However, their cost and complexity place constraints on the environments in which they are practical for use.
Gyroscopes measure the angular velocity of the sensor frame with respect to the inertial reference frame.
The zero-velocity aided inertial navigation system algorithm is implemented using a complimentary feedback filtering structure.
An INS can detect a change in its geographic position (a move east or north, for example), a change in its velocity (speed and direction of movement), and a change in its orientation (rotation about an axis).
It does this by measuring the linear acceleration and angular velocity applied to the system.
That is, the inertial navigation system works as the backbone of the system and a Kalman filter is used to estimate (track) the perturbations (errors) in the inertial navigation system.
When a zero-velocity observation is done, the Kalman filter estimates the current perturbations (errors) in the navigation state estimate of the inertial navigation system; the estimated perturbations are feedback into the inertial navigation system to correct its internal states.