Fatigue Detection System Based On Photoplethysmography

Fatigue,as a ubiquitous mental state,is often overlooked in the daily life and work,which may bring about different degrees of negative effects.In order to minimize these negative effects caused by fatigue,finding effective fatigue detection methods has become a hot topic in this field.Among these methods,fatigue detection based on bioelectrical signals has been proved to be an effective solution.There have been a large number of studies about fatigue detection based on electroencephalogram(EEG),electrocardiographic(ECG),electrooculogram(EOG),myoelectric(EMG)or fusions of hybrid biopotentials.Considerable progresses have been made.However,since the acquisition of these biopotentials requires a large number of electrodes and the signals are complex and not fit for practical applications,a novel fatigue detection method needs to be explored.This paper proposed a fatigue detection technology based on photoplethysmography(PPG).These work includes the following three parts:(1)An acquisition module of photovoltaic pulse wave based on an analog-to-digital conversion chip(ADS1292)was built.In order to prove veracity,data used for processing and fatigue detection were converted by a professional high-precision analog-to-digital conversion chip,and transmitted to the host computer using Bluetooth wirelessly.(2)The fatigue detection technology based on PPG was studied.The raw signals were preprocessed by the digital filters,which can improve the signal-to-noise ratio.Then,we extracted features by a revised algorithms.The importance of these features was ranked according to the feature selection algorithm.Finally,support vector machine(SVM)and neural network(NN)classified these features,the results showed that for single-subject analysis,the mean classification accuracy can reach 96.33% and 94.91% for fatigue detection and vigilance,respectively.(3)Based on the above researches,the smart phone was used as an algorithm operating platform to detect fatigue,the elementary fatigue detection system based on the PPG signals was combined the smart phone with a pulse wave acquisition module.