Inertial Navigation Magnetic Heading Accuracy via Dynamic Magvar
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Solution Overview
Problem
Current inertial navigation systems (INS) fail to meet magnetic heading accuracy specifications due to the drift of the north magnetic pole and high rate-of-change of magnetic variation, especially in polar exclusion areas, leading to inaccurate magnetic heading calculations.
Innovation Solution
The system determines magnetic heading by using locally stored magnetic variation and rate-of-change information, as well as a world magnetic model, to account for date and position changes, thereby avoiding polar exclusion areas and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a static magvar LUT is used, then the system is simple and easy to operate, but the magnetic heading accuracy deteriorates over time due to magnetic pole drift and high rate-of-change in polar exclusion areas
Solution Approach 1:
The patent transforms the static magvar LUT into a dynamic system by incorporating rate-of-change information and date-based updates. The system dynamically adjusts magvar values based on the current date and position, allowing the magnetic heading calculation to adapt to changing magnetic conditions over time while maintaining operational simplicity.
Solution Approach 2:
The patent changes the parameter approach by adding rate-of-change information to the static LUT. Instead of using only current magvar values, the system uses both the current value and its rate of change, then calculates the future value based on the current date. This parameter enhancement allows the system to maintain accuracy over extended periods without requiring continuous updates.
2Area of stationary object
If polar exclusion areas are included in the magvar LUT, then the coverage area is maximized, but the magnetic heading accuracy deteriorates in those areas due to high rate-of-change
Solution Approach 1:
The patent applies local quality by treating polar exclusion areas differently from other regions. Instead of using a uniform approach, the system identifies polar exclusion areas based on predefined criteria (such as magnetic latitude thresholds) and applies specialized handling only in those specific locations. This allows the system to maintain accuracy in polar regions while using standard LUT values elsewhere.
Solution Approach 2:
The patent extracts problematic polar exclusion areas from the general magvar LUT coverage. By identifying and separating these high-rate-of-change regions, the system can apply alternative calculation methods specifically for those areas while maintaining standard operations elsewhere. This extraction allows the system to preserve overall coverage while addressing the accuracy issues in specific problematic regions.
Data Source
AI summary
Systems and methods for determining magnetic heading information for a vehicle. In one example, the system identifies at least one polar exclusion area based on predefined rate-of-change of magnetic variation (magvar). Locally stored magvar information is retrieved based on received vehicle position information that is outside the polar exclusion areas. Magnetic heading is determined based on the retrieved magvar information, the received position information, and the received true heading information. In another example, the magnetic heading is determined based on the retrieved magvar and magvar rate-of-change information, on the received vehicle position and true heading information, and on the received date information. In another example, the magnetic heading is determined based on the received vehicle position, true heading, and date information, and on the magvar retrieved from a world magnetic model utilizing stored model coefficients.