Control And Simulation Of Electric Power Steering System For Automobile

EPS(Electric Power Steering)is a new type of automobile steering system developed recently, which has the advantages of saving fuel, reducing overall weight, improving driving security and producing less pollutions. EPS is taking the place of HPS gradually and becoming one of the hotspots in the research of automobile technology in the world.The rapidly enhancement of computer performance and development of virtual prototype simulation technology have provided necessary condition for the deeper research of EPS. This thesis simulates and analyzes a multi-body dynamic model of automobiles equipped with EPS based on ADAMS, which is the most authoritative and widely used simulation software in the world.Firstly, the architecture, principle and features as well as of the current development of EPS are interpreted.Secondly, a multi-body dynamic model of automobile equipped with EPS is established, which includes the front/rear suspension,steering system,front/rear wheel and road file, as well as assist torque model.The ideal form and basic parameters of EPS assist characteristic is studied and the effects of parameters of different form of assist curves were analyzed. Combined with the virtual prototype, a type of automobile assist curves is posed. The simulation results prove the notable effect of EPS in improving the steering portability and road feeling.Thirdly, the co-simulation method of ADAMS/Controls is introduced. The compensation control strategy of EPS system is studied and the control model is established in MATLAB/Simulink. A co-simulation is investigated combined with control model in MATLAB/Simulink and mechanical model in ADAMS. The simulation results prove that when steering a large angle on slippery roads, yaw compensation can improve the stability of automobiles; when steering at a low speed, return compensation can improve the lack of returnability caused by friction loss torque; In order to carry out self-adaption, using Fuzzy PD to control the current of the electric motorAt last, a simulation is investigated by using the equation through predigesting the model. Compared the result with which is get by co-simulation, it's proved that it's more true and veracious for the complex system by co-simulation.