For sufficiently accurate IMUs, like the ones found in ICBMs, you need a gravity map because otherwise the variations in gravity cause your position estimate to drift
That's helpful; so presumably for the same reason that gyrocompasses function (self-aligning vis-a-vis the local gravity vector).
A part of me was subconsciously entertaining that a subsystem of the IMU / INS was actually being used to provide gravimetric navigation (producing a coarse global position update de novo rather than correct for an error-prone open-loop one from an a priori generated gravity map).
a la
A part of me was subconsciously entertaining that a subsystem of the IMU / INS was actually being used to provide gravimetric navigation (producing a coarse global position update de novo rather than correct for an error-prone open-loop one from an a priori generated gravity map). a la
https://ieeexplore.ieee.org/document/9059124
or
https://www.researchgate.net/publication/343278497_Analysis_...