Road Magnetic Marker with 40 mT Flux Density for Vehicle Detection
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Solution Overview
Problem
Conventional magnetic marker detection systems for vehicles face issues with strong magnetic forces attracting metallic substances like nails or bolts, potentially causing tire damage due to the high magnetic force required for detection by sensors positioned above the road surface.
Innovation Solution
A magnetic marker with a reduced magnetic flux density of up to 40 mT, utilizing plastic or rubber magnets, is designed to minimize the attraction of metallic substances, combined with a magnetic sensor system using sensitive detectors like MI, fluxgate, or TMR sensors to ensure reliable detection while preventing attraction of road debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetic force of the magnetic marker is increased to ensure detection by the magnetic sensor on the vehicle, then the detection capability is improved, but the risk of attracting metallic substances such as nails or bolts increases, potentially causing tire damage
Solution Approach 1:
The patent applies parameter changes by precisely controlling the magnetic flux density of the magnetic marker to be 40 mT or less. This parameter optimization ensures that the magnetic field is sufficiently strong for detection by magnetic sensors mounted on vehicles while remaining weak enough to prevent attraction of metallic substances like nails or bolts that could cause tire damage. The patent specifies this exact threshold value to resolve the contradiction between detection capability and safety.
2Object-affected harmful factors
If the magnetic flux density is reduced to prevent attraction of metallic substances, then the safety is improved, but the detection capability by the magnetic sensor may be compromised
Solution Approach 1:
The patent resolves this contradiction by establishing the optimal parameter threshold of 40 mT for magnetic flux density. This specific parameter value has been determined to maintain sufficient detection capability for magnetic sensors while preventing harmful attraction of metallic objects. The patent explicitly sets this boundary condition to balance both requirements simultaneously.
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 reduced magnetic force of the markers decreases the risk of attracting metallic substances, while maintaining effective detection capabilities for driving support controls such as automatic steering and lane departure warnings, using sensitive sensors to detect the weaker magnetic fields effectively.
Implementation Method 1
a magnetic marker laid on a road surface so as to be detectable by a magnetic sensor attached to a bottom surface side of a vehicle
Implementation Method 2
the magnetic marker has a surface with a magnetic flux density Gs equal to or smaller than 40 mT (milli-tesla, 400 G)
Data Source
AI summary
Provided are a magnetic marker and a magnetic marker detection system with a reduced magnetic force. The magnetic marker detection system (1S) in which magnetism generated from the magnetic marker (1) laid on a road surface (53) is detected by a magnetic sensor (2) attached to a vehicle's body floor (50) of a vehicle (5) is a system with the magnetic marker (1) and the magnetic sensor (2) in combination, the magnetic marker having a surface with a magnetic flux density equal to or smaller than 40 mT and the magnetic sensor using a magneto-impedance element including an amorphous wire as a magneto-sensitive body with impedance in a high-frequency region changing in accordance with an external magnetic field.