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Compass error
1578 36 2017-12-17
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fansb181213c
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Just came back from a flight, hadn't flown for about a week and took it to the beach where I normally go. All sensors ok, GPS lock 19 sats, home point recorded. 30 seconds into the flight, i got a compass error and it started behaving erratically. It was 30m up and I was between the beach and a lagoon. No chance of magnetic influence there, have flown there maybe 50 times. Anyway, I got it back after a few anxious minutes. I did react to the sticks, but not reliably. After it landed, I restarted and went into the sensor menu and it showed no compass interference at all and also the IMU sensor was at the bottom of the indicator. So, I took off again, same thing happend after 20 seconds. I was only 4m up in the air but it started climbing and drifting. I managed to land it again. I had the same issue a few weeks ago, where it was about 100m away and I also managed to get it back and by the time it landed then, everything had returned to normal. After that experience, I re-calibrated and have flown it a couple of times without an issue. But now I am at the point where I have lost all confidence in the thing.
2017-12-17
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hallmark007
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Can you upload log to link below just click on link and follow instructions come back here and post your link, might help you understand what happened.

http://www.phantomhelp.com/LogViewer/Upload/
2017-12-17
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choban
First Officer
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I completely understand. The same thing happened to me. Two times in a row I had this happened and I lost it in the end. Did you maybe have a smartwatch on you? It's highly unlikely watches are causing these issues, but it's worth investigating...
2017-12-17
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Gunship9
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What was magnetic at the launch site?  I think the compass swings back to the real north after leaving the launch site's magentic interferrence.  That swing back to true north confuses it vs the IMU's sensor saying no swing happened.
2017-12-17
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fansb181213c
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Gunship9 Posted at 2017-12-17 15:23
What was magnetic at the launch site?  I think the compass swings back to the real north after leaving the launch site's magentic interferrence.  That swing back to true north confuses it vs the IMU's sensor saying no swing happened.

Ok... when I got home I checked the compass reading on the ground, and it was in fact off by nearly 90 degrees looking at the arrow on the app and where it was really pointing.

I did not check this at the beach, and it was most likely the cause, as the AC started misbehaving as soon as I pushed the stick forward, which would have meant the compass and gps disagreed by a large amount.

Now,  looking at the sensors at the beach before the second take-off, there was no reason to believe the compass was off and the app never gave a warning to calibrate.

So, there is a flaw in the system that allows the compass to become uncalibrated without an error being raised.

I do usually look at which way the AC is pointing on the ground and verify that it is correct on the app, but just forgot this time.
2017-12-17
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fansb181213c
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hallmark007 Posted at 2017-12-17 13:51
Can you upload log to link below just click on link and follow instructions come back here and post your link, might help you understand what happened.

http://www.phantomhelp.com/LogViewer/Upload/

Here is the log:
http://www.phantomhelp.com/LogViewer/X2DQUVLCSD7GSL52EAUU/
2017-12-17
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hallmark007
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fansb181213c Posted at 2017-12-17 15:40
Ok... when I got home I checked the compass reading on the ground, and it was in fact off by nearly 90 degrees looking at the arrow on the app and where it was really pointing.

I did not check this at the beach, and it was most likely the cause, as the AC started misbehaving as soon as I pushed the stick forward, which would have meant the compass and gps disagreed by a large amount.


Why would you calibrate ?
Your manual clearly tells not to calibrate unless prompted, you almost never will have to calibrate your compass, so if you have a perfectly good working compass how would calibration make it better? But there is a good chance you could make it worse.

Calibration gives the compass the information it needs to determine which magnetic influences are part of the Spark and what is the earth's normal magnetic field.
The compass doesn't lose calibration and doesn't ever need re-calibration unless you add or remove equipment to/from the Spark

You should always move your aircraft from the area your launching and move to another location.

2017-12-17
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fansb181213c
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hallmark007 Posted at 2017-12-17 13:51
Can you upload log to link below just click on link and follow instructions come back here and post your link, might help you understand what happened.

http://www.phantomhelp.com/LogViewer/Upload/

This is the second flight:
http://www.phantomhelp.com/LogViewer/8XC45QKQ385U4G4HP5T9/
2017-12-17
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hallmark007
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Your log shows typical magnetic interference and aircraft going into Atti mode where you picked up interference we can’t say, most interference is picked up at launch area or very close to it, it’s almost impossible that their is magnetic interference at high altitudes unless you are flying around buildings or pylons etc , so why and how it happened to you I have a theory and I’ve seen it before with launching on beaches and though I know very little about it I am always careful about launching on beaches.
There's an iron ore called magnetite that's, "sometimes found in large quantities in beach sand" as I said I don’t know a lot about it I have read about it regarding another problem with a drone, you can google magnetite on sandy beaches you will be surprised.
So this could be one thing to consider. You should also send in to dji your dat file they will be able to give you more from these files.
2017-12-17
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fansb181213c
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hallmark007 Posted at 2017-12-17 15:55
Why would you calibrate ?
Your manual clearly tells not to calibrate unless prompted, you almost never will have to calibrate your compass, so if you have a perfectly good working compass how would calibration make it better? But there is a good chance you could make it worse.

Actually... if you read my post.....I did NOT calibrate before the flight, in fact not for at least 4 weeks (after my first scare).. and it had flown it since with no errors.

2017-12-17
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fansb181213c
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hallmark007 Posted at 2017-12-17 16:15
Your log shows typical magnetic interference and aircraft going into Atti mode where you picked up interference we can’t say, most interference is picked up at launch area or very close to it, it’s almost impossible that their is magnetic interference at high altitudes unless you are flying around buildings or pylons etc , so why and how it happened to you I have a theory and I’ve seen it before with launching on beaches and though I know very little about it I am always careful about launching on beaches.
There's an iron ore called magnetite that's, "sometimes found in large quantities in beach sand" as I said I don’t know a lot about it I have read about it regarding another problem with a drone, you can google magnetite on sandy beaches you will be surprised.
So this could be one thing to consider. You should also send in to dji your dat file they will be able to give you more from these files.

I have flown there at least 50 times..............with no issues at all.
2017-12-17
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hallmark007
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fansb181213c Posted at 2017-12-17 16:19
Actually... if you read my post.....I did NOT calibrate before the flight, in fact not for at least 4 weeks (after my first scare).. and it had flown it since with no errors.


I never said you did, or that I thought that was your problem. What I said about compass was just common advice. Apologies if It came across as anything other than that.

You mentioned your compass became uncalibrated.
2017-12-17
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hallmark007
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fansb181213c Posted at 2017-12-17 16:21
I have flown there at least 50 times..............with no issues at all.

I have also flown many times from my back yard with no interference, but there has been the odd occasion for some reason no known to me where I get message to move or calibrate I always shutdown and move.
2017-12-17
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fansb181213c
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hallmark007 Posted at 2017-12-17 16:22
I never said you did, or that I thought that was your problem. What I said about compass was just common advice. Apologies if It came across as anything other than that.

You mentioned your compass became uncalibrated.

Well, when I came back from the beach I placed the Spark on the ground and the compass arrow on the app showed an almost 90 degree variation from where it was really pointing. So, I did a calibration then, and now it agrees with the app. Have not flown it again except lifting it off the ground a few feet.
There is almost certainly no magnetic influence where I had the problem, as I said before, I have flown there many times. My only conclusion is that somehow the calibration changed in the couple of weeks I had not flown and the app gave no alert that it might be necessary to calibrate. Not even sure how it can figure it out. If something affects it when it is turned  off and then it is powered up, there really is no way for it to detect that it is off. The first time the system would know if there is a large discrepancy is when the AC starts moving and the GPS direction and compass data diverge by a significant amount.
Well, that's my theory .... might get rid of it though... raises blood pressure and anxiety levels too much ;-)
2017-12-17
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Gunship9
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fansb181213c Posted at 2017-12-17 16:36
Well, when I came back from the beach I placed the Spark on the ground and the compass arrow on the app showed an almost 90 degree variation from where it was really pointing. So, I did a calibration then, and now it agrees with the app. Have not flown it again except lifting it off the ground a few feet.
There is almost certainly no magnetic influence where I had the problem, as I said before, I have flown there many times. My only conclusion is that somehow the calibration changed in the couple of weeks I had not flown and the app gave no alert that it might be necessary to calibrate. Not even sure how it can figure it out. If something affects it when it is turned  off and then it is powered up, there really is no way for it to detect that it is off. The first time the system would know if there is a large discrepancy is when the AC starts moving and the GPS direction and compass data diverge by a significant amount.
Well, that's my theory .... might get rid of it though... raises blood pressure and anxiety levels too much ;-)

Flying at the beach would get my blood pressure up.  A large portion of the area is not fit for flying or landing on (ocean, sand, buildings).  But I am thinking of it as a hobbyist, not a photographer.  Surely it is a great place for picture taking in the same way it is a horrible place to fly a RC model.

I fly model aircraft because I like controlling something flying in the sky and having a successful flight mission.  It going into ATTI where I fly would be a bonus since I would be more in command of flying it.  Like flying my 2004 era Trex 450.  That fly bar equipped helicopter is always trying to crash itself.

If you check its direction on the map, have open radio channels to use, and are prepared for ATTI you should be able to fly stress free.  As free as one can when flying a RC model.  Never fly what you can't afford to lose.  Being prepared for ATTI means you can see, and know, what direction it is pointing when you start working the sticks to fly it back to you.



2017-12-17
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fansb181213c
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Gunship9 Posted at 2017-12-17 17:50
Flying at the beach would get my blood pressure up.  A large portion of the area is not fit for flying or landing on (ocean, sand, buildings).  But I am thinking of it as a hobbyist, not a photographer.  Surely it is a great place for picture taking in the same way it is a horrible place to fly a RC model.

I fly model aircraft because I like controlling something flying in the sky and having a successful flight mission.  It going into ATTI where I fly would be a bonus since I would be more in command of flying it.  Like flying my 2004 era Trex 450.  That fly bar equipped helicopter is always trying to crash itself.

Well, I have flown model aircraft and single blade helis for a long time. I know how to control them, however, a little drone is a bit different to a heli or a plane, as it is very difficult to see what it's doing even only 100m away and it did not seem to react as I expected, certainly did not hover in any place when I let go of the sticks and started turning without any input. Also at one point it didn't seem to want to come down..... eventually it did and luckily not in the water.

2017-12-17
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fansb181213c Posted at 2017-12-17 20:54
Well, I have flown model aircraft and single blade helis for a long time. I know how to control them, however, a little drone is a bit different to a heli or a plane, as it is very difficult to see what it's doing even only 100m away and it did not seem to react as I expected, certainly did not hover in any place when I let go of the sticks and started turning without any input. Also at one point it didn't seem to want to come down..... eventually it did and luckily not in the water.

Hi, sir. Did you try to change an environment? Please try to calibrate the compass before flight. Did you shoot a video with the situation? Please keep us updated, thanks.
2017-12-18
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choban
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DJI Elektra Posted at 2017-12-18 02:10
Hi, sir. Did you try to change an environment? Please try to calibrate the compass before flight. Did you shoot a video with the situation? Please keep us updated, thanks.

I am not sure anymore when to do the calibration because it is written in the manual that compass needs to be calibrated only when prompted by the app.

I understand that the issue can be if you do your calibration somewhere where you can easily pick some interference and then Spark can use that as it's normal state. But as far as I know, there were no interferences where I calibrated mine.

How do I know then when to calibrate? What's the official policy from DJI on this issue? In my case, everything looked fine before I took off and also the arrow was pointing in right direction. So, what else is there that I can do?
2017-12-18
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djiuser_pVzOCZc
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choban Posted at 2017-12-18 03:21
I am not sure anymore when to do the calibration because it is written in the manual that compass needs to be calibrated only when prompted by the app.

I understand that the issue can be if you do your calibration somewhere where you can easily pick some interference and then Spark can use that as it's normal state. But as far as I know, there were no interferences where I calibrated mine.

A new part of my preflight routine is to check the true orientation of craft with what is being shown in the Go4.  If they don't match, then I move or re-calibrate  as necessary until they do.
2017-12-18
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hallmark007
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djiuser_pVzOCZc Posted at 2017-12-18 03:58
A new part of my preflight routine is to check the true orientation of craft with what is being shown in the Go4.  If they don't match, then I move or re-calibrate  as necessary until they do.

https://forum.dji.com/forum.php? ... &fromuid=260008

This might help.
2017-12-18
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hallmark007
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choban Posted at 2017-12-18 03:21
I am not sure anymore when to do the calibration because it is written in the manual that compass needs to be calibrated only when prompted by the app.

I understand that the issue can be if you do your calibration somewhere where you can easily pick some interference and then Spark can use that as it's normal state. But as far as I know, there were no interferences where I calibrated mine.

https://forum.dji.com/forum.php? ... &fromuid=260008

This might help...
2017-12-18
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choban
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@djiuser_pVzOCZc yep, that was also part of my routine and it was fine on that sad day.

@hallmark007 yep, saw your topic before...it's definitely worth spending a minute or two doing this before each flight, but still, even after this procedure I am not really convinced that all will be fine for the whole duration of the flight...
2017-12-18
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rimza
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By the way, what a breathtaking background.  Definitely a beautiful area to fly the drone albeit the water hazards.
2017-12-18
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fansb181213c
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DJI Elektra Posted at 2017-12-18 02:10
Hi, sir. Did you try to change an environment? Please try to calibrate the compass before flight. Did you shoot a video with the situation? Please keep us updated, thanks.

Hi,
No, nothing had changed. Really had little time to take video as it got into trouble right away.
The really strange part was after the first flight when I checked the sensors they looked perfectly normal (IMU and especially Compass), and when I took off again I got the compass error again and nearly lost it.
2017-12-18
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Bright Spark
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Also before all flights I check all the sensors' status are all in the green.
You can see the compass sensor shoot into the orange/red just by bringing the remote close to it,which contains small magnets.
No prompts  seem to appear with this low level of error. That goes for the imu/gyros too.
2017-12-18
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Bright Spark
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PS it may be your compass is somehow calibrated at variance with the imu which triggers an error as you take off. If you move the ac whilst observing the sensors - does the compass error occur as you moveit? (You could run the motors at tick over)
2017-12-18
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fansb181213c
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choban Posted at 2017-12-17 14:36
I completely understand. The same thing happened to me. Two times in a row I had this happened and I lost it in the end. Did you maybe have a smartwatch on you? It's highly unlikely watches are causing these issues, but it's worth investigating...

Well.. I think smartwatches no.. not very likely, however, watch bands with magnetic latches may be an issue when calibrating.....
2017-12-18
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DJI Elektra
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choban Posted at 2017-12-18 03:21
I am not sure anymore when to do the calibration because it is written in the manual that compass needs to be calibrated only when prompted by the app.

I understand that the issue can be if you do your calibration somewhere where you can easily pick some interference and then Spark can use that as it's normal state. But as far as I know, there were no interferences where I calibrated mine.

When you fly in a new place, I would recommend you calibrate the compass. Please stay away from things which have bad influence on compass.
flight environment.PNG
2017-12-19
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fansb181213c Posted at 2017-12-18 11:45
Hi,
No, nothing had changed. Really had little time to take video as it got into trouble right away.
The really strange part was after the first flight when I checked the sensors they looked perfectly normal (IMU and especially Compass), and when I took off again I got the compass error again and nearly lost it.

In this case, please export the flight data and the black box data for further analysis. Thanks for your support.

2017-12-19
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fansb181213c
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DJI Elektra Posted at 2017-12-19 03:18
In this case, please export the flight data and the black box data for further analysis. Thanks for your support.
https://www.youtube.com/watch?v=ngEHdAlAh9A

Trying to upload but DJIASSIST keeps saying invalid data when I press the upload button. I do not have a case number, maybe that is the problem?
2017-12-19
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fansb181213c Posted at 2017-12-19 14:23
Trying to upload but DJIASSIST keeps saying invalid data when I press the upload button. I do not have a case number, maybe that is the problem?

Please upload the data to dropbox and post the link here. Thanks for your support.
2017-12-20
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fansb181213c
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DJI Elektra Posted at 2017-12-20 04:47
Please upload the data to dropbox and post the link here. Thanks for your support.

here is the link:
https://www.dropbox.com/sh/pfl4e ... zvk4vOdqvkXDBa?dl=0
2017-12-20
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DJI Elektra
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fansb181213c Posted at 2017-12-20 11:13
here is the link:
https://www.dropbox.com/sh/pfl4eg1aqtmrui1/AABQfD5JWzXzvk4vOdqvkXDBa?dl=0

Thanks for your update. I would help you forward to our engineers for further check. Please wait patiently.
2017-12-21
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DJI Elektra
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fansb181213c Posted at 2017-12-20 11:13
here is the link:
https://www.dropbox.com/sh/pfl4eg1aqtmrui1/AABQfD5JWzXzvk4vOdqvkXDBa?dl=0

Please try to turn on your AC and calibrate the compass. Then turn if off. Put your spark on your palm and then turn it on. After self-check, you can take off your spark on land. Please keep us updated. Thanks.
2017-12-21
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fans1351c572
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I say just go to the store and buy a new drone take out the gps/compass module and put ur broken gps/compass module back in and return to store... Problem fixed and DJI will correct their problems so less returns... Everyone happy!!!
2017-12-21
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fansb181213c
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DJI Elektra Posted at 2017-12-21 02:28
Please try to turn on your AC and calibrate the compass. Then turn if off. Put your spark on your palm and then turn it on. After self-check, you can take off your spark on land. Please keep us updated. Thanks.

Hi
Ok, re-calibrated and had a couple of good flights. Looking at the log, there were no errors at all. I did put it through it's paces, usual spot at the beach. Lots of turns and also going very fast in sports mode.
Now, I am not wearing my watchband with the magnetic latch any more, and when I fitted the legs on the spark, I definitely would have touched the magnet with one of the motors and I am sure the problem would have happened, even though there would have been no error showing.
So, I think the most important advice is to closely look at the way the Spark is pointing on the ground and see if it agrees with the pointer in DJI Go, i.e. place it so it faces north and make sure it points at the "N" on the screen exactly.
2017-12-23
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fansb181213c Posted at 2017-12-23 15:19
Hi
Ok, re-calibrated and had a couple of good flights. Looking at the log, there were no errors at all. I did put it through it's paces, usual spot at the beach. Lots of turns and also going very fast in sports mode.
Now, I am not wearing my watchband with the magnetic latch any more, and when I fitted the legs on the spark, I definitely would have touched the magnet with one of the motors and I am sure the problem would have happened, even though there would have been no error showing.

Good to hear you can have some good flights. Have fun!
2017-12-25
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