The gyros of two IMUs disagree
What ArduPilot says:
- PreArm: Gyros inconsistent
On a board with two or more IMUs, each gyro in use is compared with the first: the rotation rates must not differ by more than 5°/s, a limit fixed in the code. After any failure they have to agree for 10 s in a row before the check passes, so the message stays for 10 s after the cause has gone.
What to do, most likely first
The aircraft was moved while the gyros were finding their zero at power-on, so one of them has a wrong zero.
CheckThe rotation rates in the ground station are not near zero while the aircraft stands still.
FixReboot and do not touch the aircraft for the first seconds.
The aircraft is being handled, or shaken by a running engine, right now.
FixPut it down and wait 15 s.
The board is warming up after a cold start, and the gyro zeros drift apart with temperature.
CheckIt appears a minute or two after power-on in cold weather and not on a warm day.
FixLet the board warm up for a few minutes, then reboot so the gyros find their zero at working temperature.
One gyro is faulty.
CheckIt returns at every boot, warm and still.
FixReplace the flight controller.
Parameters to look at
| Parameter | What it is |
|---|---|
INS_GYR_CAL | Gyro Calibration scheme |
INS_USE | Use first IMU for attitude, velocity and position estimates |
INS_USE2 | Use second IMU for attitude, velocity and position estimates |
INS_USE3 | Use third IMU for attitude, velocity and position estimates |
The code that sends it
PreArm: Gyros inconsistent
libraries/AP_Arming/AP_Arming.cpp AP_Arming::ins_checks() · Open in ArduPilot Copter-4.7.1