Initial Alignment for SINS Based on Pseudo-Earth Frame in Polar Regions

Area of Science:

• Navigation Systems
• Geophysics
• Aerospace Engineering

Background:

• Accurate initial alignment is crucial for inertial navigation system (INS) performance and subsequent navigation accuracy.
• Traditional alignment methods are ineffective in polar regions due to rapid meridian convergence and weak horizontal Earth rotation components.
• Existing methods struggle with obtaining accurate coarse azimuth alignment in polar environments.

Purpose of the Study:

• To propose a novel initial alignment algorithm for INS in polar regions.
• To address the challenges of meridian convergence and azimuth misalignment in polar environments.
• To facilitate subsequent polar navigation system access and unify polar alignment algorithms.

Main Methods:

• Development of a novel alignment algorithm utilizing a pseudo-Earth frame and backward process.
• Design of dynamic error modeling to handle large azimuth misalignment angles.
• Validation through semi-physical static simulation and in-motion tests employing an unscented Kalman filter (UKF).

Main Results:

• The proposed algorithm achieves initial alignment in polar regions without position error influence.
• It successfully obtains the strapdown attitude matrix relative to the local geographic frame.
• Effectiveness validated by simulations and tests, demonstrating robustness with large azimuth misalignment.

Conclusions:

• The novel algorithm provides a convenient and accurate method for INS initial alignment in polar regions.
• It overcomes limitations of traditional methods in challenging polar conditions.
• The approach contributes to unifying polar alignment algorithms and external reference information.