feature only I wasn't hovering a few feet off the ground; I was 95ft and 91ft respectively.

The full stick down in combination with what seems to be a bad downward sensor reading is what seems to be the cause here. On the first two unexpected forced landings, you had the throttle in the full down position and the downward sensors were detecting that your Mavic was 0.32 feet from the ground. I'm guessing this is being caused by either a Mavic firmware glitch or your Mavic sensors might need to be recalibrated.

 

[BudWalker]

The full stick down in combination with what seems to be a bad downward sensor reading is what seems to be the cause here. On the first two unexpected forced landings, you had the throttle in the full down position and the downward sensors were detecting that your Mavic was 0.32 feet from the ground. I'm guessing this is being caused by either a Mavic firmware glitch or your Mavic sensors might need to be recalibrated.

I'm assuming that downward sensor means OSD.sWaveHeight? And, if it's not 0 then it's a valid measurement? If so, then looking at this flight and a couple of others from my Mavic it seems like a ForcedLanding is triggered when
1) OSD.sWaveHeight > 0.0 (supposedly valid)
2) throttle full back for 1.0 sec

Also, ForcedLanding gets un-triggered when throttle is pushed full forward.

I'm not so sure that there is a problem with the sensor, at least one that could be fixed. On the P3 the vpsHeight is quite noisy and gets a lot of spurious readings when the P3 is above 10 meters. Seems like I've read that the problem is worse over water, which was the case with this flight.

 

[CCDD]

If the theoretical water 'landing' resulted from a defect with the mavic, then it doesn't even seem like dji care is applicable. Dji care isn't a substitute for the warranty that accompanies the mavic, but is an add-on to cover damage caused by misadventure or bad luck.


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I had a Phantom crash in the water and DJI covered it under warranty by sending me a new one. They never asked for me to send back the lost unit.