We are discussing the errors to consider when using IMUs for navigation. I seem to have a problem wrapping my head around the general concept of the topic and need some help.

I understand that the gyro drift or bias tells you how stable the angle rate outputs stay over time. Therefore, its units are given in deg/hr.

The accel drift or bias indicates the stability for acceleration outputs, so the units are given in mg (where g is the acceleration/gravity).

What is the relationship between the gyro bias and ARW? What is the relationship between the accel bias and VRW?

Also, there was something about PRW. I don't know what that stands for but the unit for it is given in deg/sqrt(Hz).

Any simple explanation is appreciated!


1 Answer 1


Angular rate is integrated to get angle (heading). Thus random changes (noise) in the rate will be reflected in its integral - the angle. Bias in the rate will cause heading drift.

Same goes for linear acceleration and its integral: linear velocity.


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