Vehicle Detection Magnetometers Using Orthogonal Field Segmentation
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Solution Overview
Problem
Existing contactless vehicle detection systems using compact magnetometers suffer from high error rates due to inability to distinguish vehicle positions and types accurately, especially in stationary and moving traffic, and are prone to failures, with error rates exceeding 3% due to lack of precise spatial orientation and environmental changes.
Innovation Solution
A device comprising multiple magnetometers and electronic evaluation modules that measure geomagnetic and gravitational fields in orthogonal directions, using geometric transformations and software algorithms to dynamically calibrate and differentiate magnetic field components, reducing errors and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If compact magnetometers are used for vehicle detection, then the device complexity and installation space are reduced, but the measurement precision and reliability deteriorate due to inability to distinguish vehicle positions and types
Solution Approach 1:
The magnetic field measurement is segmented into three orthogonal vector components (Bx, By, Bz) measured by three magnetometer elements. This segmentation allows the system to capture spatial information about vehicle position and orientation, enabling accurate vehicle type classification while using compact sensors embedded in the road surface.
Solution Approach 2:
The system transitions from measuring only magnetic field strength (scalar) to measuring magnetic field vector components in three orthogonal dimensions. This dimensional expansion provides spatial resolution that enables distinction between vehicles directly above versus laterally offset, and allows classification of vehicle types based on their magnetic field signatures.
2Ease of operation
If magnetometers are not precisely oriented during installation, then installation time and labor costs are reduced, but the reliability deteriorates due to loss of calibration over time
Solution Approach 1:
The system performs self-calibration by utilizing the Earth's gravitational field as a reference. The gravity sensor measures the vertical direction, and the system automatically orients the magnetic field measurement axes relative to gravity, eliminating the need for manual precision alignment during installation and maintaining reliability over time.
Solution Approach 2:
The magnetometer assembly combines magnetic field sensors with gravity/acceleration sensors into a single integrated unit. This composite sensor system allows the device to use gravitational information to reference and stabilize magnetic field measurements, compensating for installation orientation variations and environmental changes.
3Device complexity
If only magnetic field strength is measured without vector component separation, then the device complexity is reduced, but the measurement precision deteriorates due to interference from vehicle position and orientation
Solution Approach 1:
The magnetic field measurement is segmented into three orthogonal vector components (Bx, By, Bz) measured by three magnetometer elements. This segmentation allows the system to capture spatial information about vehicle position and orientation, enabling accurate vehicle type classification while using compact sensors embedded in the road surface.
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
The solution achieves a vehicle detection error rate of less than 3%, enabling reliable classification of vehicles with high accuracy in various traffic conditions by separating vertical and horizontal geomagnetic field components and compensating for misalignments, thus enhancing the reliability of vehicle detection systems.
Implementation Method 1
one or more magnetometers are used for measuring the geomagnetic field
Implementation Method 2
the at least one magnetometer comprises a device for measuring the gravitational field
Data Source
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AI summary
The device (1) has several magnetometers (2) that are provided for measuring the geomagnetic field. Several electronic evaluation modules (3) are equipped with an integrated circuit such as a microprocessor, a digital signal processor (DSP), a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC) integrated with the magnetometer. An independent claim is included for a method for contactless detection of vehicles.