A copy of the EKF was restarted on the ground
What ArduPilot says:
- EKF2 IMUN forced reset
- EKF3 IMUN forced reset
A copy of the EKF (ArduPilot's position and attitude estimator; one runs per IMU, numbered from 0) had been working, then for 5 s reported nothing it could vouch for, while disarmed. ArduPilot restarted it from scratch. This happens only on the ground, never armed. The start-up lines follow again: “initialised”, “tilt alignment complete”, “yaw alignment complete”.
What to do, most likely first
The aircraft was carried or driven about with the power on, and the estimate drifted beyond recovery.
FixNothing to change. Wait for the alignment lines before arming.
A sensor dropped out for a few seconds: a GPS or compass on a loose connector, or a dip in the sensors' 5 V supply.
CheckIt repeats every few minutes although nobody touches the aircraft; look for GPS or compass messages just before it.
FixCheck the connectors and the 5 V supply of the external sensors before flying.
Parameters to look at
| Parameter | What it is |
|---|---|
EK3_IMU_MASK | Bitmask of active IMUs |
The code that sends it
EKF2 IMUN forced reset
libraries/AP_NavEKF2/AP_NavEKF2_core.cpp NavEKF2_core::UpdateFilter() · Open in ArduPilot Copter-4.7.1
EKF3 IMUN forced reset
libraries/AP_NavEKF3/AP_NavEKF3_core.cpp NavEKF3_core::UpdateFilter() · Open in ArduPilot Copter-4.7.1