System Error - erratic behaviour - splash

[Captain Jack]

Very remote location salt water inlet - no communications - no humans nor infrastructure.
Planned Litchi waypoint mission one third completed when "System Error" reported and mission aborted. Bird stationary. Reloaded mission and bird began to return to first waypoint - not what I wanted so I paused mission and took control. All okay for first moments until I saw that it was going backward to controls, or so I believed. Plenty of power - 85%

Tried to complete part of my planned flight best I could, but maybe it was my frizzled nerves 15 metres above saltwater, because it did not seem to be responding to my stick movements, so initiated RTH. Big mistake I think although I have done this once or twice before when over water, and cancel out when the bird got nearly back to home.

The home location (boat) had shifted so Mavic flew past. I cancelled RTH or so I thought and began to fly back to boat where I descended to about 7 or 8 metres using controls then started getting into position to hand catch. While moving across the deck, heard "Landing" and looked to see the craft a metre or two above the water. Pushed sticks in panic. But she splashed.

Sank in 7 metres of dark tannin stained water, viz nearly zero.
Spent the rest of day dragging a grapple across last known position.
Zeus smiled down on last cast when nearly dark, a sodden slightly muddy bird came up dripping saltwater.
Back on board, battery removed, gimbal lock on, she went straight into a pail of fresh water and sloshed up and down, changed water and did that again, and let her sit there for a few hours. Afterwards, shook her as dry as could till next day when the sun came out hot, and bird put on deck, turned over from time to time for next 48 hours.
A week later, took a deep breath and fired up with new battery, and very surprised that she came alive with GPS, but no output on micro USB port (no DAT file). Not sure yet about recording on Micro SD, try that today when we test fly, camera working but foggy lens.
Not sure if this was pilot error or equipment malfunction. Be very pleased if a more knowledgeable member could look over my CSV file and give me their opinion.
In any case, I'm in the market for a new drone. This poor baby could never be trusted to do the sort of flying we do out here in the wilderness. It'll go up on the wall back at our shack as a reminder how serious is this business.
Litchi Mission:
Mission Hub - Litchi
CSV file: (save as)
2018-01-16_11-19-14_v2 – Jack and Jude

 

[BD0G]

Noooooooo! Sounds like a daymare.



The .csv looks fine when exported as a .kml and viewed through Virtual Lichti Mission and Google Earth.

So can you pull your flight logs and post so the pro's here can analyze?

 

[Captain Jack]

Yeah that's how it looks to me too, but when I plug the bird into my computer, only the video files come up. Flight assistant shows the logs, but bombs out on download. Any suggestion?

 

[BD0G]

Reposted from one of msingers posts.

The DAT flight logs are stored internally on your Mavic. The TXT flight logs are stored on the mobile device running DJI GO. You can find tools to retrieve/read those flight logs here.

So (in theory) you can get to your .txt flight logs.

 

[Captain Jack]

Thanks BD0G,
I was not using GO4, but running a Litchi mission and then switched to FPV Litchi - only see CSV in the flightlogs folder. There is another folder SDK, which has zip files and there are .DAT in that, but they do not load into DATCON, which reports they are NOT DAT files. Mystery to me.

 

[Kxtrain]

Should i be as impressed as I am that you actually dragged it to the service with out being able to see it. That seems against all odds.

 

[Captain Jack]

Should i be as impressed as I am that you actually dragged it to the service with out being able to see it. That seems against all odds.

Indeed, a great reward for many hours of work. We had the last known Waypoint and plotted it on GPSU and then put a 4 M radius around it. Made a grapple out of stiff fencing wire with fishing weights on the monofiliment line, then anchored our dinghy as close to the 4 m radius and began chucking out the grapple. Took several hours, and we'd given up when on the last cast it hooked the Mavic on a front arm. Amazing to say the least.

Life Afloat - Jack and Jude, explorers, photographers, authors

 

[BudWalker]

Very remote location salt water inlet - no communications - no humans nor infrastructure.
Planned Litchi waypoint mission one third completed when "System Error" reported and mission aborted. Bird stationary. Reloaded mission and bird began to return to first waypoint - not what I wanted so I paused mission and took control. All okay for first moments until I saw that it was going backward to controls, or so I believed. Plenty of power - 85%

Tried to complete part of my planned flight best I could, but maybe it was my frizzled nerves 15 metres above saltwater, because it did not seem to be responding to my stick movements, so initiated RTH. Big mistake I think although I have done this once or twice before when over water, and cancel out when the bird got nearly back to home.

The home location (boat) had shifted so Mavic flew past. I cancelled RTH or so I thought and began to fly back to boat where I descended to about 7 or 8 metres using controls then started getting into position to hand catch. While moving across the deck, heard "Landing" and looked to see the craft a metre or two above the water. Pushed sticks in panic. But she splashed.

Sank in 7 metres of dark tannin stained water, viz nearly zero.
Spent the rest of day dragging a grapple across last known position.
Zeus smiled down on last cast when nearly dark, a sodden slightly muddy bird came up dripping saltwater.
Back on board, battery removed, gimbal lock on, she went straight into a pail of fresh water and sloshed up and down, changed water and did that again, and let her sit there for a few hours. Afterwards, shook her as dry as could till next day when the sun came out hot, and bird put on deck, turned over from time to time for next 48 hours.
A week later, took a deep breath and fired up with new battery, and very surprised that she came alive with GPS, but no output on micro USB port (no DAT file). Not sure yet about recording on Micro SD, try that today when we test fly, camera working but foggy lens.
Not sure if this was pilot error or equipment malfunction. Be very pleased if a more knowledgeable member could look over my CSV file and give me their opinion.
In any case, I'm in the market for a new drone. This poor baby could never be trusted to do the sort of flying we do out here in the wilderness. It'll go up on the wall back at our shack as a reminder how serious is this business.
Litchi Mission:
Mission Hub - Litchi
CSV file: (save as)
2018-01-16_11-19-14_v2 – Jack and Jude

Looking at the .csv log that Litchi produces it appears that RTH was initiated at about 336 secs and was never cancelled.


Also, there were no stick inputs in the final 10 seconds of flight.

 

[Captain Jack]

Looking at the .csv log that Litchi produces it appears that RTH was initiated at about 336 secs and was never cancelled.

Thanks BudWalker, I saw that and brings up the burning question. I did cancel the the RTH on screen by pressing the RTH button and cancelling, and thought I had done that, and started moving into a hand catch position on my foredeck, my eyes on navigating around hatches, dinghy etc and then heard "Landing" to my horror.

Looking at the CSV was imitated around 278 sec, landing at 355 sec.

From RTH and Landing, I always have thought that I had no control, no matter what I did to the sticks, and looking at the Lat/Long in relationship to the RC sticks seems that way to me.
What do you think?

 

[BudWalker]

Thanks BudWalker, I saw that and brings up the burning question. I did cancel the the RTH on screen by pressing the RTH button and cancelling, and thought I had done that, and started moving into a hand catch position on my foredeck, my eyes on navigating around hatches, dinghy etc and then heard "Landing" to my horror.

Looking at the CSV was imitated around 278 sec, landing at 355 sec.

From RTH and Landing, I always have thought that I had no control, no matter what I did to the sticks, and looking at the Lat/Long in relationship to the RC sticks seems that way to me.
What do you think?

You do have some control during RTH, but it's attenuated because the AC is also trying to control it's movements. I know when I've done this it's a bit disconcerting - although the controls work it's clear I'm fighting the AC.

At 340 secs full negative elevator was input for about 3 secs.


Since the AC had a heading of 160 degrees it's velocity increased in a northerly direction; it flew backwards. Litchi uses the label VelocityX for velocityNorth. It's shown in blue here


You can also see the change in position go from this
to this
during the interval of full negative elevator.

 

[Captain Jack]

You do have some control during RTH, but it's attenuated because the AC is also trying to control it's movements. I know when I've done this it's a bit disconcerting - although the controls work it's clear I'm fighting the AC.

The boat had been shifted by the breeze (we were anchored) and I was trying to bring the AC to where we were then, and I did.
I thought I had cancelled the RTH and as mentioned was moving myself into a clear hand catch position, when I heard "landing." I remember operating the sticks in a last second effort to avoid ditching, but by your image, the AC went west.
I'm trying to see if the "System Error" that started this whole event could be at fault, or decide that it was pilot error.
I have had a few words with support at Litchi and have been informed shifting to "sports" clears the mission, but alas I was using their PDF copy of help which is not clear and so initiated RTH.

 

[BudWalker]

The boat had been shifted by the breeze (we were anchored) and I was trying to bring the AC to where we were then, and I did.
I thought I had cancelled the RTH and as mentioned was moving myself into a clear hand catch position, when I heard "landing." I remember operating the sticks in a last second effort to avoid ditching, but by your image, the AC went west.
I'm trying to see if the "System Error" that started this whole event could be at fault, or decide that it was pilot error.
I have had a few words with support at Litchi and have been informed shifting to "sports" clears the mission, but alas I was using their PDF copy of help which is not clear and so initiated RTH.

OK, I'm gonna change my mind on what happened here. The last part of the flight looked like this

When RTH was initiated it flew to the H symbol - the HomePoint location. RTH was actually terminated here. It responded normally to stick inputs and flew to 2, then 3, then 4 all because of the stick inputs. There were periods where there were no stick inputs but the Mavic didn't attempt to return to the HomePoint. If RTH were still active then it would have attempted to move towards the HomePoint during these periods.

Litchi seems to report things a little differently than the .txt produced by the Go App. I'm assuming that when flightMode changed from GoHome to Landing is where RTH was terminated.

When it reached 4 there were no more stick inputs for the remaining 10 secs but the Mavic descended anyway. There have been many incidents like this that were caused by the ultrasonic sensor producing faulty data making it look like the Mavic was < 0.5 meters high. Unfortunately, Litchi doesn't log the vpsHeight signal so there's no way to check this.

 

[Captain Jack]

Thank you BudWalker
Greatly appreciate your involvement with figuring out what happened. Tragic, and has shaken my confidence as a pilot, which is troubling as a I am a master of ships who is usually diligent and careful. It's a shame that I had just switched on those sensors for that flight hoping that I would lose the blades that I was occasionally getting in the video.

My wife and I have written a few books on our maritime exploits and one describing our two year Australian circumnavigation is in ebook format, I'd be please to send you a link to it if you're interested. PM your email and I'll send it to you, cheers from Tasmania.

Here's a link to one of the Mavic's last flights over the wild west coast
Unfortunately, on this one YouTube did a pretty ordinary job of rendering as it has lots of fine detail.

 

[BudWalker]

Thank you BudWalker
Greatly appreciate your involvement with figuring out what happened. Tragic, and has shaken my confidence as a pilot, which is troubling as a I am a master of ships who is usually diligent and careful. It's a shame that I had just switched on those sensors for that flight hoping that I would lose the blades that I was occasionally getting in the video.

My wife and I have written a few books on our maritime exploits and one describing our two year Australian circumnavigation is in ebook format, I'd be please to send you a link to it if you're interested. PM your email and I'll send it to you, cheers from Tasmania.

Here's a link to one of the Mavic's last flights over the wild west coast
Unfortunately, on this one YouTube did a pretty ordinary job of rendering as it has lots of fine detail.

Just sent the PM with my email address.

BTW, it's not entirely clear to me what the cause of the incident is. We don't have the .DAT and Litchi is woefully inadequate when it comes to providing a log useful for analyzing an incident. There were several intervals after 336 secs where the Mavic continued to descend in the absence of any stick inputs. That shouldn't have happened.