汽车四自由度系统模型仿真。包括车身垂直振动，俯仰振动，前轴振动，后轴振动对前后车轮的影响。(Simulation of Four - Degree - of - Freedom System Model. Including the vertical vibration of the vehicle body, pitch vibration, front axle vibration, rear axle vibration on the front and rear wheels.)