How to determine "extrinsic quaternion" in External IMU rosbag?

[congphase]

Hello all,

I intend to use IMU data from a NovAtel receiver. Here in your README, it determines the extrinsic quaternion as (0, 1, 0, 0) and modifies the launch file to those numbers.

The confusion is, as far as I know, quaternion keeps changing during the operation of the IMU as the vehicle moves. How can we determine it as fixed numbers like that?

Thank you a lot for any help.

[Livox-SDK]

I think you may need to calibrate your external IMU Then replace those calibration parameters in loam_livox_horizon_ext_imu.launch [0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0]

[seajayshore]

Can you advise what the units of that calibration parameter [0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0] are??

And how would I actually calibrate the external IMU? Would the IMU manufacturer normally provide these tools with standard format?