Map Matching with Integrity Ellipses for GNSS Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current map matching algorithms in navigation systems lack integrity guarantees, leading to unreliable road identification and failure to detect mismatches, especially in urban environments, which is critical for safety and legal applications.
Innovation Solution
A method that combines GNSS positioning with GIS information to determine passable road areas with a minimum associated probability by propagating integral areas over time, using position increase integrity ellipses to maintain high confidence levels and ensure accurate road identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional map matching algorithms are used to identify road segments, then the system can provide position adjustment to the map, but the system lacks integrity guarantees and cannot detect mismatches reliably
Solution Approach 1:
The patent implements a feedback mechanism by calculating an integrity value that compares the GNSS-derived position with the map-matched position. When the integrity value exceeds a threshold, the system generates an alarm indicating a mismatch between the actual position and the identified road segment, enabling continuous monitoring and correction of positioning errors
Solution Approach 2:
The patent replaces conventional geometric and topological map matching methods with a statistically-based integrity monitoring approach. Instead of relying solely on spatial relationships and pattern recognition, the system uses statistical analysis of position deviations and integrity ellipses to detect and alarm mismatches, providing quantifiable reliability guarantees
2Ease of manufacture
If simple geometric map matching is used, then the algorithm is easy to implement, but the precision of road identification is not assured
Solution Approach 1:
The patent transforms the map matching problem from a purely geometric exercise to a statistical parameter-based approach. By introducing integrity values, confidence levels, and statistical thresholds as key parameters, the system maintains algorithmic simplicity while achieving precise and reliable road identification through quantifiable confidence measures
3Measurement precision
If complex algorithms with pattern recognition and Kalman filters are used, then the system can adjust position to segments, but the precision is not assured and no confidence value is provided
Solution Approach 1:
The patent introduces a feedback mechanism that continuously calculates and reports an integrity value representing the confidence level of the map matching solution. This integrity information is fed back to the user or system, enabling informed decision-making about the reliability of the identified road segment and position
4Adaptability or versatility
If map matching is used to relate position information with the real world, then en route guidance can be provided, but errors in GNSS position and GIS information cause mismatches of hundreds of meters
Solution Approach 1:
The patent implements a feedback-based integrity monitoring system that continuously evaluates the consistency between GNSS positions and GIS map data. By calculating integrity values and comparing them against thresholds, the system detects when mismatches exceed acceptable levels, alerting users to potential errors in either the positioning or map data
Solution Approach 2:
The patent replaces direct geometric matching of GNSS positions to map segments with a statistically-based integrity assessment approach. This substitution allows the system to handle large position errors and GIS inaccuracies by evaluating the statistical consistency of the matching rather than relying on precise geometric alignment
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
The invention relates to a method for determining a set of passable roads or areas traveled by a user with a minimum associated probability or integrity which comprises: - receiving from a GNSS system respective position solutions PVT of said user in respective instants of time ta and tb, respectively, and respective position integrity ellipses, Ia and Ib (201), with respective minimum associated probabilities, Pa and Pb, that the user is located in each of them in ta and in tb, respectively, and a position increase Δab between ta and tb with its position increase integrity ellipse Iab (204) and its associated probability Pab; - obtaining from a GIS system respective passable areas corresponding to said PVT solutions, - determining a first passable integral area Sa = Ia ∩ TGIS (202) and a second passable integral area Sb = Ib ∩ TGIS (203) as an intersection for each instant of time of said position integrity ellipses with said passable areas; - propagating said first passable integral area to the subsequent instant tb by means of the position increase, considering the uncertainty associated to said increase determined by the integrity ellipse of the velocity Iab and its associated probability Pab (204), obtaining a propagated integral area Sab (205); - eliminating from said propagated integral area Sab the non-passable areas, obtaining a propagated passable integral area S'ab (206); - determining a final passable integral area S'b formed by a road or a set of passable roads in the second instant tb as an intersection of said second passable integral area and of said propagated passable area or as the smallest of said areas; and - determining in each case the minimum probability P'b that the user is located in said final passable integral area S'b.