The Research On Car Wire-four-wheel Steering System

The car wire-four-wheel steering system combine advantages of steer-by-wire system and four-wheel steering system. The transmission of electrical signal replaces the connection of traditional mechanical vehicle. Each wheel of the car actives independently on the control of the information processing unit combined with the motion state of the vehicle body. It makes the vehicle steering system achieve intelligent control. Not only we are free to design steering characteristics of the car, but also the feature of the vehicle steering performance can be improved by using the car wire-four-wheel steering system.In this paper, the car wire-four-wheel steering system's basic structure and composition and how the system works are elaborated, based on vehicle dynamics theory, mathematical models of each component is established on the basis of detailed analysis. The four steering angle input two degrees of freedom linear model of the car is derived based on the traditional linear two degree of freedom vehicle handling model. The most commonly used control strategy were analyzed and compared, based on the mathematical model derived by this study to determine the remote control used in wire-four-wheel steering system control strategy.1 The road feeling is generated through the feedback of the steering resistance;2 Steering actuator is controled by PID control servo with the input signal;3 The front wheel of the system by seted transmission ratio control;4 The back wheel use the front wheel angle and yaw rate feedback control strategy.Various control algorithms are obtained based on the control strategy. To control the sideslip angle to zero as the goal of the control of the entire vehicle, according to Ackermann principle, the corner of the four wheels are coordinated, the four wheels in turn are pure rolling.This article uses Simulink to establish the simulation model of each controller and the various components of wire-four-wheel steering system simulation, thereby establishing a whole system simulation model. The enter angle features of the steering wheel, the actuator response, the feedback torque characteristics of electromagnetic force on the steering and vehicle characteristics are simulated. The results shows that the control strategy can achieve the basic purpose of control, wire-four-wheel steering system can improve the car's steering characteristics.