...
Put the HMD and the platform IMU in a motion-less state (eg. stop the vehicle and put the HMD on one of the seats).
Stop the optical tracking software (eg. DTrack).
Observe on the computer screen if the image slowly difts in any direction.
Disabling autocalibration
Autocalibration can be effectively disabled by setting "noiseRmsLimit"
to 0
.