Mavic issue ???

[R.Perry]

Ok I'm shooting an autonomous video with Litchi, flight is going perfectly and then boom, drone makes a sharp turn to the left and disengages. Stops an hovers.
Flying manual with DJI and same thing, drone makes a sharp left thurn, stops and hovers, camera goes nuts.
Resumed flight and all was well. This is a Mavic pro.
Has anyone experienced anything like this? If so any ideas what the problem is?
Did not lose control of the drone, but sure surprised me.

 

[clolsonus]

Not sure if it's the same thing, but I saw something similar with my mavic 2 pro. Was flying manually with the dji go app, just looking around and taking video. I was cruising slowly back near my start point looking straight down and the entire drone did a momentary glitchy hard bank and recovered (maybe to the left, I can't remember now.) The weird thing is that camera gimbal went with the drone glitch, so I saw the glitch in the video as well as seeing the drone twitch out.

My best guess was that it seemed like the flight and gimbal controllers stopped updating for 1/2 a second and then caught itself and recovered. This happened more than once in a fairly short time frame. I got it safely on the ground. This was the first time I noticed the drone do anything like this and haven't had a chance to go out and test fly it again since that happened. I kind of want to find a big open field where I don't have to pick my way through corn or woods if the issue resurfaces worse the next time.

 

[R.Perry]

Your example mimics mine. I flew for the next hour after the occurrence with no problems. At the time it happened I was between two large buildings spaced about sixty feet apart. I've often wondered if strong routers could be the culprit. Upon arriving home, I recharged batteries and few both litchi and dji go for almost forty minutes and flights went perfectly.

 

[clolsonus]

As far as I know I was well away from any RF. It was pretty warm, that was the only thing I could think of. But then if it was a software glitch, who knows. I just thought of this as I type, I wonder if there are some logs I can find and go pick through to see if any complaints or issues pop out of that.

 

[Fred Garvin]

You could post your flight logs over on the Mavic forum.....they'll be able to tell you what happened.

 

[clolsonus]

I am trying to explore the log files on my own (for fun and education or possibly self harm...)

I can find the places where I had uncommanded roll. I can see the huge spikes in the roll angle plot. The only odd thing I can see is that I am logging a corresponding hard over RC input in roll. I know I didn't do this myself and it happened a couple times later in the flight as well. So did my flight controller glitch? Did the message decoding onboard (or some other code onboard) glitch? I dunno.

I flew today and everything was rock solid, except my ipad was at 15% battery because I must have forgot and left it on last time I used it ... <dohh>... but I got 2 full batteries flown through.

Now to see if I can stitch pictures of 8' tall corn from 75' AGL.

 

[Fred Garvin]

Post up over on Mavic and see how your analysis stacks up to the guys there.....

 

[BigAl07]

Could it possibly be the obstacle avoidance sensors gettins a FALSE reading (reflection, sunlight etc)?

 

[clolsonus]

Post up over on Mavic and see how your analysis stacks up to the guys there.....

Sorry, I don't know all the drone forums. Do you have a specific link to the site you have in mind?

Thanks,

Curt.

 

[Meta4]

Sorry, I don't know all the drone forums. Do you have a specific link to the site you have in mind?

Post it here.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.

 

[Fred Garvin]

@Meta4 can hook you up...

This forum is part of the Drone Pilots Network. Just scroll down to the bottom here and you'll see the graphics of all the different ones. Click on Mavic Pilots and you'll be taken there where you can create an account as you did here. Many of us have the same account name in several of them. I frequent here, Yuneec, Inspire, and Mavic.

 

[clolsonus]

@Meta4 can hook you up...

This forum is part of the Drone Pilots Network. Just scroll down to the bottom here and you'll see the graphics of all the different ones. Click on Mavic Pilots and you'll be taken there where you can create an account as you did here. Many of us have the same account name in several of them. I frequent here, Yuneec, Inspire, and Mavic.

Does this link work for everyone that wants to check it out out? The glitch was towards the end, I saw uncommanded RC roll input in the verbose csv I downloaded.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

I now notice a note about strong interference with the RC controller at one point ... the drone was approx. 100' away from the controller at the time. I always assumed dji uses a digital link so it would reject bad packets, but maybe some corrupted packets came through. I was near my folks house, but I'm not aware that they have any military grade signal jammers running and I've flown all around this area a number of times with no issues on other days.

 

[Meta4]

Does this link work for everyone that wants to check it out out? The glitch was towards the end, I saw uncommanded RC roll input in the verbose csv I downloaded.

Yes .. the link is fine but I'm having trouble finding anything that looks like an uncommanded roll in the flight data or any text indicating uncommanded RC roll input in the verbose csv.
It would help if you could point out where in the spreadsheet you saw this.

Going through the flight data, I see two instances early in the flight where the drone rolled >10 °, both times corresponding to your joystick inputs.
But the whole flight after 7 minutes had no roll >4 °.

I now notice a note about strong interference with the RC controller at one point ... the drone was approx. 100' away from the controller at the time.

Interference is common around houses and won't cause any spurious control signal issues.

My best guess was that it seemed like the flight and gimbal controllers stopped updating for 1/2 a second and then caught itself and recovered. This happened more than once in a fairly short time frame. I got it safely on the ground.

Was the issue a genuine flight incident or could it have just been a glitch of the gimbal like you might sometimes see flying sideways against a strong wind?

 

[clolsonus]

Shoot, I screwed something up. I didn't stop to think I could cherry pick the link for sharing the logs from the url bar in my browser, so I uploaded the file again so I could copy from the little share url message box that pops up. However, I believe I uploaded the wrong file on my 2nd try. Sorry about that and sorry for wasting people's time on this. Feel free to move on to other things, but if you are super bored, here is the correct link I believe:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

The issue starts showing up at row #11446, 2020/06/25 23:23:09.963 (OSD fly time: 1147.2)

 

[Meta4]

Shoot, I screwed something up. I didn't stop to think I could cherry pick the link for sharing the logs from the url bar in my browser, so I uploaded the file again so I could copy from the little share url message box that pops up. However, I believe I uploaded the wrong file on my 2nd try. Sorry about that and sorry for wasting people's time on this. Feel free to move on to other things, but if you are super bored, here is the correct link I believe:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

The issue starts showing up at row #11446, 2020/06/25 23:23:09.963 (OSD fly time: 1147.2)

The roll to the left starting at 19:07.4 and followed by a roll to the right appears to be a result of you applying hard left aileron and stopping that suddenly.
The whole thing only lasted about two seconds but corresponds exactly with the joystick input.

 

[clolsonus]

The roll to the left starting at 19:07.4 and followed by a roll to the right appears to be a result of you applying hard left aileron and stopping that suddenly.
The whole thing only lasted about two seconds but corresponds exactly with the joystick input.

Yup, except that wasn't my thumbs commanding that input. It came from somewhere else (interference? bad comms packets? firmware glitch? stick potentiometer glitch?) Even if I'm a little shakey from 4 cups of coffee, I'm not hard over on the sticks shakey. That doesn't happen by accident without a person noticing. (Give me 10 or 20 years and maybe I won't say that as confidently as I can say it today.)

 

[Meta4]

Yup, except that wasn't my thumbs commanding that input. It came from somewhere else (interference? bad comms packets? firmware glitch? stick potentiometer glitch?) Even if I'm a little shakey from 4 cups of coffee, I'm not hard over on the sticks shakey. That doesn't happen by accident without a person noticing.

The data shows what it recorded as 2 seconds of joystick input and a corresponding move by the drone.
Interference? bad comms packets? or firmware glitch would not cause that sort of thing, and if they did it would be unusual for it to just show for two seconds out of a long flight.
The Mavic controller has Hall Effect (magnetic) sensors rather than potentiometers, and again, it would be most unusual for a fault to only show for two seconds and then go away completely.
Here's the data showing joystick input (purple).
Yellow = roll left, pink = roll right, green = joysticks centred

 

[clolsonus]

Fair enough, all we have to go on are the logs and my recollection from my memory. I don't have video showing my hands/thumbs during the glitch to definitively show one thing or another. Thanks for taking a look.

Oh, one more interesting observation. The gimbal also glitched at the same time. I've never seen the gimbal not hold position before, but either the mavic moved so quickly the gimbal couldn't keep up (is that possible under a commanded input?) or something weird happened. After the first instance, the gimbal (video) was really glitched several more times when the mavic glitched and continued to be unsteady for the remainder of the flight.

Give me a [while] and I'll upload the youtube video. (Only to illustrate that the gimbal was also acting weird and unsteady at the same time.)

Here you go (27 second video, the first glitch is about 8 seconds into it):

 

[R.Perry]

Fair enough, all we have to go on are the logs and my recollection from my memory. I don't have video showing my hands/thumbs during the glitch to definitively show one thing or another. Thanks for taking a look.

Oh, one more interesting observation. The gimbal also glitched at the same time. I've never seen the gimbal not hold position before, but either the mavic moved so quickly the gimbal couldn't keep up (is that possible under a commanded input?) or something weird happened. After the first instance, the gimbal (video) was really glitched several more times when the mavic glitched and continued to be unsteady for the remainder of the flight.

Give me a [while] and I'll upload the youtube video. (Only to illustrate that the gimbal was also acting weird and unsteady at the same time.)

Here you go (27 second video, the first glitch is about 8 seconds into it):

If you were the only one having this issue one could question what you experienced, but I experienced the same thing, and now twice, second time Mavic turning into a wall and braking a prop. This was during a Litchi waypoint mission so there was no control stick input from me.

I will get the flight logs and put them up as soon as I can.