How does an inertial navigation system (INS) derive position and how is drift corrected?

How does an inertial navigation system (INS) derive position and how is drift corrected?

• A. INS derives position solely from accelerometer data; drift cannot be corrected.
• B. INS uses gyroscopes only to compute velocity and position.
• C. INS derives position by integrating acceleration and velocity data, without external updates.
• D. INS integrates gyroscopes and accelerometers to compute velocity and position; drift is corrected by external updates like GPS or radio-navigation data.

Answer: (D)

An INS derives position by converting measured accelerations into velocity and then integrating that velocity to obtain position, while the gyroscopes provide angular rate that keeps track of orientation. The combination allows the system to know where it is and how it’s moving in space. But every measurement carries bias and noise, so those small errors accumulate as the time goes on, causing drift in the computed position and velocity if you rely only on the inertial data. To keep the solution accurate, the INS is periodically aided by external navigation updates, such as GPS or other radio-navigation data. When these updates arrive, a state estimator (often a Kalman filter) blends the inertial estimates with the external measurements, correcting the accumulated drift and re-aligning position and velocity to the true values. Without these external updates, the drift would continue to grow and the reported position would diverge from reality.

An INS derives position by converting measured accelerations into velocity and then integrating that velocity to obtain position, while the gyroscopes provide angular rate that keeps track of orientation. The combination allows the system to know where it is and how it’s moving in space. But every measurement carries bias and noise, so those small errors accumulate as the time goes on, causing drift in the computed position and velocity if you rely only on the inertial data.

To keep the solution accurate, the INS is periodically aided by external navigation updates, such as GPS or other radio-navigation data. When these updates arrive, a state estimator (often a Kalman filter) blends the inertial estimates with the external measurements, correcting the accumulated drift and re-aligning position and velocity to the true values. Without these external updates, the drift would continue to grow and the reported position would diverge from reality.