Patent ID: 7066295

Claim:
A vehicle steering apparatus for changing a steering angle of steered wheels according to turning of a steering wheel, the apparatus comprising: a variable transmission ratio device having a motor for steering the steered wheels, wherein the steering angle of the steered wheels is determined by superimposing a first steering angle based on a turning angle of the steering wheel and a second steering angle based on the activation of the motor on each other, and wherein the variable transmission ratio device adjusts the second steering angle, thereby changing the ratio of the steering angle of the steered wheels to the turning angle of the steering wheel; a calculation unit for calculating a variable value that continuously changes in accordance with a steering characteristic of the vehicle, based on any one of a difference value between an actual yaw rate and a target yaw rate, a difference value between an actual slip angle and a target slip angle, and a difference value between a front wheel slip angle and a rear wheel slip angle; a control unit, wherein, when the variable value indicates that the steering characteristic is understeer, the control unit controls the variable transmission ratio device to change the second steering angle such that the greater the understeer indicated by the variable value, the smaller the steering angle of the steered wheels relative to the turning angle of the steering wheel becomes; and a correction unit, wherein, when the differentiated value of the variable value indicates that the understeer is changing to increase, the correction unit corrects the variable value such that the greater the degree of change of the understeer indicated by the differentiated value, the greater the understeer indicated by the variable value becomes.