Research On EPS Assist Characteristic

The developing process of steering system has experienced several phases from the simple Mechanical Steering System, Mechanical-Hydraulic Steering System to Electric-Hydraulic Steering System, till the Electric Power Steering System (EPS) with lower energy consumption and higher performance.EPS is a new type of automobile steering system, which has the advantages of saving fuel, light, safety and producing less pollution. EPS is taking the place of HPS gradually and becoming the trend of steering system. It's rapidly become the hotspots in the research of automobile technology of the world.This article discusses the characteristics of EPS, working principle, composition and the research status of domestic and abroad. Through the analysis of components of EPS system and the steering system, EPS' dynamics model, full vehicle model with two degrees of freedom and tire model was built. Then the state function of the combination system model was deduced and the model for simulation was built in this paper. Given the EPS performance evaluation, analysis and compare the three types of assist characteristic, and then design a new type of assist curve in order to reduce the steering force which based on the parameters of a certain type of car, Then the dynamic simulation of the ESP system with the designed assist curve has been obtained by MATLAB/SIMULINK to prove that steering force can be reduced by the designed assist characteristic. And theoretical feasibility of this design method has been confirmed.