Dynamic Assessment Of Mental Fatigue Under Continuous Workload

Flight is a kind of work with highly quantitive mental workload. Longperiod of work will result in mental fatigue probably.Airaccident investigationshowed that the mental fatigue attributed a lot to accidents due to humanfactors.Fast and effective assessment of the state of mental fatigue can play animportant role in safe flights.At present, the methods to assess fatigue included the subjective and theobjective evaluation methods. Subjective assessment is simple, rapid,noninvasive, which put it into comprehensive use. But it is difficult to ensure theaccuracy of the assessment. Compared with that, objective evaluation methodsare charactered with standardization and lack of subjective affection, so it is atrend to assess fatigue in this way. Nowadays the methods mainly in use is thesimply indicator, such as EEG, pupil detection and so on.But these techniquesneed much investment and fussy procedure. And these methods are still inexploration.Because the fatigue mechanism is so complex that until now there is no theory can explain it clearly. And the process of fatigue is affected byphysiological, psychological, and many other factors.So it is difficult to assessthe status of fatigue accurately with the use of such a single method.Consideringthe principle of simple operation and fast assessment, this study choosed thescale of NASA-TLX, HRV, critical fusion frequency, static posturography,reaction time as the the items of psychological and physiological methods toassess the status of fatigue. The objective was to assess the status of fatiguefastly from multiple aspects. In this study, the training wordload and continuousmental work were used as the models.The parameters of the NASA-TLX scale,flicker fusion frequency, heart rate variability, static posturography and reactiontime were used as the indexes to show the changing of the status of fatigue,which were measured in different time points of the workload.Finally thefollowing conclusions were drawn:(1) Changes in the results of static posturography were significant, whichcan assess the state of mental fatigue in this study, but it was affected by somepsychological factors probably.（2）Compared with the training workload in this study, the biologicalrhythem has an obvious effect on the status of fatigue.（3）In the continuous workload of this study, static postugrography,reaction time, critical fuse frequency and scale of NASA-TLX changed indifferent trend with the increasing time of workload.