Steering control apparatus

1. A steering control apparatus, comprising:

a steering wheel;

steered wheels mechanically disconnected from the steering wheel;

a direction varying actuator to operate the steered wheels;

a steering reaction actuator to apply steering reaction torque to the steering wheel;

a steering controller configured to output a control command to the direction varying actuator for applying a direction varying torque to the steered wheels in accordance with the steering status of the steering wheel; and

a backup mechanism disposed between the steering wheel and the steered wheels to permit mechanical connection and disconnection of the steering wheel and the steered wheels; wherein

the steering controller is configured to output a control command to the steering reaction actuator for applying a steering reaction torque to the steering wheel in accordance with the direction varying status of the steered wheels;

the steering controller is configured to gradually increase the steering reaction torque with the lapse of time when the direction varying angle of the steered wheels reaches the vicinity of the maximum direction varying angle; and

the steering controller is configured to, when a target direction varying angle generated from a steering angle reaches the vicinity of the maximum direction varying angle of the steered wheels, selectively perform a backup control process of outputting a mechanical connection command to the backup mechanism and selectively perform a steering reaction torque correcting control process of gradually increasing the steering reaction torque with the lapse of time during a period of time from the mechanical connection command to completion of the mechanical connection.

2. The steering control apparatus according to claim 1 , wherein the steering controller is configured to selectively reduce the steering reaction torque and to selectively leave a predetermined torque after the mechanical connection is completed by the backup mechanism.

3. The steering control apparatus according to claim 2 , wherein the steering controller is configured to selectively leave the steering reaction torque corresponding to inertia of the steering wheel after the mechanical connection is completed by the backup mechanism.

4. The steering control apparatus according to claim 1 , wherein the steering controller is configured to selectively reduce the direction varying torque and to selectively leave a predetermined torque after the mechanical connection is completed by the backup mechanism.

5. The steering control apparatus according to claim 4 , further comprising:

a steering torque sensor for detecting a steering torque input to the steering wheel; and

wherein the steering controller is configured to selectively leave an assist torque of a steering assist control process in accordance with the detected steering torque value after the mechanical connection is completed by the backup mechanism.

6. The steering control apparatus according to claim 1 , wherein the steering controller is configured to selectively maintain the direction varying torque of a steer-by-wire control process during a predetermined period of time of which a maximum period of time is from the time when the mechanical connection command is output to the backup mechanism to the time when the mechanical connection is completed by the backup mechanism.

7. The steering control apparatus according to claim 1 , further comprising:

a steering torque sensor for detecting a steering torque input to the steering wheel; and

wherein the steering controller is configured to selectively increase an amount of enhancement correction of the steering reaction torque as the detected steering torque value becomes greater.

8. The steering control apparatus according to claim 1 , further comprising:

a rudder angular velocity sensor for detecting a steering angular velocity of the steering wheel or a direction varying angular velocity of the steered wheels; and

wherein the steering controller is configured to selectively increase an amount of enhancement correction of the steering reaction torque as the detected steering angular velocity value becomes greater.

9. The steering control apparatus according to claim 1 , further comprising:

a vehicle behavior sensor for detecting an amount of vehicle behavior; and

wherein the steering controller is configured to selectively increase an amount of enhancement correction of the steering reaction torque as the detected vehicle behavior value becomes greater.

10. The steering control apparatus according to claim 1 , further comprising:

a vehicle speed sensor for detecting vehicle speed; and

wherein the steering controller is configured to selectively decrease an amount of enhancement correction of the steering reaction torque as the detected vehicle speed value becomes greater.

11. The steering control apparatus according to claim 1 , further comprising:

a temperature sensor for detecting a temperature of the steering reaction actuator; and

wherein the steering controller is configured to selectively decrease an amount of enhancement correction of the steering reaction torque as the detected temperature value of the steering reaction actuator becomes greater.

12. A steering control apparatus, comprising:

a steering wheel;

at least one steered wheel mechanically disconnected from the steering wheel;

a direction varying actuator to operate the at least one steered wheel;

a steering reaction actuator to apply steering reaction torque to the steering wheel;

a backup mechanism disposed between the steering wheel and the at least one steered wheel to permit mechanical connection and disconnection of the steering wheel and the at least one steered wheel;

an angular velocity sensor for detecting one of a steering angular velocity of the steering wheel and a direction varying angular velocity of the at least one steered wheel; and

a steering controller configured to output a control command to the direction varying actuator for applying a direction varying torque to the steered wheels in accordance with a steering status of the steering wheel,

to output a control command to the steering reaction actuator for applying a steering reaction torque to the steering wheel in accordance with the direction varying status of the at least one steered wheel;

to selectively increase an amount of enhancement correction of the steering reaction torque as the detected angular velocity value becomes greater; and

to, when a target direction varying angle generated from a steering angle reaches the vicinity of the maximum direction varying angle of the steered wheels, selectively perform a backup control process of outputting a mechanical connection command to the backup mechanism and selectively perform a steering reaction torque correcting control process of gradually increasing the steering reaction torque with the lapse of time during a period of time from the mechanical connection command to completion of the mechanical connection.

13. The steering control apparatus according to claim 12 wherein the steering controller is configured to selectively reduce the steering reaction torque and to selectively leave a predetermined torque after the mechanical connection is completed by the backup mechanism.

14. The steering control apparatus according to claim 12 wherein the steering controller is configured to selectively reduce the direction varying torque and to selectively leave a predetermined torque after the mechanical connection is completed by the backup mechanism.

15. The steering control apparatus according to claim 14 , further comprising:

a steering torque sensor for detecting a steering torque input to the steering wheel; and

wherein the steering controller is configured to selectively leave an assist torque of a steering assist control process in accordance with the detected steering torque value after the mechanical connection is completed by the backup mechanism.

16. The steering control apparatus according to claim 12 wherein the steering controller is configured to selectively maintain the direction varying torque of a steer-by-wire control process during a predetermined period of time of which a maximum period of time is from the time when the mechanical connection command is output to the backup mechanism to the time when the mechanical connection is completed by the backup mechanism.

17. The steering control apparatus according to claim 12 , further comprising:

a steering torque sensor for detecting a steering torque input to the steering wheel; and

wherein the steering controller is configured to selectively increase the amount of enhancement correction of the steering reaction torque as the detected steering torque value becomes greater.

18. The steering control apparatus according to claim 12 , further comprising:

a vehicle behavior sensor for detecting an amount of vehicle behavior; and

wherein the steering controller is configured to selectively increase the amount of enhancement correction of the steering reaction torque as the detected vehicle behavior value becomes greater.

19. The steering control apparatus according to claim 12 , further comprising:

a vehicle speed sensor for detecting vehicle speed; and

wherein the steering controller is configured to selectively decrease the amount of enhancement correction of the steering reaction torque as the detected vehicle speed value becomes greater.

20. The steering control apparatus according to claim 12 , further comprising:

a temperature sensor for detecting a temperature of the steering reaction actuator; and

wherein the steering controller is configured to selectively decrease the amount of enhancement correction of the steering reaction torque as the detected temperature value of the steering reaction actuator becomes greater.