Drone did not RTH!

[scjerry]

Would you please provide your reference for this statement. I am trying to find the reference. Instead, I found this on page 52 of the Mavic User Manual: "Only calibrate the compass when the DJI GO 4 app or the status indicator prompt you to do so."

JeepDSL and SAR104: Thanks for prompting me to continue to pursue this thread. I just learned about the Compass Sensor monitor in Main Controller Settings of DJI Go 4. Some of my flights may have been affected by power lines, so will check my next outing, though I doubt it, since they are an AC signal source, not DC magnetic like a large deposit of iron. All I know is that when I didn't calibrate, it went off into the weeds. See my past post: Dynamic Home Point Setting Doesn't Work

See: Compass Calibration Guide
Better than this post, which provides little science: Calibrate the mavic compass at each start?

Be reminded that the interface to the quad's sensors is s/w that depends upon a analog-to-digital conversion and flash storage...any thing can go wrong, including a bad quad. Nice to have the sensor readings for comparison. It's not included in the Flight List entries (look at the spreadsheet files).


Excerpt: "Compass Interference
You can view the current compass interference in the "Main Controller Settings" --> "Advanced Settings" --> "Sensors" section of DJI GO. The colored bars should be in the green (Excellent) range when the Mavic is in a location that is away from magnetic influences. If the bars are in the red (Poor) range or close to it, move the Mavic to a different location and check again. If the compass interference is still in the red (Poor) range or close to it, the compass could need calibrated or it could be magnetized/damaged."

Excerpt: "When Should I Calibrate?
You do not need to calibrate before every flight and in some cases you definitely should not calibrate. That doesn't mean you shouldn't ever bother doing it. It only takes one time for it to go very wrong. The most important aspect of compass calibration is making sure the magnetic "neighborhood" around your Mavic is consistent between calibration and during flight."

 

[Dogtown]

Since these problems, I cheat abit and just use the RTH function to turn the MP is the correct direction then cancel it and manually fly it in.

My 2 cents worth

The problem with that in this situation is that the MP flies back to a previous HP not your actual HP

 

[sar104]

JeepDSL and SAR104: Thanks for prompting me to continue to pursue this thread. I just learned about the Compass Sensor monitor in Main Controller Settings of DJI Go 4. Some of my flights may have been affected by power lines, so will check my next outing, though I doubt it, since they are an AC signal source, not DC magnetic like a large deposit of iron. All I know is that when I didn't calibrate, it went off into the weeds. See my past post: Dynamic Home Point Setting Doesn't Work

See: Compass Calibration Guide
Better than this post, which provides little science: Calibrate the mavic compass at each start?

Be reminded that the interface to the quad's sensors is s/w that depends upon a analog-to-digital conversion and flash storage...any thing can go wrong, including a bad quad. Nice to have the sensor readings for comparison. It's not included in the Flight List entries (look at the spreadsheet files).


Excerpt: "Compass Interference
You can view the current compass interference in the "Main Controller Settings" --> "Advanced Settings" --> "Sensors" section of DJI GO. The colored bars should be in the green (Excellent) range when the Mavic is in a location that is away from magnetic influences. If the bars are in the red (Poor) range or close to it, move the Mavic to a different location and check again. If the compass interference is still in the red (Poor) range or close to it, the compass could need calibrated or it could be magnetized/damaged."

Excerpt: "When Should I Calibrate?
You do not need to calibrate before every flight and in some cases you definitely should not calibrate. That doesn't mean you shouldn't ever bother doing it. It only takes one time for it to go very wrong. The most important aspect of compass calibration is making sure the magnetic "neighborhood" around your Mavic is consistent between calibration and during flight."

Glad to be of help but I'll repeat - you do not need to calibrate unless the software detects that the calibration is bad, which is also what is stated in the references that you found. And mostly when you get compass warnings it is due to the local magnetic environment, not a bad calibration, and is fixed by changing location.

If you have a "bad quad", as you put it, then calibration is not going to fix it. Otherwise, as also noted previously, if the aircraft flies off instead of coming back to you on RTH then that indicates a home point problem, not a compass problem. In any case a simple analysis of the log files will indicate why that happens.

 

[scjerry]

sar104 You wrote: If you have a "bad quad", as you put it, then calibration is not going to fix it. Otherwise, as also noted previously, if the aircraft flies off instead of coming back to you on RTH then that indicates a home point problem, not a compass problem. In any case a simple analysis of the log files will indicate why that happens."

Nothing is simple with the log file interpretation. It's not all-inclusive. As to RTH, I assume the algorithm uses compass headings to compliment the GPS data...corrupted or not, and although the compass heading is included in the log files, it isn't very useful and there are no sensor columns, either for the two hor. and vert. compass devices, or the two IMU sensors . Note that the compass calibration guide states: "IMPORTANT: The lack of a compass error does NOT mean your compass is working and calibrated properly." I'm still in the experimentation mode to get to the root cause of my concerns.

Note from a previous submission, HP doesn't get updated to the RC if the HP at launch is activated with a "precise location" checked box above the launch slider. That, too!

Thanks for your comments.

 

[sar104]

sar104 You wrote: If you have a "bad quad", as you put it, then calibration is not going to fix it. Otherwise, as also noted previously, if the aircraft flies off instead of coming back to you on RTH then that indicates a home point problem, not a compass problem. In any case a simple analysis of the log files will indicate why that happens."

Nothing is simple with the log file interpretation. It's not all-inclusive. As to RTH, I assume the algorithm uses compass headings to compliment the GPS data...corrupted or not, and although the compass heading is included in the log files, it isn't very useful and there are no sensor columns, either for the two hor. and vert. compass devices, or the two IMU sensors . Note that the compass calibration guide states: "IMPORTANT: The lack of a compass error does NOT mean your compass is working and calibrated properly." I'm still in the experimentation mode to get to the root cause of my concerns.

Note from a previous submission, HP doesn't get updated to the RC if the HP at launch is activated with a "precise location" checked box above the launch slider. That, too!

Thanks for your comments.

All the data that you mention being interested in is in the DAT file. But in any case, the regular log file is generally enough to determine RTH problems. Why is the compass heading value not useful in considering this question? If the compass is reporting incorrectly then the heading and the track, once corrected with the pitch and roll angles, will show a discrepancy.

Anyway - to be more specific, the compass error message, or lack of it, that you refer to is on startup before there are dynamic data. In flight, compass errors correlate to a mismatch between the corrected magnetometer readings and the integrated yaw gyro values, and cause the aircraft to drop out of P-GPS mode. When that happens, RTH is not available anyway, so I still do not understand why you think that RTH to an unexpected location is a compass problem.

 

[JeepDSL]

JeepDSL and SAR104: Thanks for prompting me to continue to pursue this thread. I just learned about the Compass Sensor monitor in Main Controller Settings of DJI Go 4. Some of my flights may have been affected by power lines, so will check my next outing, though I doubt it, since they are an AC signal source, not DC magnetic like a large deposit of iron. All I know is that when I didn't calibrate, it went off into the weeds. See my past post: Dynamic Home Point Setting Doesn't Work

See: Compass Calibration Guide
Better than this post, which provides little science: Calibrate the mavic compass at each start?

Thank you for the reference. It was helpful.

 

[sar104]

Note from a previous submission, HP doesn't get updated to the RC if the HP at launch is activated with a "precise location" checked box above the launch slider. That, too!

I saw that post too, and I was not sure what to make of it. It seemed inconsistent so I guess I need to test it. I read it to mean that if RTH is activated and the option of current or original is offered, then current is ignored, even if selected, if the precise location option was previously chosen at takeoff. That's still not going to send it somewhere random or unexpected though - it will just return to its takeoff location, presumably.

 

[Dronewerkz]

You can and should always confirm the RTH point visually on your screen before setting out on your flight. It's right there on the screen under your nose......
This stuff is just as important as looking both ways before you cross the street. Very sorry to see this happen to you Lone Droner!

 

[Lone Droner 10]

Wow! Thank you all for your insights, suggestions, alternatives etc. It is very disconcerting to look down at your iPhone and see the drone heading off into the sunset and not be able to stop it. I hit the RTH cancel several times to no avail. I am still confused though - why does the DJI Go 4 app seem selective on where it will connect to the controller or drone (not sure what it connects to)? I took my new one out today and attempted to fly it but the app would not connect. I was out in the middle of the desert here in Casa Grande AZ. I got a message saying something about "no wifi"?

I then drove about 1 mile away on the same road to a mountain trail I had been to before with my Phantom 3 Advanced. The app connected fine with zero problems. Just doesn't make any sense whatsoever. Needless to say, I pay a lot more attention to the telemetry data than I did before I lost the first Mavic. But, I am a big fan of figuring out WHAT NOT TO DO AGAIN or finding out how the app, the controller and the drone work together. Here is another interesting thing. I also have the DJI goggles. Those connect to the controller/drone without even having my iPhone connected to the controller. I do not understand. Anyone out there have the answers?

I did confirm I could record video with just the controller but that really isn't much fun as you cannot see what you are recording!

 

[Lone Droner 10]

I saw that post too, and I was not sure what to make of it. It seemed inconsistent so I guess I need to test it. I read it to mean that if RTH is activated and the option of current or original is offered, then current is ignored, even if selected, if the precise location option was previously chosen at takeoff. That's still not going to send it somewhere random or unexpected though - it will just return to its takeoff location, presumably.

Mine did not RTH even though I did select "precision landing" before it took off. Going to be interesting when I hear from DJI - if I ever do.

 

[scjerry]

All the data that you mention being interested in is in the DAT file. But in any case, the regular log file is generally enough to determine RTH problems. Why is the compass heading value not useful in considering this question? If the compass is reporting incorrectly then the heading and the track, once corrected with the pitch and roll angles, will show a discrepancy.

Anyway - to be more specific, the compass error message, or lack of it, that you refer to is on startup before there are dynamic data. In flight, compass errors correlate to a mismatch between the corrected magnetometer readings and the integrated yaw gyro values, and cause the aircraft to drop out of P-GPS mode. When that happens, RTH is not available anyway, so I still do not understand why you think that RTH to an unexpected location is a compass problem.

Only because in several cases it's headed in a totally erroneous direction (with no HP destination recorded as a destination) , as verified by the trajectory history in the File List file in the DJI Go 4 app. Just repeated the experiment and it went off again and I had to abort.

OK, lots of parameters, not the least of which is electromagnet interference (not recorded in the flight data, either, but recorded in a warning as "wireless inteference" ) perhaps affecting my iPad's GPS, as well as the quad's RC transmission. I'm going to conduct more experiments in areas less affected by power lines.

Also, I tried the only DAT files I could find ... Flight logs ... are about 3K in length and contain only in-flight messages. The only other Flight Record files are unintelligible txt files.

Thanks again

 

[Dronewerkz]

With out wifi through your phone data connection you won't get a visual map feature (google earth map) but there still should be a "home" symbol or icon in close proximity for you to see and verify. (if I remember correctly- haven't played with my toy in a few weeks.... going through withdrawal symptoms....[emoji15])

 

[Lone Droner 10]

I guess when I see the red "disconnected" in the status bar I just assumed nothing on the app works so I did not try. Frankly, it is much easier to hit the RTH on the controller itself. But, I am still not understanding the wifi connection question. When I was out in the desert, I can assure you I did not have any wifi but the DJI Go 4 app worked once I moved to the north about a mile or less.

 

[sar104]

Only because in several cases it's headed in a totally erroneous direction (with no HP destination recorded as a destination) , as verified by the trajectory history in the File List file in the DJI Go 4 app. Just repeated the experiment and it went off again and I had to abort.

OK, lots of parameters, not the least of which is electromagnet interference (not recorded in the flight data, either, but recorded in a warning as "wireless inteference" ) perhaps affecting my iPad's GPS, as well as the quad's RC transmission. I'm going to conduct more experiments in areas less affected by power lines.

Also, I tried the only DAT files I could find ... Flight logs ... are about 3K in length and contain only in-flight messages. The only other Flight Record files are unintelligible txt files.

Thanks again

How can it be headed in an erroneous direction if it has no home point recorded? In that situation I think it will default to the last recorded home point, though don't quote me on that. Are you not waiting for a home point to be recorded before taking off? If so then no further analysis needed.

The simple flight logs are not the same as the main flight logs or the DAT files. The internal DAT files have to be decoded. Go to CsvView/DatCon for instructions.

 

[scjerry]

How can it be headed in an erroneous direction if it has no home point recorded? In that situation I think it will default to the last recorded home point, though don't quote me on that. Are you not waiting for a home point to be recorded before taking off? If so then no further analysis needed.

The simple flight logs are not the same as the main flight logs or the DAT files. The internal DAT files have to be decoded. Go to CsvView/DatCon for instructions.

Of course I wait for the HP to be recorded! Then I can't change it. S/W needs to be debugged and analyzed. Chinese s/w or US contractor?

How can it be headed in an erroneous direction if it has no home point recorded? In that situation I think it will default to the last recorded home point, though don't quote me on that. Are you not waiting for a home point to be recorded before taking off? If so then no further analysis needed.

The simple flight logs are not the same as the main flight logs or the DAT files. The internal DAT files have to be decoded. Go to CsvView/DatCon for instructions.

Dynamic Home Point Setting Doesn't Work

OK, I repeat my previous post. I no longer have time to engage in this debate. There is a problem and many Mavic users share in awaiting the solution. Several have lost their quads. I believe there is an solvable solution....DJI recognition of the problem. I attempting to step through the possible causes...as are many others.

 

[sar104]

Of course I wait for the HP to be recorded! Then I can't change it. S/W needs to be debugged and analyzed. Chinese s/w or US contractor?



Dynamic Home Point Setting Doesn't Work

OK, I repeat my previous post. I no longer have time to engage in this debate. There is a problem and many Mavic users share in awaiting the solution. Several have lost their quads. I believe there is an solvable solution....DJI recognition of the problem. I attempting to step through the possible causes...as are many others.

I'm sure you don't. The dynamic home point thread is interesting, but also appears to have nothing to do with an alleged compass problem that you were pushing in this thread. At this point your complaints are changing too fast to try to keep up, so I'll quit trying to help.

 

[gnirtS]

Not sure whats going on here. I played earlier, flew and set home point during the flight. It worked as expected. Am i missing something?

 

[scjerry]

I'm sure you don't. The dynamic home point thread is interesting, but also appears to have nothing to do with an alleged compass problem that you were pushing in this thread. At this point your complaints are changing too fast to try to keep up, so I'll quit trying to help.

The fact that you don't believe they are connected is part of the impediment to the solution.

 

[sar104]

The fact that you don't believe they are connected is part of the impediment to the solution.

Belief has nothing to do with it. If you want to advance the hypothesis that they are connected then you need to suggest a mechanism for that, and/or back it up with some log file data that shows at least a correlation between unexpected RTH and anomalies in the compass data. You have done neither of those - you just keep asserting an undefined connection with the compass, along with other unrelated explanations.

 

[MDJAK]

I've owned 3 drones, most recently the MP. I love it. I wish I understood better all the very helpful replies here though. It may not be rocket science but it's drone science and some of it is over my head, no pun intended. But this seems like a great place to learn. I didn't even know about the blue circle. I'll have to check that out.