The Research Of Visual Fatigue Estimated Method Based On ECG And Pulse Signal

VDT(Visual Display Terminal)operation is a new work form accompanied by the popularization of computers. As continuously improving of the society information, VDT operation has became the most representative work in modern work. The form of VDT operation and the effect on operators in physical and psychological is different from the traditional office and shop floor operations, which improve the production efficiency, also do tremendous harm in human health at the same times, it is that causing visual fatigue, leading to other eye disease further. Questionnaire survey is the main methods to diagnose and estimate visual fatigue at home and abroad at present, there is not an objective evaluation method can quantify the impact of visual fatigue on human effectively. The traditional research method of psychological signal is irrelevant in time,and detect biological system separate.one single signal is analyzed and processed respectively, for example ECG and pulse signal, two or numbers of relational biomedical signals are analyzed and processed at the same time is one kind of very promising method. This paper proceed from simultaneous analysis of two, through investigating the impact on human physiological signals of fatigue,present a method estimating visual fatigue based on ECG and pulse signals. Mainly contents researched as following:1) The relationship between visual fatigue and ECG,pulse signal is demonstrated, and the result show that the method authenticating visual fatigue state based on the information contained by ECG and pulse signal is feasible.2) A LabVIEW-based data collection platform is developed with MP425 data acquisition card and acquisition peripheral circuit, with which pulse and ECG signals is acquired synchronously. Simulate VDT operating environment, the visual fatigue experiment is designed in the study of student-volunteers, and then experimental data is acquired before and after visual fatigue.3) Comparing the result of a variety of filtering method, Notch filtering method is selected to eliminate the 50 Hz interference of ECG and pulse signal and the zero-phase filter is used to remove the baseline drift, wavelet transformation is used to eliminate noise, and then a reliable source of data is provided for feature points extracting.4) Teager Energy Operator is used to detect QRS wave of ECG signal, and ECG feature is extracted.For the pulse wave signal is distorted seriously and the signal characteristics is not obvious after visual fatigue, use the synchronization relationship of ECG and pulse in time domain, a new way that use the ECG signal's T and R wave to locate the pulse peek and dicrotic wave of pulse is proposed, After analyzing and experimental verification, It has strong interference-free ability, The positions of pulse peek and dicrotic wave can be exactly determined by adopting this method。The significance level P<0.01 of each feature information detected by T test.5) The results show that the ECG and pulse signal characteristics change significantly before and after visual fatigue experiment by comparing signal characteristics, the accuracy rate of classification is reached 100% by using Support Vector Machine and combination features of ECG and pulse wave signals, surpass the accuracy rate classified by one kind of biomedical signal.The results of experimental show that electrocardiogram(ECG)and pulse signal in human body contain health information and the method by extracting the information feature from these signals to identify the visual fatigue state is feasible and promising.