长时驾驶任务中脑力负荷多维特征变化趋势研究

Changing Mechanism of Mental Workload Multidimensional Characteristics During Long-term Driving Tasks

研究长时驾驶任务中驾驶人脑力负荷多维特征随时间的变化趋势,对构建长时驾驶任务中脑力负荷的动态测评方法有着重要意义。现有研究缺少对脑力负荷动态变化的深入分析,尚未能揭示脑力负荷多维特征随时间的变化趋势。设计基于模拟驾驶场景下不同任务难度的时间纵向驾驶任务仿真试验,采用双因素(3任务难度×6时间段)组内试验设计,记录了驾驶人脑力负荷的主观测评、驾驶行为绩效以及眼动、皮电和心电等多模态生理测评指标数据,通过重复测量的方差分析方法系统地分析了脑力负荷多维特征在长时驾驶任务中的变化机理。结果表明:在长时驾驶任务中,随着驾驶时长增加,驾驶人的主观脑力负荷产生累积增加现象,驾驶行为绩效变差,瞳孔直径先快速变小后趋于平稳,皮肤电导水平先快速变大后趋于平稳,心率变异性pNN20指标随时间缓慢降低,心率低频与高频的能量比LF/HF在一段时间平稳后变大。任务难度对主观脑力负荷、驾驶行为绩效、眼动及皮电指标都有显著影响。不同任务难度下脑力负荷特征的变化趋势有所不同。研究结果揭示了长时驾驶任务中脑力负荷的多维特征变化趋势,可为进一步探究长时驾驶任务中脑力负荷的动态测评方法提供参考依据。

Examining the trend of drivers'multidimensional mental workload characteristics over time is important to develop dynamic assessment methods for mental workload during long-term driving tasks.However,a lack of in-depth research exists on the dynamic changes in mental workload,and the trend of multidimensional mental workload characteristics over time has not been fully understood.In this study,a long-term driving experiment was designed based on different levels of mental workload under simulated driving scenarios.A two-factor(three task difficulty levels×six time periods)within-subjects experimental design was used.Data on drivers'subjective mental workload,driving behaviors,and multimodal physiological characteristics(i.e.,measures of eye movements,electro-dermal activity,and electrocardiogram)were collected.The changing trend of each characteristic of mental workload in long driving tasks was systematically analyzed using repeated measures analysis of variance.The results show that,as driving time increases,mental workload increases.Similarly,pupil diameter decreases rapidly and then remains constant.Skin conductance level increases rapidly and then remains constant.Heart rate variability(i.e.,pNN20)decreases slowly over time.The low-frequency to high-frequency component ratio(LF/HF)in heart rate variability first remains constant and then increases during the last time period.Task difficulty significantly affects mental workload,driving behaviors,eye-tracking measures,and skin conductance.The changing trends in characteristics of mental workload for different task difficulty levels vary with time.The results reveal the changing trends in mental workload during long-term driving tasks and provide implications for developing dynamic assessment methods for mental workload in these scenarios.