A Novel Linear Model Based on Code Approximation for GNSS/INS Ultra-Tight Integration System.

Area of Science:

• Navigation Systems Engineering
• Satellite Navigation
• Inertial Navigation

Background:

• Ultra-tightly coupled GNSS/INS navigation systems are superior but face challenges with complex, nonlinear observation models.
• Existing models based on I/Q measurements can be highly complex, impacting system performance and stability.

Purpose of the Study:

• To develop a novel, more stable, and accurate navigation model for GNSS/INS ultra-tight integration.
• To address inherent nonlinearities and improve positioning accuracy and convergence characteristics.

Main Methods:

• A new nonlinear model and linearization method are proposed, retaining second-order components for enhanced precision.
• A novel method to approximate code-phase is introduced to mitigate positioning errors from code-loop deviation without new measurements.

Main Results:

• The proposed model demonstrates higher positioning accuracy and better convergence compared to traditional methods.
• The code-phase approximation significantly reduces the impact of code errors, particularly in unstable tracking loop conditions.

Conclusions:

• The developed model and linearization technique offer improved integrity and stability for GNSS/INS ultra-tight integration.
• Experimental validation confirms the effectiveness and superiority of the proposed methods for enhanced navigation performance.