Comparative Study of CKF and UKF in Dimensionality Reduction Fast Transfer Alignment of Inertial Navigation Systems of Shipborne Equipment

Aiming at the problem of large azimuth between the ship-borne equipment coordinate system and the ship center coordinate system, a fast transfer alignment method is proposed. The nonlinear error equation of strapdown inertial navigation system (SINS) under the condition of large azimuth misalignment angle and ship deflection model are established. According to the requirements of rapidity and accuracy of transfer alignment, the state space model of reduced-dimension transfer alignment is constructed, and the fast transfer alignment method of speed plus attitude is designed. Using the high-precision inertial navigation information of ship-borne with strong anti-interference and autonomy as auxiliary information, and using CKF and UKF nonlinear filtering algorithms, the rapid transfer alignment of ship-borne inertial navigation under the condition of large azimuth misalignment angle is realized. The simulation results show that regardless of the level of sea conditions, CKF and UKF can achieve accurate estimation of attitude misalignment angle, which is the main alignment parameter of shipborne inertial navigation system, and the alignment accuracy can reaches the level of angular division.