Magnetic Field Sensor Wheel Rotation Detection

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Solution Overview

Problem

Existing methods for detecting the direction of rotation and speed of a two-wheeler's wheel, such as magnetic sensors and acceleration sensors, face challenges like imprecision in slow movements, energy consumption, and inability to differentiate between forward and reverse travel.

Innovation Solution

A method using a magnetic field sensor coupled to the two-wheeler's frame, detecting changes in magnetic field components to determine the direction of rotation by comparing initial and subsequent magnetic field sensor signals, allowing for the derivation of wheel direction and speed with minimal rotation and energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic wheel speed sensors are used to detect rotation, then speed measurement is achieved, but detection precision deteriorates for very slow rotary movements

Engineering Contradiction:
Improvedetection precisionVSAvoidrotational speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The system performs a learning phase before normal operation where it records magnetic field sensor signals during a known preferred direction of travel (forward direction). This preliminary action creates a reference data set that enables precise detection during subsequent operations, including very slow movements where traditional pulse-based methods fail.

Inventive Principle:
Principle #10Preliminary action

2Loss of information

If traditional magnetic sensors are used, then speed detection is achieved, but the ability to differentiate forward and reverse travel is lost

Engineering Contradiction:
Improvedirection informationVSAvoidsensor system complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The system records magnetic field sensor signals during a learning phase when the preferred direction of travel is known, storing this reference data for later comparison. This preliminary action enables the system to determine direction of travel during normal operation by comparing current signals against the stored reference, thereby recovering direction information without adding complex sensor hardware.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback by comparing current magnetic field sensor signals against previously stored reference signals from the learning phase. This comparison provides feedback that enables determination of both speed and direction of travel, transforming a unidirectional detection system into a bidirectional detection system through intelligent signal processing.

Inventive Principle:
Principle #23Feedback

3Loss of information

If acceleration sensors are used to detect direction, then direction of movement can be determined, but energy consumption increases

Engineering Contradiction:
Improvedirection informationVSAvoidenergy consumption
Core Design Contradiction:
Loss of informationVSUse of energy by moving object

Solution Approach 1:

The system replaces acceleration sensors (mechanical/physical measurement devices that consume energy) with a magnetic field sensor combined with a learning-phase-based computational approach. This substitution uses magnetic field detection and signal processing instead of physical acceleration measurement, significantly reducing energy consumption while maintaining the ability to determine direction of travel.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If at least two pulses are required for speed detection, then speed can be calculated, but detection time increases

Engineering Contradiction:
Improvedetection speedVSAvoiddetection time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary recording of magnetic field sensor signals during a learning phase, storing reference data that enables immediate speed and direction determination during normal operation. This preliminary action eliminates the need to wait for multiple pulses during actual measurement, allowing faster detection response.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system introduces an intermediary reference data set recorded during the learning phase, which serves as a mediator between the magnetic field sensor and the speed calculation process. This intermediary enables direct comparison and immediate determination of speed and direction without requiring multiple measurement pulses, thereby reducing detection time.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables precise and efficient detection of wheel direction and speed, reducing energy usage and eliminating ambiguity between forward and reverse travel, facilitating control and navigation systems.

Implementation Method 1

a magnetic field sensor is coupled to the frame of the two-wheeler... first magnetic field sensor signals are recorded, which represent the movement of the magnet on the moving or rotating wheel

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP3435096B1Method and device for detecting the rotational direction of a wheel
Publication Date: 2023.08.09 ROBERT BOSCH GMBH
  • EP3435096B1 patent drawingFigure 1a~1b
  • EP3435096B1 patent drawingFigure 2~3
  • EP3435096B1 patent drawingFigure 4a~4b

AI summary

The invention, with the features of the independent claims, claims a method and a device for determining the direction of rotation of a wheel on a two-wheeler, as well as a two-wheeler that performs such a method, for example, in a computing unit or the device. For this purpose, it is provided that a magnetic field sensor is arranged on the two-wheeler, e.g., on or in the frame or on a frame-adjacent two-wheeler component. Furthermore, it is provided that the wheel whose direction of rotation is to be determined has a magnet, e.g., in or on the tire casing or on or in the rim. To carry out the method according to the invention or to use the device according to the invention, information about the direction of movement of the two-wheeler is first acquired. Subsequently, during a learning phase, depending on the knowledge of the direction of movement of the two-wheeler, initial magnetic field sensor signals are acquired, which indicate the movement of the magnet on the moving or...The first signal represents a rotating wheel. At a later point, second magnetic field sensor signals can be acquired, independent of the initial information about the wheel's direction of movement. By comparing the first and second magnetic field sensor signals, information about the wheel's direction of rotation can be obtained. This information can then be made available to other systems. The magnetic field sensor signal must exhibit a different waveform depending on the direction of movement.