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Horizon Tilt regardless of Gimbal Roll Adjustment mid flight

jtcfilms

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Hi pilots, I just got the mavic recently and am having constant horizon tilt issues. I've done all calibrations and even adjust the gimbal roll mid flight and once I turn the horizon tilts again. Im in follow mode and not FPV either. Its driving me crazy. I've read several other threads about this and there is no clear answer. Please help :)

I want to start doing videos for real estate agents, but how am I supposed to circle a house without terrible tilt... Sure I can edit post production but that affects the letterbox effect in Final Cut Pro X.... Just looking to fix the mavic to how it should be.

Appreciate any and all help on the horizon tilt before getting DJI support involved.
 

Humanparody

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I've been battling the horizon tilt issue for months hoping for an update that will address it. It hasn't. What I can tell you is that there are multiple sensors that are working together to attempt to figure out what "down" actually is using complicated algorithms. The sensors are not flawed, it's the algorithms could use some work though. What I have noticed is that the atttitude of the Mavic has a bearing on what numbers are plugged into the algorithms. Also, the longer the attitude is in a certain position, the bigger the bias in the numbers that the algorithm uses.

In plain terms, say you were in sport mode and going full throttle forwards for awhile. The aircraft is pitched forward and slowly the "down" the aircraft senses migrates to a different angle corresponding to the forward pitch of the aircraft.
You don't notice this change in the sensed angle until you turn the aircraft 90° left or right, in which case you will see the horizon is pitched clockwise or counterclockwise depending on which way you turned. You'll also notice that if you turn the aircraft back toward the way you were traveling that screwed up the angle, the horizon is level. You'll also notice that if you spin 180° from there that the horizon is still level, but it's lower.

The same also happens if your Mavic is fighting against a side wind to stay in posistion. A wind from the left will cause the aircraft to have to roll left to maintain it's posistion. Stay there long enough and the sensors will slowly start to think "down" is a slightly different angle. Now your horizon will be off based on the direction of the wind that day.

It's crazy to think that something as simple as a plumbob would instantly be able to tell which direction was down and correct this issue, but unfortunately there's no space for one of those in a drone so it relies on microscopic gyroscopes and magnetometers to do that job, and those have inherent flaws. They rely on, first and foremost, having a good calibration on startup, meaning make sure you power up on a horizontal surface. From there then on, they are literally just measuring changes in the aircraft's position and doing their best to make sure everything is back to zero when the aircraft is level.

So, now that you know what causes them to get screwed up, you should know what to do to correct it while in flight. The manual roll adjustment is terrible, unreliable, and should be avoided at all costs(leave it at zero). First, I recommend not doing any quick and hard maneuvers that will skew your algorithms almost instantly. Keep it slow and steady. Second, once you start to see how the wind or long periods off single-direction flight start to skew the algorithms, you can actually counter it by doing the opposite. If you were facing one way and the wind was to the left for a minute, turn the craft around and let it fight the wind from the right for a minute. It will slowly fix itself. If it's not windy at all that day and a hard maneuver screwed up the horizon, just let the craft hover for a bit and it will slowly but surely level itself back out. A great tool to use is the horizon indicator option in the lower left hand corner where the map is. Choose the crosshair and it will bring up the flight bubble/power usage indicator. Watching that while you're flying will give you a good indicator as to how your horizon will be screwed up and will help you orient the aircraft afterwards to fix it. I hope this helps.
 

Carlosmingos

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Might be worth investigating if you can fix this in post? I personally don't know enough about it to advise but i would imagine it would be the sort of thing that video editing software could resolve pretty easily...

Sorry OP just re-read and noticed your reasons for not wanting to rely on post prod
 
Last edited:

Carlosmingos

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Great info by the way, Humanparody, thanks for the level of detail! It's great to get advice on that level about the Mavic's behaviour, really helps to understand the nuances of how to pilot it better. Interesting to find out that it adjusts and resets its level to compensate for wind etc. and that rotating will mean this compensation then skews the horizon level (except at 180°) until it can adjust again. Very interesting!
 
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curso88

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I've been battling the horizon tilt issue for months hoping for an update that will address it. It hasn't. What I can tell you is that there are multiple sensors that are working together to attempt to figure out what "down" actually is using complicated algorithms. The sensors are not flawed, it's the algorithms could use some work though. What I have noticed is that the atttitude of the Mavic has a bearing on what numbers are plugged into the algorithms. Also, the longer the attitude is in a certain position, the bigger the bias in the numbers that the algorithm uses.

In plain terms, say you were in sport mode and going full throttle forwards for awhile. The aircraft is pitched forward and slowly the "down" the aircraft senses migrates to a different angle corresponding to the forward pitch of the aircraft.
You don't notice this change in the sensed angle until you turn the aircraft 90° left or right, in which case you will see the horizon is pitched clockwise or counterclockwise depending on which way you turned. You'll also notice that if you turn the aircraft back toward the way you were traveling that screwed up the angle, the horizon is level. You'll also notice that if you spin 180° from there that the horizon is still level, but it's lower.

The same also happens if your Mavic is fighting against a side wind to stay in posistion. A wind from the left will cause the aircraft to have to roll left to maintain it's posistion. Stay there long enough and the sensors will slowly start to think "down" is a slightly different angle. Now your horizon will be off based on the direction of the wind that day.

It's crazy to think that something as simple as a plumbob would instantly be able to tell which direction was down and correct this issue, but unfortunately there's no space for one of those in a drone so it relies on microscopic gyroscopes and magnetometers to do that job, and those have inherent flaws. They rely on, first and foremost, having a good calibration on startup, meaning make sure you power up on a horizontal surface. From there then on, they are literally just measuring changes in the aircraft's position and doing their best to make sure everything is back to zero when the aircraft is level.

So, now that you know what causes them to get screwed up, you should know what to do to correct it while in flight. The manual roll adjustment is terrible, unreliable, and should be avoided at all costs(leave it at zero). First, I recommend not doing any quick and hard maneuvers that will skew your algorithms almost instantly. Keep it slow and steady. Second, once you start to see how the wind or long periods off single-direction flight start to skew the algorithms, you can actually counter it by doing the opposite. If you were facing one way and the wind was to the left for a minute, turn the craft around and let it fight the wind from the right for a minute. It will slowly fix itself. If it's not windy at all that day and a hard maneuver screwed up the horizon, just let the craft hover for a bit and it will slowly but surely level itself back out. A great tool to use is the horizon indicator option in the lower left hand corner where the map is. Choose the crosshair and it will bring up the flight bubble/power usage indicator. Watching that while you're flying will give you a good indicator as to how your horizon will be screwed up and will help you orient the aircraft afterwards to fix it. I hope this helps.
Hello

In my Mavic, after IMU calibration and Gimbal Auto Calibration my gimbal need a correction to leveled horizon using the Adjust Gimbal Roll option and setting a value of -0.4

I have asked many users and many comment that the horizon has to manually calibrate with this option and manually adjust the Gimbal Roll, but other users do not have to make these corrections.

Is normal that my Mavic needed a slight adjustment with the Adjust Gimbal Roll option because when doing the Gimbal Auto Calibration option the position of the gimbal and the horizon is -0.4 degrees out of level? Is it a normal manufacturing margin or is it a manufacturing defect?

Thanks in advance

Roll position in 0.0
5449e0ca8999140bc9665eb4359eb09a.jpg

Roll position in -0.4 (Horizon corrected)
d37acc420e8dfd735195d141047b2577.jpg
 

Strafe1

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Joined
Jan 2, 2017
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Hello

In my Mavic, after IMU calibration and Gimbal Auto Calibration my gimbal need a correction to leveled horizon using the Adjust Gimbal Roll option and setting a value of -0.4

I have asked many users and many comment that the horizon has to manually calibrate with this option and manually adjust the Gimbal Roll, but other users do not have to make these corrections.

Is normal that my Mavic needed a slight adjustment with the Adjust Gimbal Roll option because when doing the Gimbal Auto Calibration option the position of the gimbal and the horizon is -0.4 degrees out of level? Is it a normal manufacturing margin or is it a manufacturing defect?

Thanks in advance

Roll position in 0.0
5449e0ca8999140bc9665eb4359eb09a.jpg

Roll position in -0.4 (Horizon corrected)
d37acc420e8dfd735195d141047b2577.jpg
normal.
 

SteelFlyer

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Joined
Jan 17, 2017
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Age
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Just a note on fixing this in post. If you shoot at 2.7k or 4K and are producing 1080p final content then you could crop the image and key frame a rotation to fix the horizon. It's a pain but works.
 
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