Mavic First Flight Uncontrolled - Magnetic Interference

[Rich Sugden M.D.]

Very good info, thanks!!
The "mag warning" I was referring to, displays on screen as "mag interf"... which I believe means magnetic interference. On my first day flying it behind my house (with houses nearby on one side, but wide open space on the other side), I was frequently getting that warning. On my second day flying in the same place, I got no such warnings.

Had this error on boot up today, and in middle of large field ... No video, no info on many of the data pages ... BLANK ... "Disconnected" error ... after extensive checking all controller pages w/o finding any info, motors started and hovered OK ... landed and further checking found iPhone lightening cable not fully plugged in!!! Pressed in and all OK ... NO IDEA WHY THIS ERROR?? I suspect common problem as lightening cable is difficult to fully seat ... need to check every flight I think...

 

[Kermit215]

Had this error on boot up today, and in middle of large field ... No video, no info on many of the data pages ... BLANK ... "Disconnected" error ... after extensive checking all controller pages w/o finding any info, motors started and hovered OK ... landed and further checking found iPhone lightening cable not fully plugged in!!! Pressed in and all OK ... NO IDEA WHY THIS ERROR?? I suspect common problem as lightening cable is difficult to fully seat ... need to check every flight I think...

Had this error on boot up today, and in middle of large field ... No video, no info on many of the data pages ... BLANK ... "Disconnected" error ... after extensive checking all controller pages w/o finding any info, motors started and hovered OK ... landed and further checking found iPhone lightening cable not fully plugged in!!! Pressed in and all OK ... NO IDEA WHY THIS ERROR?? I suspect common problem as lightening cable is difficult to fully seat ... need to check every flight I think...

Is your compass saying "Disconnected"? If so, i had the same issue and had to send it in for repair.

 

[Falcorma]

I have gone through a few of these threads about the mavic not doing what it's told or moving without any input. It obviously has me a little bit concerned. There is not one time with my Phantom 3 that I felt like I had to worry about anything.

I helped film a commercial in a fuel tank fabrication shop with my P3. I'm talking metal everywhere, zero satellites, inside a warehouse. I even went as far as flying through one of the 10 foot diameter steel tubes used for the tanks.

I want that same amount of trust in my Mavic. Now I have had over 10 flawless flights so far, but I have had some pop up interference warnings from time to time. I just hope I would be able to do the same things with my Mavic as I could with my P3

Sent from my Pixel XL using MavicPilots mobile app

 

[Manfrenjensen]

@Manfrenjensen - next flight, GUN IT hard. Go to sports mode and go full throttle back and forth.

I forgot to follow up on this....
I did try this and I got no warnings or bad behavior. So I guess that means I don't have this problem. I still haven't had all those warnings and strange behavior since the first day. So.. either a fluke or a magically healing mavic.

 

[erkme73]

I forgot to follow up on this....
I did try this and I got no warnings or bad behavior. So I guess that means I don't have this problem. I still haven't had all those warnings and strange behavior since the first day. So.. either a fluke or a magically healing mavic.

That's awesome. I think the load-induced compass noise, if present, is pretty easy to consistently reproduce the interference warnings. If you're not seeing them, and you're on the latest firmware, you're hardware (on this issue) is golden.

 

[Mr Spock]

Here is why some Mavics got the issue and some don't and also here is how to fix this:
DIY rear compass cabling fix

 

[communistche]

Ok so I got a Mavic and I am a total newb. During my 3rd or 4th flight the Mavic went crazy when I went under some train tracks and crashed into a wall. I chipped a propeller. Threw another on and went back under the L tracks and it went crazy again. I didn't get any crazy notification on my controller saying there was interference... but when I checked the log thats what happened.

The drone seems to be fine. But is there anyway I can test that its ok? Also is there a way to make sure there is no interference when flying?

 

[larkin]

Stay away from steel and things carrying electrical current. Especially stay away from things that combine those two and you should be set.

Sent from my XT1650 using MavicPilots mobile app

 

[nuncafilmes]

There were three flights included in the posted .DAT files. The second flight corresponds to the video in the first post. In summary, the Mavic was launched from a geomagnetically distorted site causing the Yaw (heading) to be incorrect. This incident is similar to some P3 incidents that I've looked at. Here is a recent one.

The Mavic gets it's heading info from a combination of sensors; mostly the gyros, then the accelerometers. Shortly after batteryOn the Flight Controller initializes the Yaw value based on the compass magnetometers but after that it's info coming from the gyros and accelerometers that determine Yaw. After this the magnetometers have only a small effect on the value of Yaw.

If the launch site is geomagnetically distorted the Yaw value will be incorrect because of the effect on the magnetometers. When the Mavic has cleared the effects of the geomagnetic distortion the compass/magnetometers become correct, BUT the Yaw is being determined by the gyros which hasn't changed.

That's what happened in this incident.
View attachment 2503
magYaw is a diagnostic value calculated by DatCon from the magnetometer data. Here, magYaw and Yaw (the value that the Mavic uses for heading) are the same incorrect value until the Mavic launches at time 3.2 secs. Then magYaw (blue line) changes to -134, the correct value, BUT Yaw (green line) stays at the old, incorrect, value of -115. I looked at the video to confirm that magYaw is correct.

The Mavic is different from the P3 in that the P3 would have switched to ATTI because it has to assume that it's possible Yaw is incorrect. The Mavic did not switch to ATTI but from pilot's description appears to taken a different strategy. I haven't seen enough Mavic incidents to know if the Mavic was trying to navigate at this point. From looking at the control inputs and motor speeds my best guess is that the Mavic was attempting to both navigate and respond to control inputs.

View attachment 2505
View attachment 2507
View attachment 2508
At time 15.38 the only control input is full negative throttle but the Mavic proceeded across the traffic circle. In the GoogleEarth view the AC location is shown as an A. The blue line is the magYaw value and the green line is the Yaw value.

This incident was not caused by a compass calibration problem. It was all due to the geomagnetic distortion at the launch site. Note that the magYaw/Yaw stops separating when the Mavic reaches 1.6 meters. If the pilot had hand launched higher than 1.6 meters there would not have been an incident. The effect of a compass calibration is to compensate for onboard magnetic distortions. A compass calibration does not compensate or know about local or regional geomagnetic distortions. All the compass calibration needs is a geomagnetic field that 1) isn't distorted within the confines of the compass dance and 2) has a strength that isn't drastically different from the launch site. The pilot achieved this in the flight previous to this one.

Unfortunately, checking the magMod value isn't much use in detecting this situation before launch. The geoMagnetic field is distorted but it's strength hasn't changed enough to notice. The only way to really detect this kind of problem is to eyeball the Mavic, know which way it's pointing, and check that with the red arrow in the display. Having said that, I'll also add that I never do this.

Hi there! I'm a totally new-bee in drone and mavic world and I'm not a native english speaker.. so please be patient with me ...I still get a doubt: If I calibrate my compass and take off from a secure place (non distorted geomagnetic spot), during my flight if I pass throug some geomagnetic distortion spot I would get some warnings and beeps but the mavic wouldn't assume that suicidal behaivior, just some lacks of connection with the RC, right?.. I mean.. the most important is that the place you take off must be a " clean" spot (in terms of magnetic interference)... I allways think about some videos that shows drones following cars, city enviroment, drones passing through buildings and I wonder how don't they get magnetic interference? How do they do such takes... And now reading these histories I'm so afraid of magnetic interference that I ask myself If I only can film beaches and mountains with my mavic.. Obviously during my learning period (probably several months) I will always fly with my drone in very open spaces and with noone around.. I'm just want to to know how sesitive and danger the mavic could be in a urban area for future shots

 

[BossBob]

Hi there! I'm a totally new-bee in drone and mavic world and I'm not a native english speaker.. so please be patient with me ...I still get a doubt: If I calibrate my compass and take off from a secure place (non distorted geomagnetic spot), during my flight if I pass throug some geomagnetic distortion spot I would get some warnings and beeps but the mavic wouldn't assume that suicidal behaivior, just some lacks of connection with the RC, right?.. I mean.. the most important is that the place you take off must be a " clean" spot (in terms of magnetic interference)... I allways think about some videos that shows drones following cars, city enviroment, drones passing through buildings and I wonder how don't they get magnetic interference? How do they do such takes... And now reading these histories I'm so afraid of magnetic interference that I ask myself If I only can film beaches and mountains with my mavic.. Obviously during my learning period (probably several months) I will always fly with my drone in very open spaces and with noone around.. I'm just want to to know how sesitive and danger the mavic could be in a urban area for future shots

Why are you calibrating the compass? The manual clearly says not to calibrate the compass unless it is required by the app. I've had my Mavic since early March, more than 80 flights and never calibrated the compass ever. The drone has flown perfectly except for one occasion when I flew it into some old ivy.

 

[BudWalker]

Hi there! I'm a totally new-bee in drone and mavic world and I'm not a native english speaker.. so please be patient with me ...I still get a doubt: If I calibrate my compass and take off from a secure place (non distorted geomagnetic spot), during my flight if I pass throug some geomagnetic distortion spot I would get some warnings and beeps but the mavic wouldn't assume that suicidal behaivior, just some lacks of connection with the RC, right?.. I mean.. the most important is that the place you take off must be a " clean" spot (in terms of magnetic interference)... I allways think about some videos that shows drones following cars, city enviroment, drones passing through buildings and I wonder how don't they get magnetic interference? How do they do such takes... And now reading these histories I'm so afraid of magnetic interference that I ask myself If I only can film beaches and mountains with my mavic.. Obviously during my learning period (probably several months) I will always fly with my drone in very open spaces and with noone around.. I'm just want to to know how sesitive and danger the mavic could be in a urban area for future shots

Welcome to the forum nuncafilmes.
You're right, it's a good idea to check the Yaw value prior to launch. Do this by looking at the red arrow in the Go App map display. For example, if it looks like this and you can see your Mavic is pointed the same then Yaw is OK.



There is no need to calibrate before flight unless the Go App directs you to. I've never calibrated mine.

Urban environments can be tricky. There aren't any specific rules that are guaranteed to keep the Mavic out of trouble. It's more likely you'll encounter GPS problems flying next to or between buildings. Another check you can do before launch is to make sure the gps graph display on the RC is showing at least 4 bars

You're right, passing through a geomagnetic distortion won't cause a problem; if it's brief. But, if the Mavic lingers in the presence of a geomagnetic distortion the Yaw value will gradually become the same value as the incorrect compass value.

Good luck and have fun.