Contraction Hierarchies for Multi-Link Constraint-Aware Routing
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Solution Overview
Problem
Navigation systems often provide impractical or impassable routes due to multi-link constraints, such as prohibited maneuvers or obstacles, which are not adequately accounted for in existing contraction hierarchy techniques, leading to suboptimal user experiences.
Innovation Solution
The identification and scoring of paths based on multi-link constraints during pre-computation and real-time navigation, using shortcut links to replace or supplement node maps, ensuring that paths avoiding such constraints are prioritized, thereby enhancing route optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If contraction hierarchy techniques are used to precompute shortcuts for commonly traveled routes, then query time processing speed is improved, but multi-link constraints such as prohibited maneuvers or obstacles are not adequately accounted for, leading to impractical or impassable routes
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing constraint information during the contraction hierarchy preprocessing phase. Multi-link constraints are identified and stored alongside shortcut links before query time, enabling fast retrieval without sacrificing route practicality. This resolves the contradiction by preparing constraint data in advance, so that both speed and reliability are maintained during actual navigation queries.
Solution Approach 2:
The patent introduces an intermediary mechanism by adding constraint scoring and filtering layers between the shortcut link selection and final route determination. During query processing, the system evaluates potential shortcuts against stored multi-link constraints and assigns scores based on constraint violations. This intermediary evaluation step ensures that fast pre-computed shortcuts do not lead to impractical routes, resolving the reliability issue while maintaining processing speed.
2Productivity
If shortcut links are added to represent contracted nodes in the contraction hierarchy, then navigation query processing is accelerated, but the complexity of ensuring constraint compliance increases
Solution Approach 1:
The patent reduces verification complexity by performing preliminary constraint analysis during the preprocessing phase. Multi-link constraints are identified, stored, and organized in advance, so that during query processing, the system only needs to retrieve and evaluate pre-computed constraint information rather than analyzing constraints from scratch. This maintains productivity while managing complexity through advance preparation.
Solution Approach 2:
The patent uses copying by creating and storing simplified representations of multi-link constraints alongside shortcut links. Instead of storing complex original constraint definitions, the system creates condensed constraint models that capture essential compliance requirements. This copying approach accelerates query processing by working with simplified constraint representations while maintaining compliance verification capability.
3Use of energy by moving object
If existing contraction hierarchy methods are used without considering multi-link constraints, then computational efficiency is improved, but the generated routes may include prohibited maneuvers or impassable paths
Solution Approach 1:
The patent maintains computational efficiency by performing constraint identification and scoring operations during the preprocessing phase rather than during real-time query processing. Multi-link constraints are analyzed and stored in advance, allowing the query system to simply retrieve and evaluate pre-computed information. This preliminary action ensures route usability without sacrificing computational efficiency during actual navigation.
Solution Approach 2:
The patent introduces constraint scoring as an intermediary evaluation step between shortcut selection and final route confirmation. During queries, the system quickly scores potential routes based on pre-stored constraint information, filtering out unusable paths without complex real-time analysis. This intermediary scoring mechanism ensures route usability while maintaining computational efficiency through simplified evaluation.
Data Source
AI summary
A system described herein may provide a technique for the generation of a node map using contraction hierarchy techniques in a manner that accounts for multi-link constraints. Multi-link constraints may include a sequence of two or more links through the node map, and paths that include such multi-link constraints may be associated with an additional cost based on such inclusion. Shortcut links that represent paths through nodes contracted out of the node map may be associated with portions of multi-link constraints. Paths through such shortcut links, where such paths include the remainder of the multi-link constraint, may be considered as including the multi-link constraint, and the cost of such paths may be calculated accordingly. The costs of links and/or paths, including paths that include multi-link constraints, may be used in determining a path from a source node to a target node of the node map.