PPG Heart Rate Detection With Frequency Domain Motion Artifact Removal
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Solution Overview
Problem
Conventional heart rate estimation using photoplethysmography (PPG) is compromised by motion artifacts from wearable devices, leading to degraded signal quality and reduced accuracy.
Innovation Solution
A method that involves receiving PPG and acceleration signals, converting them into frequency domain signals, calculating the difference between the two signals to remove motion artifacts, and estimating heart rate based on the cleaned PPG signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PPG signal is used for heart rate detection, then heart rate can be measured non-invasively, but motion artifacts degrade signal quality and reduce measurement accuracy
Solution Approach 1:
The PPG signal is segmented into multiple sections, and the amplitude variation across these segments is analyzed to identify and remove motion artifact components. This segmentation allows differentiation between genuine physiological signals and motion-induced noise.
Solution Approach 2:
An intermediary processing step is introduced that calculates amplitude variations across signal segments and uses this information to construct a corrected PPG signal. This intermediary analysis acts as a mediator between the raw contaminated signal and the final clean signal used for heart rate detection.
2Measurement precision
If conventional PPG processing is used, then processing complexity is low, but heart rate estimation accuracy is reduced due to motion artifact
Solution Approach 1:
The method performs preliminary analysis of amplitude variation across signal segments before final heart rate detection. This preliminary action identifies motion artifact characteristics in advance, allowing the subsequent processing to focus specifically on removing these identified artifacts rather than applying complex general-purpose filtering.
Solution Approach 2:
The method changes the analysis parameter from direct frequency domain analysis to amplitude variation analysis across time segments. This parameter change simplifies the processing by using a more direct measure that naturally separates motion artifact from physiological signal without requiring complex spectral analysis.
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 enables accurate heart rate measurement by eliminating motion artifacts, thereby improving the quality and reliability of heart rate estimation.
Implementation Method 1
Photoplethysmography (PPG) is one method of detecting a heart rate by detecting changes of a blood flow rate using light. In PPG, light (infrared or red light) passes through a finger or earlobe, and then an amount of reflected or transmitted light is measured using a light-receiving sensor.
Implementation Method 2
a PPG signal and an acceleration signal from a wearable device
Data Source
AI summary
A method of detecting a heart rate using a photoplethysmography (PPG) signal with a removed motion artifact includes receiving, by a heart rate measurement device, a PPG signal and an acceleration signal; converting, by the heart rate measurement device, the PPG signal and the acceleration signal into signals in a frequency domain; calculating, by the heart rate measurement device, a difference between the PPG signal and the acceleration signal in the frequency domain and obtaining a PPG signal with a removed motion artifact; and estimating, by the heart rate measurement device, a heart rate based on the PPG signal with the removed motion artifact.