Abstract:

In order to weaken the inertial elements errors to the precision of initial alignment, the strapdown inertial navigation system (SINS) based on rate biased ring laser gyroscope (RBRLG) and its initial alignment algorithm are studied. Firstly, the error characteristics of RBRLG and accelerometer in the initial alignment process are given; then, the second-order nonlinear error models for gyroscope scale factors and accelerometer biases are established, and these errors are estimated and compensated online; finally, the gyro drifts are estimated by using an available Kalman filter, and the initial alignment direction cosine matrix is obtained. The experiment results show that this algorithm can effectively eliminate the impact of scale factor errors and drift errors of RLG and drift errors of accelerometers on the alignment precision. While the initial alignment time is 3 min, the alignment accuracy of the leveling angle is about 2″ and the alignment accuracy of the azimuth angle is better than 30″. By using this algorithm, the rapidity and accuracy of initial alignment are significantly improved.