Time-Dependent Route Calculation Using Regional Cost Profiles
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Solution Overview
Problem
Existing route planning algorithms, such as Dijkstra and A* methods, are slow due to the need to explore a vast number of possible routes, especially when traffic conditions change, leading to suboptimal route calculations.
Innovation Solution
A method that determines cost profiles of routes using map data, allowing users to select travel times based on cost alterations, and employs pre-processing techniques like dividing maps into regions and generating bit vectors to accelerate route calculation, while considering time-varying traffic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional route planning algorithms (Dijkstra, A*) are used to calculate routes, then route accuracy is maintained, but processing time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing cost profiles for multiple departure times before actual route planning is needed. The system pre-processes traffic conditions and stores cost information for different time periods, so when a route query is made, the pre-computed data can be quickly retrieved and used without performing full route calculations at query time. This resolves the contradiction by maintaining route accuracy through pre-computed cost profiles while dramatically reducing processing time during actual use.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing cost profiles for multiple departure times before actual route planning is needed. The system pre-processes traffic conditions and stores cost information for different time periods, so when a route query is made, the pre-computed data can be quickly retrieved and used without performing full route calculations at query time. This resolves the contradiction by maintaining route accuracy through pre-computed cost profiles while dramatically reducing processing time during actual use.
2Productivity
If pre-processed map data with static shortest paths is stored to reduce processing time, then processing speed increases, but route optimization deteriorates when traffic conditions change
Solution Approach 1:
The patent applies dynamics by transitioning from static shortest path storage to dynamic cost profile storage that accounts for time-varying traffic conditions. Instead of storing fixed shortest paths that become obsolete when traffic changes, the system stores cost profiles associated with different departure times and traffic scenarios. This allows the route planning system to adapt to changing conditions by selecting appropriate cost profiles, thereby maintaining both processing speed through pre-computation and route optimization through time-dependent cost data.
Solution Approach 2:
The patent applies parameter changes by storing cost profiles that vary with departure time parameters rather than storing static path data. The cost profiles incorporate time-dependent cost values that reflect changing traffic conditions. When traffic conditions change, the system can retrieve cost profiles corresponding to the new time parameters without reprocessing the entire map, thus maintaining both processing efficiency and route optimization accuracy.
3Loss of time
If the number of paths explored during route calculation is reduced through pre-processing, then processing time decreases, but the ability to handle time-varying traffic conditions deteriorates
Solution Approach 1:
The patent applies universality by creating cost profiles that serve multiple functions and multiple departure time scenarios simultaneously. A single pre-processed cost profile can be used for various departure times and traffic conditions without requiring separate processing for each scenario. This multi-functional cost profile approach allows the system to handle time-varying traffic conditions adaptably while maintaining reduced calculation time, as the same pre-computed data structure serves multiple purposes across different time parameters.
Data Source
Figure 1~3a
Figure 2
Figure 3b~4
AI summary
This invention concerns a method of determining a route using map data comprising a plurality of navigable paths, the map data divided into a plurality of regions. The method comprises using at least one processing apparatus to: receive an origin and a destination on the map data and a travel time, determine a route from the origin to the destination using the map data and minimum cost data that identifies minimum cost paths between regions of the map data. The minimum cost data identifies more than one minimum cost path between a pair of the regions if different minimum cost paths exist between the pair of regions at different times and determining a route comprises identifying from the minimum cost paths for the pair of regions comprising the origin and destination, the minimum cost path having a lowest cost at the travel time.