The Simulational Analysis And Control Study Of The Electric Power Steering System

As electronic technology more widely used in automotive, automotive's safety, comfort and handling and many other properties have been improved significantly. Because of the emergence of the electric power steering system, the vehicle can easily steer when driving at a relatively low speed and have good manipulation when driving an a relatively high speed. It is due to the distinct advantages owned by the electric power steering system that it is gradually replacing the traditional hydraulic power steering system. The electric power steering system represents the future direction of the steering system. It is of great importance to highlight the study of the electric power Steering System.This paper focuses on the controlling strategies of the electric power steering system. In order to fully take use of the PID control's advantages such as having mature technology and good robustness and the fuzzy control's advantages such as not requiring the accuracy of the mathematical models to control the electric power steering system,there is a combination of the PID control and the fuzzy control.Firstly,this article briefly describes the organization and working principles of the electric power steering system, then there is an introduction to the common strategies of the electric power steering system, which mainly include the conventional PID control strategy, the intelligent PID control strategy, intelligent control method and the H 8 control strategy;。Secondly, there is a force analysis to the electric power steering system, which mainly include analyzing the torque of the steering wheel and the resisitance of the front wheel. On the basis of the force analysis, the electric power steering system's dynamic model is established. The electric power steering system's dynamic model mainly include the torque sensor's model, tire's model and motor's model,.In order to analyze the electric power steering system's impact on the vehicle yaw rate, the vehicle's two degrees'freedom model is built.Finally, through the analysis of the electric power steering system's mathematical model, the corresponding simulation models are established. On the basis of full study of the assisting characteristics of the electric power steering system, the requirements which the ideal assisting characteristics curve should satisfy are acquired. Then through using fuzzy control to design the assisting characteristics curve, the assisting characteristics curve is drawed. On the basis of this, this paper takes use of the PID control and the fuzzy self-adjusting PID control to control the assisting characteristics of the electric power seeing system. Through the comparison study of the two controlling strategies, it is easy to find out that the fuzzy self-adjusting PID control has advantage over the conventional PID control.