Research And Design Of Vehicle EPS System

The themes of the present era are energy-saving and environmental protection. As an important part of the car, Steering system should also keep to the point of the times. Therefore, Electronic Power Steering (EPS) comes into being. Compared with traditional hydraulic steering system, EPS is more security, comfort better and more convenient to maintain, the most important is more energy-saving and more advantageous to environmental protection, and it's the inexorable trend of the future steering system.The subject investigated of this paper is EPS. On the base of the in-depth research and analysis of the development history of the automotive steering system and the domestic and international development status, the structure of EPS was simplified and the structure chart was drawn, at the same time, all parts of the graph were introduced and this paper established the dynamics mathematical model of EPS, the mathematical model of tire and the power motor, and the model of transmission function, which laid the base for the establishment of simulation model, In order to establish the simulation models and determine the output values, this paper selected one specific model and determined the parameters of the power motor, such as rated torque, rated voltage and rated power etc. In order to identify the target current of the power motor, this paper also researched the helping-hand characteristic of EPS and selected the fuzzy control strategy to control target current of the motor armature. Two kinds of the power motor control strategies which were the conventional PID control and the fuzzy adaptive PID control were studied. Then, according to the dynamic mathematical model of EPS, this paper established its simulation model and identified the variation trend of the target current with the torque and speed changes. At the same time, this paper also verified the feasibility of the fuzzy controller and the follow-on characteristic of target current under the action of the conventional PID controller and fuzzy adaptive PID controller. Through verification, the effect of the fuzzy adaptive PID controller is better than the conventional PID controller.