GPS Integrity Parameter Determination Using Lookup Tables
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Solution Overview
Problem
Current algorithms for determining integrity risk in global positioning systems, such as the Galileo system, provide conservative estimates that can lead to unnecessary reduction in system availability, as they fail to accurately reflect the actual integrity due to neglecting probabilities of missed detection and requiring high computational efforts.
Innovation Solution
A method and apparatus that use a look-up table-based approach to determine integrity indicating parameters, such as integrity risk and protection level, by considering probabilities of single failure events and missed detection, reducing computational burdens and providing more accurate estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conservative algorithms are used to determine integrity risk, then safety is improved, but system availability deteriorates due to unnecessary reduction
Solution Approach 1:
The patent changes the parameters used in integrity risk determination by incorporating detection probability into the calculation model. This transforms the conservative estimate approach into a more accurate probabilistic model that considers the actual detection capabilities of the monitoring system, thereby improving accuracy without unnecessarily reducing availability
Solution Approach 2:
The patent implements feedback by using the detected failure information and detection probabilities to continuously refine the integrity risk assessment. The system feeds back the actual detection performance into the risk calculation, allowing for more accurate real-time assessment rather than relying on conservative static estimates
2Measurement precision
If accurate integrity determination considering missed detection probability is implemented, then integrity assessment accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing detection probabilities and failure event characteristics in lookup tables before actual integrity assessment. This pre-processing step eliminates the need for complex real-time calculations during operation, achieving accurate integrity determination with reduced computational complexity
Solution Approach 2:
The patent uses partial action by implementing a simplified calculation model that focuses on the most critical factors (single failure events and detection probabilities) while neglecting less significant contributions. This partial approach achieves sufficient accuracy for practical applications without the full computational burden of a complete model
Data Source
AI summary
The present invention relates to a method and an apparatus for determining an integrity indicating parameter (e.g. an integrity risk IR or a protection level PL) indicating the integrity of positioning information determined from positioning information signals disseminated from a plurality of space vehicles SAT1, SAT2, SAT3 of a global positioning system. An input parameter (e.g. an alert limit AL or an integrity risk IR) is provided, a plurality of integrity information parameters (σSISA, σSISMA or equivalent, σX, kX) are received, and the integrity indicating parameter (IR; PL) is determined on the basis of the input parameter (AL; IR) and on the basis of a first relation between the integrity indicating parameter (IR; PL) and the input parameter (AL; IR) and the plurality of integrity information parameters (σSISA, σSISMA or equivalent, σX, kX).