Steering control device, steering control method, and non-transitory computer readable storage medium

1. A steering control device for controlling and linking a movement of a steering member by a steering actuator and a movement of a turning wheel by a turning actuator in an automatic driving mode of a vehicle, the steering control device comprising:

a steering angle control unit that is configured to control an actual steering angle of the steering member via the steering actuator;

a turning angle control unit that is configured to control an actual turning angle of the turning wheel via the turning actuator; and

a target generation unit that is configured to generate a target steering angle, which is a control target for the actual steering angle, and a target turning angle, which is a control target for the actual turning angle, wherein:

before the turning angle control unit controls the actual turning angle toward the target turning angle to follow a planned trajectory scheduled for the vehicle, the steering angle control unit controls the actual steering angle toward the target steering angle to follow the planned trajectory.

2. The steering control device according to claim 1 , wherein:

the target generation unit is configured to generate the target steering angle at a future control point after a current control point on the planned trajectory, in conjunction with generation of the target turning angle at the current control point on the planned trajectory.

3. The steering control device according to claim 1 , wherein:

the target generation unit is configured to generate the target turning angle at a current control point on the planned trajectory by delaying a phase with respect to the target steering angle at a future control point after the current control point on the planned trajectory.

4. The steering control device according to claim 1 , wherein:

the target generation unit generates the target steering angle at a future control point after a current control point on the planned trajectory by advancing a phase with respect to the target turning angle at the current control point on the planned trajectory.

5. The steering control device according to claim 2 , wherein:

the target generation unit adjusts a control time from the current control point to the future control point according to a control parameter in the automatic driving mode.

6. The steering control device according to claim 2 , wherein:

when an emergency condition for instructing an emergency motion to the turning wheel is satisfied, the target generation unit adjusts a control time from the current control point to the future control point to be shorter than when the emergency condition is not satisfied.

7. The steering control device according to claim 2 , wherein:

when an emergency condition for instructing an emergency motion to the turning wheel is satisfied, the target generation unit adjusts an angular velocity at the target steering angle at the future control point to be smaller than when the emergency condition is not satisfied.

8. The steering control device according to claim 2 , wherein:

when a go-straight condition for instructing a go-straight motion to the turning wheel is satisfied, the target generation unit forcibly sets a control time from the current control point to the future control point to be zero.

9. The steering control device according to claim 2 , wherein:

when a go-straight condition for instructing a go-straight motion to the turning wheel is satisfied, the target generation unit forcibly sets the target steering angle to be a conversion value from the target turning angle at the current control point.

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

one or more processors; and

a memory coupled to the one or more processors and storing program instructions that when executed by the one or more processors cause the one or more processors to provide at least: the steering angle control unit; the turning angle control unit; and the target generation unit.

11. A steering control method for controlling and linking a movement of a steering member by a steering actuator and a movement of a turning wheel by a turning actuator in an automatic driving mode of a vehicle, the steering control method comprising:

controlling an actual steering angle θf the steering member via the steering actuator;

controlling an actual turning angle θf the turning wheel via the turning actuator; and

generating a target steering angle, which is a control target for the actual steering angle, and a target turning angle, which is a control target for the actual turning angle, wherein:

before the actual turning angle is controlled toward the target turning angle to follow a planned trajectory scheduled for the vehicle in the controlling of the actual turning angle, the actual steering angle is controlled toward the target steering angle to follow the planned trajectory in the controlling of the actual steering angle.

12. The steering control method according to claim 11 , wherein:

the generating of the target steering angle and the target turning angle includes: generating the target steering angle at a future control point after a current control point on the planned trajectory, in conjunction with generation of the target turning angle at the current control point on the planned trajectory.

13. The steering control method according to claim 11 , wherein:

the generating of the target steering angle and the target turning angle includes: generating the target turning angle at a current control point on the planned trajectory by delaying a phase with respect to the target steering angle at a future control point after the current control point on the planned trajectory.

14. The steering control method according to claim 11 , wherein:

the generating of the target steering angle and the target turning angle includes: generating the target steering angle at a future control point after a current control point on the planned trajectory by advancing a phase with respect to the target turning angle at the current control point on the planned trajectory.

15. The steering control method according to claim 12 , wherein:

the generating of the target steering angle and the target turning angle includes: adjusting a control time from the current control point to the future control point according to a control parameter in the automatic driving mode.

16. The steering control method according to claim 12 , wherein:

when an emergency condition for instructing an emergency motion to the turning wheel is satisfied, the generating of the target steering angle and the target turning angle includes: adjusting a control time from the current control point to the future control point to be shorter than when the emergency condition is not satisfied.

17. The steering control method according to claim 12 , wherein:

when an emergency condition for instructing an emergency motion to the turning wheel is satisfied, the generating of the target steering angle and the target turning angle includes: adjusting an angular velocity at the target steering angle at the future control point to be smaller than when the emergency condition is not satisfied.

18. The steering control method according to claim 12 , wherein:

when a go-straight condition for instructing a go-straight motion to the turning wheel is satisfied, the generating of the target steering angle and the target turning angle includes: forcibly setting a control time from the current control point to the future control point to be zero.

19. The steering control method according to claim 12 , wherein:

when a go-straight condition for instructing a go-straight motion to the turning wheel is satisfied, the generating of the target steering angle and the target turning angle includes: forcibly setting the target steering angle to be a conversion value from the target turning angle at the current control point.

20. A non-transitory tangible computer readable storage medium comprising instructions being executed by a computer, the instructions including a computer-implemented method for controlling and linking a movement of a steering member by a steering actuator and a movement of a turning wheel by a turning actuator in an automatic driving mode of a vehicle, the instructions including:

controlling an actual steering angle θf the steering member via the steering actuator;

controlling an actual turning angle θf the turning wheel via the turning actuator; and

generating a target steering angle, which is a control target for the actual steering angle, and a target turning angle, which is a control target for the actual turning angle, wherein:

before the actual turning angle is controlled toward the target turning angle to follow a planned trajectory scheduled for the vehicle in the controlling of the actual turning angle, the actual steering angle is controlled toward the target steering angle to follow the planned trajectory in the controlling of the actual steering angle.