| 摘要 |
PURPOSE:To suppress an increase of an understeering tendency by correcting the steering ratio so that the steering state of front wheels and the steering state of rear wheels are in the opposite phase relationship and making the correction quantity automatically variable when a lateral force is a predetermined value or more. CONSTITUTION:A rear wheel steering mechanism interlocked with the steering of front wheels has a pulse motor 30 moving a rear wheel steering rod and a pump drive motor 44 applying a hydraulic assist force and is controlled by a control unit 50. In this case, the control unit 50 is constituted of a steering ratio characteristic selecting unit 59 selecting one of multiple steering ratio characteristics stored in a memory unit 58 based on the detected value of a lateral force and a rear wheel steering angle arithmetic unit 60 calculating the rear wheel steering angle based on the steering ratio characteristic and the detected values of the steering angle and the vehicle speed. This steering ratio is selected so that the steering state of front wheels and the steering state of rear wheels are in the opposite phase relationship when the lateral force is a predetermined value or more, and this selection is made automatically variable in response to a signal from a torque sensor 57. |
