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Recently, many kinds of machines are introduced in various fields in our society. We are touching machine systems everyday at various times. Therefore, we need to establish the method of the evaluation quantitatively and synthetic, because of comfortable and safe operating conditions in human-machine systems. In order to consider those aspects simply, the method of task evaluation is divided into the following classes. One is operating achievement to determine the ability of each operator, the other is the relationship between the efficiency of the mechanical system and control result to determine the human-machine system. Recently, a lot of research has been done in the latter field. Therefore, it seems that the performance of mechanical systems have been developed rapidly.However, at the point of the task evaluation, it is very im-0.4n . I I I 1 : Respiratory sinus arrhythmia Activity index for parasympathetic part of autonomic nervous system. This index rise during rest. 0 0.2 0.4 0.6 0.8 Frequency (Hz or l/Ekat) fig.1 Heart Rate variability measuring zone for modeling 0 Start Y iron plate ' Curve B ' fig.2 Experimental Courseportant to consider not only performance of the total humanmachine system but also the mental stress and degree of effort of the operator. Because human beings have a high adaptability to surroundings. Therefore, in order to take into account these aspects, many researches on the Mental Work Load (MWL) of the operator have been done recent years.As the MWL can not be measured directly, the value is estimated by the vital reaction during the operation. For example, heart rate, brain wave, breathing, skin temperature and so on. The measurement techniques of the vital reactions are almost completed, but the making of fundamental evaluation is still in the making.Although a lot of these methods are constructed from the view points of the average task load, the evaluation for the quantification of strict time history has not yet been established. Almost operations change every moment, so it is important to the dynamical evaluation, that we construct the dynamic human model to describe the dynamics of the Heart Rate Variability (HRV), because a strong relation exists between the MWL and the HRV which is determined by the . , "0 50 100 150 a 0.002 "0 n "0 50 100 150 Time(s) fig.3 Instantaneous Heart Rate and Result of RRV analysis 0-7803-5731~0

Human error has been implicated as a causal factor in a large proportion of road accidents. Automated driving systems purport to mitigate this risk, but self-driving systems that allow a driver to entirely disengage from the driving task also require the driver to monitor the environment and take control when necessary. Given that sleep loss impairs monitoring performance and there is a high prevalence of sleep deficiency in modern society, we hypothesized that supervising a self-driving vehicle would unmask latent sleepiness compared to manually controlled driving among individuals following their typical sleep schedules. We found that participants felt sleepier, had more involuntary transitions to sleep, had slower reaction times and more attentional failures, and showed substantial modifications in brain synchronization during and following an autonomous drive compared to a manually controlled drive. Our findings suggest that the introduction of partial self-driving capabilities in vehicles has the potential to paradoxically increase accident risk.

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