REAR WHEEL STEERING DEVICE FOR FOUR-WHEEL STEERING VEHICLE

PURPOSE:To perform steering control accurately on rear wheels, and improve durability of an electric motor for steering the rear wheels in a four-wheel steering vehicle. CONSTITUTION:A microcomputer 35 determines a target rear wheel steering angle according to vehicle speed detected by a vehicle speed sensor 31, a yaw rate detected by a yaw rate sensor 32 and a front wheel steering angle detected by a front wheel steering angle sensor 33, and this determined target rear wheel steering angle is restricted withing a range obtained by adding a limit steering angle variation determined according to speed performance and accelerating performance of an electric motor 21 to a present rear wheel steering angle or the target rear wheel steering angle. According to a difference between the determined and restricted target rear wheel steering angle and a rear wheel steering angle detected by a rear wheel steering angle sensor 34, rotation of the electric motor 21 is controlled, and rear wheels RW1 and RW2 are steered at the target rear wheel steering angle.