Year: 2016
Type: dissertation
Abstract: This bachelor thesis proposes a solution on how to reduce motion artifacts in photoplethysmographic (PPG) signals and therefore make the retrieving of the heartbeat more accurate.This can be used to further improve the accuracy of wearable sport tracking devices and smartwatches.The recording of the PPG signals was done with two Infra-Red light emitting diodes and two sensors that measured the changes in the blood volume.Since the measurements were done at the wrist, the PPG signal is corrupted with motion artifacts.In this thesis different techniques are used to filter these motion artifacts out of the PPG signal.The two types of adaptive filters that were tested were the Least Mean Squares and Recursive Least Squares filters.They were tested on 12 different data sets containing data from different test subjects running at various speeds.The results show that between these two filters the least mean squares filter with spectral peak tracking produces the best results.The system achieves a mean absolute error of 1.66 and has a computation time of 42 seconds over all the data sets.The Sports Motion Artifact Removal Technique (SMART) was presented as a combination of multiple techniques and provides the overall best results with a mean absolute error of 1.42 and a computation time of 37 seconds.Since the measurements of the sport devices needs to be real time, a low computation time is important and SMART provides a robust and fast solution.v Abbreviations • ANC -Adaptive Noise Cancellation • BPM -Beats per Minute • ECG -Electrocardiography • FFT -Fast Fourier Transform • GW RLS -Growing Window RLS • HR -Heart Rate • Hz -Hertz • IR -Infrared • LED -Light Emitting Diode • LMS -Least Mean Squares • MA -Motion Artifact • MAE -Mean Absolute Error • NLMS -Normalised Least Mean Squares • PPG -Photoplethysmography • PSD -Power Spectral Density • RLS -Recursive Least Squares • SNR -Signal-to-Noise ratio • SpO2 -Peripheral capillary oxygen saturation • SPT -Spectral Peak Tracking • SSA -Signal Decomposition • SSR -Sparse Signal reconstruction vii 1
Authors: Generowicz, B. (author), Wesdijk, X. (author)
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2612372297