基于实时脉搏信号处理的VDT视疲劳状态识别研究
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摘要
随着VDT (Visual Display Terminal)广泛应用于各个领域,它给人们带来方便和高效率的同时也产生了一些新的职业卫生问题,比如与VDT相关的视觉疲劳、精神疲劳和肌体疲劳等,在医学上称为VDT综合征或计算机视觉征候群。本课题即是基于此现状,寻找一种实时、客观的评测VDT视疲劳的方法。
脉搏信号是一种生理信号,蕴含着丰富的人体生理、病理信息,反映了身体各子系统的生理状态变化,通过对脉搏波信号的分析处理有望获取反映人体健康状态的特征参数。本文采用简便、易用的光电式指端脉搏传感器,通过对指端脉搏波信号的实时处理和分析,提取了诊断和评测VDT视疲劳状态的客观参数。在检测视疲劳上找到了一种低复杂度计算和具有良好性能的方法,有望以后用于VDT作业者视疲劳的实时监护。
首先从国内外研究现状分析了VDT视疲劳研究存在的问题,并论证基于生理信号研究VDT视疲劳的可行性,找到了能实时、客观的评测VDT视疲劳的方法,有望以后在临床上实现实时监护。
从生理学和人体工效学的角度对VDT视疲劳的产生原因以及影响因素进行了简要概述。简要介绍了脉搏波信号的基础知识。同时从理论上论证脉搏信号与视疲劳之间的关系,表明本课题研究的可行性。
介绍了自主研发的脉搏波信号采集系统和设计的VDT视疲劳实验。从VDT视疲劳的简介知道,影响VDT视疲劳的因素很多,所以在VDT视觉疲劳实验设计上也尽量减弱、减少或去除其它因素对实验的干扰。本实验通过主观疲劳症状问卷调查结果和闪光融合频率(Critical Flicker Fusion Frequency, CFF)的变化情况表明被试者VDT实验后均处于视疲劳状态。
对采集到的指端脉搏波信号进行处理和分析。本课题采用简单整系数滤波器对信号进行预处理,此滤波器实时、有效而且具有低复杂度计算,便于以后在硬件上实现,简单整系数滤波器很理想的满足了实验要求。基于实时考虑分别从时域和频域提取特征：波形高度和幅度谱峰值。这俩特征视疲劳后都下降非常显著(P<0.001),分类正确率都达到94.59%,体温下降显著(P<0.01),说明视疲劳后脉搏信号的能量降低。基于脉搏周期进行散点图分析,发现SD1：短时心率变异程度和SD2：长时心率变异程度变化均不显著,而SD1/SD2下降显著(P<0.05)。
VDT (Visual Display Terminal) has become ubiquitous in various fields. However, while bringing numerous benefits, this technology is accompanied by work-related health disorders, including visual fatigue, musculoskeletal discomfort, and mental fatigue, which are collectively referred to as VDT Syndrome or Computer Vision Syndrome in medical science. In this paper, I intend to propose an objective and real-time detection method for evaluating VDT visual fatigue.
Pulse signals are a kind of physiological signals containing abundant human physiological and pathology information which reflects various physical and physiological changes in subsystems of human body. It may be desirable that analysis of these pulse signals can help us obtain information which will reveal the health condition. In this thesis, simple and easily used photoelectric finger pulse sensor is applied to making a real-time analysis on finger pulse wave signals in order to obtain the objective parameters used as the diagnosis and evaluation of VDT. Meanwhile, we apply photoplethysmography (PPG) to fatigue detection, which is a method of low computational complexity and good performance and is expected to be used in real-time inspection of the visual fatigue of VDT workers.
This paper analyzes problems existing in studies about VDT visual fatigue based on researches at home and abroad and confirms the feasibility of carrying out VDT visual fatigue research through studying physiological signals, providing a real-time and objective detection method for evaluating VDT visual fatigue which is expected to be adopted in clinical healthcare.
This paper also gives a brief summary of reasons for and influencing factors in VDT visual fatigue from the perspective of Physiology and Ergonomics. Meanwhile, basic information about pulse signals is introduced, and the paper provides a theoretical confirmation of the connection between pulse signal and visual fatigue, demonstrating the feasibility of this subject.
We design an electrophysiological data acquisition system and the VDT visual fatigue experiments. According to the brief introduction to VDT visual fatigue, we know that there are lots of factors influencing VDT visual fatigue; therefore, in designing VDT visual fatigue experiments, we try to reduce or remove factors that may disturb the experiments. The fatigue assessment questionnaire and critical flicker fusion frequency (CFF) counter have both shown that all subjects participating in VDT experiments experience visual fatigue.
Pulse signals are processed. In pre-processing signals, simple integer coefficient filters are adopted. This filter not only works effectively in real time but also has low computational complexity and is expected to be implemented in hardware. Simple integer coefficient filter meets our requirements ideally. The pulse signals are analyzed both in time domain and frequency domain, and physiological features like waveform height and magnitude spectrum peaks are obtained. The results have shown that the peak-to-trough amplitudes and magnitude spectrum peaks all significantly decrease in visual fatigue (P<0.001) and classification accuracy reaches 94.59%. There is also remarkable decrease in body temperature (P<0.01). All the above information indicates that the strength of pulse signals decrease after visual fatigue. Based on pulse-to-pulse interval, we analyze the Poincare plot and find that there are no significant changes in the SD1 and SD2. However, the SD1/SD2 have obviously decreased after fatigue compared to that before fatigue (P<0.05).
脉搏信号是一种生理信号,蕴含着丰富的人体生理、病理信息,反映了身体各子系统的生理状态变化,通过对脉搏波信号的分析处理有望获取反映人体健康状态的特征参数。本文采用简便、易用的光电式指端脉搏传感器,通过对指端脉搏波信号的实时处理和分析,提取了诊断和评测VDT视疲劳状态的客观参数。在检测视疲劳上找到了一种低复杂度计算和具有良好性能的方法,有望以后用于VDT作业者视疲劳的实时监护。
首先从国内外研究现状分析了VDT视疲劳研究存在的问题,并论证基于生理信号研究VDT视疲劳的可行性,找到了能实时、客观的评测VDT视疲劳的方法,有望以后在临床上实现实时监护。
从生理学和人体工效学的角度对VDT视疲劳的产生原因以及影响因素进行了简要概述。简要介绍了脉搏波信号的基础知识。同时从理论上论证脉搏信号与视疲劳之间的关系,表明本课题研究的可行性。
介绍了自主研发的脉搏波信号采集系统和设计的VDT视疲劳实验。从VDT视疲劳的简介知道,影响VDT视疲劳的因素很多,所以在VDT视觉疲劳实验设计上也尽量减弱、减少或去除其它因素对实验的干扰。本实验通过主观疲劳症状问卷调查结果和闪光融合频率(Critical Flicker Fusion Frequency, CFF)的变化情况表明被试者VDT实验后均处于视疲劳状态。
对采集到的指端脉搏波信号进行处理和分析。本课题采用简单整系数滤波器对信号进行预处理,此滤波器实时、有效而且具有低复杂度计算,便于以后在硬件上实现,简单整系数滤波器很理想的满足了实验要求。基于实时考虑分别从时域和频域提取特征：波形高度和幅度谱峰值。这俩特征视疲劳后都下降非常显著(P<0.001),分类正确率都达到94.59%,体温下降显著(P<0.01),说明视疲劳后脉搏信号的能量降低。基于脉搏周期进行散点图分析,发现SD1：短时心率变异程度和SD2：长时心率变异程度变化均不显著,而SD1/SD2下降显著(P<0.05)。
VDT (Visual Display Terminal) has become ubiquitous in various fields. However, while bringing numerous benefits, this technology is accompanied by work-related health disorders, including visual fatigue, musculoskeletal discomfort, and mental fatigue, which are collectively referred to as VDT Syndrome or Computer Vision Syndrome in medical science. In this paper, I intend to propose an objective and real-time detection method for evaluating VDT visual fatigue.
Pulse signals are a kind of physiological signals containing abundant human physiological and pathology information which reflects various physical and physiological changes in subsystems of human body. It may be desirable that analysis of these pulse signals can help us obtain information which will reveal the health condition. In this thesis, simple and easily used photoelectric finger pulse sensor is applied to making a real-time analysis on finger pulse wave signals in order to obtain the objective parameters used as the diagnosis and evaluation of VDT. Meanwhile, we apply photoplethysmography (PPG) to fatigue detection, which is a method of low computational complexity and good performance and is expected to be used in real-time inspection of the visual fatigue of VDT workers.
This paper analyzes problems existing in studies about VDT visual fatigue based on researches at home and abroad and confirms the feasibility of carrying out VDT visual fatigue research through studying physiological signals, providing a real-time and objective detection method for evaluating VDT visual fatigue which is expected to be adopted in clinical healthcare.
This paper also gives a brief summary of reasons for and influencing factors in VDT visual fatigue from the perspective of Physiology and Ergonomics. Meanwhile, basic information about pulse signals is introduced, and the paper provides a theoretical confirmation of the connection between pulse signal and visual fatigue, demonstrating the feasibility of this subject.
We design an electrophysiological data acquisition system and the VDT visual fatigue experiments. According to the brief introduction to VDT visual fatigue, we know that there are lots of factors influencing VDT visual fatigue; therefore, in designing VDT visual fatigue experiments, we try to reduce or remove factors that may disturb the experiments. The fatigue assessment questionnaire and critical flicker fusion frequency (CFF) counter have both shown that all subjects participating in VDT experiments experience visual fatigue.
Pulse signals are processed. In pre-processing signals, simple integer coefficient filters are adopted. This filter not only works effectively in real time but also has low computational complexity and is expected to be implemented in hardware. Simple integer coefficient filter meets our requirements ideally. The pulse signals are analyzed both in time domain and frequency domain, and physiological features like waveform height and magnitude spectrum peaks are obtained. The results have shown that the peak-to-trough amplitudes and magnitude spectrum peaks all significantly decrease in visual fatigue (P<0.001) and classification accuracy reaches 94.59%. There is also remarkable decrease in body temperature (P<0.01). All the above information indicates that the strength of pulse signals decrease after visual fatigue. Based on pulse-to-pulse interval, we analyze the Poincare plot and find that there are no significant changes in the SD1 and SD2. However, the SD1/SD2 have obviously decreased after fatigue compared to that before fatigue (P<0.05).
引文
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