| When people are in a state of mental fatigue,the efficiency of work and study will be reduced,and it may even lead to irreparable accidents.Existing fatigue state monitoring equipment on the market is not only complicated to operate and expensive,but also often has relatively strict restrictions on human physical activities.It can only be used in fixed scenarios and is not suitable for daily work.In this paper,a simple,wearable and low-cost multi-physiological signal acquisition system is designed and realized.The system can be used to judge mental fatigue by collecting human EEG,ECG and proximal body surface temperature.The system not only displays three kinds of signals in real time in the upper computer,but also calculates the four evaluation parameters of mental fatigue in real time:the energy ratio of θ wave,α wave and β wave of the EEG（ηθ+α,p）,the standard deviation of RR interval in the heart rate variability（SDNN）,the energy ratio of low frequency component to high frequency component（ηLF,HF）in the frequency domain and the change of body temperature（ΔT）.After the performance test,the whole system can accurately collect the physiological signals of the subjects,and the whole process will not interfere with the normal activities or work of the subjects.Except for the physiological signal collection electrodes,the size of the main control board of the hardware circuit of the whole system is only 65mm × 35mm × 5mm.In this paper,its appearance is designed as a hairband type to realize the wearability of the system.We design the corresponding mental fatigue monitoring simulation experiment and observe the change trend of the four parameters（ηθ+α,β、SDNN、ηLF,HF and T）to make the following conclusions:as the fatigue of the subjects deepens,the four parameters will rise to varying degrees.Based on the obtained results,we have developed an evaluation standard for the system to monitor the mental fatigue state of the subjects without interfering with their daily work. |
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