IMU calibration in a dynamic environment

[MavicZoomNewbie]

Ok, I am a Captain of a 280 ‘ supply vessel in the Gulf of Mexico. I am currently offshore my vessel is rocking and rolling . I wanted to fly my drone around my vessel to get some aerials but when I power my Zoom up it gives me a IMU calibration I know what it is but is there any way you can store a previous calibration like from when I’m on stable ground so that the drone will know level flight when I try to fly it off my boat? Is there a work around for this? I’m sure I’m not the only one that’s ever tried to take off form a moving vessel

 

[BD0G]

You have to have a stable platform to do a "cold" IMU calibration. There are no two ways about that.
Perhaps you can find a point on the boat that is pretty much level . Center of boat? Then try a "cold" IMU calibration , but honestly I would not trust it to perform a flight afterwards out at sea even if the calibration was successful.

Too much chance of something going wrong and loosing the Mavic to Davey Jones Locker.

 

[old man mavic]

if you had done a calibration on land perfectly level theres no reason why it should need doing on the boat perhaps if you can hold the mav level on power up it might fix it

 

[msinger]

is there any way you can store a previous calibration like from when I’m on stable ground so that the drone will know level flight when I try to fly it off my boat?

The drone automatically stores and recalls the data from the last IMU calibration each time it's powered on. There is no way to manually recall data saved from a specific IMU calibration performed in the past.

 

[Thomas B]

Assuming no heavy seas, and agreeing with the posts above, I wonder if the pilot would just have to take control. The ship is likely moving anyway...that is to say not use RTH, but actually fly the bird. Or maybe that’s what everyone meant.

 

[BD0G]

It is my understanding from what was posted that the Mavic is presenting a message within the DJIGO4 app that REQUIRES an IMU calibration before allowing takeoff and flight. Since the boat is rocking and reeling then performing a dead level "cold" IMU calibration would not be possible.

So in this situation one is presented with a no fly scenario until that IMU is cold calibrated. You own a rock until this is performed successfully.

If one trys the calibration with constantly changing elevations and accelerations then the IMU would be receiving data during the calibration that was changing dynamically with the rocking of the boat. So even it the process completed successfully the Mavic may fly really wonky. Not something you want to chance over the sea or the ground for that matter.

 

[Former Member]

Simple solution, centuries old. This will counteract either pitch or roll, depending on what the seas are. Jump in and calibrate.

Someone on the ship has got to have one.

 

[brett8883]

Simple solution, centuries old. This will counteract either pitch or roll, depending on what the seas are. Jump in and calibrate.

Someone on the ship has got to have one.


View attachment 66268

I don't believe the Mavic will even calibrate when moving. If you look at the IMU status in DJI GO 4 if the gyroscopes detect movement it won't register a calibration. I think it does this to protect against a bad calibration.

The OP might be able to do an Assistant 2 IMU calibration but I am really not sure if that will do it.

@MavicZoomNewbie have you tried taking off and its preventing you?

 

[Meta4]

Ok, I am a Captain of a 280 ‘ supply vessel in the Gulf of Mexico. I am currently offshore my vessel is rocking and rolling . I wanted to fly my drone around my vessel to get some aerials but when I power my Zoom up it gives me a IMU calibration I know what it is but is there any way you can store a previous calibration like from when I’m on stable ground so that the drone will know level flight when I try to fly it off my boat? Is there a work around for this? I’m sure I’m not the only one that’s ever tried to take off form a moving vessel

The calibration is not the problem and unless you crash your drone, it should never need to have the IMU recalibrated.
And besides, when you calibrate the IMU, the drone has to be perfectly still and level.
The problem is that you are trying to launch from a rocking launch point.
On a boat, hand launching is usually better since the person holding the drone can keep it more stable than simply putting it on the deck.

 

[old man mavic]

The calibration is not the problem and unless you crash your drone, it should never need to have the IMU recalibrated.
And besides, when you calibrate the IMU, the drone has to be perfectly still and level.
The problem is that you are trying to launch from a rocking launch point.
On a boat, hand launching is usually better since the person holding the drone can keep it more stable than simply putting it on the deck.

thankyou Meta4 that is what i was trying to say in my own way

 

[Watash48]

Simple solution, centuries old. This will counteract either pitch or roll, depending on what the seas are. Jump in and calibrate.

Someone on the ship has got to have one.


View attachment 66268

This would only cover one axis of the pitch and roll

 

[Former Member]

This would only cover one axis of the pitch and roll

Yes thats right. Sometimes a boat will pitch or roll more than the other axes depending on the seas.

 

[lomposlapos]

Taking off from a small (3 m in length) boat rocking on even mild waters visibly will screw up the controlability of the aircraft. Aircraft may drift, or perform other mild but erratic movements for example (of course IMU, compass, proximity sensors are calibrated on land). This is particularly dangerous when landing by hand catch.

Is there a way to "disable" motion, position, etc. sensors just until the aircraft lifts off and hovers in position in order to avoid a false sensory state interpretation caused by the rocking boat?

Is DJI aware of this issue and have a remedy?

 

[jsflyrv]

Just pondering, if you do get it to take off from a boat and it goes into a stable hover won't the boat sail away from under the drone? So unless it is in follow mode you would have to be ready to start flying it manually to stay with the boat?

 

[zapsizzle]

So this just happened to me on a boat that hired me to get drone shots. Incredibly stressful situation given that a lot of time and money was riding on this job but what was interesting was that even though IMU calibration kept failing on my Mavic 2 Zoom at the 2/5 or 3/5 point I ended up calibrating the compass which sort of soft fixed the IMU and let me take off even though IMU calibration never succeeded. I say soft fixed because every time I brought the drone back to battery swap, the IMU would give me problems with takeoff then a compass calibration sorta fixed it again where I could take off. It was a weird situation.

 

[Meta4]

So this just happened to me on a boat that hired me to get drone shots. Incredibly stressful situation given that a lot of time and money was riding on this job but what was interesting was that even though IMU calibration kept failing on my Mavic 2 Zoom at the 2/5 or 3/5 point I ended up calibrating the compass which sort of soft fixed the IMU and let me take off even though IMU calibration never succeeded. I say soft fixed because every time I brought the drone back to battery swap, the IMU would give me problems with takeoff then a compass calibration sorta fixed it again where I could take off. It was a weird situation.

Why were you trying to recalibrate anything, it shouldn't have been necessary at all?
A boat is the last place to try to recalibrate the IMU because the drone has to be stable and level on a rock-solid, non-moving surface for IMU calibration.
The compass is completely independent of the IMU and unrelated.
But neither would have required recalibration anyway, you could have just flown without messing around with that.

 

[zapsizzle]

Why were you trying to recalibrate anything, it shouldn't have been necessary at all?
A boat is the last place to try to recalibrate the IMU because the drone has to be stable and level on a rock-solid, non-moving surface for IMU calibration.
The compass is completely independent of the IMU and unrelated.
But neither would have required recalibration anyway, you could have just flown without messing around with that.

I'm not sure you understand, I would never try to calibrate that unless forced by the drone. I could not take off until the IMU was calibrated my controller was telling me. I had tested the drone out the day before just fine so I'm guessing somewhere along the way in transportation it got messed with.

I should also mention I attempted to take off with that IMU calibration message and was unable so if you think that you should be able to take off then DJI locks you out at least on this particular DJI model, maybe other drones work differently.