Route Speed Determination Using GPS Trajectory Data
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Solution Overview
Problem
Current GPS navigation systems inaccurately estimate arrival time and optimize routes due to inability to differentiate actual vehicle speeds in different lanes at intersections, which is crucial for public safety personnel responding to emergencies.
Innovation Solution
A method and system that determine route speed by calculating differential trajectory distance and time between specific points on a route segment, allowing for accurate averaging and storage of average route speeds for each segment, enabling selection of the optimal route with minimum total route time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS navigation systems use posted speed limits to estimate arrival time, then the estimation process is simple, but the accuracy is poor because it cannot differentiate actual speeds in different lanes at intersections
Solution Approach 1:
The system uses the GPS navigation units already present in vehicles to collect speed data, rather than requiring external sensors or infrastructure. Each navigation unit contributes its own trajectory data to the database, making the system self-sustaining and avoiding additional hardware complexity
Solution Approach 2:
A server acts as an intermediary that collects trajectory data from multiple GPS navigation units, processes the speed information, and stores average route speeds in a database. This mediator enables accurate speed differentiation without requiring complex sensors in each individual vehicle
2Measurement precision
If traffic speed sensors are installed in each individual lane to accurately measure speeds, then arrival time estimation accuracy improves, but the cost and complexity of installation and maintenance increases significantly
Solution Approach 1:
Instead of installing physical sensors in each lane, the system creates a virtual model of lane speeds by collecting and processing trajectory data from GPS navigation units. The server reconstructs speed information from multiple data sources, providing accurate lane-specific speed measurements without physical infrastructure
Solution Approach 2:
The GPS navigation units serve multiple functions: they provide turn-by-turn navigation to drivers and simultaneously contribute speed data for route optimization. This multi-functionality eliminates the need for dedicated speed sensors while achieving accurate speed measurement
3Ease of operation
If GPS navigation units average all actual speeds of all lanes to estimate arrival time, then the calculation is simplified, but the accuracy deteriorates because it does not account for lane-specific speeds intended for different maneuvers
Solution Approach 1:
The system segments the route into distinct route segments based on intersections and maneuvers. Each segment has its own average speed calculated from relevant trajectory data, allowing the system to account for different speeds in different lanes without complex overall averaging
Data Source
AI summary
The route speed of a mobile global positioning satellite (GPS) navigation unit in a vehicle movable along one of a plurality of available route segments of a route having a plurality of intersections, is determined by locating a first and a second of the intersections, by locating a start boundary point, by locating a plurality of end boundary points for all the route segments, and by receiving geographic location information of the vehicle at an initial trajectory point located past the start boundary point, and a subsequent trajectory point past the end boundary point in the one route segment into which the vehicle moved. The trajectory points are associated with trajectory times. A server determines the route speed of the one route segment by dividing a differential distance between the trajectory points by a differential time between the trajectory times. The route speed of the other route segments is likewise determined to aid in route optimization.