Tiling-Based Route Estimation for Navigation Run Time
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Solution Overview
Problem
Existing navigation systems face limitations in determining optimum routes due to imprecise estimation functions and memory/run time constraints, particularly in handling large road networks, where algorithms like Dijkstra's and A* may be inefficient and impractical.
Innovation Solution
A method and system that employ a tiling-based approach, where resistance values for each tile represent a lower bound for costs associated with routes connecting vertices on the tile boundary, allowing for the determination of an estimation function that provides a more accurate and efficient route calculation using the A*-algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Dijkstra's algorithm or A*-algorithm is applied to large road networks, then correct optimum route can be found, but memory and run time restrictions are exceeded
Solution Approach 1:
The patent divides the road network into a grid structure with multiple grid points, where each grid point maintains distance information to its neighboring grid points. This segmentation allows the algorithm to process the road network in smaller, manageable units rather than treating the entire network as a single large graph, thereby reducing memory requirements and improving computational efficiency while still guaranteeing correct optimum route determination.
2Productivity
If air-line distance based estimation function is used, then algorithm run time is reduced, but estimation precision deteriorates
Solution Approach 1:
The patent pre-calculates and stores distance information between adjacent grid points before the actual route determination process. This preliminary action creates a foundation of accurate distance data that can be quickly referenced during the A* algorithm execution, providing both precise estimation and fast computation without requiring complex real-time calculations.
Solution Approach 2:
The patent introduces a grid-based spatial structure as an additional dimension for organizing road network data. By mapping road segments and vertices onto a grid system with predefined distance relationships, the algorithm gains a more accurate spatial estimation capability compared to simple air-line distance, while maintaining computational efficiency through the structured grid organization.
3Measurement precision
If more road segment vertices are visited for better estimation, then estimation precision is improved, but algorithm run time increases
Solution Approach 1:
The patent pre-computes distance information for all grid points and stores it in a distance matrix before the route determination process begins. This preliminary computation eliminates the need to calculate distances during the actual A* algorithm execution, allowing the algorithm to use pre-prepared accurate distance estimates without incurring additional computational cost during route finding, thus avoiding the trade-off between precision and time.
Data Source
AI summary
A method and system for determining a route from a starting point to a destination on a road network are provided, where an estimation function for vertices of the road network is employed, and where a tiling covers an area in which at least a portion of the road network is contained. A resistance value of each tile of the tiling is provided, and the values of the estimation function for vertices of the road network are determined in accordance with the resistance values of the tiles of the tiling. In an example implementation, the resistance value of a given tile is a lower bound on or the minimum of the costs associated with an optimum route connecting any pair of vertices located on the boundary of the given tile divided by an air-line distance of the pair of vertices.