文中基于相平面分析方法研究车辆行驶稳定性，根据相图变化规律确定车辆稳 定性判定方法．首先，利用实车试验数据建立了非线性单轨车辆仿真模型，并以此建立了β-β · 相图作为判定稳定性的依据;然后，分析了现有相图稳定区域划分方法的不足，提出改进的五特征值菱形稳定区域划分方法，根据相图的变化规律选用了随平衡点移动的菱形区域作为稳定区域;通过大量仿真建立了全工况下稳定区域的特征值的查表数据库，分析了特征值及稳定区域的变化规律;最后，将基于相平面法的车辆稳定性判定结果作为稳定性算法介入控制的依据，仿真结果表明，该判定方法可以为稳定性算法提供准确的依据，提高车辆稳定性．

In this paper,the vehicle stability is analyzed on the basis of phase plane method,and a vehicle stability criterion is determined according to the change laws of the phase plane.First,a nonlinear single- track vehicle mo- del is constructed by using vehicle test data.On this basis,a sideslip angle- sideslip angular velocity phase plane is established as the stability criterion.Then,by analyzing the shortcomings of the existing phase stability region divi- sion methods,a new method using five characteristic values to determine the diamond stability region is proposed,specifically,the diamond region moving with the equilibrium point is selected as the stability region according to the change laws of the phase plane.Moreover,a dataset of the characteristic values of the stability region under full condition is built by a large number of simulations and the change laws of both the characteristic values and the sta- bility region are discussed.Finally,the results obtained by the stability criterion based on phase plane method are used to determine the introduction of the stability algorithm.Simulation results show that the proposed stability cri- terion can provide a basis for stability control algorithms and improve vehicle stability.