基于MATLAB/Simulink四轮转向机构的运动仿真与分析

Motion Simulation and Analysis of Automobile Four-wheel Steering Mechanism Based on MATLAB/Simulink

根据运动学相关理论,在前轮转向二自由度汽车模型上建立四轮转向汽车的数学模型,运用MATLAB/Simulink软件进行建模,汽车在匀速直线运动下给定一个方向盘转角作为仿真条件,观察两种转向机构的横摆角速度和质心侧偏角的变化特点并比较。仿真结果表明,低速状态下,四轮转向系统汽车运用前后轮同时做逆向运动,提供了比前轮转向系统更大的横摆角速度,质心侧偏角在短时间内稳定为零,减小了转弯半径,灵活性增加;高速状态下,四轮转向系统汽车前后轮同时做同向运动,横摆角速度小于前轮转向系统的横摆角速度,质心侧偏角最终为零,且保持稳定,操纵稳定性提高。装备了四轮转向系统的汽车优于装备前轮转向系统的汽车。

According to the kinematic theory,the mathematical model of four-wheel steering vehicle is established on the twodegree-of-freedom vehicle model of front wheel steering.The modeling is carried out by using MATLAB/Simulink software.A steering wheel angle is given as the simulation condition under the uniform linear motion.The characteristics of yaw rate and mass center sideslip angle of the two steering mechanisms are observed and compared.The simulation results show that under low velocity condition,the vehicle with four-wheel steering system uses the front and rear wheels to do reverse motion at the same time,providing a greater yaw speed than the front wheel steering system.The center of mass side angle is stable to zero in a short time,so as to reduce the radius of its own turning and increase the flexibility.At high speed,the front and rear wheels of the four-wheel steering system move in the same direction at the same time,and the yaw velocity is less than that of the front wheel steering system.The yaw velocity of the four-wheel steering system is also lower than that of the front wheel steering system.The sideslip angle of the center of mass is finally zero,and it remains stable,and the handling stability is improved.Therefore,the car equipped with fourwheel steering system is better than the car equipped with front-wheel steering system.