Mental Fatigue Monitoring Using a Wearable Transparent Eye Detection System.

Kota Sampei,Carlos Torres,Norihisa Miki,Miho Ogawa,Munehiko Sato

doi:10.3390/mi7020020

Abstract

We propose mental fatigue measurement using a wearable eye detection system. The system is capable of acquiring movement of the pupil and blinking from the light reflected from the eye. The reflection is detected by dye-sensitized photovoltaic cells. Since these cells are patterned onto the eyeglass and do not require external input power, the system is notable for its lightweight and low power consumption and can be combined with other wearable devices, such as a head mounted display. We performed experiments to correlate information obtained by the eye detection system with the mental fatigue of the user. Since it is quite difficult to evaluate mental fatigue objectively and quantitatively, we assumed that the National Aeronautics and Space Administration Task Load Index (NASA-TLX) had a strong correlation with te mental fatigue. While a subject was requested to conduct calculation tasks, the eye detection system collected his/her information that included position, velocity and total movement of the eye, and amount and frequency of blinking. Multiple regression analyses revealed the correlation between NASA-TLX and the information obtained for 3 out of 5 subjects.

Highlights

Assessment of the physical and mental states of the workers is of great benefit to enhance the work efficiency and secure the safety, amongst which we consider that the mental fatigue or stress that we experience is one of the most important factors
Other than the information acquired by the eye detection system, the number of the tasks (1 to 6) was investigated
Based on the comparison among the six factors (MD, physical demand (PD), temporal demand (TD), OP, EF, FR) prior to the tasks, we formulated equations to calculate the workload for all five subjects (A–E), as shown in Equations (2–6), respectively

Summary

Introduction

Assessment of the physical and mental states of the workers is of great benefit to enhance the work efficiency and secure the safety, amongst which we consider that the mental fatigue or stress that we experience is one of the most important factors. Subjective ratings are widely used to describe the physical and mental states and to assess the workload of tasks. National Aeronautics and Space Administration Task Load Index (NASA-TLX) was developed to quantitatively estimate the workload [1]. This method requires both a priori and a posteriori ratings by the subjects. Dry electrodes that do not need skin pretreatment or conductive gel are currently studied [7,8], which may allow EEGs to be used for the mental fatigue monitoring with a miniaturized measurement system. In particular, the high frequency and low frequency activities, are known to correlate with the fatigue

Objectives

Methods

Conclusion