OWAS Integrity Monitoring for Multi-GNSS Satellite Fault Detection
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Solution Overview
Problem
Current GNSS navigation systems, such as GPS, lack the capability for timely fault detection and integrity monitoring, particularly in aviation, where multiple satellite faults can compromise safety, and existing RAIM methods struggle to provide high availability and accuracy simultaneously.
Innovation Solution
The Optimally Weighted Average Solution (OWAS) method uses two independent GNSS constellations, like GPS and Galileo, to detect and manage satellite signal faults by trading accuracy for integrity, providing protection levels that ensure user safety through enhanced RAIM functionality, specifically designed for vertically guided approaches and non-precision air navigation phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RAIM methods are used for fault detection, then the system can detect single satellite faults, but the availability of integrity monitoring remains insufficient for high-safety applications
Solution Approach 1:
The patent segments the satellite constellation into multiple groups and performs fault detection on each group independently using RAIM. This segmentation allows the system to detect multiple simultaneous faults that would be indistinguishable in traditional single-constellation RAIM, thereby improving integrity monitoring availability without requiring a complete system redesign
Solution Approach 2:
The patent introduces an intermediary comparison mechanism where position solutions from different satellite groups are compared against each other. This intermediary comparison serves as a mediator to identify faults that would be undetectable by traditional RAIM, enhancing the system's ability to provide high-availability integrity monitoring
2Measurement precision
If more satellites are used for position determination, then accuracy can be improved, but the ability to detect multiple simultaneous faults decreases
Solution Approach 1:
The patent divides the set of visible satellites into multiple independent groups and calculates position solutions for each group separately. This segmentation enables the system to maintain high position accuracy using all available satellites while simultaneously detecting multiple faults by comparing the consistency of solutions from different groups
Solution Approach 2:
The patent implements a feedback mechanism where the position solutions from different satellite groups are continuously compared. When inconsistencies exceed predetermined thresholds, the system provides feedback indicating potential faults, allowing the receiver to identify and exclude faulty satellites while maintaining accurate positioning
3Reliability
If RAIM provides high availability for integrity monitoring, then user safety is improved, but the position accuracy may be degraded
Solution Approach 1:
The patent changes the parameter being monitored from raw position accuracy to the consistency of position solutions derived from different satellite groups. By focusing on solution consistency rather than individual position accuracy, the system can provide high-integrity monitoring while maintaining acceptable positioning performance through the use of all available satellite measurements
Data Source
AI summary
The present invention relates to providing navigation guidance for mobile users, using Global Navigation Satellite Systems (GNSSs) for applications where the user position needs to be determined in real time while meeting the navigation requirements, especially integrity requirement, for the given application. The present invention assists in providing guidance with a high availability of integrity function by trading accuracy for integrity for two different types of navigation applications. A first type of application requires a capability of detecting an occurrence of multiple satellite signal faults; the first embodiment of the invention provides this capability with a high availability of integrity, using two or more independent GNSSs. A second type of application requires a capability of detecting an occurrence of a single satellite signal fault; the second embodiment of the invention provides this capability with a high availability of integrity, using any one or a combination of GNSSs. The detecting and deriving of both methods are (i) in position domain and (ii) determinative of mobile user safety.