An Online Gravity Modeling Method Applied for High Precision Free-INS.

Area of Science:

• Geodesy
• Navigation Systems

Background:

• High-degree spherical harmonic models (SHM) are computationally intensive for real-time inertial navigation system (INS) applications.
• Traditional normal gravity models (NGM) are often used but lack sufficient accuracy for high-precision INS.

Purpose of the Study:

• To develop a computationally efficient and accurate gravity compensation model for real-time INS.
• To improve upon the limitations of both SHM and NGM in INS applications.

Main Methods:

• Derived a two-dimensional second-order polynomial model from SHM based on regional disturbing potential characteristics.
• Calculated deflections of vertical (DOVs) using SHM on dense grids to obtain polynomial coefficients.
• Synchronously updated polynomial coefficients and applicable regions for global navigation.

Main Results:

• The polynomial model requires less storage and computational time than high-degree SHM, with only minor precision loss.
• The proposed polynomial model demonstrates higher accuracy compared to the traditional NGM.
• Numerical tests and INS experiments confirmed the superiority of the proposed method over traditional gravity models for high-precision free-INS.

Conclusions:

• The developed polynomial gravity model provides an effective balance between computational efficiency and accuracy for real-time INS.
• This method enhances the performance of high-precision inertial navigation systems by offering improved gravity compensation.