Research On The Characteristics Of Soldiers-equipment Man-machines In The Load-bearing State

Soldier system is a typical man-machine system.Only by keeping the soldiers and equipment in harmony can the combat effectiveness of the whole system be brought into play.Improving the ergonomics and compatibility between equipment is an effective way to improve the operational efficiency of the whole individual soldier system.In this paper,a combination of experimental and simulation methods is used to study the comfort and fatigue of soldiers under load.Using the surface electromyography(sEMG),the plantar pressure and the three-dimensional motion capture testing system,three kinds of military life rucksacks with differentd structure layouts under the load-bearing condition are tested,including human body balance ability test,gait test and myoelectricity test of lower limbs.The analysis and comparison index includes the sloshing amplitude of swaying in the anterior-posterior direction,left-right direction of foot pressure center,the enveloping area of plantar pressure center,the average sloshing speed,the gait plantar contact time,the peak value of gait plantar force and the integrated electromyogram(IEMG)of the major muscle groups of the lower limbs.The results show that the amplitude of the swaying in the anterior-posterior direction of the plantar pressure center has a significant effect on the value of the soleus muscle integrated electromyogram(IEMG).The muscle and skeletal model of the soldier is established to compare the activation of the main force muscle,including the shoulder,the waist and the leg,and the stress of main lumbar joints(L1,L3,L5),under the same weight load in different military life backpacks.The structure of military life knapsack is optimized.The results present that the activation of the whole body muscle reaches the minimum and the ergonomics is optimal when the distance between the shoulders is changed to 0.0767m and the lowest belt side contact position is-0.111m.Using the surface myoelectricity test system,the fatigue characteristics of the lower limbs major muscle groups is analyzed when the human body performed the tactical climbing in both the loaded and unloaded conditions.The integrated electromyogram(IEMG),the median frequency(MF)and mean power frequency(MPF)are analyzed,and the EMG characteristics and the change law of each muscle group are obtained.The conclusions are followed that the muscles with significant changes in the time domain parameters are the anterior tibialis and gastrocnemius muscles,the muscles with significant changes in the frequency domain parameters are the gastrocnemius muscle and the soleus muscle.The changes of the median frequency and the average power frequency of the frequency domain evaluation index are consistent,and the variation of the median frequency is more significant than the average power frequency.Compared to the unload condition,the time of both the time domain and frequency domain evaluation indexes comes into the extreme is advanced under the load.