Technical question about IMU and compass calibration

[Jeff2020]

MA2 Gurus - and you know who you are - I have a technical question for you all:

When executing IMU and compass calibration activities, what is the acceptable distance from and general mass of metal objects before the calibration will be negatively affected?

Ok so here's the backstory.... it's safe (and easy) to assume a vehicle, disposal dumpster, rail car, or bridge could cause a bad calibration.... but what about other smaller less obvious items??
For instance, an aluminum or carbon fiber tripod (with metal fittings) used as an elevate landing pad?

Just trying to gage my level of magnetism - pun intended.

Your thoughts and ideas are greatly appreciated.

Jeff

 

[Deleted member 103366]

I can't offer a good answer but I have had something ridiculously small like a pair of tweezer or maybe even something smaller create a magnetic field warning with either a Mini or an M2P.
Your post brought the incident back to mind. The offending object was about 1ft from the drone under some papers.

 

[MA2 317]

For instance, an aluminum or carbon fiber tripod (with metal fittings) used as an elevate landing pad?

Just trying to gage my level of magnetism - pun intended.

Aluminum is a non ferrous metal so it shouldn't have a problem with a COMPASS calibration or an IMU calibration.

The IMU calibration can be done inside on a table as long as it's level.

I haven't had to do ether on the MA2 yet and I did it with the Spark a loooong time ago.
So far, so good.

From what I have read in the past, carbon fiber is not good for radio transmissions?

It tends to reflect or absorb the frequencies?

 

[Phantomrain.org]

MA2 Gurus - and you know who you are - I have a technical question for you all:

When executing IMU and compass calibration activities, what is the acceptable distance from and general mass of metal objects before the calibration will be negatively affected?

Ok so here's the backstory.... it's safe (and easy) to assume a vehicle, disposal dumpster, rail car, or bridge could cause a bad calibration.... but what about other smaller less obvious items??
For instance, an aluminum or carbon fiber tripod (with metal fittings) used as an elevate landing pad?

Just trying to gage my level of magnetism - pun intended.

Your thoughts and ideas are greatly appreciated.

Jeff

Considering all of us that take off from the Car roof ,the hood and in Dirks case the back of his pickup. I would not assume that.

Magnetism can be found a a lot of elements and that will challenge the calibration and cause magnetic interference but not all metals are bad or have any effect least of all aluminum or carbon fiber should not be an issue with the drone.

The Magnet on the back of a phone cold be a different story. Dumpsters railways , might not be an issue either. .considering
we had no issue with the phantom 4 taking off from the Motorcycle seat or the inside of the railways

The Mavic 2 is even better at negotiating the environment that the Phantom 4 but testing your area is key.

So if you do get magnetic interference: Shut down move away and start up again but so
far we have not had any issues with the Mavic Series taking off from obscure areas except for 1 concrete slab where aliens must have buried the time machine. lol

I made a video of that area and how it knocks out the phantom 4 and my camera sound . but I have not tested it on the Mavic as the area has been closed off do to Covid .





Phantomrain.org
Gear to fly your Mavic 2 in the Rain and Float on Water.

 

[Meta4]

When executing IMU and compass calibration activities, what is the acceptable distance from and general mass of metal objects before the calibration will be negatively affected?

It's not metal that matters, it's iron and steel.
Steel makes no difference to IMU calibrating.

It's not distance.
It's distance + mass of the iron or steel.
A car can deflect your drone's compass at >3 ft
A nail might deflect your compass at just a few inches

 

[JohnLietzke]

It is all over the place in my experience. I have had bad compass calibrations out in an empty field at different locations. I think that sometimes moving the remote away helps but it may have just been coincidental.

 

[boblui]

Two meters away from big steel objects like car , containers or rebars buried underground is sufficient.

The fact is compass calibration just require an external magnetic field of constant direction and strength across the space the craft is moved in the process. The magnetic field does not need to be pointing north or south.

 

[hiflyer201]

Considering all of us that take off from the Car roof

I had no luck trying that..but I only tried once...Mainly I wanted to comment on your photo..love the drone holder on your bike...clever! and is that the rain suit on your Phantom?

 

[Deleted member 103366]

I have never taken off from a car roof and from memory when I have set a drone (phantom 3) on the dar roof whilst doing other things the app was warning of magnetic problems.

 

[Phantomrain.org]

I had no luck trying that..but I only tried once...Mainly I wanted to comment on your photo..love the drone holder on your bike...clever! and is that the rain suit on your Phantom?

lol Yes it is the Phantom 4 Pro Wet Suit Design called Orca : The Cycle Caddy works well on both the Mavic and the Phantom 4 and despite the bumps and that I have never used a Gimbal Lock.

 

[Phantomrain.org]

I have never taken off from a car roof and from memory when I have set a drone (phantom 3) on the dar roof whilst doing other things the app was warning of magnetic problems.

The Phantom 3 /4 were prone to more Magnetic Interference than the Mavics has shown.
I always recommend testing your car as they are not all the same , but so far the Mavic has been pretty car Proof.

I thought when taking off from the hood in the rain with the windshield wipers going and radio blue tooth i might get some issue
but it was a flawless take off as shown in the video with the home point recorded . That was with the Mavic 2 and the Air 2 .

We can take off from inside the Trunk of the Audi with both the Mavic and Phantom 4 Pro .
Just need to get to test your Car for drone friendliness. is that a word.

 

[hiflyer201]

despite the bumps and that I have never used a Gimbal Lock.

Orca! super name and very neat looking. I've heard you mention not using a Gimbal lock before..I'm too afraid of snagging it on something but I did leave it off my Air 1 until I got a better one that was easier to install. Thanks for the reply.

 

[DanMan32]

I believe there are two compass concerns here, with only one being focused on, and the OP seeming to be asking about the other.

Magnetic interference during a compass calibration, which will likely cause issues with flights from all locations pending a good calibration

Magnetic interference at takeoff location or during flight where moving to another location solves this temporary situation without itself requiring calibration.

As for IMU, I don't think one needs precision leveling but rather free from movement during calibration. After all in some of the IMU calibration positions, you can't get it plumb/level, and there are two ways it will be steady without being held.

 

[MA2 317]

So if you do get magnetic interference: Shut down move away

You're picture of the railroad reminded me of a test flight I did with Spark last year to see how much interference to expect when filming close to tracks.

I didn't get a warning until I sat the Spark on the rail itself.

It did better than I expected.




Good ol Spark.

 

[Jeff2020]

See....?
I knew there were Gurus out there. [emoji1]
Thanks to all who responded! This is really very helpful. While my takeaway is not a solid Yes/No answer, it does offer insights as to the environmental and/or random variables that face different drones during execution of IMU and compass calibrations.
Thanks again to all for making me a bit smarter!!