GNSS Position Integrity Assessment via Exclusion Zones
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Solution Overview
Problem
GNSS receivers face challenges in maintaining accuracy and reliability, particularly in complex environments like large cities where high-rise buildings cause multipath propagation and reduced satellite visibility, leading to potential output of incorrect position information, which is critical for autonomous driving applications.
Innovation Solution
A method is introduced to assess the integrity of GNSS position information by discarding preliminary positions that satisfy specific conditions, such as being within high-error areas, and using these conditions to define integrity criteria, ensuring only verified positions are output to higher-level control systems, thereby preventing incorrect information from being provided.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS position information is processed without excluding problematic areas, then the quantity of position information is maximized, but the integrity and reliability of the position information deteriorates due to multipath propagation and reduced satellite visibility in complex environments
Solution Approach 1:
The patent applies preliminary action by pre-defining exclusion zones based on geographic coordinates where GNSS integrity cannot be guaranteed. Before performing integrity assessment, the system checks whether the current position falls within these pre-defined problematic areas (such as urban canyons with high-rise buildings). This preliminary filtering prevents wasted computational effort on positions that are inherently unreliable, thereby improving overall system reliability without proportionally increasing complexity.
Solution Approach 2:
The patent segments the assessment process into two independent stages: first checking whether the position falls within pre-defined exclusion zones, and second performing integrity assessment only on positions outside these zones. This segmentation allows the system to handle the complexity of integrity assessment selectively, applying full assessment only where needed rather than uniformly across all positions, thus improving reliability while controlling computational complexity.
2Reliability
If integrity assessment is performed on all GNSS positions, then the reliability of position information is improved, but the computational effort and time required for processing increases
Solution Approach 1:
The system performs a preliminary check against pre-stored exclusion zone coordinates before initiating full integrity assessment. Positions falling within these zones are immediately identified as unreliable without requiring computationally intensive assessment calculations. This preliminary filtering significantly reduces the number of positions that require full integrity assessment, thereby reducing processing time while maintaining reliability for positions where assessment is performed.
Solution Approach 2:
The patent applies partial action by performing complete integrity assessment only on a subset of positions that fall outside pre-defined exclusion zones, rather than assessing all positions uniformly. For positions within exclusion zones, the system applies a simpler rejection criterion based on geographic location. This selective approach ensures high reliability for assessed positions while minimizing the total computational effort and processing time required.
3Productivity
If exclusion zones are pre-defined and stored, then the processing speed for integrity assessment is improved, but the memory usage increases to store the exclusion zone data
Solution Approach 1:
The system performs preliminary action by pre-calculating and storing only the essential exclusion zone boundary coordinates rather than storing complete geographic information or performing real-time complex environmental analysis. This pre-processing condenses the exclusion zone information into compact coordinate representations that can be efficiently stored and quickly queried during operation, improving processing speed while minimizing memory requirements.
Solution Approach 2:
The patent uses a simplified representation (copy) of exclusion zones using only boundary coordinates rather than storing detailed geographic features, building information, or environmental data. This coordinate-based copying approach captures the essential information needed for rapid position checking while using minimal memory, achieving high processing speed without proportionally increasing storage requirements.
Data Source
AI summary
A method for processing and assessing the integrity of GNSS position information incudes (a) receiving GNSS signals and ascertaining a preliminary GNSS position, (b) checking the preliminary GNSS position ascertained in step (a) against a first condition and discarding the preliminary GNSS position if the first condition is satisfied, (c) ascertaining the integrity of the GNSS position based on an integrity criterion ascertained in the field which was determined excluding GNSS positions that satisfy the first condition, and (d) if the GNSS position was not discarded in step (b), outputting the preliminary GNSS position as a verified GNSS position.