Spooky Action at a Distance

[Ender]

...
Still unanswered are
1) Does the magZ noise lead to the Yaw/magYaw separation,
2) Does the Yaw/magYaw separation cause TBE
3) Is the magZ noise particular to @erkme73's Mavic or does it occur with other Mavics. I can test this here when the weather clears.

Beeing new to DJI but handling Motor Interference since years for APM / Pixhawk, let me say this:

(1) Yes, it should cause a Heading difference if (graphs dont show it) you didnt do a "real" yaw on the craft. if one would log a full 360 turn undr perfect conditions one could estimate how much but thats academic and not precise anyways. But i guess its a HUGE gap.

(2) if i interprete the graphs correctly you were still in GPS mode, NOT ATTI, so YES a serious heading difference would cause a TBE.

(3) whenever you pack hich currents and a compass sensor close together you'll see that, i needed 3 Generations of DIY before i was satisfied having left only a little motor interference but YES it will always be there. Of couse a similar flight pattern logged from another Mavic would be good, as i havent received mine i cannot help in that :-(
The 2 things against it are:
-Build the Craft in a way that this motor Interference is minimized (it cannot be avoided).
---> As this is not DJI's first Multicopter i trust they tried hard although its the first in this size class.

-Reduce the remaining Interference by smart "motor compensation", so building tables which motor at which current causes what kind of compass drift then recalc the heading.
And adding to that whenever you fly straight, & fast use the (then trustworthy) GPS geading to correct and adapt your assumptions thus improving the motor compensation which each flight.
---> I think & hope DJI royally f*cked up on that.
Hoping as that would mean a FW fix can do the job.
IF there reallx is a relation between sports mode and TBE then i guess they "only" did a wrong dynamic adaption of the motor correction.

But thats a bit speculative But thats what i would look for and correct on a Pixhawk DIY craft where i COULD change stuff. Not here, just crossing fingers...

Ender

 

[E92Vancouver]

Well, FWIW, I did another calibration, nothing metallic on or near me. Third flight out, and boom... TBE on one pause. Curiously it was just after getting a warning about controller interference - which happened during my epic near loss a few nights ago.

Here's today's circular adventure:

Notice how it goes from the middle of the yard, shoots south, then starts circling the drain - all without any directional stick input.

If it really is a compass calibration issue, I really think the next step is to be buck nekkid in the field by my clubhouse. Watch the evening news for the highlights...

What is TBE? "The Best Ever"?

 

[Guest]

TBE = Toilet Bowl Effect

 

[niclariv]

And Spooky Action At a Distance refers to entangled particles in quantum physics.

Einstein's "Spooky Action at a Distance" Paradox Older Than Thought


Sent from my iPhone using MavicPilots

 

[Logger]

I have reported to engineering. We will see what they say. If we can get the owner to download the .DAT files to a hosting site like Dropbox that would be helpful

Hi First post here for me.
I had a similar TBE event last week when using Litchi. So I have all the litchi logs from Healthy drones along with the full DJI Assistant DAT files from the Mavic including VM + the video. Are these files of any use to anyone here. If so I can pass a link to them at Google Docs where I have them posted.

Mavic was flying around a bend at 20mph in a ~ 30 mph crosswind when it departed my programmed route, slowed up to a near halt and went into a TBE spiral. Then drifted off downwind until I manually flew it home.

I have reported my event and passed the link to DJI support who said they would pass it on to the appropriate dept.

 

[BudWalker]

Hi First post here for me.
I had a similar TBE event last week when using Litchi. So I have all the litchi logs from Healthy drones along with the full DJI Assistant DAT files from the Mavic including VM + the video. Are these files of any use to anyone here. If so I can pass a link to them at Google Docs where I have them posted.

Mavic was flying around a bend at 20mph in a ~ 30 mph crosswind when it departed my programmed route, slowed up to a near halt and went into a TBE spiral. Then drifted off downwind until I manually flew it home.

I have reported my event and passed the link to DJI support who said they would pass it on to the appropriate dept.

Yes, could we please have the link to the .DAT file.

 

[erkme73]

Once is a fluke. Twice is a coincidence. Three times is a pattern. We're approaching a dozen different users who have all experienced the same phenomenon. Houston, I believe we have a problem.

 

[Logger]

Sorry for the delay. It is all in a zip at https://drive.google.com/open?id=0Bw1jH6lWD_8aVTBsWndxeHcyRGc

Very interested to see what you find.
Was not in Sports mode at the time. But as I was using Litchi I toggled to Sports a minute or two after the event to recover control and fly home.

 

[BudWalker]

Sorry for the delay. It is all in a zip at https://drive.google.com/open?id=0Bw1jH6lWD_8aVTBsWndxeHcyRGc

Very interested to see what you find.
Was not in Sports mode at the time. But as I was using Litchi I toggled to Sports a minute or two after the event to recover control and fly home.

The .DAT appears to be not from the same flight as shown in the .kml. The .DAT shows two successful mission flights. Since they are identical flights the second is superimposed on the first and they present as a single flight.


Here is the .kml file.


If you can locate the right flight in DJI Assistant 2 select just the FC. DatCon doesn't know about the stuff in the Vision Module and including it will only make the .DAT file larger.

 

[Logger]

**** will go back an look for it. I did indeed fly 3 consecutive laps and the third was when it went haywire. Odd that you are seeing two not three. Because between the mission I simply landed, waited for rotors to shut off then pretty much hit the litchi start button again.

EDIT..

Unfortunately it is no longer on the Mavic. Overwritten I assume. I was so sure it was the most recent log in the list when I pulled it and it was the first thing I did after the flight. The CSV files linked definitely relate to the flight.

Your kml looks to show first good lap + first part of second lap where I flew 100m aborted an returned to start, but misses full lap 2 and 3 where it went weird.

Are you sure there is not more there , because when does the DJI assist log usually start stop. Is it Mavic powered on to powered off or is it take off to land or something else. Why does it have two flights not more or less? Cheers.

HealthyDrones.com - Innovative flight data analysis that matters
HealthyDrones.com - Innovative flight data analysis that matters
HealthyDrones.com - Innovative flight data analysis that matters
HealthyDrones.com - Innovative flight data analysis that matters

Seems you have the first 2 and not the last two.

 

[BudWalker]

**** will go back an look for it. I did indeed fly 3 consecutive laps and the third was when it went haywire. Odd that you are seeing two not three. Because between the mission I simply landed, waited for rotors to shut off then pretty much hit the litchi start button again.

The one I have looks like the first was flown, then an attempted second mission that you aborted by initiating a GoHome. This was then followed by a third successful mission identical to the first.

 

[Logger]

That makes sense. But I swear there was no later DAT file to pull on the day and the offending flight was straight after the third successful mission with no power off in between. All I did was tweak a couple of litchi Camera POI heights and send it off again. So odd the first three in the series are there and the offender is not.

 

[BudWalker]

OK, I have it. When you ran DJI Assistant did you select 2 FCs. The second FC would be the flight in question. When the .DAT is produced it contains all of the FCs selected. DatCon and CsvView just assumes the user has selected just one FC and ignores any subsequent FCs. I don't know why the flight was split into 2 separate FCs. There is a separate app called ExtractDJI that can be used to extract multiple flights from the .DAT. I had thought it would be an unnecessary complication and most users won't be interested in this.Maybe not. Got all that?

The cause of the TBE seems to be unrelated to what happened in @erkme73s flight. Let me look some more. Did you send the .DAT to DJI engineering? They need to see it.

 

[erkme73]

OK, I have it. When you ran DJI Assistant did you select 2 FCs. The second FC would be the flight in question. When the .DAT is produced it contains all of the FCs selected. DatCon and CsvView just assumes the user has selected just one FC and ignores any subsequent FCs. I don't know why the flight was split into 2 separate FCs. There is a separate app called ExtractDJI that can be used to extract multiple flights from the .DAT. I had thought it would be an unnecessary complication and most users won't be interested in this.Maybe not. Got all that?

The cause of the TBE seems to be unrelated to what happened in @erkme73s flight. Let me look some more. Did you send the .DAT to DJI engineering? They need to see it.

I'm happy for @Logger that it's not like mine. But, that does raise the question - just how many other variables exist that can cause the same TBE and wonky flight controls? Seems like there is more than just one bug that need squishing.

 

[Logger]

OK, I have it. When you ran DJI Assistant did you select 2 FCs.

Certainly not intentionally. Was literally the second time I have used DJI Assistant and all I can recall doing was setting it to grab the VM as well. But may have done so accidentally.

The second FC would be the flight in question. When the .DAT is produced it contains all of the FCs selected. DatCon and CsvView just assumes the user has selected just one FC and ignores any subsequent FCs. I don't know why the flight was split into 2 separate FCs. There is a separate app called ExtractDJI that can be used to extract multiple flights from the .DAT. I had thought it would be an unnecessary complication and most users won't be interested in this.Maybe not. Got all that?

barely but main thing is you have actually got the offending bit..

The cause of the TBE seems to be unrelated to what happened in @erkme73s flight. Let me look some more. Did you send the .DAT to DJI engineering? They need to see it.

YES I sent it to DJI support with a note to say I am not looking for any special support, simply...
" ..passing this info on in the hope that the included files may be of assistance to your engineers in assessing and fixing whatever is causing this problem. "

They replied " I have forward the details to the team. Hope the next firmware will fix it.".

 

[OCsurfer411]

Hi All,

Well, I had my first problem with the mavic a few days ago. I've made about 30 flights so far without incident, it's a fantastic machine. I was flying around a lake far from power lines and using tap-fly as sort on an autopilot so I could concentrate on camera settings. I began getting yaw drift, to the point where I was almost flying sideways, as I could tell from the video feed. The rest of this story is told after reviewing the flight log many times. I then began heading back toward my home point, at which time I got the message "weak GPS signal". It had been showing 18 satellites, and still did, although the strength bars went down to 2 and turned red. The aircraft went into ATTI mode, as it should have, but began flying backwards and drifting sideways while maintaining an altitude of 150 feet. I made sure tap-fly mode was off. When I saw that the mavic was pointed in my general direction I pushed the right stick forward 100 % and got it back above me. I let go of both sticks and it began "toilet bowling", moving in circles above me without any input. I saw that the satellite strength bars were increasing and soon I had control back and was able to land.

I know that the yaw drift was probably from a bad compass calibration. I had just calibrated it at the park and there were frisbee golf goals not too far away, they may have caused a problem so my bad on that. However, after reading countless posts about the sudden loss of gps, and my own experience, I think the mavic does have a flaw. I think the gps unit is faulty and prone to sudden gps loss. I can understand going from 18 satellites to 10, but going from 18 to 0 in an instant in open country has got to be the gps unit. I don't know how to upload my flight log, if anyone knows how, let me know.View attachment 1613View attachment 1613View attachment 1614

Same EXACT thing happened to me today at the southern end of California's central valley. Guess I'll try recalibrating the compass and see what happens.

Sent from my SM-G930V using MavicPilots mobile app

 

[Logger]

Just a thought BudWalker, As I understand it, you should now have in my logs the 2 successful complete circuits of my route along with the TBE event effected one. Can the 2 good circuits be used as a baseline comparison for the TBE event to see how they diverge?

 

[Marty Markoe]

AACU = Acronyms & Abbreviations Commonly Used

OP used abbreviation TBE but that is not in list?
Thanks,
Marty

 

[halley]

OP used abbreviation TBE but that is not in list?

Toilet Bowl Effect, when the drone seems to lose yaw control and spins in place or in very small circles.

 

[erkme73]

Toilet Bowl Effect, when the drone seems to lose yaw control and spins in place or in very small circles.

Generally correct, but I just want to add that it doesn't have to be in 'small circles'. When it gets going, the spiraling can extend to a radius greater than 100'