Research On Active And Passive Vibration Suppression Method Of Vehicle Multibody System On Continuous Bumpy Road

As an important branch of mechanics,multibody system dynamics is widely used in many fields and industries,such as aerospace,vehicles,robots,biodynamics and so on.When dealing with the complex systems with multiple degrees of freedom,the dynamics is usually modelled using the global formulation based on Cartesian coordinates.However,this method has the limitation of low computational efficiency.To make up for this defect,the Spanish scholar Javier García de Jalón proposed a two-step semi-recursive multibody dynamics modeling method,which is based on the independent relative coordinates.This method has the advantages of high computational efficiency on the premise of ensuring solution accuracy.This makes it have great potential in real-time simulation and active control applications particularly for autonomous vehicles.With the vigorous development of autonomous vehicles,the active control of various vehicle scenarios has also become the focus of current research.For the complex vehicle multibody system with passive suspensions,to suppress the vertical vibration on bumpy road conditions,this thesis studies and explores the active speed control and suspension parameter optimization methods.The research contents of this thesis are summarized as follows:1.For a 17-DOF vehicle,based on the two-step semi-recursive multibody dynamics theory,the system tree-topology is built using the cut-joint and rod-removal techniques.Next,on the basis of urban conditions,the bumpy road model is developed with the use of speed bumps,and it is defined by the absolute coordinate method finally embedded in the vehicle multibody model.In addition,the commercial software Car Sim is used to model the same vehicle system,and the Carsim and multibody models are simulated under the same steering conditions,so as to verify the effectiveness of the vehicle multibody dynamics model.2.To deal with the issue of vehicle’s vertical vibration,taking advantages of modern control technology,three control strategies,namely PID control,fuzzy control,and optimal control are designed for active speed control to make the vehicle pass through the bumpy road in an reasonable speed and achieve the goal of vibration suppression.Furthermore,the dynamic simulations are performed on different bumpy road conditions to verify the effectiveness of the proposed control strategies.3.From the perspective of the passive strategy of vibration suppression,the response surface model of the vehicle vibration peaks and the sequential quadratic programming algorithm are used for further improve the ride performance.More specifically,the suspension parameters of the vehicle are optimized,where the optimization goal is to minimize the mean value of the vertical vibration acceleration peak.In final,we combine the active speed control strategy and the suspension parameter optimization strategy to suppress the vehicle’s vibration for enhanced ride performance.The effectiveness of the comprehensive vibration suppression strategy is also verified on different bumpy roads.