Ride Comfort Analysis And Optimization Of Heavy Truck Based On Human-Vehicle Coupling Model

The ride comfort of the vehicle is one of the main properties related to vehicle dynamics.As people pay more attention to health and hope for a more comfortable environment,people have higher and higher requirements for vehicle ride comfort.For heavy trucks,the ride comfort is not only related to the health and comfort of the occupants,but also affects the integrity of the transported goods.Therefore,it is of great significance to establish a dynamics model of heavy trucks,and to carry out simulation analysis and optimization design of heavy truck ride comfort.At present,there are several problems in the simulation analysis and optimization research of vehicle ride comfort.Firstly,in the process of building the vehicle dynamics model,each part of the vehicle is generally regarded as a rigid body,which ignores the influence of the flexible frame’s modal on the ride comfort simulation.Secondly,when evaluating the human comfort,generally only the vertical vibration response of the human body is considered,resulting in an inaccurate correspondence between the simulation results of the human body vibration response and the subjective feelings of the human body.In this paper,the pitching dynamics model of human body in sitting position is introduced,combined with finite element analysis,a human-vehicle coupling dynamics model considering the mode of the flexible frame is established,the ride comfort of the heavy truck is simulated and analyzed.The key parameters that affect the ride comfort of heavy trucks are determined through DOE,and simulation efficiency is improved by constructing approximate models.Finally,the NSGA-II based on elite strategy and PSO are used to optimize the vibration response of human body and carriage.When building the vehicle dynamics model,the finite element analysis of the frame is used to obtain its modal information.Simplify the vibration of the frame to the bending vibration of the beam,and realize the coupling of the frame and the multi-rigid body components.The rigid body model and the rigid-flexible coupling model are used to simulate the ride comfort of the heavy truck.The results show that the bending vibration of the frame has different effects on the simulation results of the vibration response of the cab and the carrage in three directions,and the influence of low-order bending modes is more obvious.The pitching dynamics model of human body in sitting position is introduced,and the subjective feeling of the human body is evaluated by weighting the frequency and direction of the multi-axis vibration signals of multiple parts of the human body.Multi-objective optimization of vehicle ride comfort is carried out based on the human-vehicle coupling dynamic model considering the bending mode of the frame.The optimization takes the RMS of the weighted acceleration of human body’s comprehensive vibration and the RMS of vehicle’s comprehensive vibration acceleration as the objective function.Firstly,the sensitivity of the parameters is analyzed through the DOE,and the parameters that have significant impact on the ride comfort of heavy trucks are selected as the variables for subsequent optimization.Secondly,construct the approximate model by RSM and SVM,and select the SVM model as a substitute model for optimization by comparing their fitting accuracy.Finally,optimize the ride comfort of heavy trucks by NSGA-II and PSO,and the Pareto solution sets of optimization algorithms are compared.The results show that,NSGA-II has better global search ability than PSO,and its solution set is more extensive.Through multi-objective optimization,at five different vehicle speeds of 40～80km/h,the weighted RMS value of human body’s comprehensive vibration decreases by more than25%,and the RMS of vehicle’s comprehensive vibration acceleration decreases by more than 28%.The ride comfort of the vehicle has been improved significantly.