IMU Door Monitoring for Accurate Domestic Appliance Angle Control

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Solution Overview

Problem

Conventional systems for detecting the opening angle of domestic appliance doors face accuracy issues due to sensor placement near high-temperature areas and complexity, making it difficult to precisely control the opening and closing speed and angle.

Innovation Solution

A monitoring system utilizing an inertial measurement unit (IMU) with a combination of accelerometers and gyroscopes, arranged at a maximum distance from the hinge axis and in low-temperature areas, such as within the door handle or front panel, to accurately determine the door's angle, angular speed, and angular acceleration, and control its movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If sensors are arranged at the door hinge or close to the door hinge to detect opening angle, then the detection system can be compactly integrated, but it becomes difficult to detect exactly the opening angle of the door

Engineering Contradiction:
Improvesensor integrationVSAvoidopening angle detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The sensor is extracted from the door hinge area and relocated to the door handle area, which is at maximum distance from the hinge axis. This extraction resolves the contradiction by separating the sensor from the problematic hinge region while maintaining compact integration within the door handle structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The solution transitions from measuring door angle directly at the hinge (one-dimensional rotation point) to measuring at the door handle (extended radial dimension). By utilizing the maximum radial distance from the hinge axis, the system achieves better angular resolution through dimensional leverage.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If sensors are arranged in positions close to the door hinge, then the system structure can be simplified, but the temperature in those positions is very high which impairs the accuracy of the sensor

Engineering Contradiction:
Improvesystem structureVSAvoidsensor accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The sensor is extracted from the high-temperature region near the door hinge and relocated to the door handle area, which is thermally isolated from the heating elements. This extraction simultaneously simplifies the system structure by maintaining compact integration while eliminating thermal interference.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The solution applies local quality by selecting a specific location (door handle) with favorable thermal characteristics. The door handle area provides a local environment with lower temperature and stable thermal conditions, creating an optimal measurement zone within the door structure.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If the door sensor is arranged at a maximum distance from the hinge axis, then the measuring accuracy is improved, but the sensor placement becomes more constrained

Engineering Contradiction:
Improvemeasuring accuracyVSAvoidsensor placement flexibility
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The door handle structure is designed to serve multiple functions: it provides the user interface for door operation, structural support, and now also houses the door sensor. This multi-functionality resolves the contradiction by making the door handle the universal mounting location that satisfies both the maximum distance requirement for accuracy and the manufacturing constraints.

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

This solution provides improved accuracy and reduced complexity in detecting the door's state, allowing for precise control of the door's movement, avoiding measurement errors caused by high temperatures and mechanical tolerances, and enabling efficient automatic or manual operation.

Implementation Method 1

The door sensor (22) is an inertial sensor. In this example, the door sensor (22) is an inertial measurement unit (IMU), wherein said inertial measurement unit includes at least one accelerometer and at least one gyroscope. The accelerometer is provided for detecting a linear acceleration of the door sensor (22).

Methodology Applied
Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

The gyroscope is provided for detecting a rotational speed of the door sensor (22).

Methodology Applied
Scientific EffectGyroscope: Gyroscope

Data Source

PatentEP3633271B1Domestic appliance comprising a monitoring sytem for the door
Publication Date: 2022.12.21 ELECTROLUX APPLIANCES
  • EP3633271B1 patent drawingFigure 1
  • EP3633271B1 patent drawingFigure 2
  • EP3633271B1 patent drawingFigure 3

AI summary

The present invention relates to a monitoring system for a door (12) of a domestic appliance (10). The monitoring system comprises at least one door sensor (22; 24, 26, 28; 30, 32) arrangeable or arranged at or within the door (12). The door sensor (22; 24, 26, 28; 30, 32) is an inertial measurement unit (IMU) including at least one accelerometer and/or at least one gyroscope. The accelerometer can be provided for detecting a linear acceleration of the door sensor (22; 24, 26, 28; 30, 32). The gyroscope can be provided for detecting a rotational speed of the door sensor (22; 24, 26, 28; 30, 32). The monitoring system determines at least one of the angle (α,α'), the angular speed and the angular acceleration of the door (12).