紧急情况下驾驶员能否做出准确、及时的判断和操作，对于防止交通事故具有重要的现实意义。为 保证车辆行驶安全，有必要对车辆行驶中紧急度做出判断，并给出相应的控制算法。首先提出基于相对距离、 车速和驾驶员基本特征的车辆行驶中紧急度，同时给出基于模糊推理的车辆行驶控制算法，并对其进行了仿真 运算。仿真结果表明：情况越紧急，驾驶员会越快地采用最大制动减速度；驾驶员基本特征对制动操作的影响 明显。总之，通过模糊推理控制后车的制动减速度，能实现后车的行车安全。

It is very important whether a driver can give correct decision and precise operation in emergency． So，it is necessary to judge the emergency degree of environment and provide control algorithm of vehicle motion for ensuring the lives and properties’safety．The emergency degree is firstly given based on relative distance， velocity and drivers’characteristics．Then the control algorithm of vehicle motion based on fuzzy logic is established and is simulated with Simulink．The results show that the higher the emergency degree，the bigger the maximum deceleration is used to control the vehicle．The results also show that the drivers’characteristics have obvious effect on the braking operation．The fuzzy logic is valid to control vehicle’s deceleration．