Gimbal roll and Horizon level

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I try to calibrate the Gimbal to avoid any roll but I still see my horizon tilted sometimes. Does my AC have to be on a perfectly level ground (like a board with a bubble level)? I usually let the AC be on the ground in the park when I calibrate.

Do I also need to calibrate the IMU before every flight? I do not even see an option to calibrate the IMU in the app.
 
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Yes it should be on an absolutely flat surface. No you do not need to calibrate before every flight unless you travel some distance from your previous launch point.


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I try to calibrate the Gimbal to avoid any roll but I still see my horizon tilted sometimes. Does my AC have to be on a perfectly level ground (like a board with a bubble level)? I usually let the AC be on the ground in the park when I calibrate.

Do I also need to calibrate the IMU before every flight? I do not even see an option to calibrate the IMU in the app.

Do IMU calibration on perfectly flat and leveled surface at home (ground level recommended). As an option you can do a "cold calibration" by putting your AC in refrigerator (not freezer) for 15 minutes before calibration. IMU calibration option is under AC/Advanced/Sensors. Gimbal calibration is done right after IMU calibration is completed without moving AC. You should also calibrate a compass after that, but outside, away from any metal objects
I calibrate IMU/gimbal only after firmware updates and compass if I'm away more then 100km from my previous calibration.
 

JTE

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When I do an IMU calibration I use a 9 inch professional metal bubble level across the top of the landing skids behind the camera (but not touching it) & two smaller 3 inch ones across the top of 9 inch at 90 degrees. So I have level in 2 different directions. I suppose you could just get a bubble level and make it easier but you won't find them readily available. I'm not sure it matters or what is perfectly level and how do you exactly measure perfectly level but I tried. I also had my remote 10 feet away during the IMU calibration.

Even with an IMU, gimbal & compass calibration I still find times when I have to adjust the gimbal roll manually in flight to get that horizon level. I pull up the grid markings for reference. I've had 2 Phantom 4s and both behaved the same in this regard so I think this is the way it is. It's my understanding the Phantom 4 has a 90 degree field of view - that's pretty wide still and it's more difficult to keep level on the ends of frame-especially super wide which is just hooky ridiculous IMHO when buildings and vertical lines slant. If I had my way the 4K cam on the Phantom 4 would be equivalent to a 28 mm or higher lens. It would look more natural and you just increase altitude to expand the field of view. But that is what some of the more expensive drones are for.
 
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When I do an IMU calibration I use a 9 inch professional metal bubble level across the top of the landing skids behind the camera (but not touching it) & two smaller 3 inch ones across the top of 9 inch at 90 degrees. So I have level in 2 different directions. I suppose you could just get a bubble level and make it easier but you won't find them readily available. I'm not sure it matters or what is perfectly level and how do you exactly measure perfectly level but I tried. I also had my remote 10 feet away during the IMU calibration.

Even with an IMU, gimbal & compass calibration I still find times when I have to adjust the gimbal roll manually in flight to get that horizon level. I pull up the grid markings for reference. I've had 2 Phantom 4s and both behaved the same in this regard so I think this is the way it is. It's my understanding the Phantom 4 has a 90 degree field of view - that's pretty wide still and it's more difficult to keep level on the ends of frame-especially super wide which is just hooky ridiculous IMHO when buildings and vertical lines slant. If I had my way the 4K cam on the Phantom 4 would be equivalent to a 28 mm or higher lens. It would look more natural and you just increase altitude to expand the field of view. But that is what some of the more expensive drones are for.
I use 50x50cm ceramic tile on top of motor hubs and bubble level on it to make it perfectly leveled when doing IMU calibration.

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You don't need to do an IMU, gimbal, or compass calibration before every flight. As mentioned, do a cold-IMU calibration on a level surface. I chill the bird in the freezer for 15-20 minutes without the battery, have the controller & app ready to go, then as soon as the bird is connected & ready I perform the IMU calibration. As soon as this finishes do the Gimbal Auto-Calibration.

Even if you do these things the horizon will sometimes be off. It may be perfect one flight & tilted the next. It is quirky & just the way things are.

I try to calibrate the Gimbal to avoid any roll but I still see my horizon tilted sometimes. Does my AC have to be on a perfectly level ground (like a board with a bubble level)? I usually let the AC be on the ground in the park when I calibrate.

Do I also need to calibrate the IMU before every flight? I do not even see an option to calibrate the IMU in the app.
 
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You don't need to do an IMU, gimbal, or compass calibration before every flight. As mentioned, do a cold-IMU calibration on a level surface. I chill the bird in the freezer for 15-20 minutes without the battery, have the controller & app ready to go, then as soon as the bird is connected & ready I perform the IMU calibration. As soon as this finishes do the Gimbal Auto-Calibration.

Even if you do these things the horizon will sometimes be off. It may be perfect one flight & tilted the next. It is quirky & just the way things are.

****. If I wanted to work I'd get a job! :D
 
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Even if you do these things the horizon will sometimes be off. It may be perfect one flight & tilted the next. It is quirky & just the way things are.

Yes, they ALL have some degree of horizon tilt. Mine is flat about 80% of the time, pretty good about 15% of the time (where you have to pay attention to see it) and 5% of the time the tilt is quite noticeable and annoying.
 
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Also, I suspect that dji have an integral term built into the gimbal controller, so that tends to level itself over a period of time [ and assumes that the aircraft is level]. I notice that the problem seems worse if you are flying with a steady wind from one side. The bird sits at an angle to counter the wind, and the horizon slowly adjusts by itself to be horizontal. Then, If you then suddenly turn it 180 deg, it is sometimes is way off in the opposite direction for about 5 seconds & then slowly corrects again. Maybe it's my imagination.
 
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I was just wondering about this as well. Thanks for the information; I have been letting the AC boot up on my slightly slanted concrete driveway and noticed the horizon was pitched about the same as the driveway.

Prior to reading this I adjusted the gimbal roll left about 1.1 (I assume that's degrees) and thought it might be a bit extreme. I suppose I will find out next time I boot up and check it but I'll ask anyway: Will that reset with a AC reset?

Also, what is the benefit of putting the craft in the fridge for a "cold" calibration?

Thanks in advance,
Matt


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I was just wondering about this as well. Thanks for the information; I have been letting the AC boot up on my slightly slanted concrete driveway and noticed the horizon was pitched about the same as the driveway.

Prior to reading this I adjusted the gimbal roll left about 1.1 (I assume that's degrees) and thought it might be a bit extreme. I suppose I will find out next time I boot up and check it but I'll ask anyway: Will that reset with a AC reset?

Also, what is the benefit of putting the craft in the fridge for a "cold" calibration?

Thanks in advance,
Matt


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It will boot up faster.
 

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