Virtual Gantry Detection Using Total Probability Value
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Solution Overview
Problem
Existing GNSS-based road tolling systems face issues with erroneous vehicle passage detection due to obstructed satellite signals, leading to lower user confidence and increased operational costs, with existing methods failing to provide sufficient reliability in surveillance and position detection.
Innovation Solution
A method and system that utilize multiple GNSS observations and geospatial design to calculate a Total Probability Value (TPV) for vehicle passage through virtual gantries, allowing for individual road width and tolerance definitions to enhance detection accuracy, using complementary probabilities and statistical methods like Root Mean Square Error (RMSE) or Mean Absolute Error (MAE) to assess passage reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional GNSS-based detection methods are used, then the system is simple to operate, but the detection reliability is low due to obstructed satellite signals causing erroneous position estimates
Solution Approach 1:
The detection process is segmented into multiple independent validation checks: (1) geometric validation of position estimates against passage line equations, (2) temporal validation of crossing sequences, (3) spatial validation of distances between consecutive gantries, and (4) directional validation of vehicle movement. Each segment operates independently to verify different aspects of passage validity, collectively improving reliability without requiring a completely complex new system.
Solution Approach 2:
Virtual passage lines and mathematical models serve as intermediaries between the raw GNSS position data and the final passage detection decision. The passage lines act as virtual detectors that translate complex satellite signal interpretations into simple geometric validation problems, mediating between the unreliable raw data and the reliability requirement.
2Measurement precision
If multiple validation checks are implemented, then the detection accuracy improves, but the computational complexity increases
Solution Approach 1:
The patent replaces complex mechanical or hardware-based validation systems with mathematical and computational methods. Instead of using multiple physical sensors or complex hardware validators, the system uses mathematical models (passage line equations, distance calculations, temporal sequence analysis) to perform validation checks, achieving high detection accuracy through software-based computation rather than hardware complexity.
3Reliability
If virtual gantries are defined with strict geometric parameters, then false registrations are reduced, but missed recognition of actual passages increases
Solution Approach 1:
The validation system dynamically adjusts its criteria based on the specific characteristics of each passage candidate. Rather than using fixed, static thresholds, the system evaluates multiple dynamic factors including the sequence of crossings, distances between consecutive gantries, temporal patterns, and geometric relationships. This dynamic evaluation allows the system to maintain strict geometric parameters while adapting to real-world variations in vehicle behavior and GNSS signal quality.
Solution Approach 2:
The system changes multiple parameters simultaneously to optimize the balance between false registration reduction and passage detection sensitivity. These include adjusting the number of required validation checks, modifying distance thresholds based on road geometry, varying temporal window sizes for sequence validation, and adapting geometric tolerance levels based on local conditions. This multi-parameter adjustment allows flexible optimization for different operational scenarios.
Data Source
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AI summary
Method and system for detecting passages by vehicle at a virtual gantry controlled by a GNSS system comprising an OBU in every vehicle to be surveyed by the system, said OBU receiving signals from satellites to consistently and frequently estimate positions for the vehicle, the method comprising the steps of: defining a virtual gantry in terms of a number of ordered passage lines (PL) across a road; determining intersection points (i) from the intersection between the GNSS trace and the passage line(PL); calculating a value representing probability of a true passage at that passage line (PL); for each vehicle for which intersection points (i) have been determined for at least two different passage lines (PL), calculating a total probability value based on the individually calculated probability values; concluding of a true passage by the vehicle in question only if the total probability value is exceeding a predefined minimum value.