| Insufficient light and relatively narrow and complex space are two typical characteristics of confined space.Long time working in confined space is prone to fatigue,distraction and other symptoms,which not only affects the efficiency of work,but also may endanger the personal safety of operators and cause safety accidents.In view of this,this paper uses ergonomics,biomechanics,signal processing,mechanical transmission and other theoretical knowledge to carry out a series of experiments,such as confined space light environment experiment,sEMG based fatigue test of side down work in confined space,and uses numerical simulation method to select illumination and working posture to carry out Confined space human factor parameters on operators Research on the influence and protection of fatigue.First of all,the data were collected in the confined working space of 50LX?700LX.The results show that the pupil diameter decreases with the increase of illumination,and the relationship between pupil and illuminance accords with power function relationship;the change rate of pupil diameter fluctuates between-12%and 8%under the illumination of 4001x,5501x and 7001x,and the degree of visual fatigue increases with the increase of illumination intensity;the pupil diameter changes under the environment of low illumination of 50lx,100lx and 2001x The visual fatigue rate was between-8%and 4%,and the degree of visual fatigue increased with the decrease of intensity.In this study,a windowed pupil diameter standard deviation(?)is proposed to judge the time of visual fatigue.The fatigue degree caused by weak light is greater than that caused by strong light.The recommended illumination for confined space operation is 3001x.Secondly,on the basis of exploring the light environment in the confined space,aiming at the problem of confined space height and confined working posture,the typical working posture in confined space was selected,and three groups of typical working posture models in confined space were established by using jack simulation software to evaluate the ergonomics of typical working posture.It was found that squatting(knee joint torque 62 N·m)and bending posture(bending moment 59 N·m)were more harmful to the waist and knee,respectively.In contrast,the neck side bending posture can better adapt to the characteristics of confined space and height limitation.At the same time,using anybody simulation platform to simulate the force of the main key muscles involved in the neck side bending posture.The simulation results show that with the increase of the lateral bending angle,the load of the main force bearing side muscles of the neck is increasing,but the increase range is different.The force of different muscles in the process of head lateral bending is very different.When the degree of lateral curvature was more than 22.5 degrees,the force of neck muscles increased significantly.Thirdly,sEMG fatigue test was carried out for the typical working posture in confined space,that is,the neck side bending posture.On the basis of ergonomic evaluation and neck stress analysis,three stress gradients were selected and sEMG was used to test the fatigue of three neck muscles,sternocleidomastoid muscle,sandwich muscle and trapezius muscle of shoulder in the confined space of high humidity and heat environment.The results show that the absolute value of median frequency slope increases gradually with the increase of cervical lateral curvature angle,and the fatigue degree increases.The changes of iEMG in long-term flexion posture can reflect the fatigue status of neck to a certain extent.The increase of iEMG reflects the degree of muscle fatigue to a certain extent.When the muscle has severe fatigue,the iEMG fluctuation increases significantly.MPF has better nonlinear characteristics.In this study,we propose a new method to extract muscle fatigue characteristics by using the derivative accumulation degree of MPF windowed.Combined with this experiment,in the case of long-term lateral curvature of the neck,it is recommended that the duration of single operation posture should not exceed 20 minutes to protect the cervical spine.Finally,based on the analysis of the physiological characteristics and functions of the neck,an exoskeleton neck protection system is developed according to the principle of exoskeleton for the protection of neck muscles involved in typical working posture.The system has the function of self-locking and self unlocking,which is mainly composed of three parts:base wearing,connecting rod hinge and self-locking and self unlocking control system.This study provides a scientific reference for the protection of the environment and typical working posture of operators in confined space,and provides certain technical support for safety production in confined space. |
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