Research On The Multiple Influence Factors Of The Carrying System Based On Surface Emg Signal

The main reasons for the fatigue and illness of the long-term shoulder workers are the unreasonable structure design of the current shoulder system,which is mainly reflected in the unsatisfactory effect of load reduction,the pressure of the backpack is too concentrated,and there is no reasonable gravity transmission,so the most scientific load reduction effect can not be achieved.We study on the surface electromyogram signal(sEMG)of cluster muscles in trunk and the fatigue evaluation with different experimental combinations when people are walking with two-shoulder load,and explore the functional status and fatigue property of human muscles.Methods Firstly,under different shoulder strap width,weight bearing and cushion hardness,the sEMG of two targeted back muscles(upper trapezius and erector spinae)from ten participants when walking are collected,and the subjective tests are performed.Then,the time domain evaluation index(mean amplitude,aEMG),frequency domain evaluation index(median frequency,MF)and subjective test data are processed and analyzed.Results Load size and shoulder strap width have a significantly effect on fatigue(P < 0.01),and the change of cushion hardness has no significantly effect on fatigue(P>0.05);there is an interaction effect between load size and shoulder strap width,and there is no interaction effect between load size,shoulder width and cushion hardness.For backpack carrying system,the combination of 10%-weight load and 50mm-width strap is the best one for relieving fatigue.Subjective test also shows that subjective feelings of muscle fatigue are related to load and width,which is same to sEMG test results.Conclusions The experimental results show that the combination of sEMG and subjective physical fatigue scale is feasible to evaluate the physical fatigue rate.The research findings of this paper provide theoretical basis and practical basis for improving the weight-bearing method and backpack performance,and for designing more ergonomic carrying system.