Damping Rotating Grid SINS Based on a Kalman Filter for Shipborne Application

The measurement error of the inertial measurement unit (IMU) significantly affects the navigation accuracy of the grid strap-down inertial navigation system (SINS) applied in polar regions. In this paper, the single-axis rotation modulation grid SINS is designed to suppress the navigation error caused by IMU constant error. Then on the basis of rotation modulation scheme, a novel external horizontal damping algorithm based on a Kalman filter is conducted to further suppress the 84.4 min Schuler oscillation caused by IMU random error. The Kalman filter is established based on the error model of shipborne grid SINS. When the reference velocity provided by Doppler velocity log is usable, the Schuler oscillation can be restrained through feedback calibration by calibrating the grid horizontal attitude errors and grid horizontal velocity errors. The simulation results demonstrate that the proposed external horizontal damping algorithm can efficiently suppress the Schuler oscillation, meanwhile compared with traditional external horizontal damping algorithm based on damping network, the proposed algorithm has the advantage of reducing the overshoot errors in the process of state switching.