Seated Human Body Vibration Test And Three-dimensional Dynamic Model Parameter Identification

As an important index to evaluate vehicle performance,people pay more attention to vehicle ride comfort.No matter for passenger cars in daily life or commercial vehicles for production purposes,if the driver and passenger factors are not considered,the vehicle comfort will be difficult to meet the design requirements.The dynamic comfort of the vehicle is evaluated by the real vehicle test.The subjective feelings as the evaluation standard have the disadvantages of strong subjectivity and low reliability.One of the ways to solve the above problems is to establish a reasonable sitting posture human body model in the initial stage of vehicle design to assess the ride comfort objectively.However,the current human simulation model of sitting posture is mainly developed from the European or North American population,and those population do not include Chinese drivers or passengers,while the distribution,human characteristics and joint torque of Chinese drivers or passengers are quite different from those of European and American drivers.At the same time,most of currently available human body models are either one-dimensional(1D)or two-dimensional(2D)models,which can only analyze the vibration response of human body in one-dimensional or two-dimensional directions,and can-not truly restore the threedimensional vibration response of human body in the real vibration environment.In view of the above limitations,it is necessary to develop a three-dimensional sitting posture human body model in line with the human characteristics of Chinese drivers or passengers.In this study,based on biodynamic vibration models in the literature a multi-body dynamic model of three-dimensional sitting human body is developed.The model is composed of feet,calves,thighs,upper torso and head neck,which can simulate the longitudinal,lateral and vertical translational motion and the pitching,roll and yaw motions.Based on the dynamic analysis of the sitting human body dynamic model,the mathematical model is established,and the frequency response function of the seat head vibration transfer rate is obtained by MATLAB programming.The low-frequency and multi-directional vibration tests of human body in sitting position were carried out.By using the six degree of freedom vibration test-bed of MTS and three-axis acceleration sensors and other equipment,through the parameter identification and model verification test of the combination of seat attitude and excitation mode,Specifically,parameter identification test: sinusoidal excitation,cushion angle ? = 0 °,backrest angle ? = 0 °;model verification test:(1)sinusoidal excitation,cushion angle ? = 0 °,backrest angle ? = 15 °;(2)sinusoidal excitation,cushion angle ? = 10 °,backrest angle ? = 15 °;(3)random excitation,cushion angle ? = 10 °,backrest angle ? = 15 °.The low-frequency three-way vibration tests of 8 Chinese subjects were carried out,and finally the acceleration response data of human head were obtained.The test data of seat head vibration transmission rate are obtained by collected the data.Parameter identification of human dynamic model is based on genetic algorithm(GA).The genetic algorithm,which does not depend on the selected initial value and is a global optimization,is selected as the parameter identification method.The objective function is established by the minimum sum of the square of the difference between the test value of human seat head vibration transmission rate and the simulation value of the model,and the human body parameters are finally obtained by programming with MATLAB.According to the identified parameters,the response of vibration transmissibility of the human body model in different seat posture is obtained and compared with that of the human body test.The parameter identification effect is evaluated by taking Goodness of Fit as the index.The results show that the model can simulate the response of seat head vibration transmission rate well.On the basis of the above research results,this study establishes a three-dimensional multi-body dynamic model of sitting human body,which accords with the characteristics of Chinese human body.Therefore,the establishment of this model has certain theoretical significance and practical application value for guiding the design of automobile comfort.