Door and Window State Detection Under Magnetic Field Distortion

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Solution Overview

Problem

Existing door and window detection methods based on angular velocity data suffer from increasing deviation over time, while magnetometer-based methods are unreliable due to magnetic field distortions in real environments.

Innovation Solution

A method and device that first detect magnetic field distortion and use magnetometer data only when stability is ensured, combining it with angular velocity and acceleration data to determine the state of doors or windows, and update initial angles to reduce errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If detection is performed based on magnetometer data, then the state detection can be simplified, but the accuracy deteriorates due to magnetic field distortion in real environments

Engineering Contradiction:

Improvedetection method complexityVSAvoidstate detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent dynamically selects between magnetometer-based detection and angular velocity-based detection based on real-time assessment of magnetic field stability. When magnetic field distortion is detected, the system switches to angular velocity integration; when stable, it uses magnetometer data. This dynamic adaptation resolves the contradiction by making the detection method flexible rather than fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the detection parameter from purely magnetometer-based to a conditional hybrid approach. By introducing a stability judgment mechanism that monitors magnetic field characteristics, the system adjusts which parameter (magnetometer data or angular velocity data) is used for state determination, thereby maintaining accuracy across varying environmental conditions.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If detection is performed based on angular velocity data, then the detection can be performed without magnetic stability requirements, but the accuracy deteriorates due to cumulative deviation in integrated opening angle

Engineering Contradiction:

Improveenvironmental adaptabilityVSAvoidopening angle calculation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the system continuously monitors magnetic field stability and uses this information to control the selection of detection methodology. The stability judgment unit provides feedback about environmental conditions, and based on this feedback, the system adjusts its detection approach—using angular velocity integration only when magnetic instability is detected, otherwise preferring magnetometer data for higher accuracy.

Inventive Principle:

Principle #23Feedback

3Device complexity

If the system always uses magnetometer data for detection, then the device complexity is reduced, but reliability deteriorates in environments with magnetic field distortion

Engineering Contradiction:

Improvedetection system complexityVSAvoiddetection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent performs preliminary assessment of magnetic field stability before executing the state detection. The stability judgment unit evaluates the magnetic environment in advance, and based on this preliminary assessment, the system pre-selects the appropriate detection method. This preliminary action ensures that the reliable detection path is chosen before actual measurement, preventing reliability issues from arising.

Inventive Principle:

Principle #10Preliminary action

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 approach enhances detection accuracy by ensuring reliable magnetometer data usage and correcting for angular velocity deviations, providing precise door or window state determination.

Implementation Method 1

receiving sensor data from a sensor arranged on the door or window, the sensor data comprising magnetometer data

Methodology Applied

Scientific EffectMagnetic field detection: Magnetometer

Implementation Method 2

angular velocity data measured by an angular velocity sensor generally includes deviation which will increase with time, possibly resulting in deviation of the calculated opening angle from the actual value

Methodology Applied

Scientific EffectAngular velocity measurement:

Implementation Method 3

sensor data comprising magnetometer data and at least one of angular velocity data and acceleration data

Methodology Applied

Scientific EffectAcceleration measurement: Accelerometer

Data Source

PatentUS12625158B2Method and device for detecting state of door or window

Publication Date: 2026.05.12 ROBERT BOSCH GMBH

AI summary

A method for detecting a state of a door or window is provided, comprising: receiving sensor data from a sensor arranged on the door or window, the sensor data comprising magnetometer data and at least one of angular velocity data and acceleration data; judging whether magnetic field distortion is present on the basis of the sensor data; and when it is judged that the magnetic field distortion is not present, determining the state of the door or window on the basis of the magnetometer data. The accuracy of state detection is thereby increased.