汽车转向非线性平衡点求解新方法及其应用

针对汽车转向非线性稳定性平衡点确定问题，提出了求解汽车转向非线性平衡点的一种新方法。建立了汽车转向非线性2自由度模型，采用简化魔术公式轮胎模型描述非线性轮胎侧向力。给出了转向非线性平衡点的表示，对粒子群算法进行了简要分析，提出了求解转向平衡点的粒子群算法。设计了前轮转角、路面附着系数和车速分别变化的3种行驶条件，对3种行驶条件下的转向非线性平衡点进行了求解。结果表明，粒子群算法可以准确求得汽车转向非线性平衡点，适应值小于设置的10-4的精度。

A New Method for Solving the Nonlinear Equilibrium Point While Steering a Vehicle

The paper proposes a new method to determine the nonlinear equilibrium point for vehicle steering. The nonlinear two degree-of-freedom steering model is established, and the simplified magic formula tire model is used to describe the nonlinear tire lateral force. The particle swarm optimization algorithm is briefly analyzed, and applied to solve the steering nonlinear equilibrium point. Three driving conditions with different front wheel steer angles, the values of road adhesion coefficient and vehicle speeds are designed, under which the nonlinear equilibrium points are obtained respectively. The results show that the particle swarm optimization algorithm can accurately estimate the steering nonlinear equilibrium point,and the fitness value is less than the set accuracy of 10-4.