驱动力矩对汽车动力学特征的影响

Effect of Driving Torque on Dynamic Characteristics of Vehicles

为分析驱动力矩对汽车系统动力学特征的影响,以魔术公式为基础建立了引入驱动力矩的五自由度(纵向速度、侧向速度、横摆角速度、前轮角速度和后轮角速度)汽车系统平面运动的非线性动力学模型;以后轮驱动系统为例,通过多初值点的相空间分析、单初值点的时域分析及相应轮胎力的分布特征分析,探讨了前轮转角为0时恒定驱动力矩对汽车动力学特征的影响;通过对恒定驱动力矩试验的进一步分析,计算了系统状态变量的分岔图.结果表明:在零转角条件下,随着驱动力矩数值的增大,五自由度汽车动力学系统将发生分岔现象;驱动力矩对汽车的动力学特征存在明显的影响.

In order to discover the effect of driving torque on the dynamic characteristics of vehicle system,firstly,a planar-motion nonlinear dynamic model of the vehicle system with five degrees of freedom( longitudinal velocity,lateral velocity,yaw rate,front-wheel rotational velocity and rear-wheel rotational velocity) is established on the basis of Magic tyre formula. Then,by taking the rear-wheel driving system as an example,the phase space analysis of multiple initial values,the time domain analysis of single initial value as well as the corresponding tyre-force distribution feature analysis is carried out,and the effect of constant driving torque on the dynamic characteristics of vehicle without front-wheel steering angle input is discussed. Finally,through a further analysis of the numerical calculation with constant driving torque,the bifurcation diagrams of system state variables are plotted. The results show that,under the condition of zero steering angle input,bifurcation phenomenon of the vehicle dynamic system with 5 degrees of freedom may occur with the increase of driving torque; and that driving torque has an obvious effect on the dynamic characteristics of vehicles.