GNSS Integrity Bounds Adjustment via Satellite Signal Sub-solutions
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Solution Overview
Problem
Current GNSS systems face accuracy issues due to faulty satellite signals, leading to increased integrity limits that can prevent safe operations, even when the fault does not significantly impact navigation parameters.
Innovation Solution
Implementing alternative uncertainty limits by generating sub-solutions that exclude different satellite signals, selecting a fault-free sub-solution, and adjusting the main solution's integrity bounds to maintain navigation integrity, allowing safe operations even with detected satellite faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a faulty satellite signal is excluded from the navigation solution, then measurement integrity is improved, but the number of available satellites decreases leading to reduced navigation accuracy
Solution Approach 1:
The patent segments the navigation solution into multiple alternative solutions, each excluding a different satellite signal. By generating and comparing multiple sub-solutions (each without one satellite), the system can identify the best solution that maintains integrity while preserving accuracy through selective satellite exclusion.
Solution Approach 2:
The system changes the parameter of satellite signal inclusion by generating multiple solutions with different satellite combinations. By evaluating and selecting among these varied configurations, the system optimizes the balance between integrity (exclusion of faulty signals) and accuracy (inclusion of sufficient satellites).
2Measurement precision
If a faulty satellite signal is retained in the navigation solution, then the number of available satellites is maintained for better accuracy, but measurement integrity deteriorates due to the faulty signal
Solution Approach 1:
The patent implements a dynamic approach by continuously generating and evaluating multiple alternative solutions based on current satellite conditions. The system adapts by selecting the optimal solution from multiple possibilities, dynamically adjusting which satellites are included or excluded based on their signal quality and impact on integrity.
Solution Approach 2:
The system uses feedback by comparing multiple sub-solutions and evaluating their integrity bounds. By analyzing the differences between solutions and selecting the one with the best integrity characteristics, the system creates a closed-loop process that continuously optimizes the navigation solution based on observed signal conditions.
Data Source
AI summary
A method for computing and applying alternative uncertainty limits is provided. The method includes generating a main solution from a plurality of received measurement signals. A solution separation is applied using a filter bank to generate sub-solutions from the received plurality of measurement signals. Each sub-solution uses all of the measurement signals from the plurality of measurement signals except one measurement signal to generate the associated sub-solution. Each sub-solution excludes a different measurement signal. One sub-solution is selected as fault free. A difference between the main solution and the selected sub-solution is determined. The determined difference is added to a rare normal protection limit to create a solution with improved integrity bounding. The solution with improved integrity bounding is then implemented.