研究目的
To improve the accuracy of beat-to-beat peak detection in time domain for heart rate estimation from Photoplethysmography Imaging (PPGI) signals by developing an adaptive bandpass filter based on temporal spectrogram analysis.
研究成果
The proposed adaptive bandpass filter method significantly improves heart rate estimation accuracy for PPGI by reducing noise and interference through temporal spectrogram analysis. It outperforms state-of-the-art methods (spectrum-based, simple bandpass filter, Hilbert transform) across all tested PPGI algorithms (ICA, CHROM, 2SR, POS) and scenarios, particularly in motion-affected conditions. Future work should address light artefacts and evaluate in more application scenarios.
研究不足
The adaptive bandpass filter may not recover all pulse peaks if BVP signals are severely polluted or pulsatile components are badly smeared by artefacts. It is sensitive to noise influences on primary frequency estimation, especially with smaller window sizes. The method does not account for light artefacts in spectrogram analysis, and performance degrades in scenarios with strong head motions.
1:Experimental Design and Method Selection:
The study involves designing an adaptive bandpass filter that uses temporal spectrogram analysis of BVP signals with a sliding time window to determine adaptive cutoff frequencies. This is compared against existing methods like frequency spectrum peak detection, simple bandpass filtering, and Hilbert transform for heart rate estimation.
2:Sample Selection and Data Sources:
A database with RGB videos of 26 subjects (20 males, 6 females, aged 23-33) recorded in 4 scenarios (natural lighting, scale movement, translatory movement, writing) with each video lasting 2 minutes at 30 fps. Reference data from ECG and plethysmography using SomnoScreen plus.
3:List of Experimental Equipment and Materials:
RGB camera, monochrome camera, ECG sensor, plethysmography device (SomnoScreen plus), MATLAB software for implementation.
4:Experimental Procedures and Operational Workflow:
Extract raw RGB signals from regions of interest (e.g., forehead or cheek) using face alignment based on supervised descent method. Apply PPGI algorithms (ICA, CHROM, 2SR, POS) to derive BVP signals. Process BVP signals with the adaptive bandpass filter (window size L=30s for primary frequency estimation, FFT window l=5s, bandwidth Δf=0.8Hz) and compare heart rate estimation methods (spectrum-based, bandpass filter, Hilbert transform, adaptive bandpass filter) using a sliding window of 30s.
5:8Hz) and compare heart rate estimation methods (spectrum-based, bandpass filter, Hilbert transform, adaptive bandpass filter) using a sliding window of 30s.
Data Analysis Methods:
5. Data Analysis Methods: Use Area under Curve (AUC) metric to evaluate percentage of heart rate estimates within error tolerance [0,5] bpm. Perform correlation analysis between estimated and reference heart rates.
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