Navigation Server Partial Link Cost Weighting
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Solution Overview
Problem
Existing navigation systems face reliability issues in estimating traffic states due to deviations in traffic conditions across different parts of a link, leading to inaccurate information provided to users.
Innovation Solution
A navigation server that determines total movement costs by preferentially using partial movement costs with high freshness, reducing the influence of less fresh data and improving accuracy through map matching and the use of reference movement costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traffic state is displayed using link-level aggregation, then the system complexity is reduced and ease of operation is improved, but measurement precision and reliability of traffic state information deteriorate when traffic conditions vary within the link
Solution Approach 1:
The patent divides a link into multiple partial links and calculates movement costs for each partial link separately based on probe information. This segmentation allows the system to capture traffic variations within different segments of the link while maintaining the overall link-level display structure, thereby improving measurement precision without significantly increasing system complexity.
2Area of stationary object
If link length is increased to cover broader areas, then the coverage area is improved, but reliability of traffic state information deteriorates due to greater variation in traffic conditions across the link
Solution Approach 1:
The patent applies local quality by assigning different movement costs to different partial links within the same link based on their specific traffic conditions. This allows the system to maintain broad coverage through longer links while accurately representing local traffic variations through segment-specific cost calculations, thereby preserving reliability across diverse traffic scenarios.
3Area of stationary object
If probe information from multiple sources is integrated to improve coverage, then coverage area is improved, but device complexity increases due to data integration requirements
Solution Approach 1:
The patent merges probe information from multiple navigation clients and integrates it with reference movement costs to calculate comprehensive movement costs for each partial link. This merging approach improves coverage by incorporating diverse data sources while managing complexity through a unified calculation framework that processes all inputs systematically.
4Reliability
If real-time probe information is prioritized over historical data, then reliability of current traffic state is improved, but loss of historical information increases
Solution Approach 1:
The patent uses reference movement costs as an intermediary between real-time probe information and historical traffic patterns. The total movement cost combines both real-time probe data and reference costs, allowing the system to prioritize current traffic state reliability while preserving historical information through the reference cost component.
Data Source
AI summary
Provided is a navigation server capable of improving reliability or estimation accuracy of traffic state information for a user in view of the present traffic state. A partial movement cost Cik being each of movement costs in plural partial links Lik constituting a designated link Li is used to determine a total movement cost Ci in the designated link Li. The higher an occupancy ratio r of a first partial link Lim among a series of the partial links Lik, the more preferentially a partial movement cost Cim in the first partial link Lim is used than a partial movement cost Cin in a second partial link Lin to determine the total movement cost Ci of the designated link Li. In particular, only the partial movement cost Cim in the first partial link Lim is used to determine the total movement cost Ci of the designated link Li.