Novice Mistake but got lucky!

sar104 · Jan 31, 2019

Camino Ken said:
Hey sar104, some of us enjoy hypothesizing.

Nothing wrong with that.

FormerMember07122019_2 · Jan 31, 2019

sar104 said:
Nothing wrong with that.

Thanks. I was just kidding but I am very curious as to the root cause.

Drone on · Jan 31, 2019

JenksKenny said:
I thought flying through an old steel bridge would make a good video. I should have realized the potential danger. Steel and radio signals don't mix well. Got lucky though. See video. Effects of steel on drone Control

great suspense

JenksKenny · Jan 31, 2019

old man mavic said:
in this case it wasnt so much about loss of signal but the affect on the compass which made it go into atti mode the poor drone didnt have a clue where it was you were very lucky it did not crash into the bridge or go in the water

That makes sense to me.

JenksKenny · Jan 31, 2019

madkaw said:
And to think, I was gonna go through a similar bridge today...omg. Jenks thanks for the video.

Welcome!

JenksKenny · Jan 31, 2019

Drone on said:
great suspense

JenksKenny · Jan 31, 2019

JDawg said:
Loss of GPS would not make it shoot out the side of the bridge the way it did unless Jenks instructed it to or there was a gust of wind. It would be cool to see the flight log. I think this is compass intereference all the way.

No, I absolutely did not instruct it to go past the steel and it was not a very windy day. That's what was so weird. It seemed to just jump past that steel. I was trying to get it to go the opposite direction, but it had no response to my command at that point. From my point of view I could not see the openings between the steel members. Afterward I looked and there was not a great deal of clearance there. I don't know, maybe it got a clear GPS signal that close to the edge of the bridge and suddenly adjusted position. Or, maybe interference or signal reflection where worse there? Its a mystery to me.

JenksKenny · Jan 31, 2019

sar104 said:
If you want to know exactly what caused the issues, rather than generating completely random guesses, then post the flight log.

How do you get the flight log?

sar104 · Jan 31, 2019

JenksKenny said:
How do you get the flight log?

This really requires the DAT log from your mobile device, but you will need to identify the file. To do that, first get the txt log:

TXT log: DJI Flight Log Viewer | Phantom Help

That will tell you the DAT file index number, and you can then get the DAT file:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

JenksKenny · Feb 1, 2019

sar104 said:
This really requires the DAT log from your mobile device, but you will need to identify the file. To do that, first get the txt log:

TXT log: DJI Flight Log Viewer | Phantom Help

That will tell you the DAT file index number, and you can then get the DAT file:

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

I use CrystalSky for my mobile device along with the DJI controller. So far, I have not had any luck getting into the devices to view the files. I found old files on my android phone that I used before getting the CrystalSky. I also found the bridge video with the original sound but no way to get it off of the CrystalSky. I'll try again later.

star4870 · Feb 1, 2019

I think is not steel itself that made this issue, there are power cables going next to it. Each of this cable generate electromagnetic fild around, part of the fild passing through the steel beems this genereate small electric curent and a lots of small electromagetic fields on each beam, making this bridge perfect signal interference device.

JDawg · Feb 1, 2019

JenksKenny said:
I use CrystalSky for my mobile device along with the DJI controller. So far, I have not had any luck getting into the devices to view the files. I found old files on my android phone that I used before getting the CrystalSky. I also found the bridge video with the original sound but no way to get it off of the CrystalSky. I'll try again later.

I hope someone can help you get the files as it would be very interesting to see what the Bird was 'thinking'.

sar104 · Feb 1, 2019

JenksKenny said:
I use CrystalSky for my mobile device along with the DJI controller. So far, I have not had any luck getting into the devices to view the files. I found old files on my android phone that I used before getting the CrystalSky. I also found the bridge video with the original sound but no way to get it off of the CrystalSky. I'll try again later.

Connect the CrystalSky device to your computer via USB and mount it as a drive. Then you can retrieve the log files.

JenksKenny · Feb 2, 2019

Finally, got the files!

sar104 · Feb 2, 2019

JenksKenny said:
Finally, got the files!

Yes - the steel bridge generated compass errors, causing the FC to make inappropriate course corrections. It did not switch to ATTI mode though.

JDawg · Feb 2, 2019

Thanks sar104 and thanks to the OP for coming back and posting the logs, I learn so much from this stuff. It took me a while to realize how important it can be to have atti mode available and to know how to fly in it.

JenksKenny · Feb 2, 2019

sar104 said:
Yes - the steel bridge generated compass errors, causing the FC to make inappropriate course corrections. It did not switch to ATTI mode though.

View attachment 61510

Thank you for the analysis! I learned a lot as well and can now see how much more there is to learn. I was unaware of the log files. Great tool! Thx again!

BD0G · Feb 2, 2019

The pucker factor was high on this one. I was just waiting for the Mavic to slam into one of the steel beams and plummet. You got sooooo lucky! The sound effects were a perfect addition as they added an element of suspense and foreboding.

The log files will tell one exactly what was occurring during the flight and lots of information can be extracted from them. Then there is no guessing or speculating.

You get to fly another day!

JenksKenny · Feb 4, 2019

BD0G said:
The pucker factor was high on this one. I was just waiting for the Mavic to slam into one of the steel beams and plummet. You got sooooo lucky! The sound effects were a perfect addition as they added an element of suspense and foreboding.

The log files will tell one exactly what was occurring during the flight and lots of information can be extracted from them. Then there is no guessing or speculating.

You get to fly another day!

Thanks for your comment! The log files were finally posted on Saturday.