Research On Vehicle Seat Sitting Comfort Based On Passengers' Pressure Distribution And Physiologic Information

With the rapid development of science and constant improvement of living standards,drivers and passengers are having higher requirements upon seat comfort.The research on human-machine has entered the new era where machines must adapt to meet demands from human being.Because of long contact with the seat,drivers'back,waist,buttock and thigh tend to have muscular fatigue,causing travel fatigue and even occupational disease like lumbar disc herniation.Therefore,high driving comfort is not only the key to improve the driving experience and reduce fatigue,but also the core technology of developing high quality vehicle seats,and the key technique to enhance market competitiveness.Researches in the paper about vehicle seat sitting comfort based on passengers'pressure distribution and physiologic information.Through dynamic manipulation of human seat musculoskeletal model,the consistency correlation analysis between real test measurement and dynamic manipulation simulation was carried out,testing the hard point size in the comfortable driving posture.A mapping was established between subjective comfort and objective indicators,to quantitatively evaluate the driving comfort,and the layer by layer decomposition was carried out.Body pressure distribution and physiologic information difference during short and long driving,and the recessive injury of muscle and lumbar vertebrae during long driving were analyzed.Considering the body pressure distribution,physiological information and subjective comfort,the comfort prediction model was established.The main research contents are as follows:Firstly,comfortable driving posture evaluation under dynamic manipulation.In the paper,starting from the biomechanical characteristics of human bone muscle,based on the Hill muscle mechanics model,constructed the human seat musculoskeletal model of 5percentile,50 percentile and 95 percentile sign of Chinese human body under dynamic manipulation.The six degree of freedom flexible test bench was built,and the optimization of test times was completed by using the central composite method.The mechanical characteristics of bone muscle,bench test and simulation analysis were combined to complete the screening of test muscle groups.The consistency analysis of real test and dynamic manipulation simulation was carried out,to measure the hard point size of comfortable driving posture,and verify the results are reasonable and feasible.Secondly,quantitatively evaluation of the driving comfort.Instead of traditional static tests,the comfort test of driving posture under dynamic control of real vehicle road condition was carried out to obtain subjective perception and objective parameters of comfort.Established an evaluation model for the driving comfort,and the expert deviation calculation and data screening were completed by cluster analysis.A new comprehensive weighting method-AHP to limit entropy method was raised,to establish the mapping between subjective comfort and objective parameters,and quantitatively analyze the driving experience.And finally the weights of the comfort of shoulder,back,waist,buttock and thigh on the overall sitting comfort were obtained,0.056,0.346,0.308,0.193 and 0.096,respectively.Furthermore,comfort difference during short and long term driving,and the potential injuries of muscle lumbar vertebrae during long term driving.This thesis studied from the biomechanics of human body,the pressure distribution,and the pathological point of lumbar vertebrae caused by long-term driving,extracted the bioelectric parameters and the characteristic parameters of pressure distribution,researched the difference of comfort during short and long term driving.The mechanism of muscle hidden injury caused by long-term driving was revealed by combining magnetic resonance images and lumbar keyboard force.The results showed that with the increase of driving time,the influence of thigh and back have on comfort increased as well.The impact of pressure distribution on driving comfort are ultimately reflected in average contact pressure and average contact force between driver-seat interface,thigh,upper limbs and calf tend to feel weary since they were in a continuous powering condition.In addition,the test results of magnetic resonance imaging and the simulation of comfort were combined,showing that L_4-5intervertebral disc and the L₅-S₁intervertebral disc were prone to degenerative lesions,causing invisible injury of muscle and lumbar vertebrae.Finally,optimal design on major human-machine arrangement parameters,like vehicle seat,pedal and steering wheel,and comfort prediction model.Through overall analysis about the pressure distribution and physiological information,using the regularization RBF neural network,the comfort prediction model based on objective parameters was set up.By combining the comfort prediction model,the human-seat skeletal muscle mechanical model and the pressure distribution,the human-machine layout parameters such as vehicle seat,pedal and steering wheel were analyzed comprehensively,and the optimal human-machine arrangement parameters of drivers with different signs were studied.The results showed that the average deviation and Theil inequality coefficients of regularization RBF neural network prediction results were 0.9141%and 0.0071,proving its better prediction accuracy and fitting degree comparing with BP neural network.By using the comfort prediction model,the human-seat skeletal muscle mechanical model and the pressure distribution,the influence of the human-machine arrangement parameters such as the vehicle seat,pedal and steering wheel on the driving posture comfort were analyzed,realized the optimization design of the optimal human-machine arrangement parameters of drivers with different signs.