Magnetic Wheel Sensor for Vehicle State Detection

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Solution Overview

Problem

Conventional displacement sensors used in vehicle monitoring systems are costly and provide only approximate differentiation between stationary and moving states, leading to high power consumption and interference risks.

Innovation Solution

Equipping vehicle wheels with magnetic sensors to detect variations in the magnetic field, allowing for accurate discrimination between stationary and moving states without the need for conventional displacement sensors, and using two magnetic sensors positioned orthogonally to determine the wheel's position and direction of rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional displacement sensors (roll switches or accelerometers) are used to determine vehicle state, then the vehicle state can be detected, but the cost is high and the measurement precision is low requiring high thresholds

Engineering Contradiction:

Improvestate of travel detection precisionVSAvoidsensor cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical displacement sensors (roll switches) and accelerometer-based systems with a magnetic field detection system. A magnetic sensor mounted on the wheel hub detects variations in the magnetic field caused by the rotation of the wheel and the movement of the vehicle, thereby substituting mechanical sensing with magnetic field sensing to achieve lower cost and improved precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary medium to detect wheel rotation and vehicle movement. By placing a magnetic sensor on the wheel hub and detecting magnetic field variations caused by wheel rotation and vehicle motion, the system uses the magnetic field as a mediator to translate mechanical movement into detectable signals without direct mechanical contact or complex sensor mechanisms

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional displacement sensors are used with high thresholds (40 km/h), then the system can differentiate between stationary and moving states, but the power consumption increases and interference risk increases

Engineering Contradiction:

Improvestate differentiation reliabilityVSAvoidbattery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic action by using the cyclic variations in magnetic field strength that occur during wheel rotation. The magnetic sensor detects periodic changes in the magnetic field as the wheel rotates, and these periodic signals are used to determine both the rotation state and the vehicle's movement state, enabling reliable detection at any speed without requiring high thresholds

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies dynamics by detecting the frequency and characteristics of magnetic field variations to dynamically determine vehicle state. The system analyzes the dynamic patterns of magnetic field changes - whether the wheel is rotating and whether the vehicle is moving - to provide reliable state differentiation without fixed speed thresholds, thereby reducing power consumption and interference risks

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If conventional displacement sensors are used, then vehicle state can be monitored, but the boundary value between stationary and moving states is determined only very approximately

Engineering Contradiction:

Improvestate boundary detection accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the detection function into two independent magnetic sensors: one mounted on the wheel hub to detect wheel rotation through magnetic field variations, and another mounted on the vehicle body to detect vehicle movement. This segmentation allows precise determination of both wheel state and vehicle state independently, providing accurate boundary detection between stationary and moving states without complex sensor systems

Inventive Principle:

Principle #1Segmentation

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 method provides quick, accurate, and cost-effective determination of vehicle state and wheel position, reducing power consumption and interference, while allowing for reliable speed calculation and low-cost implementation.

Implementation Method 1

measuring a signal at the terminals of the magnetic sensor so as to deliver a signal representative of the variations in the values of the magnetic field as detected by said magnetic sensor

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS7432851B2Method and device for determining the state of travel of a vehicle

Publication Date: 2008.10.07 CONTINENTAL AUTOMOTIVE FRANCE SAS

AI summary

A method and a device for determining the state of travel, whether stationary or moving along, of a vehicle. The method includes equipping at least one wheel (2) with a magnetic sensor (4) having an axis of maximum sensitivity, measuring a signal at the terminals of the magnetic sensor (4) so as to deliver a signal representative of the variations in the values of the magnetic field as detected by the magnetic sensor, and in providing either information that the vehicle is stationary if there are no variations in the signal delivered, or information that the vehicle is moving along when there is a cyclic variation in the signal.