Patent ID: 6560518
Filing Date: 2003-05-06
Classification: B62D

Abstract:
A method for mapping a vehicle steering ratio as a function of vehicle velocity and yaw rate having the steps of:determining the length, L, of the wheelbase of the vehicle; determining the understeer coefficient, Kus, of the vehicle; accelerating the speed, U, of the vehicle past a predetermined value; turning the vehicle steering wheel through a plurality of steering wheel angles at predetermined angular rate about a known vehicle center axis in the clockwise direction and repeat in the counterclockwise direction; measuring the yaw rate, r, of the vehicle at each one of the plurality of predetermined steering wheel angles; calculating the front tire steer angles, &dgr;{f}, of the vehicle according to the equation &dgr;{f}=r/U*[L+U2(Kus/g)]for each value of U and each predetermined steering wheel angle;calculating the steering ratio of the front tires from the predetermined steering wheel angle and the front tire steer angle; repeating the previous steps for a plurality of vehicle speeds and predetermined steering wheel angles; and then calculating a linear curve through each curve representing a steering ratio wherein the linear curve follows the general equation y=mx+b wherein b is the value of steering ratio at zero velocity for each predetermined steering wheel angle and m is the slope of the curve.