【作者】 姚永杰；

【导师】 孙喜庆； 常耀明；

【作者基本信息】 第四军医大学 ， 航空、航天与航海医学， 2007， 博士

【摘要】 脑力负荷是完成一项或多项任务时所产生的生理和心理需求。脑力负荷不是一个固有的特性,当任务需求、工作环境、操纵者的技能、行为和感知交互作用的时候,脑力工作负荷就产生了。完成飞行任务和确保飞行安全对脑力需求的提高必然导致脑力负荷的增加,进而影响飞行人员的作业绩效,威胁飞行安全。脑力工作超负荷引起信息获取分析的失误和决策错误,是导致事故征候和事故发生的重要原因。研究表明,60%～90%的飞行事故和事故征候发生在脑力工作负荷强度大,应激水平高的起飞、低能见度仪表或手动进近和着陆阶段,而且多是由人为差错引起的。因此,为提高飞行作业绩效,维护飞行安全,测量和评定飞行员空中脑力工作负荷具有越来越重要的现实意义。飞行脑力负荷是一个多维的构建,目前尚无统一的标准去测量。对操作者的认知活动进行生理测量是一个实时、客观的方式,生理测量的优势在于能在从低脑力负荷到脑力超负荷的较宽范围内提供敏感性较高的总体评价。例如心率和HRV的测量被用于模拟空中交通管制的研究,发现其在脑力超负荷水平的评定中具有较高的敏感性。以NASA-TLX为代表的飞行员脑力负荷的主观评定方法是指让飞行员陈述飞行过程中的脑力负荷体验或根据这种体验对飞行作业项目进行过程排序、质的分类或量的评估,具有无侵入性、效度高、经济性的特点,是常用的脑力负荷测量方法。我国在飞行脑力负荷评价方面的研究起步较晚,经验较少,且仅限于实验室和飞行模拟器研究,缺乏实际飞行资料。为探讨不同飞行科目、不同飞行阶段和不同飞行员飞行过程中的脑力负荷水平的变化,本研究从心理生理测量和主观评价两个方面对飞行员实际飞行时的脑力负荷状态进行了评定。通过机载飞行参数记录系统和生理检测设备,同步采集记录了飞行状态和飞行员的多种心理生理参数的变化,使心理生理参数变化与飞行状态形成精确对应。分析了起落航线飞行和基本特技飞行条件下歼击机飞行员心率、呼吸率、HRV的时域和频域指标的变化规律和脑力负荷水平的变化。采用NASA-TLX脑力负荷评价量表(经过修改),对军用直升机飞行员仪表飞行时的脑力负荷进行了主观评价。研究分以下四部分:1歼击机飞行员空中生理参数与飞行状态变化动态对应的可行性研究本研究利用歼××机载飞行参数记录系统和某型通用飞行训练质量评估专家系统,对飞行参数、飞行过程、飞行阶段、飞行动作和姿态进行动态识别,结合KF2型动态多参数生理检测仪的记录和分析,精确获得每一飞行瞬态的心率、呼吸率、体温、过载和体动情况以及每一阶段的HRV时域和频域指标等生理指标。为空中动态精确分析飞行员的心理生理指标和脑力负荷的变化提供了一种方法和技术手段。2.歼击机飞行员起落航线飞行时脑力负荷的心理生理评定观察了起落航线飞行条件下11名歼击机飞行教员和10名新飞行员的心率、呼吸率、1.5 min短时程快速HRV分析的时域和频域指标的变化规律,分析了不同飞行阶段的脑力负荷水平。在起飞爬升阶段,新飞行员表现为心率和呼吸加快,SDNN、RMSSD、TINN以及HRV总功率TP和低频功率LF的减小,飞行教员表现为呼吸的加快和SDNN、TINN以及HRV低频功率LF的减小,新飞行员的心率显著高于飞行教员该阶段的心率。该阶段心理生理参数的变化反映了脑力负荷的增加,新飞行员的脑力负荷水平高于飞行教员。在下滑着陆阶段,两组飞行员的心率和呼吸均显著升高,SDNN、TINN和LF显著降低,RMSSD和HF达到最低值,而LF/HF达到最高水平。飞行教员的HF功率显著低于飞行前,LF/HF显著高于飞行前。这表明,在下滑降落阶段,两组飞行员的脑力负荷和紧张应激状态达最大水平。在该阶段飞行过程中,飞行教员的心理压力和生理需求显著增加,并稍高于新飞行员。在第三边平飞阶段,两组飞行员的心率回落至飞行前水平,飞行教员的呼吸也显著回落,SDNN、RMSSD和TINN也恢复至飞行前水平。说明在平飞阶段,飞行员的脑力负荷程度与起飞和下降着陆阶段比较有所降低。3.歼击机飞行员基本特技飞行时脑力负荷的心理生理评定观察了基本特技飞行条件下歼击机飞行教员和新飞行员的心率、呼吸率、1.5 min短时程快速HRV分析的时域和频域指标的变化规律,分析了飞行前休息,起飞爬升,坡度60度盘旋,半滚倒转,筋斗,半筋斗翻转,返航阶段,下滑着陆阶段的脑力负荷水平。两组飞行员的心率在完成基本特技动作飞行过程中显著升高,在返航阶段有所回落,但是在下滑着陆阶段又显著增加。在完成基本特技动作阶段,新飞行员表现为高的心率和呼吸反应,而飞行教员仅表现为心率的增加,呼吸率显著低于新飞行员。在完成特技飞行动作的各阶段,两组飞行员的SDNN、RMSSD、TINN、HF和HF norm显著降低,而LF、LF norm和LF/HF显著升高,提示两组飞行员较高水平的脑力负荷。在不同的机动动作之间,即在坡度60度盘旋、半滚倒转、筋斗和半筋斗翻转的过程中,没有表现出脑力负荷水平的差异。在返航阶段,两组飞行员HF的显著回升,提示脑力负荷有所减轻,但此时新飞行员的LF norm显著低于飞行教员的LF norm,而HF norm则显著高于后者,反映了在完成规定的特技动作后返航阶段某种放松和满足感,脑力负荷和飞行教员比较相对较小。飞行教员在下滑着陆时的SDNN为整个飞行过程的最低值,而新飞行员在整个飞行过程中,起飞爬升阶段的SDNN最低。在下滑着陆阶段,飞行教员的RMSSD显著低于新飞行员的RMSSD,TP较飞行前显著降低,LF/HF较飞行前显著升高。反映了起飞阶段和着陆阶段两者的脑力负荷水平的差异,即新飞行员起飞阶段的相对高脑力负荷,着陆阶段的相对低脑力负荷,而飞行教员则相反,即起飞阶段的相对低负荷和着陆阶段的相对高负荷。4.仪表飞行时直升机飞行员脑力负荷的主观评价采用NASA-TLX脑力负荷评价量表(经过一定的修改),对军用直升机飞行员仪表飞行时的脑力负荷进行了主观评价。发现在起飞爬升阶段、巡航平飞阶段、下滑着陆阶段飞行员的总脑力负荷值分别为:34.46±17.25, 32.11±13.11, 53.95±17.76。下滑着陆阶段飞行员的总脑力负荷值显著高于起飞爬升阶段和巡航平飞阶段的总脑力负荷值。对不同飞行阶段的总脑力负荷评价值和飞行小时数的线性回归分析表明,总脑力负荷的评价值均与飞行小时数呈显著负相关。在起飞爬升阶段,总脑力负荷的评价值与飞行小时数的线性回归方程为:总脑力负荷评价值=42.20– 0.01203×飞行小时数(r = - 0.810, p < 0.01);在巡航平飞阶段,总脑力负荷的评价值与飞行小时数的线性回归方程为:总脑力负荷评价值=38.51– 0.00604×飞行小时数(r = - 0.535, p < 0.05);在下滑着陆阶段,总脑力负荷的评价值与飞行小时数的线性回归方程为:总脑力负荷评价值=62.57– 0.00814×飞行小时数(r = - 0.532, p < 0.05)。更多还原

【Abstract】 Mental workload is defined as the physiological and mental demands that occur while performing a task or a combination of tasks. Mental workload is not an inherent property, but rather it emerges from the interaction between the requirements of a task, the circumstances under which it is performed, and the skills, behaviors, and perceptions of the operator. Pilots in modern military flight systems have to process a considerable amount of complex information, much more comprehensive than in older systems. The information and decision making processes have become more and more demanding and the risk of mental overload has increased. Furthermore, any mistake by pilots could lead directly to a serious accident or at least a dangerous situation. Not only is pilot under mental stress but also physical stress as well, i.e. changes in acceleration, atmospheric pressure, vibration and temperature. Therefore, the pilot is considered to be under workload at whole flight course.The need to assess pilot workload during flight has become an important factor in the development of new aircraft, support systems and operating procedures. This applies both to combat aircraft, where the success of the mission may be compromised by excessive workload, and to civil transport, where the increasing use of automation may lead to underload and complacency and thus reduce levels of safety.Human factors are identified broadly as contributing to most aircraft accidents. Although percentages vary, most would agree that somewhere between 60%-80% of aviation accidents are due, at least in part, to human error, especially in the phases of take-off, instrument or manual approach and landing, when mental overload occurs. Mental overload directly affects human performance and threats to flight safety. Assessment of pilot mental workload is, therefore, an important aviation management issue, as enhancing flight performance and ensuring flying safety are considered.There is general agreement that in-flight mental workload is a multidimensional construct, and a lack of standardized and accepted assessment techniques makes it difficult to measure. Psychophysiological measurements are of particular importance in the flight environment since they offer a non-intrusive method to collect objective data about the mental workload of pilots and other crew members. A benefit of psychophysiological measurements is their potential sensitivity over the entire workload range from underload to overload. An increase in workload results in an increase of HR, whereas HRV decreases.Subjective rating scales, such as multidimensional NASA-TLX, are the most widely used workload assessment tools. The advantages of subjective workload assessments are ease of implementation, low cost, and limited intrusion on task performance. Rating scales generally provide a good indication of the total workload.Measurement of mental workload has been widely used for evaluation of aircraft design, mission analysis and assessment of pilot performance during flight operations. Research on mental workload in West has been carried on for more than twenty years while in our country it is just underway, most of which was experimental or flight simulator study, but little real flight assessments reported.In order to evaluated in-flight mental workload of military pilots of various kinds of flight course and flight phase, in the present study psychophysiological measures were obtained while different grades of fighter pilot performed real traffic pattern flight tasks and basic acrobatic flight tasks, and we also performed subjective workload assessment of three flight phases using modified NASA-TLX on military helicopter pilots after instrument flight.The main findings are as follows:1. Feasibility study of the changing in-flight physiological parameters of fighter pilot match exactly with changing flight status parameters.In the present study, three fighter pilots were investigated while performing routine flight training. ECG, respiration wave, body temperature, body movement and acceleration (Gz & Gx) were continuously measured and analyzed using a small recording device strapped around the chest. The flight parameters, critical event as well as flight path of each flight were recorded using flight parameters recorder during the real flight and analyzed after all flight procedures performed. The instantaneous heart rate and respiration rate of any flight status can be differentiated and determined through analysis flight parameters recorded using flight parameters recorder. Time-domain analysis and frequency-domain analysis of short-time rapid HRV can be matched with different flight phases. This study provides an available technique to analyze exactly in-flight psychophysiological parameters and to measure mental workload dynamically.2. Mental workload assessment in fighter pilots using psychophysiological measure in traffic patterns flight.There were 11 experienced fighter pilots (flight instructors) and 10 less experienced novice fighter pilots on active flying status who participated in this study. The subjects performed four uninterrupted traffic patterns flight missions with two-seat jet trainers, an experienced pilot seated in rear seat and a novice pilot seated in front seat. The psychophysiological parameters were continuously measured using a small recording device strapped around the chest. Heart rate, respiration rate, time-domain analysis and frequency-domain analysis of short-time rapid HRV (1.5 min) in different flight phases were compared and mental workload were analyzed.During take-off and climb phases, heart rates and respiration rates of novice fighter pilots were significant higher, while SDNN, RMSSD, TINN, TP and LF of them were significant lower than those during preflight baseline, but in flight instructors, only respiration rates was significant higher, while SDNN, TINN and LF were found reduced significantly as compared with preflight. Heart rates of novice fighter pilots were significant higher than those of flight instructors. During the phase of cruising on downwind leg, heart rates, SDNN, RMSSD, RMSSD and TINN in both groups were returned to level of preflight baseline; however, respiration rates in novice fighter pilots were still higher than those of preflight. During approach to landing phase, heart rates and respiration rates were significant higher, while SDNN, TINN and LF were significant lower than those of preflight baseline in both groups. RMSSD and HF reached their lowest values, but LF/HF reached its highest value in both groups, there were significant differences in HF and LF/HF of flight instructors as compared with preflight.The changes of psychophysiological data in both groups reflect enhancement of mental workload in take-off and climb phase, somewhat depress (but still high) in phase of cruising on downwind leg, and again enhancement (to highest level) of mental workload and stress state during approach to landing phase. The results also indicate that, mental workload among novice fighter pilots were greater than those of flight instructors during take-off and climb phase, however, during approach to landing phase the case was the opposite, mental workload of flight instructors were greater than those of novice fighter pilots.3. Mental workload assessment in fighter pilots using psychophysiological measures in basic acrobatic flight.The psychophysiological parameters were continuously measured in 10 fighter pilots (flight instructors) and 10 novice fighter pilots during basic acrobatic flight missions with two-seat jet trainers. During the flight, instructor seated in rear seat and novice pilot seated in front seat. Heart rate, respiration rate, time-domain analysis and frequency-domain analysis of short-time rapid HRV (1.5 min) in different flight phases were compared and mental workload were analyzed.Heart rates in both groups were significant higher than those of preflight baseline during the course of acrobatic flight, in phase of return to base, showed somewhat fallback, and in phase of approach to landing again increased significantly. During the course of performing acrobatic maneuvers, higher respiration responses were observed among novice fighter pilots; while in flight instructors, respiration rates were significant lower than those of novice fighter pilots. During circle with 60-degree bank angles, splits, somersault, hemi-somersault rollover flight phases, SDNN, RMSSD, TINN, HF and HF norm in both groups were significantly reduced; LF, LF norm, LF/HF were significantly increased. During the phase of return to base, HF in both groups was enhanced in some degree; in this phase, LF norm of novice fighter pilots was significant higher than that of flight instructors, but HF norm was significant lower than the latter group. The flight instructors SDNN value reached to its lowest level during approach to landing phase, but in novice fighter pilots, the lowest value of SDNN was seen in the take-off and climb phase. During approach to landing phase, TP of flight instructors were significant lower, and LF/HF of them were significant higher than those of preflight baseline; as compared with novice fighter pilots, RMSSD of flight instructors were significant lower in this phase.The findings suggested that two group fighter pilots have high mental workload during circle with 60-degree bank angles, splits, somersault, hemi-somersault rollover flight phases, no difference in mental workload were found between the two groups. Psychophysiological data in both groups during phase of return to base reflect relative mitigation of mental workload, and novice fighter pilots’mental workload was relative lower than that of flight instructors. The results also indicate different mental workload represents in the two groups during take-off and climb phase and during approach to landing phase, i.e. relative high workload during take-off and climb phase and relative low workload during approach to landing phase for novice fighter pilots; relative low workload during take-off and climb phase and relative high workload during approach to landing phase for flight instructors.4. Mental workload assessment of helicopter pilots in instrument flight with subjective-ratings measurementsIn order to evaluated in-flight mental workload of helicopter pilots. Fifteen male military helicopter pilots from a corps participated in this study. Flight mission was instrument flight. At the end of the flight, subjective mental workload assessment for three different flight phases were rated using multidimensional subjective measures (i.e., modified NASA-TLX questionnaire). The overall TLX subjective workload ratings scores for the take-off, cruise, and landing phases were 34.46±17.25, 32.11±13.11, 53.95±17.76, respectively. The landing TLX scores were significant higher in comparison with take-off and cruise phases. Significant negative correlations between flight hours and subjective workload ratings scores were noted for the three flight phases. During the take-off phase coefficient of correlation between flight hours and subjective workload ratings scores was -0.810 (p < 0.01) and the linear regression equation of the two variables was: TLX scores = 42.20– 0.01203×flight hours. During the cruise phase, coefficient of correlation between flight hours and subjective workload ratings scores was -0.535 (p < 0.05) and the linear regression equation of the two variables was: TLX scores = 38.51–0.00604×flight hours. During landing phase, coefficient of correlation between flight hours and subjective workload ratings scores was -0.532 (p < 0.05) and the linear regression equation of the two variables was: TLX scores = 62.57– 0.00814×flight hours. Analysis of the TLX scores for our participants reveals that the subjective mental workload is higher during landing phase as compared with other phases. The results also indicate that, subjective in-flight mental workload is alleviative with the accumulation of flight experience.更多还原