Research on Underwater Alignment Technology Assisted by Acoustic Positioning Information Based on Kriging Interpolation Method

Underwater navigation plays a critical role in submarine operations and autonomous underwater vehicle (AUV) missions. The Strapdown Inertial Navigation System (SINS), widely used for its high autonomy and strong concealment capabilities, suffers from significant error accumulation and a strong dependence on accurate initial attitude information. To address these issues, acoustic positioning has gained attention as a GPS-free alternative for underwater alignment. However, its low data refresh rate often leads to Kalman filter update delays, thereby reducing the accuracy of state estimation. To address the above problem, this paper proposes an underwater alignment method assisted by acoustic positioning based on Kriging interpolation. Firstly, a moving base alignment model was established according to the principles of strapdown inertial navigation system alignment. Secondly, the impact of gyroscope random walk-induced nonlinearities on the adaptability of the state equation under sparse observations is analyzed. Thirdly, Kriging interpolation is employed to enhance the refresh rate of external observations, thereby improving alignment performance. The improvement was evaluated through simulations and experimental data. In this study, multiple voyages were conducted to collect experimental data. Experimental results demonstrate that after improving the refresh rate of external observations using the Kriging interpolation method, the alignment results were applied to the navigation system, reducing the positioning error by up to 43.9% and by no less than 33%. In conclusion, the Kriging interpolation method effectively enhanced the accuracy of underwater alignment under stable acoustic conditions, providing reliable support for navigation systems.