inertialnavigation

Inertial navigation is a self-contained method of estimating the position, velocity, and orientation of a moving object by processing measurements from an inertial measurement unit (IMU) that contains accelerometers and gyroscopes. Without external references, the system relies on integrating these measurements to track motion over time, providing continuous navigation data.

In strapdown INS designs, the IMU is fixed to the vehicle. Angular rates from the gyroscopes update the attitude estimate, while the measured accelerations, after removing the gravity component, are integrated to yield velocity and then position. In gimballed or stabilized platforms, sensors are mounted on a rotating frame that maintains a known reference orientation. Modern systems typically fuse digital signals through filters to manage the integration and compensate for sensor biases.

Inertial navigation suffers from error growth due to sensor biases, scale factors, noise, and temperature effects, causing drift over time. Error models and Kalman or complementary filters are used to estimate biases and correct drift, often by incorporating external measurements such as GPS, Doppler data, or visual odometry in an integrated navigation system (INS/GPS).

Applications include aircraft, submarines, missiles, spacecraft, autonomous vehicles, and handheld devices. Advances in MEMS sensors have enabled compact, low-cost INS, while high-end platforms use ring laser or fiber optic gyroscopes for improved accuracy. Despite drift, inertial navigation remains essential for navigation in GPS-denied environments and as a robust autonomic navigation backbone when fused with other sensors.