A Personal Stress Evaluation and Relaxation System Based on Measurement of Photoplethysmography Signal

• Main Authors: Chiz-WeiLee, 李知瑋
• Other Authors: Ching-Hsing Luo
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/40196845306797765166

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 100 === World Health Organization (WHO) estimates that depression will be the number two cause of lost years of healthy life worldwide by the year 2020. Nowadays, people experience more nervous conditions than ever, including physical and mental aspects, and they would bring out pressure which might be accumulated if we do nothing to release it. Some people are used to relaxing themselves by listening to music or watching videos, and some choose aromatherapy to relieve stress. Till now most of the studies use questionnaires to judge the levels of the users’ relaxation condition, but it’s not objective because the result would be affected by the users’ subjectivities and grading strategies. As to estimating relaxation condition through physiology signal, most studies choose Electrocardiography (ECG), but the method of collecting ECG signals wouldn’t be convenient enough and its signal is electrical signal, which would make some users have misgivings of the safety as operating such devices. Even though there are numbers of ways to relax, but few people could measure easily the level of relaxation and the physiology influence that the various ways result in. This study designs a measure and analysis procedure which is easy to operate and the data could be analyzed rapidly. The system is designed to estimate the users’ regulation conditions of autonomic nervous system (ANS) through analyzing the users’ photoplethysmography (PPG) signals instead of ECG. The study also designs a new therapy of virtual relaxation to study whether different relaxation methods could be integrated or not and if the users’ reception would affect the relaxation results. Study result shows that subjects’ relaxation conditions could be estimated by analyzing their photoplethysmography (PPG) signals, and the average correlation coefficient between LF/HF and STAI questionnaire is 0.82, which represents highly positive relationship. The study integrates relative music, odors, and video to construct visual relaxation therapy, and the experiment results shows that subjects’ LF/HF drops 44%, which is higher than 32%, the result by music therapy. The experiment result also shows highly positive relationship between the subjects’ fondness and the result of the relaxation therapy. The correlation coefficient between fondness and short-term stress relaxation is 0.824, and that between fondness and long-term stress relaxation is 0.807. The study provides a new method to obtain subjects’ regulation conditions of ANS, and it not only improves the inconvenience of traditional ECG measurement, but resolves the subjectivity that questionnaires would bring out. We hope that the study would be helpful for future research about relaxation, thereby, people would be able to have their ANS conditions in hand and choose the most suitable method to relax, and finally develop a physically and mentally healthy life.