Road Magnetic Marker Sensing with Displacement-Based Interference Filtering

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Solution Overview

Problem

Conventional magnetic marker detection systems for vehicles are compromised by external magnetic disturbances from structures like bridges and tunnels, leading to reduced reliability in detection.

Innovation Solution

A sensor unit equipped with both magnetic sensors and non-contact displacement sensors to measure magnetism from magnetic markers and displacement relative to the road surface, allowing for improved detection reliability by filtering out external magnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic sensors are used to detect magnetic markers on the road, then vehicle control functions such as automatic steering and lane departure warning can be achieved, but detection reliability is degraded due to external magnetic disturbances from structures like bridges and tunnels

Engineering Contradiction:

Improvemagnetic marker detection reliabilityVSAvoidexternal magnetic disturbances

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces non-contact displacement sensors as an intermediary measurement tool. These sensors measure the displacement between the vehicle and road surface, providing indirect information about magnetic marker position. By using this intermediary measurement method, the system avoids direct reliance on magnetic sensors that are susceptible to external magnetic disturbances from bridges and tunnels, thereby maintaining detection reliability in environments with strong magnetic interference

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the magnetic field-based detection system with a mechanical/optical-based non-contact displacement sensing system. Instead of using magnetic sensors that detect magnetic fields from magnetic markers, the system uses non-contact displacement sensors (such as optical sensors) to measure the physical displacement between the vehicle and road surface. This substitution eliminates the vulnerability to external magnetic disturbances while achieving the same lane detection function

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If only magnetic sensors are used in the sensor unit, then the device complexity is low, but the detection reliability is impaired due to susceptibility to external magnetic fields

Engineering Contradiction:

Improvedetection reliabilityVSAvoidsensor unit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges magnetic sensors and non-contact displacement sensors into a single integrated sensor unit. This combination allows the system to use both detection methods simultaneously, where the non-contact displacement sensors provide reliable position information unaffected by magnetic interference, while magnetic sensors can still be used when conditions permit. The integrated design achieves improved detection reliability without requiring completely separate systems

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sensor unit is designed with multi-functionality, where the non-contact displacement sensors serve dual purposes: measuring both the displacement relative to the road surface and indirectly detecting magnetic marker positions. This universal approach allows a single sensor type to perform multiple detection functions, reducing the need for specialized magnetic sensors in challenging environments while maintaining system versatility

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 integration of non-contact displacement sensors enhances the detection of magnetic markers by measuring displacement, effectively eliminating external magnetic disturbances and improving detection reliability.

Implementation Method 1

one or plurality of magnetic sensors which measures magnetism acting from the magnetic marker

Methodology Applied

Scientific EffectMagnetism: Magnetic Field

Implementation Method 2

one or plurality of non-contact displacement sensors which measures a displacement relative to a surface where the magnetic marker is laid

Methodology Applied

Scientific EffectOptical measurement: LIDAR

Data Source

PatentUS12601612B2Vehicle system including sensor unit for detecting magnetic marker laid on a road

Publication Date: 2026.04.14 AICHI STEEL CORP

AI summary

A vehicle system includes a sensor unit including magnetic sensors for detecting a magnetic marker and non-contact displacement sensors which measure a displacement relative to a road surface where the magnetic marker is laid, a processing circuit which performs detection process for detecting the magnetic marker by processing a magnetic measurement value by the plurality of magnetic sensors, and a switching circuit which switches the detection process in accordance with displacement measurement values by the non-contact displacement sensors. By switching the detection process in accordance with the displacement measurement values by the non-contact displacement sensors, the magnetic marker can be detected with high reliability.