The instantaneous axis when the human body rotates relative to the ground is called the human body rolling axis. The axis passes through the instantaneous rotation centers on the cross section of the front and rear axles of the vehicle body. These two instantaneous centers are called rolling centers.The distance from the roll center to the ground is called the height of the roll center. The position of the roller center is high, the distance from the center of mass of the car body is shortened, the lateral force arm and the roller moment are reduced, and the inclination angle of the car body is also reduced. However, an excessively high roll center will cause a large change in the wheelbase when the body is tilted, accelerating tire wear.2. Suspension inclination rigidityThe tilt stiffness of the suspension refers to the rolling time (the wheels remain on the ground). When the body unit turns, the suspension system gives the body total elasticity to restore the coupling torque.