Abstract: A steering angle control apparatus for controlling steering angles of front wheels and rear wheels of a vehicle includes a yaw rate detector for detecting an actual yaw rate of the vehicle. A desired yaw rate calculator estimates a desired yaw rate for causing the vehicle to drive stably. A yaw rate disturbance calculator calculates a yaw rate disturbance which causes the detected yaw rate to deviate from an ideal yaw rate of the vehicle assuming driving in ideal driving conditions. A desired yaw rate compensator compensates the desired yaw rate based on the calculated yaw rate disturbance and produces a compensated yaw rate so that the desired yaw rate tracks the compensated yaw rate.

Abstract: A control system robust with respect to a vehicle dynamic characteristic variation by a vehicle speed change by estimating an unknown characteristic term in a target yaw rate following system so as to reduce a side slip angle at a transmission time, wherein right and left rear wheels are directly steered using an electric motor controller, and an instruction signal to the motor controller is calculated with a simple calculation using a vehicle speed characteristic estimator with a control amount calculator so that a real yaw rate may follow a target yaw rate calculated by a target yaw rate calculator using respective sensor output values of a vehicle speed sensor, a yaw rate sensor, a steering wheel angle sensor, and a rear wheel steering sensor for each control period.

Abstract: A steering angle of rear wheels of a four-wheel steering vehicle is controlled so that a quick response of an electric motor mounted in the rear wheels is achieved only when it is necessary, thereby avoiding wasteful consumption of power. In addition, a yaw rate feedback system is kept stable. When unstable vibration of the electric motor is detected, a gain to the yaw rate is adjusted.

Abstract: A steering angle of rear wheels of a four-wheel steering vehicle is controlled so that a quick response of an electric motor mounted in the rear wheels is achieved only when it is necessary, thereby avoiding wasteful consumption of power. In addition, a yaw rate feedback system is kept stable. When unstable vibration of the electric motor is detected, a gain to the yaw rate is adjusted.