The Research On Vibration Of Commercial Vehicle Seat Suspension Based On Multi Degree Of Freedom Human Body Model

Commercial vehicle needs high load capacity,they always have large suspension stiffness,and often be used in complex driving conditions and bad working environment.Because of road roughness,the cab vibration problem is prominent in commercial vehicles.Commercial vehicle drivers are prone to fatigue due to prolonged exposure to vibration,which reduces operation accuracy and even do harm to their health,causing a series of occupational diseases.It is the direction for scholars to effectively isolate and attenuate the cab vibration of commercial vehicles and improve the ride comfort of drivers.Using a good seat suspension system has become an effective way to improve the ride comfort for commercial vehicles.The traditional passive seat suspension adopts the methods of adjusting the seat structure and optimizing the stiffness and damping of seat suspension to improve the vibration characteristics of the seat,but it can not meet the requirements of the pavement condition perfectly.Due to the complex structure and high price of active seat suspension and the insufficiency of passive seat suspension,semi-active seat suspension is becoming the focus for researchers.At the same time,MR damper has the advantages of easy fabrication,simple structure and good control ability.The semi-active seat suspension with MR damper has become a hot spot.This paper will study and discuss the key technology of the seat suspension system in practical engineering,combining with the development project of a commercial vehicle seat suspension.The main researching jobs of this paper is based on the following four aspects:(1)Optimize the passive seat suspension system.Considering the influence of human body vibration on the seat suspension system,a dynamic model of the multi-freedom "human seat" system is established.According to the power spectral density of the commercial vehicle cab floor,which is input to the seat vibration by the national standard,the vibration domain excitation input of the seat suspension is obtained through the inverse Fourier transform method.The stiffness and damping of the passive seat suspension system is optimized based on the elitist strategy of the nondominated genetic algorithm(NSGA-II),which improves human vibration to a certain extent.(2)Experimenting and modeling of dynamic characteristics of MR damper based on semi-active seat suspension system.The dynamic characteristic of the damper are performed according to the related standards,using MATLAB to obtain the magnetic MR damper hyperbolic tangent model through the experimental data,and design a dynamic simulation experiment with the model;The experimental values are compared with the simulated values,and the result proves that the established hyperbolic tangent model is reliable.(3)Formulate the control strategy of the semi-active seat suspension system.Developed two kinds of control algorithms for semi-active seat suspension based on MR damper,and analyze the characteristics of the algorithm.Establish a simulation model of semi-active seat suspension based on MR damper in MATLAB/SIMULINK.Adopted two different control algorithms to control the model respectively,and carried out some dynamic simulation with the model.Finally analyzed and compared the simulation results.(4)Apply the multi-degree of freedom "body-seat-suspension" system on the commercial vehicle: Dongfeng EQ1141.Established a dynamic mode with 1/4 body vehicle which have seven degrees of freedom "body seat suspension",and the time domain roughness model of C grade pavement and D level pavement.Simulated the seven degrees of freedom semi-active seat suspension based on MR damper,and analyzed its vibration reduction effect.In order to improve the environment of commercial vehicle cab and improve the driver's comfort,the seat suspension has some advantages,and it is easy to realize.It has practical significance to apply it to commercial vehicles.