PreArm: Gyros inconsistent

ArduCopter Copter 4.5
1

Hi,

I use a Cube Orange in my 28" quadcopter. It is running Arducopter 4.5.7.

After mounting it in the drone it was recalibrated (full accel calibration and level calibration). I don’t use a compass in my application - the drone has double GPS setup.
The FC is YAW90 (calibration done with AHRS_ORIENTATION set to 2) and artificial horizon works correctly. Before the flight I did some ground tests.

After a boot I don’t touch the drone till it’s fully ready and Ready to Arm. Then I moved it in pitch and roll (sometimes yaw but it seems to be irrelevant). From time to time the FC reports PreArm: Gyros inconsistent. In logs I can see that sometimes gyros can’t keep up but only in rapid movements. When I move it slower, everything is green. PreArm: Gyros inconsistent disappears after 10s of being steady (so it’s perfect when stationary - also based on logs).

There were some bug reports regarding weird PreArm: Gyros inconsistent for non 0 BRD_BOOT_DELAY. Initially it was set to 0, I tested FC with 3000 too. In both cases behaviour is the same.

Any idea? I need to be 100% sure before I fly.

2

The gyros have a drift that is temperature dependent.
Either perform a IMU temperature calibration to remove that temperature dependent bias. Or just wait longer in the ground (waiting for the gyros to warm up and their drift to be learned while they are stationary) before taking off.

3

Thank you for the answer. I was testing different scenarios. IMUs were warmed up. They were on for several minutes and reboot was done after that time. The drift is not a problem cuz they synchronize every time the drone is stationary. The issue only occurs when I moved the drone rapidly.

4

Here are logs: Unique Download Link | WeTransfer

5

Have you done IMU temperature calibration?

6

Hi, I did it one more time today just in case and results after the calibration are the same: