Abstract:

In case of that the error model of the strapdown inertial navigation system is nonlinear with large azimuth misalignment, it is very significant to study the nonlinear filter algorithm. The precision of EKF (Extended Kalman Filter) is low, which needs to calculate the complex Jacobian matrices. Although the theoretical precision of CDKF (Central Difference Kalman Filter) is a little higher, the amount of calculation is large and the algorithm is unstable. To overcome the above shortcomings, the ISR-CDKF (Iterative Square Root Central Difference Kalman Filter) is proposed, and is utilized in initial alignment. The results of simulation show that the ISR-CDKF has higher precision and convergence, and has stronger numerical stability.

Key words: large azimuth misalignment, strapdown inertial navigation system, initial alignment, iterative square root central difference kalman filter (ISR-CDKF)