Altitude issue.

[Peio64270]

Hello, you all.

Since my last firmware update, I have a rather important issue with altitude measurement.

I went out today for some tests of the camera and did two flights at a very short distance from my home point (max home distance about 150') and at relatively low altitude (no more than about 50').

If altitude appeared to be well estimated at the begining of both flights, it decreased with time and reached negative values while I was hovering or moving slightly forward or backward at the same level.

When I landed approximatively at my home point (take off), altitude measurement was as low as -156 feet (see the 1st flight log hereunder, 10 min to the end).

The "drift" in altitude measurement begins at roughly 6m 40s and continues till landing, increasing regularly.

Strange enough, the last data after switching off the motors returns to the right value (zero feet).

What can explain these errors and how to correct it ?

I can not fly Litchi missions with such huge errors.

The first flight analysis :
Phantom Log Viewer - PhantomHelp.com

The second one, less regular but also erratic in altitude :
Phantom Log Viewer - PhantomHelp.com

Thank you in advance for your answers...

[Edit : I'd like to add that the Mavic did not climb or went down while the altitude measurement was drifting. It remained absolutely stable, hovering or moving at the same high]

 

[BlakPhoenix]

Just spitballing here, but was there any dramatic change in air pressure during your flight?

 

[Peio64270]

Just spitballing here, but was there any dramatic change in air pressure during your flight?

No : very nice weather, sunny and no wind at all. Temp at about 15°C.
Further, you can observe about the same drift during the two consecutive flights around the same place and at about the same true altitude (between 10m and 30m, say between 30 and 50 feet).

 

[gecarey]

I am having the same issue with mine. I am noticing a difference of 20-30 feet between the VPS and the height data. I landed with -24 feet and the VPS said +.3 ft. Once I shut the motors down, the -24 went to 0 and VPS stayed at +.3.
Battery #2, I took off and had it in a hover at 3 feet, the #s matched at that point. Flew the battery out and on landing, I was showing 6 ft on the screen and 1.6 on the VPS prior to landing.
Batteries 3,4 and 5 all did the same thing and the variations were all within about 5-6 feet .
Very Strange......
Also, I have NOT done any updates on this mavic.

 

[Peio64270]

I am having the same issue with mine. I am noticing a difference of 20-30 feet between the VPS and the height data. I landed with -24 feet and the VPS said +.3 ft. Once I shut the motors down, the -24 went to 0 and VPS stayed at +.3.
Battery #2, I took off and had it in a hover at 3 feet, the #s matched at that point. Flew the battery out and on landing, I was showing 6 ft on the screen and 1.6 on the VPS prior to landing.
Batteries 3,4 and 5 all did the same thing and the variations were all within about 5-6 feet .
Very Strange......
Also, I have NOT done any updates on this mavic.

Two days ago, I did two other flights after IMU calibration with the same (bad) result.
This looks not to depend on the battery used (I have 3 of them) but I remarked that measurement of altitude remains accurate as long as I do not play with the throttle joystick.
As soon as I change voluntarily the drone altitude, it begins to send (and to register) frentic values. At the end of these two new flights, I could travel normally at was displayed as -20m and landed (2m away from my take-off point) at -28m !

I'm waiting for an answer from DJI support but for now, I stopped using my Mavic.
Very sad...

 

[Robbyg]

Same here. VPS says I am 50ft up the height says 2ft and I am actually at 2ft. When it touches the ground VPS suddenly drops to Zero. Sometimes VPS is correct but more often it is wrong!

 

[Peio64270]

Same here. VPS says I am 50ft up the height says 2ft and I am actually at 2ft. When it touches the ground VPS suddenly drops to Zero. Sometimes VPS is correct but more often it is wrong!

Did you report this to DJI support ? If not, could you share the flight data where such errors are recorded ? Thanks in advance.

 

[pgitug]

When you IMU calibrate it is SO important to not be near any metal, concrete, structures or closer than 20' of the controller.


Sent from my iPhone using MavicPilots

 

[Peio64270]

Last news :

I received today a mail from DJI saying :

________________
Jillian Chen (DJI)


Feb 27, 11:49 HKT

Hello Pierre,
Greetings.
It seems that your barometer is not working properly and if you have calibrated IMU but it still doesn't work well then we need to take it back for service.
Please reply with the following information so I can help you create a case and get everything fixed.
_________________

Therefore, I recommand to those who are impacted by a similar issue with their Mavic to contact DJI support.

 

[Peio64270]

When you IMU calibrate it is SO important to not be near any metal, concrete, structures or closer than 20' of the controller.

The (huge) problem was there before IMU calibration.
Moreover, IMU calibration was not asked by the app. I did it to satisfy the demand of the French DJI support but the problem is unchanged following it.

I think that there is something wrong with the barometric probe of my Mavic (and maybe in other drones of the same brand). Thus take care in distant flights and over all, during automatic flights. I don't know how the drone would behave during a Litchi waypoint mission when you programmed, say, +100m altitude at a waypoint and it measures actually -30m at this location...

 

[Peio64270]

Last news :

A case has been opened for repair of my Mavic.

DJI support suspects (as I did) a bad barometer functioning.
Take care of this with your Mavics since the issue came suddenly, from one flight to the next one, and it was fully present at the outset.

 

[Peio64270]

Last news :

A case has been opened for repair of my Mavic.

DJI support suspects (as I did) a bad barometer functioning.
Take care of this with your Mavics since the issue came suddenly, from one flight to the next one, and it was fully present at the outset.