| The 6-DOF spindle coupled road simulator is the most representative equipment which is used to test vehicle durability and can load six directions of force or torque on the wheel hub.By simulating the force acting on the axle shaft in the actual running,the true multi-directional stress state of the vehicle parts can be reproduced accurately achieving the requirement of vehicle durability road simulation test.Because the whole system consisting of vehicle and spindle coupled road simulator is a nonlinear system with strong coupling,the coupling characteristics of each channel have a negative affect on the performance of the system and increase difficulty of control.Accordingly,this thesis focuses on the coupling characteristics of the the 6-DOF spindle coupled road simulator.Firstly,the design index,system composition and working principle of the 6-DOF spindle coupled road simulator are introduced.The system model of the 6-DOF spindle coupled road simulator is established,which includes the kinematic model and the dynamic model of the system.The kinematic analysis of the road simulator is carried out by using vector operation and the Jacobi matrix of the road simulator is obtained.The dynamic equations of the road simulator are obtained by using the Kane method.Secondly,in order to analyze the coupling characteristics of the single angle configuration road simulator,the electro-hydraulic servo force control model of six channel is established.Through hysteresis correction and PID control,the electrohydraulic control of each channel can satisfy demand basically.The double wishbone suspension system is chosen as the load of single angle configuration road simulator and the Simulink-Adams co-simulation model is built.The coupling characteristics of kinematics and dynamics and coupling mechanism are analyzed.Again,in order to analyze the coupling characteristics of four angle configuration road simulators the vibration system model is established including the four round of the road model and the seven degrees of freedom vehicle vibration model.The vibration system model of vehicle is verified using CarSim software.Finally,the coupling characteristics of four angle configuration road simulators with vehicle are analyzed.The Simulink-Adams co-simulation model of four angle configuration road simulators loading on vehicle is established.By using the generated load spectrum as a given loading signal,the coupling characteristics of the reproduced vertical load spectrum are analyzed.As for influence of different parameters on the coupling strength of the four axis configuration coupling road simulation test platform.The reproduction accuracy of the four angle configuration road simulators at different road roughness,vehicle speed and suspension stiffness is analyzed comparatively.As a result,t he influence of different elements on the coupling characteristics of spindle coupled road simulators is obtained. |
