How to avoid request for calibration?

[Mosherf]

Hi,
In one of my projects with my M2P I'm requested to land on and then take off of a big metal roof (about 8 feet high). A problem arise when I bring the props to full stop (either taking the left stick down all the way, or pulling both sticks inward and down) - then I get the message that a calibration is needed (due to magnetic interference), and I can't take off again without taking the drone and dancing the calibration dance which makes the whole thing impractical.
My current improvised solution is to land very very slowly with the stick and have the props rotate on minimum rpm, but sometimes I still make them shut down accidently.
Is there any way to bypass the request for calibration on the DJI GO 4 app?
Will I get the message if I use Lichi for example to fly the drone instead?

Thanks for your help

 

[Saladshooter]

You will not be able to bypass the warning in either GO or Lichi. Additionally, the issue is real, your drone is at risk when it is near the metal roof due to the interference.... there have been plenty of crashes on this board centered around interference from cement and metal structures.

 

[Meta4]

Hi,
In one of my projects with my M2P I'm requested to land on and then take off of a big metal roof (about 8 feet high). A problem arise when I bring the props to full stop (either taking the left stick down all the way, or pulling both sticks inward and down) - then I get the message that a calibration is needed (due to magnetic interference), and I can't take off again without taking the drone and dancing the calibration dance which makes the whole thing impractical.

That warning message is very badly worded.
What's happening is that the compass is warning you that there's a big problem close by and recalibrating the compass won't do a thing to fix the problem.
Your compass doesn't need recalibrating at all.

But you should pay attention to the warning and avoid landing and relaunching from the steel roof.
Tell your client that it's just not possible and you'd prefer not to crash your drone doing something very risky.

Is there any way to bypass the request for calibration on the DJI GO 4 app?

Yes ... don't land on a steel roof.

Will I get the message if I use Lichi for example to fly the drone instead?

The message doesn't come from the app, it comes from your drone.
And it would be exactly the same whatever app you use.

 

[Mosherf]

Thank you for the answers. I'm very much aware of the meaning of the message and the risk, but still want to find a way to bypass this issue.
Any ideas? Some suggested landing on a thick rubber surface that will screen the magnetic interference.

 

[Meta4]

Thank you for the answers. I'm very much aware of the meaning of the message and the risk, but still want to find a way to bypass this issue.
Any ideas? Some suggested landing on a thick rubber surface that will screen the magnetic interference.

No .. landing on a sheet of rubber won't make any difference to the way the steel roof deflects the compass which would only be a few millimeters from the steel.

There is a simple way to avoid the issue, but you've dismissed it

 

[Cagey]

I want to echo the advice not to try and circumvent the warning!
The risks associated with a compass error may not just be the loss or damage to the drone. Compass errors are the main cause of fly-aways and so the potential for harm and damage may be beyond your ability to control.
If someone is injured and you are found to have ignored or disabled a key safety feature……. ?

 

[sonof40]

If he lands but DOES keep the props running would the danger still exist?

 

[Mosherf]

No .. landing on a sheet of rubber won't make any difference to the way the steel roof deflects the compass which would only be a few millimeters from the steel.

There is a simple way to avoid the issue, but you've dismissed it

What do you mean 'a few millimeters from the steel'? Where is the compass located on the drone?

 

[Meta4]

What do you mean 'a few millimeters from the steel'? Where is the compass located on the drone?

Both compasses are inside the body of the Mavic.
To avoid the problem they would have to be at least a metre away from the steel roof.

 

[Rich QR]

If he lands but DOES keep the props running would the danger still exist?

The danger comes if the IMU's idea of its heading becomes too different from reality.

The IMU is initialized with the magnetic compass. Also, during operation, the IMU is constantly compared to the magnetic compass, and when they disagree, the IMU will slowly be updated to agree with the magnetic compass.

So a brief time in a magnetic field won't be a problem, unless the IMU is initialized during that brief time. But an extended time can result in wrong heading in the IMU.

I'm not sure how much time spent in the magnetic field would cause a problem. It depends on how distorted the field is.

 

[BigAl07]

What do you mean 'a few millimeters from the steel'? Where is the compass located on the drone?

The Rubber Mat would only be adding a few millimeters distance between the metal roof and the aircraft and probably wouldn't give any benefit.

I've never needed to do this but I did see a someone using a "Plastic Card Table" as a landing platform on a metal roof but it wasn't an M2P they were using. They had to place the aircraft directly in the middle of the table to avoid the "metal tubing frame" of the table itself but it was the only way he could launch from the roof top without the "Calibration Dance" each and every time.

 

[GFields]

Good advice has been shared. If you cannot launch or land away from the steel roof, I'd pass on doing this job/project as it's too risky.

 

[Ralph thompson]

Ironic Mosherf, I just posted a similar question, will be interested in the responses

magnetic shielding

If you're filming indoors & had to launch a drone (M2P in my case) off a reinforced concrete floor (most certainly full of reinforcing bars), could you avoid compass interference by laying an insulating fabric, Faraday blocking material under the drone? Has anyone tried this? Seen on amazon...

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