Random veering right (loss of control) - Phantom 3 Advance

[SeanL]

Hi All

Apologies for my lack of correct terminology however I'm slightly new to this drone game.

I have a DJI Phantom 3 Advanced that has developed an issue of veering off to one side (generally uncontrollable however some minor control remains). The only way to control the drone is to bring it down as quickly as possible.

This is a re-occuring issue and I have tried recalibrating the IMU and do a compass calibration before every flight. The loss of control only seems to happen randomly theres no trigger and it doesn't happen on all flights (but majority of time it does and I don't trust to fly it safely in its current state). The issue has happened in multiple locations so I don't think its any signal interference.

I have attached an image of the first occurrence of this issue and you can see how the drone erratically veers right and then I had to bring it down. The same thing has occurred on subsequent test flights (video - IMG_0121.MOV).

I have tried using CsvView to examine the .dat file however to be honest I'm not quite sure what I'm looking for. I have attached the .dat file for the first occurrence (the instance pictured on the attached image). DAT file - FLY092.DAT.zip

Has anyone else had a similar issue or know of how I might go about resolving this? Submitted a request with DJI however I don't believe they will look at it because its out of warranty period.


Thanks in advance

Sean

 

[Chris TDT]

It could be a partial power loss on the right side. If it’s not strong enough of a loss, the left rotors can increase enough to prevent vertical descent, but the result is acceleration to the right.

DJI would probably look at it, but they’ll certainly charge you. You can try that route, or a local DJI authorized repair centre if there is one near you. Either way, I wouldn’t fly it again until it’s addressed. Especially since you’ve done the usual IMU/compass calibration already to rule that out.

 

[SeanL]

Thanks Chris, how would I diagnose power loss to one side?

Yeh so reason I'm fixing it is because I'm wanting to sell it. Ideally I'd sell it working (obviously fully repaired and tested) but if I cant fix then I'll have to sell for spares. Aka I don't really want to pay for DJI to fix it plus I'm i the UK and I don't think there are many DJI authorised repair places (or at least any that I can find).

 

[Fly Dawg]

The loss of control only seems to happen randomly theres no trigger and it doesn't happen on all flights (but the majority it does and I don't trust to fly it safely in its current state). The issue has happened in multiple locations so I don't think its any signal interference.

It looks like you have a compass issue. There are compass errors all over beginning approx 8 seconds after takeoff. This could be the result of a magnetized compass, which will never calibrate properly. This is just a quick look at your data but initially that is what it appears to be.

 

[SeanL]

It looks like you have a compass issue. There are compass errors all over beginning approx 8 seconds after takeoff. This could be the result of a magnetized compass, which will never calibrate properly. This is just a quick look at your data but initially that is what it appears to be.

View attachment 105636

Thanks for this! Tried doing a bit of research on magnetised compasses but cant really find much info. You think it would be worth replacing the compass?

If this was the case what would be making it suddenly chuck out such a huge error after flying fine for a few minutes? Keen to learn how these things work!

 

[Fly Dawg]

Tried doing a bit of research on magnetised compasses but cant really find much info. You think it would be worth replacing the compass?

Being that you stated this occurs at varying locations, and assuming you calibrated the compass originally far away from any metallic objects ( Which will cause this as well ), you may try a compass degausser such as a Cfixer from here: Cfixer

 

[Chris TDT]

Being that you stated this occurs at varying locations, and assuming you calibrated the compass originally far away from any metallic objects ( Which will cause this as well ), you may try a compass degausser such as a Cfixer from here: Cfixer

Have you used cfixer by chance? I’d be curious to hear a real world example of its success!

 

[SeanL]

Being that you stated this occurs at varying locations, and assuming you calibrated the compass originally far away from any metallic objects ( Which will cause this as well ), you may try a compass degausser such as a Cfixer from here: Cfixer

Yep calibrated in a grass field. The thing I'm trying to get my head around is what causes the sudden change.

 

[Fly Dawg]

I’d be curious to hear a real world example of its success!

Do a search around here, there are quite a few examples of it's success in multiple threads.

 

[Fly Dawg]

The thing I'm trying to get my head around is what causes the sudden change.

It could be caused by any number of different things. Primarily if your aircraft has been near any sort of magnetic field, while in storage. There have been quite a few instances of pilots transporting the aircraft near speakers for instance, which will magnetize the compass and it will not calibrate properly until degaused.

 

[WV. Rootman]

I have read posts where degaussing worked well. Search the archives on this forum.

 

[3rdof5]

Check this thread:
Unstable flight. Compass error.