Bifurcation Detection Using Heading Vector Angle Analysis
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Solution Overview
Problem
Localization in bifurcations is challenging for positioning and map matching systems due to small errors in gyroscope measurements and miscalibrations, leading to incorrect location and direction display on navigation devices.
Innovation Solution
A method for detecting bifurcations using GPS and gyroscope positioning systems to accurately determine the correct leg of a bifurcation by analyzing location measurements, determining possible segments, and calculating an angle between the heading vector and the second possible segment, with the navigation device displaying the correct position on one of the segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional positioning systems are used in bifurcations, then the system is simple to operate, but localization accuracy deteriorates due to gyroscope measurement errors and miscalibrations
Solution Approach 1:
The method segments the navigable feature into multiple possible segments (first possible segment, second possible segment, etc.) and evaluates the probability of the device being on each segment. This segmentation allows the system to handle bifurcation ambiguity by considering multiple hypotheses simultaneously rather than committing to a single potentially incorrect location.
Solution Approach 2:
The system changes the parameter of evaluation from simple distance-based matching to probability-based segment evaluation. By calculating probability ratings for each possible segment based on location measurements and comparing them against threshold values, the system can more accurately determine the correct segment even in the presence of gyroscope errors and miscalibrations.
2Measurement precision
If probability-based segment evaluation is implemented, then localization accuracy improves, but computational complexity increases
Solution Approach 1:
The system performs partial evaluation by focusing computational resources on evaluating only the most likely segments (first possible segment, second possible segment) rather than exhaustively evaluating all possible segments in the map database. This partial action approach reduces computational complexity while maintaining high detection accuracy.
Solution Approach 2:
The patent replaces traditional mechanical/geometric matching methods with a probabilistic evaluation system. Instead of relying solely on geometric constraints and distance calculations, the system uses probability ratings that can incorporate multiple sources of information (GPS measurements, gyroscope data, map attributes), providing a more robust solution that is less sensitive to measurement errors.
3Reliability
If multiple possible segments are evaluated, then the risk of map mismatch is reduced, but the time required for location determination increases
Solution Approach 1:
The system performs preliminary evaluation of segments by establishing probability thresholds before final determination. By pre-defining threshold values for segment probability ratings, the system can quickly eliminate unlikely segments and focus computation on promising candidates, reducing the overall time required for location determination while maintaining high reliability.
Solution Approach 2:
The system uses feedback from probability rating comparisons to iteratively refine segment evaluation. By comparing calculated probability ratings against threshold values and adjusting the evaluation focus based on these comparisons, the system can efficiently converge on the correct segment without exhaustively evaluating all possibilities, thus reducing determination time while maintaining reliability.
Data Source
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AI summary
At least one example embodiment discloses a method of detecting a bifurcation in a navigable feature. The method includes first determining a first possible segment and a second possible segment of the navigable feature based on location measurements along the navigable feature, the location measurements representing a heading vector and the location measurements having a higher probability of being on the first possible segment than on the second possible segment, second determining an angle based on the heading vector and a vector between the second possible segment and one of the location measurements, and detecting a bifurcation based on the angle.