基于李雅普诺夫和相平面图的车辆失稳机理研究

Study on Vehicle Instability Mechanism Based on Lyapunov First Method and Phase Plane

为了提高分布式驱动无人驾驶平台的操纵稳定性,基于李雅普诺夫第一法和相平面图对车辆的失稳机理进行了系统的分析.首先建立基于Fiala轮胎模型的非线性二自由度车辆动力学模型;然后对车辆非线性系统平衡点进行求解并分析;最后在不同工况下分析车辆的质心侧偏角和横摆角速度相平面图,并对稳定性条件和失稳机理进行了分析.研究结果表明:当车轮转向角小于分叉点对应的转向角度时,车辆能够很好地执行驾驶意图;当车轮转向角大于分叉点对应的角度,则稳定平衡点消失,从而导致车辆失稳.该方法为车辆稳定性分析提供了理论依据.

In order to improve the handling stability of the distributed driverless platform,the instability mechanism of the vehicle is systematically analyzed based on the Lyapunov first method and the phase plane diagram.Firstly,the nonlinear bicycle model is established using the Fiala tire model.Then,the equilibrium point of vehicle’s nonlinear system is solved.Besides,the phase diagram of the sideslip angle and yaw rate of vehicle’s mass center is analyzed under different working conditions,Finally,the stability conditions and instability mechanism are analyzed.The research results show that,when the steering angle is less than the angle corresponding to the bifurcation point,vehicle can welly execute driver's intention;however.When the steering angle is greater than the angle corresponding to the bifurcation point,the balance point disappears,resulting in vehicle instability.This method provides theoretical basis for the vehicle handling stability analysis.