Can anyone please tell me what IMU is ? i've not come across this before.

IMU means: An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the magnetic field. On a drone, it responsible for bringing all the parts to work together.

DJI-Mark Posted at 2017-10-10 14:09
IMU means: An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the magnetic field. On a drone, it responsible for bringing all the parts to work together.

Thanks Mark,

Would it be ok for me to calibrate even though i't not asking me to do so.

IMU "Inertial measurement unit" .

As far as I see it, IMU calibration on a level surface updates a table of values the flight controller software uses as a reference for a level stationary hover. From there the craft responds predictably to flight commands.  It also likely measures any sensor noise and thermal drift so that these technical imperfections are accounted for when using IMU sensor data in flight. - this is likely why there must be no vibrations during the calibration process.


Bad IMU calibration could cause drift and attitude issues as the flight controller fights to hold the craft in what it thinks is the correct attitude as opposed to the correct physical attitude.


The IMU usually has 2 types of sensors – angle and acceleration and in turn 3 sensors of each type measuring in the X,Y and Z axis. These sensors can, through vibration, aging, impact etc, drift in their response over time and thus an IMU calibration will establish a new reference for the IMU’s level/stationary state that the flight controller can work with to restore stable flight.


Think of calibration as the bringing back into line the measured craft attitude with the true physical craft attitude.


As to how often an IMU calibration is needed, Refer to your manual.

Paul Tomo Posted at 2017-10-10 14:41
Thanks Mark,

Would it be ok for me to calibrate even though i't not asking me to do so.

Unless you have a problem that is traced to IMU calibration, it is best not to do it.

Paul Tomo Posted at 2017-10-10 14:41
Thanks Mark,

Would it be ok for me to calibrate even though i't not asking me to do so.

It shouldn't hurt anything to do it. Make sure the aircraft is on a level surface and do not move it or touch it while it is calibrating. Sometimes it is a good idea to do an IMU calibration after a firmware upgrade. There are a number of discussions about this. Look into why you should cool your aircraft down before an IMU calibration. I won't go into a lengthy conversation about it, but you may find it interesting. Sometimes, it is suggested to calibrate your compass after an IMU calibration and it might be worth also calibrating your gimbal afterwards to. That way you should have everything as good as it can get.

The calibration of the IMU is best done with a chilled droned.
I enjoy this aspect of calibration process the best. Chill and serve.... ;-) service. With a smile?


I will also recalibrate after doing an update to firmware or of the Go app.


RedHotPoker

Paul Tomo Posted at 2017-10-10 14:41
Thanks Mark,

Would it be ok for me to calibrate even though i't not asking me to do so.

If your Phantom is operating correctly, it's not going to be improved in any way by recalibrating anything.

Labroides Posted at 2017-10-10 15:34
If your Phantom is operating correctly, it's not going to be improved in any way by recalibrating anything.

Geebax & Labroides speak truth to power here...DO NOT do a recal if the UAV or system is not indicating that you need to do so.
You are messing with a very sensitive piece of equipment with some important sensors within, not something you want to risk disturbing unnecessarily if you do not have too.  A bad IMU recalibration will result in a regrettable situation that could very well lead to you loosing your drone or damaging it.

This is definitely one of those "if it ain't broke, don't fix it" things!

Paul Tomo Posted at 2017-10-10 14:41
Thanks Mark,

Would it be ok for me to calibrate even though i't not asking me to do so.

Personally, I would not suggest to calibrate the IMU if the APP does not prompt to do so.

DJI Susan Posted at 2017-10-10 19:38
Personally, I would not suggest to calibrate the IMU if the APP does not prompt to do so.

Thank you all very much for that information on IMU calibration. just to add, I made the new firmware upgrade about 3 weeks ago and I've also added 3 new batteries to my setup, nothing is asking for calibration so I guess all is well.

I will leave well alone for now and thanks again.

Paul Tomo Posted at 2017-10-10 23:54
Thank you all very much for that information on IMU calibration. just to add, I made the new firmware upgrade about 3 weeks ago and I've also added 3 new batteries to my setup, nothing is asking for calibration so I guess all is well.

I will leave well alone for now and thanks again.

You are welcome. Wish you have a great time on flying the drone.