Personal Care Device Position Tracking With Skin Contact Sensing

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Solution Overview

Problem

Existing personal care devices lack the accuracy in determining their location on a body part during operations, necessitating improvements for better performance monitoring and user guidance.

Innovation Solution

A personal care device equipped with an orientation sensor to measure 3D angular orientation relative to Earth's gravity, a surface-displacement sensor for 2D displacement relative to the skin surface, and a processing unit to determine location based on these measurements and a skin contact signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only orientation sensors and movement sensors are used to determine device location, then the device can determine its position on the body part, but the accuracy of location determination is insufficient

Engineering Contradiction:
Improvelocation determination accuracyVSAvoidmissing skin contact information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent combines multiple sensing modalities (orientation sensors, movement sensors, and skin contact sensors) into a unified location determination system. The skin contact sensor signal is merged with orientation and displacement data to create a more accurate location estimate, resolving the contradiction by integrating previously separate information sources.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The skin contact sensor acts as an intermediary that provides critical contact information to the location determination algorithm. This intermediary signal bridges the gap between device motion data and actual skin contact status, enabling more precise location determination than motion sensors alone could achieve.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple sensors are added to improve location accuracy, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improvelocation determination accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The skin contact sensor serves multiple functions: it detects skin contact status, provides feedback for location determination accuracy, and enables the system to distinguish between device movement and body part movement. This multi-functionality justifies the added sensor complexity by delivering multiple benefits from a single component.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The skin contact sensor provides real-time feedback to the location determination algorithm, allowing the system to adjust its calculations based on actual contact conditions. This feedback loop improves measurement precision by enabling dynamic adaptation to varying contact scenarios, making the additional sensor complexity worthwhile.

Inventive Principle:
Principle #23Feedback

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

Enhances the accuracy of determining the device's location on the body part, enabling improved performance monitoring and user guidance during personal care operations.

Implementation Method 1

an orientation sensor configured to measure a three-dimensional, 3D, angular orientation of the personal care device relative to Earth's gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4551367B1Personal care device and method for determining a location of the personal care device on a body part
Publication Date: 2026.02.18 KONINKLIJKE PHILIPS NV
  • EP4551367B1 patent drawingFigure 1
  • EP4551367B1 patent drawingFigure 2
  • EP4551367B1 patent drawingFigure 3

AI summary

According to an aspect, there is provided a personal care device (2) for performing a personal care operation on a subject, the personal care device (2) being configured to determine a location of the personal care device (2) on a body part of the subject. The personal care device (2) comprises an orientation sensor (6) configured to measure a three-dimensional, 3D, angular orientation of the personal care device (2) relative to Earth's gravity over time and output a corresponding orientation measurement signal; a surface-displacement sensor (10) configured to measure a two-dimensional, 2D, displacement of the personal care device (2) relative to a skin surface of the body part and output a corresponding surface- displacement measurement signal; a processing unit (22) configured to determine the location of the personal care device (2) on the body part based on the orientation measurement signal, the surface- displacement measurement signal and a skin contact signal indicating whether the personal care device (2) is in contact with the skin surface of the body part.