公路平曲线超高／反超高对车辆操纵的影响

为得到超高率对车辆方向控制的影响，以“道路-驾驶人-车辆”仿真系统为手段，以超高率／反超高率和行驶速度为试验变量，以小客车为仿真车型，以一条设计速度为30km／h的三级公路为试验对象，进行了三维路面上行车动力学的仿真试验．试验结果表明：①超高会减轻侧向力作用下轮胎的侧偏角，从而减低对方向盘角输入的需求；②超高会减小弯道上的轮胎拖距，并减弱前轮转动对车体的抬升作用，明显降低曲线行驶时的操舵矩，从而使操纵变得容易；③超高也会增加车辆的侧倾摆动（朝曲线内侧），对于低速车辆，其摆动会更明显；④小半径曲线上的双向路拱或者反超高会增加转向需求，当车速较高时，其方向将难以控制．

The effect of superelevation/reverse superelevation on vehicle steering control

To find out the effect of the superelevation rate of curved segment on the vehicle direction control, driving simulation tests on 3D road surface with superelevation was conducted by means of ＂road-driver-vehicle＂ simulation system. In which superelevation rate and driving speed was selected as test variables,a passenger car was selected as test vehicle type,and a rural road with design speed of 30 km/h was the test objective. The result shows that： （1）superelevation of horizontal curves will alleviate the tyre slip angle under the action of side force, thus reducing the requirements of steering inputs; （2）superelevation can obviously decrease the steering moment of vehicles traveling on curves, thus making the steering easier, because the superelevation will reduce the pneumatic trail on a bend and weaken the lifting action of front wheel drive on the vehicle body; （3） superelevation can also increase the tilting oscillation of vehicles （towards the inside part of the curve）,with such oscillation more apparent for lower speed vehicles; （4）for sharp curves,two-way road crown or reverse superelevation will increase the steering requirements and result in the lose of steering control while driving at a higher speed.