Influence of velocity change on handling and stability of vehicle

To improve the handling and stability of vehicle while velocity changing, a dynamic steering model was established, and all of the coefficients of differential equations describing the model changed with velocity change. The influence of velocity change on the handling and stability was quantitatively researched by varying parameter dynamic simulations. Study result shows that when vehicle decelerates, part load is transferred from rear axle to front axle caused by the positive longitudinal inertial force of vehicle, the corner stiffness of front axle increases, the corner stiffness of rear axle decreases, and vehicle steering gain increases, so the handling and stability of vehicle deteriorate. Vehicle steering gain increases more rapidly and obviously with higher early velocity and/or bigger deceleration. When vehicle accelerates, part load is transferred from front axle to rear axle caused by the negative longitudinal inertial force of vehicle, the corner stiffness of front axle decreases, the corner stiffness of rear axle increases, and vehicle steering gain decreases. Obviously, avoiding big deceleration, lowing vehicle mass center and enlarging wheelbase as far as possible during vehicle design and manufacture are effective methods to lessen the degree that the handling and stability become worse rapidly in slowing vehicle down.