Map Matching Device Using Movement Cost for Position Accuracy
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Solution Overview
Problem
In systems where a server collects position measurement points from multiple on-board units via a network, irregular intervals or long intervals between data collection can lead to inaccurate determination of a vehicle's position on a map, as the server may incorrectly identify the link the vehicle is on due to lack of precise information about the vehicle's movement between measurement points.
Innovation Solution
A map matching device that includes a candidate location extraction unit, movement cost determination unit, movement possibility judgment unit, and matching location determination unit, which assesses possible movements between candidate locations based on movement costs and estimated movable distances to accurately determine the vehicle's position on the map, even with long intervals between position measurement points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the server collects position measurement points at long intervals to reduce communication amount, then communication efficiency is improved, but position determination accuracy deteriorates
Solution Approach 1:
The system pre-calculates and stores movement costs for all possible link combinations between position measurement points before they are needed for position determination. This preliminary preparation allows the server to quickly and accurately determine vehicle positions even when position measurement points are collected at long intervals, as the computationally intensive movement cost calculations have already been performed.
Solution Approach 2:
The system dynamically adjusts the position determination process by calculating movement costs based on actual vehicle movement patterns between position measurement points. Rather than using fixed or static methods, the system adapts its calculations to the specific dynamics of vehicle movement, enabling accurate position determination even with irregular or long intervals between measurements.
2Productivity
If the server collects position measurement points at irregular intervals, then communication efficiency is improved, but position determination accuracy deteriorates
Solution Approach 1:
The system pre-calculates movement costs for all possible link combinations in advance, storing them for later use. This preliminary preparation ensures that regardless of when position measurement points are collected (regular or irregular intervals), the server has the necessary cost data ready to accurately determine vehicle positions without being constrained by communication timing.
Solution Approach 2:
The system changes the approach from requiring frequent position measurements to using pre-calculated movement costs that can handle irregular intervals. By transforming the problem parameters - using stored cost data rather than continuous measurements - the system maintains position determination accuracy while accommodating irregular communication patterns.
3Speed
If the server determines position without considering movement cost, then processing speed is improved, but position determination accuracy deteriorates
Solution Approach 1:
The system pre-calculates and stores movement costs for all possible link combinations before they are needed for position determination. This preliminary action moves the computationally intensive calculations to a preparation phase, allowing the actual position determination to proceed quickly by simply comparing pre-computed costs, thus maintaining both speed and accuracy.
Data Source
AI summary
A map matching device includes: a candidate spot extraction unit that extracts candidate spots onto a link based on position measurement points; a movement cost determination unit that determines the movement cost of a combination of links connecting one of first candidate spots extracted based on one position measurement point to one of second candidate spots extracted based on another position measurement point, the movement cost determined separately for each combination of a first and a second candidate spot; a movement possibility judgment unit that judges, for each combination of first and second candidate spots, whether a moving body can move from the first to the second candidate spot, based on the movement cost; and a matching spot determination unit that determines, as the position of the moving body on the map, one of the candidate spots included in a combination for which movement was determined to be possible.