SINS Stationary Base Initial Alignment Based on Backtracking Scheme

In order to shorten the alignment time while ensuring the initial alignment accuracy of the Strapdown Inertial Navigation System (SINS), a SINS stationary base initial alignment scheme based on backtracking is proposed. This method improves the alignment accuracy by processing inertial measurement unit (IMU) data forward and backward repeatedly. Then based on the statistical analysis of the error covariance matrix, an optimal backtracking number criterion is designed to judge whether filtering process is converged, then achieve the same accuracy as the traditional alignment method by using fewer amount of data and time. Through simulation tests, for the gyroscope with constant drift of 0.01°/h, when the estimation of yaw misalignment angle is converged, the alignment accuracy can reach 2.51' by using 150s IMU data after two times of backtracking calculation, which only takes 153.6s to achieve the same accuracy by performing one-time traditional alignment calculation with 300s data length. The experimental results show that the proposed method can achieve a balance between the alignment accuracy and rapidity.