Optimal Two-Position Alignment for Strapdown Inertial Navigation System

The optimal two-position alignment using Kalman filter is newly derived for strapdown inertial navigation system (SINS). During the alignment process, SINS is rotated with respect to the heading axis. The Kalman filter estimates the misalignments and gyro drifts at these two positions. In terms of the relationship between yaw misalignments and gyro drifts, the horizontal gyro drifts can be computed. The final alignment works after the horizontal gyro drifts are compensated. So the influence of the horizontal gyro drifts on yaw misalignment could be eliminated effectively. The simulation show this alignment method makes the horizontal gyro drifts computable under stationary base, and the estimation accuracy of yaw misalignment is higher by using this method than conventional stationary alignment methods.