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摘要:
空间站飞行过程中航天员容易产生脑力疲劳,其是影响作业效率和引起失误的主要因素。为此,研究人体脑力疲劳的快速检测方法,将有利于保障在轨运行安全。脑电波(EEG)的特征变化能够反映出大脑疲劳状态,但现有EEG方法分析脑力疲劳时需要多个导联的信号,这严重限制了其在空间站环境中的实际应用。通过地基实验,采用36 h睡眠剥夺的方式成功诱发出45名受试者的多种脑力疲劳状态。针对EEG信号的非平稳性,设计的8层db4小波变换结构,有效分解出了
δ 、θ 、α 和β 脑节律波。先使用方差分析( ANOVA)和Logistic回归筛选出脑力疲劳敏感特征,再依据脑力疲劳敏感特征数量进一步筛选出脑力疲劳敏感导联,应用6个敏感导联的特征分别构建了随机森林回归模型。加权融合6个导联处的回归模型,形成脑力疲劳快速检测模型,其平均精确率高达85.25%。Abstract:During the flight in space station, astronauts are prone to mental fatigue, which is the main factor that affects the efficiency of operations and causes errors. For this reason, studying rapid detection methods for human mental fatigue will help ensure the safety of on-orbit operations. The characteristic changes of the electroencephalogram (EEG) can reflect the fatigue state of the brain. Still, the existing EEG method requires multiple lead signals when analyzing mental fatigue, which seriously limits its practical application in the space station environment. This study successfully induced various mental fatigue states in 45 subjects through a foundation experiment using 36 hours of sleep deprivation. Aiming at the non-stationarity of EEG signals, the designed 8-layer db4 wavelet transform structure effectively decomposes
δ ,θ ,α , andβ brain rhythm waves. First, screen out the mental fatigue sensitivity characteristics using analysis of variance (ANOVA) and Logistic regression. Secondly, according to the number of sensitive features of mental fatigue, the sharp leads of mental fatigue were further screened out. Finally, the characteristics of 6 keen leaders were used to construct random forest regression models. Finally, the weighted fusion of the regression models at 6 leads to a rapid detection model of mental fatigue, with an average accuracy rate of up to 85.25%. -
表 1 脑力疲劳主观评分及等级划分
Table 1. Subjective score and grade division of mental fatigue
脑力疲劳分级 主观评分 无疲劳感 s<2 轻微疲劳 2≤s<4 中度疲劳 4≤s<6 较严重疲劳 6≤s<8 很严重疲劳 s≥8 表 2 脑力疲劳的敏感特征统计
Table 2. Statistics of sensitive characteristics of mental fatigue
敏感特征 导联位置 P AUC α波绝对能量 F3 0.000 4 0.695±0.054 θ/β相对能量 FZ 0.000 6 0.682±0.049 Hjorth复杂性 OZ 0.000 8 0.669±0.057 Renyi熵 FZ 0.000 8 0.655±0.062 α/(δ+θ+α+β)相对能量 O1 0.001 2 0.647±0.053 δ波绝对能量 O2 0.001 8 0.649±0.042 Tsallis熵 F3 0.003 7 0.603±0.057 Shannon熵 F4 0.005 1 0.612±0.046 δ/(δ+θ+α+β)相对能量 FC1 0.008 3 0.623±0.052 Hjorth活动性 F4 0.012 9 0.598±0.051 (α+θ)/(α+β)相对能量 PZ 0.014 6 0.587±0.045 β波绝对能量 O1 0.017 3 0.591±0.050 Teager平均能量 F4 0.024 0 0.584±0.049 对数能量熵 OZ 0.026 9 0.575±0.054 (α+θ)/β相对能量 F3 0.030 5 0.572±0.043 θ波绝对能量 O1 0.034 9 0.565±0.038 Hjorth移动性 CZ 0.038 5 0.560±0.047 α/β相对能量 FZ 0.042 7 0.552±0.039 β/(δ+θ+α+β)相对能量 FZ 0.048 3 0.554±0.042 表 3 脑力疲劳敏感导联的重要特征
Table 3. Important characteristics of mental fatigue sensitive leads
FZ O1 F4 O2 OZ F3 θ/β相对能量 α/(δ+θ+α+β)相对能量 Hjorth活动性 δ波绝对能量 Hjorth复杂性 α波绝对能量 Renyi熵 β波绝对能量 Shannon熵 α/(δ+θ+α+β)相对能量 Teager平均能量 (α+θ)/β相对能量 α/β相对能量 θ波绝对能量 θ/β相对能量 Hjorth复杂性 对数能量熵 Tsallis熵 β/(δ+θ+α+β)相对能量 Hjorth活动性 δ波绝对能量 θ/β相对能量 α/β相对能量 θ/β相对能量 δ波绝对能量 Teager平均能量 δ/(δ+θ+α+β)相对能量 (α+θ)/(α+β)相对能量 β/(δ+θ+α+β)相对能量 α/(δ+θ+α+β)相对能量 Teager平均能量 δ波绝对能量 (α+θ)/(α+β)相对能量 Teager平均能量 Shannon熵 δ波绝对能量 Hjorth活动性 θ/β相对能量 Hjorth移动性 对数能量熵 Hjorth移动性 Hjorth活动性 Renyi熵 Shannon熵 β波绝对能量 Hjorth移动性 β波绝对能量 α/β相对能量 β波绝对能量 Hjorth移动性 Renyi熵 α/β相对能量 (α+θ)/β相对能量 Renyi熵 (α+θ)/(α+β)相对能量 α/β相对能量 Teager平均能量 θ波绝对能量 θ/β相对能量 Teager平均能量 表 4 敏感导联回归模型的AUC值
Table 4. AUC value of sensitive lead regression model
敏感导联 无疲劳感 轻度疲劳 中度疲劳 较重疲劳 严重疲劳 FZ 0.7951 0.7056 0.7854 0.7056 0.7469 O1 0.7458 0.6891 0.7121 0.7905 0.7854 F4 0.7956 0.7236 0.7541 0.7125 0.7965 O2 0.7521 0.7532 0.6957 0.7558 0.7236 OZ 0.8023 0.7456 0.7554 0.7415 0.7451 F3 0.7685 0.6785 0.7028 0.7307 0.8218 表 5 脑力疲劳融合检测模型的比较
Table 5. Comparison of fusion detection models for mental fatigue
模型 Logistic ANN RF SVM 0.4456↓ 0.3895↑ 0.0245↑ Logistic 0.2453↑ 0.0187↑ ANN 0.0236↑ RF 注:↑指横向单元格中的方法优于纵向单元格中的方法, ↓指横向单元格中的方法差于纵向单元格中的方法。 表 6 脑力疲劳检测模型的分类结果
Table 6. Classification results of mental fatigue detection model
检测模型 精确率/% 召回率/% F1/% 无疲劳感 87.71 20.82 33.65 轻度疲劳 81.04 31.20 45.05 中度疲劳 82.71 29.86 43.88 较重疲劳 86.08 19.64 31.98 严重疲劳 88.73 18.29 30.33 平均值 85.25 23.96 36.98 -
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