Adaptive PPG Motion Artifact Filtering Using Acceleration Data

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Solution Overview

Problem

Existing methods for filtering pulse signal motion interference in photoplethysmography (PPG) signals require large amounts of data, complex calculations, multiple PPG sensors, are limited to static measurements, and only allow post-processing, failing to effectively address motion artifacts in real-time heart rate monitoring.

Innovation Solution

A method and apparatus that uses a green light source to acquire pulse signals in real-time, preprocesses the signals with an infinite impulse response filter to remove baseline data and high-frequency noise, and adaptively filters motion artifacts using acceleration data to improve signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing methods for filtering pulse signal motion interference are used, then motion artifact reduction is achieved, but the methods require large amounts of data, complex calculations, multiple PPG sensors, are limited to static measurements, and only allow post-processing

Engineering Contradiction:
Improveheart rate estimation performanceVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes motion artifact components from the PPG signal through adaptive filtering techniques. The motion artifact is separated from the pulse signal by identifying and eliminating the specific interference components, achieving motion artifact reduction without requiring complex multi-sensor systems or large amounts of training data

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an adaptive filter as an intermediary component between the PPG signal acquisition and heart rate estimation. This filter acts as a mediator that processes the raw signal in real-time, removing motion artifacts while preserving the physiological information needed for accurate heart rate measurement

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If existing filtering methods are applied, then motion interference is reduced, but real-time processing capability is lost due to post-processing only approach

Engineering Contradiction:
Improvesignal qualityVSAvoidprocessing speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent performs motion artifact filtering as a preliminary action during signal acquisition rather than as a post-processing step. The adaptive filter operates in real-time on the incoming PPG signal, removing motion artifacts before heart rate estimation is performed, thus enabling both real-time processing and high signal quality

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical multi-sensor systems with a simplified signal processing approach using adaptive filtering. Instead of using multiple PPG sensors and complex hardware configurations, the invention uses computational methods to achieve the same motion artifact reduction effect with a single sensor and real-time processing

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

3Measurement precision

If multiple PPG sensors are used to reduce motion artifact, then measurement accuracy improves, but device complexity and cost increase

Engineering Contradiction:
Improvepulse signal accuracyVSAvoidnumber of sensors
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent creates a computational model or reference signal that represents the motion artifact component. Instead of using multiple physical sensors to capture different aspects of the signal, the invention uses adaptive filtering to create and remove a copy of the motion artifact based on the relationship between acceleration data and PPG signal variations

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent changes the approach from hardware-based multi-sensor solutions to software-based adaptive filtering with varying filter parameters. The filter adapts its parameters in real-time based on the characteristics of the incoming signal and acceleration data, achieving high measurement precision with a single sensor by dynamically adjusting processing parameters

Inventive Principle:
Principle #35Parameter changes

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 the accuracy and reliability of heart rate measurements by effectively filtering motion interference in real-time without extensive data or multiple sensors, simplifying calculations, and improving the signal-to-noise ratio.

Implementation Method 1

The photoplethysmography (PPG) signal is mostly used for heart rate (HR) monitoring and is a key technology for many existing wearable products and clinical devices. In order to obtain this signal, LEDs are used to illuminate the human skin, and then a photodiode is used to measure the change in the intensity of reflected light caused by a blood flow.

Methodology Applied
Scientific EffectPhotoplethysmography: Photoelectric Effect

Implementation Method 2

preprocessing the acquired pulse signal; and adaptively filtering the preprocessed pulse signal based on acceleration data of the target human body acquired in real time

Methodology Applied
Scientific EffectInfinite impulse response filtering: Filter (electronic)

Implementation Method 3

a method that introduces motion information of a motion sensor as a noise signal source

Methodology Applied
Scientific EffectAcceleration detection: Accelerometer

Data Source

PatentEP4388994B1Method, apparatus and system for filtering pulse signal motion interference
Publication Date: 2026.02.04 KINGFAR INTERNATIONAL INC
  • EP4388994B1 patent drawingFigure 1~2A
  • EP4388994B1 patent drawingFigure 2B~3B
  • EP4388994B1 patent drawingFigure 3C~4

AI summary

The present disclosure provides a method, an apparatus and a system for filtering pulse signal motion interference. The method comprises: irradiating a skin of a target human body in motion with a green light source in real time, so as to acquire a corresponding pulse signal from the target human body in real time; preprocessing the acquired pulse signal; and adaptively filtering the preprocessed pulse signal based on acceleration data of the target human body acquired in real time, so as to filter out a motion artifact interference of the pulse signal. The present disclosure can effectively improve the accuracy and effectiveness of filtering the pulse signal motion interference of a person in motion without a large amount of data, with a simple calculation process and without a plurality of PPG sensors, and can effectively improve the real-time performance for filtering the pulse signal motion interference, thereby greatly improving the accuracy and reliability of the heart rate measurement performed based on the pulse signal with the motion interference filtered out.