Study On Key Techniques Of Automobile Electric Power Steering System

Electric Power Steering (EPS) is a new type of vehicle steering system. It has the efficiency of assistance and the sense of speed, which any other type of system doesn' t have. According to the speed of vehicle and torque on steering wheel, Electric Control Unit (ECU), a main part of EPS, can decide the amount of power to assist. The EPS techniques make progress perfectly and it is going to replace traditional Hydraulic Power Steering (HPS). It is a new high-tech which follows the development of modern automobile. In this thesis, we first analyze the development process of the traditional HPS system, the electronic controll HPS system and the EPS system. Then, their merits and defects are also compared. The present developing situation and prospect of EPS is outlined and the principle, structure and characteristics of EPS are discussed. Some key techniques of EPS are also presented.Based on the analysis of key techniques of EPS, the main research focus on two aspects—structure analysis and control methods. A reduction gear is designed and the parameters are optimized. In addition, we present the PD control and fuzzy control schemes on the math model of two degrees of freedom, and simulate by Matlab6.5. At last, we carried out tests in testing bed and minibus with EPS implemented. The results of simulation and test prove that the math mode is correct and effective, and the controller is suitable for improving the dynamic performance of the electric power steering.