Representative PPG Waveform Extraction Under Arrhythmia and Motion Noise
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Solution Overview
Problem
Existing bio-signal estimation methods, particularly for blood pressure estimation using PPG signals, suffer from reduced accuracy due to arrhythmia and motion noise, leading to degraded signal quality.
Innovation Solution
A method and apparatus for extracting a representative waveform of a bio-signal by dividing the signal into sub-signals, selecting and overlapping them based on reference points, applying weights, and iteratively adjusting these weights to ensure the quality of the representative waveform meets predetermined criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PPG signals are used directly for blood pressure estimation, then the process is simple, but the accuracy is reduced due to arrhythmia and motion noise
Solution Approach 1:
The PPG signal is divided into multiple sub-signals based on heartbeat cycles. Each sub-signal corresponds to a specific heartbeat period, allowing individual quality assessment and selective processing. This segmentation enables the system to isolate and process only high-quality segments, improving overall measurement accuracy while managing complexity through modular processing.
Solution Approach 2:
The patent applies weight coefficients to different sub-signals based on their quality metrics. By dynamically adjusting these weight parameters according to signal quality (e.g., assigning higher weights to sub-signals with clearer waveform characteristics and lower noise), the system optimizes the representative waveform construction to maximize blood pressure estimation accuracy.
2Reliability
If all sub-signals are processed to create a representative waveform, then completeness is improved, but processing time and computational load increase
Solution Approach 1:
The patent extracts and selects only high-quality sub-signals that meet predetermined quality criteria for constructing the representative waveform. Low-quality sub-signals contaminated by motion noise or arrhythmia are excluded from processing. This selective extraction maintains waveform reliability while significantly reducing the number of sub-signals that require computational processing.
Solution Approach 2:
Instead of processing all available sub-signals equally, the patent applies partial processing by focusing computational resources only on the most valuable high-quality sub-signals. The system processes a subset of sub-signals with weights greater than zero, rather than uniformly processing the entire set, thereby reducing computational load while maintaining or improving representative waveform quality.
3Measurement precision
If weight adjustment iterations are performed to optimize the representative waveform, then accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent implements an iterative weight adjustment process where the representative waveform is evaluated against quality metrics, and weight coefficients are adjusted based on feedback from this evaluation. The system compares the representative waveform characteristics with expected physiological patterns and refines weights accordingly. This feedback mechanism systematically improves accuracy by learning from each iteration's results.
Solution Approach 2:
The patent performs preliminary quality assessment of sub-signals before the iterative weight adjustment process. By pre-identifying high-quality sub-signals and assigning initial weights based on their quality metrics, the system reduces the search space for optimization. This preliminary action prepares the data structure and initial parameters, making the subsequent iterative refinement more efficient and less computationally intensive.
Data Source
AI summary
A method of extracting a representative waveform of a bio-signal includes receiving an input of the bio-signal; dividing the bio-signal into a plurality of sub-signals; selecting at least one sub-signal for extracting a representative waveform from among the divided sub-signals; extracting a representative waveform by using the at least one selected sub-signal; evaluating a quality of the extracted representative waveform; and based on the representative waveform satisfying a predetermined quality criterion corresponding to the evaluation, determining that the representative waveform is a final representative waveform.