汽车动力学稳定性的研究

Research on vehicles′ dynamic stability

首先用相平面法判断车辆的稳定状态,对横摆和侧偏随转向输入角和车速变化的收敛性进行了分析,证明了随车速和转向角输入的增大稳定域减小最后消失.其次用奇点分岔法对车辆稳定性进行了分析,把无耦合的侧向力和垂向力矩分别作为外部输入,分析其对侧偏和横摆收敛的影响.结果表明,垂向力矩输入对侧偏角和横摆角速度的结点都有影响,侧向力输入对侧偏角结点影响相对较大.因而,可以根据不同的横摆角速度和侧偏角,选择不同的侧向力和横摆力矩的组合以改善车辆稳定性.

Firstly, use phase-plane method to judge the stability of vehicle. Analyse the convergences of the yaw velocity and side slip angle following the change of the steering angle and velocity. It proves the stability region of the vehicle diminishes and finally disappears. Secondly, use the bifurcation method to analyse the stability of vehicle. Take the free-coupled side force and vertical force moment as external inputs, and analyse their effect on the convergences of yaw velocity and side slip angle. Results show that vertical force moment affects both the yaw velocity and the side slip angle conversation points while the side force affects side slip angle especially its node points severely. So to combine different side force and vertical force moment can improve the vehicle stability under different yaw velocities and side slip angles.