REAR WHEEL STEERING ANGLE CONTROL METHOD

A rear wheel steering control method in which a rear steering command is retrieved from a three dimensional (3D) lookup table as a function of both front wheel steering angle (Df) and vehicle speed (Nv) in normal operating modes, and from a two dimensional (2D) lookup table as a function of front wheel steering angle without regard to the vehicle speed under conditions where the vehicle speed information is deemed not credible. If the measured vehicle speed is judged to be not credible, it is replaced with an estimated or recently measured credible vehicle speed value, and the replacement value is then used in connection with the measured front wheel steering angle signal to retrieve a rear wheel steering angle command from the 3D lookup table. However, when the front wheels (12,14) have been returned to the straight ahead position, the rear wheel steering angle command is retrieved from the 2D lookup table as a sole function of the measured front wheel steering angle. When the vehicle speed signal abnormality is corrected and the front wheels are returned to the straight ahead position, the apparatus reverts to the normal operating mode in which the rear wheel steering angle command is retrieved from the 3D lookup table as a function of both the front wheel steering angle and the measured vehicle speed.