Simulation Study For The Effect Of EPS Parameters On Vehicle Handling And Stability At Adhesion Limit Of Tires

Along with the development of vehicle technology, the people's demands on ride, handling and stability of Automotive are so raised higher and higher. EPS is much superior to hydraulic power steering system, more and more cars have equipped with EPS. But people know very litter about the affection to handling and stability of EPS and some parameters, especially when the adhesion between the tires and the road reach the physical limit. In this situation, the handling and stability may directly affect the active safety of the cars. In this thesis, vehicle model was built in ADAMS/Car, and EPS model was built in MATLAB/Simulink, ADAMS/Control was employed to connect the vehicle model and the EPS model. Vehicle model in ADAMS/Car also been employed to take some experiments for building Assist Characteristics. The co-simulation model was used to research the affection to handling and stability of EPS and some parameters when the car reaches the adhesion limit.The thesis includes six chapters:In chapter one, the history of power steering systems, the features of them were introduced. The structure, principle and classification of EPS were presented. The development of Vehicle Dynamics Simulation and EPS, the technical route were also introduced in this chapter.In chapter two, introduced the research methods -- multi-body system dynamics theory and the control system software. The theoretical basis of ADAMS and excellent control system software MATLAB were introduced.In chapter three, introduced the modeling process of ADAMS/Car and described the simplification and assumptions in detail, modeling methods of various subsystems and vehicle assembly were introduced too.In chapter four, introduced EPS modeling and described the implementation of co-simulation. The concept, classification and design criteria of power characteristic curve were described in detail. Double lane change simulation was employed to verify the co-simulation model achieved the basic functions of power characteristic curve.In chapter five, introduced the simulation and conclusion of research on the affection to handling and stability of EPS and some parameters when the car reaches the adhesion limit. The working conditions of tire adhesion limit and the handling and stability in this situation were described in detail. In chapter six, the main work of this thesis was summed up, and introduced the shortcomings of thesis and the prospects of the future work.