What are the triggering conditions for Accels inconsistent & Gyros inconsistent messages?

Ground Control Software Mission Planner
1

According to Pre-Arm Safety Checks — Copter documentation
The triggering condition for the Accels inconsistent message is that the accelerometer error of the IMU is >1m/s/s
The starting condition for the gyroscope inconsistency message is that the gyroscope error is >20dps
But after analyzing the contents of the IMU through the bin file, I found that even if the accelerometer error is >1m/s/s, the Accels inconsistent message may not appear.

Does anyone know the detailed triggering conditions of these two messages?

For example, how often is a judgment made? Or when the error is just larger than a certain amount, a message will definitely appear? Or will this message appear when multiple groups of IMUs meet startup conditions at the same time?

2
  1. This has nothing to do with Mission Planner. It is decided by the flight controller.

About 1 minute search in the source code you can easily find the answer.
Gyros:

Any used gyro compared to primary gyro.
if (vec_diff.length() > radians(5)) → inconsistent

Accels:
Accel threshold is user defined via ARMING_ACCTHRESH
Accels vector length is compared to primary accel.
BUT

  • IMU3 is using a threshold * 3 s it runs at a different temperature to IMU1/IMU2
  • Z vector difference is divided by two because EKF is less sensitive to Z-axis error
3

Thank you so much for such a clear explanation, it helped me a lot.
I’m very sorry that I couldn’t reply to you in time due to delays in other projects.