Inductive Loop Vehicle Detection for Straddling Lanes

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Solution Overview

Problem

Existing inductive loop systems struggle to accurately determine whether a vehicle is straddled between lanes and its lateral position, leading to miscounting and inaccurate road usage data due to varying vehicle sizes and positions, especially in adverse weather conditions.

Innovation Solution

The method involves measuring inductance change values from adjacent loops, summing or taking the logarithm of these values, and comparing them against a threshold to differentiate between single vehicles straddling lanes and two vehicles in separate lanes, using logarithmic calculations and correction terms to refine the assessment and estimate lateral positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the geometric mean of peak inductance change is used to distinguish between one and two vehicle scenarios, then vehicle detection can be performed, but the accuracy is insufficient especially when vehicles are straddled between lanes

Engineering Contradiction:

Improvevehicle detection accuracyVSAvoidconsistency in distinguishing one vs two vehicle scenarios

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent transforms the inductance change measurements by taking logarithms of the peak values before computing their geometric mean. This parameter transformation linearizes the relationship between vehicle position and measurement values, making the geometric mean more robust for distinguishing between single and multiple vehicle scenarios, particularly when vehicles are straddled between lanes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary processing to the inductance measurements by calculating logarithms of the peak values before performing the geometric mean calculation. This preliminary transformation prepares the data in a form that enhances the reliability of vehicle scenario classification, addressing the inconsistency problem in advance.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If a high threshold is set to account for all vehicle arrangements and sizes, then heavy vehicles with low chassis clearance can be handled, but the threshold becomes higher than ideal and requires separate tests for different vehicle types

Engineering Contradiction:

Improvehandling of different vehicle types and sizesVSAvoidthreshold accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent creates a universal detection method that works for all vehicle types and sizes by using the logarithmic transformation of inductance measurements. This transformation normalizes the data across different vehicle configurations, allowing a single threshold to effectively distinguish between one and two vehicle scenarios regardless of vehicle type, eliminating the need for separate tests.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If inductive loops are used to detect traffic, then overhead sensor disadvantages are avoided, but miscounting occurs when vehicles are straddled between lanes due to inductive disturbances in adjacent loops

Engineering Contradiction:

Improvedetection reliability in various weather conditionsVSAvoidvehicle count accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent merges the measurements from multiple adjacent inductive loops by computing the geometric mean of their logarithmic peak values. This combination approach allows the system to distinguish whether a single vehicle is straddling lanes or multiple vehicles are in separate lanes, eliminating miscounting while maintaining the reliability of inductive loop detection in adverse weather conditions.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the accuracy of vehicle detection and position estimation, allowing for more precise road usage data and improved camera triggering in ANPR systems, even in adverse conditions, by providing a consistent and adaptable method for various vehicle types and sizes.

Implementation Method 1

apparatus for and methods of assessing a vehicle on a carriageway using inductive loop measurements

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS11263898B2Apparatus and methods for assessing vehicles straddled between lanes

Publication Date: 2022.03.01 RED FOX I D LTD

AI summary

A method of assessing whether a vehicle is straddled between lanes (12,14) on a multi-lane carriageway, the method comprising the steps of: a) measuring inductance change values from two adjacent inductive loops (22a, 20b) situated at a loop site, as the vehicle traverses the loop site; b) summing separate logarithms of the inductance change values, or taking a logarithm of the product of the inductance change values, to obtain a value; and c) comparing the value from step (b) against a predetermined threshold value to make a determination as to whether: i) a single vehicle is straddling multiple lanes (12,14), where the value from step (b) is on one side of the predetermined threshold value, or ii) two vehicles are present in adjacent lanes (12,14), where the value from step (b) is on the other side of the predetermined threshold value.