Vehicle steering control

• US 20070131476A1
• Filed: 12/05/2006
• Published: 06/14/2007
• Est. Priority Date: 12/09/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Eguchi, Takaaki, Kubokawa, Noriki
• Granted Patent: US 7,900,742 B2
• Time in Patent Office: Days
• US Class Current: 180/444
• CPC Class Codes: B62D 1/163 Part of the steering column replaced by flexible means, e.g. cable or belt
• CPC Class Codes: B62D 5/003 Backup systems, e.g. for manual steering B62D5/30 takes precedence
• CPC Class Codes: B62D 5/006 power actuated
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

A steer-by-wire system is provided with a driver operating unit, a turning unit, a backup mechanism, a steering reaction actuator, a wheel turning actuator and a controller. The backup mechanism mechanically connects the driver operating unit to the turning unit via a first shaft to transmit an input torque from the driver operating unit to the turning unit when the driver operating unit and the turning unit are mechanically connected by the backup mechanism. The steering reaction actuator applies a steering reaction torque to the driver operating unit. The wheel turning actuator applies a wheel turning torque to the turning unit via a second shaft. The controller controls the wheel turning actuator and the steering reaction actuator. The controller is configured to control the steering reaction actuator based on an operating parameter of the wheel turning actuator.

Claims

1. A steering apparatus for a vehicle having at least one steered wheel comprising:

a driver operating unit;

a turning unit;

a backup mechanism selectively operable to mechanically connect the driver operating unit to the turning unit via a first shaft to transmit an input torque from the driver operating unit to the turning unit when the driver operating unit and the turning unit are mechanically connected;

a steering reaction actuator operable to apply a steering reaction torque to the driver operating unit;

a wheel turning actuator operable to apply a wheel turning torque to the turning unit via a second shaft; and

a controller operable to control the wheel turning actuator and the steering reaction actuator, the controller being configured to control the steering reaction actuator based on an operating parameter of the wheel turning actuator.

2. The steering apparatus according to claim 1 wherein

the controller is configured to control the steering reaction actuator based on a value corresponding to the wheel turning torque that the wheel turning actuator applies to the turning unit via the second shaft.

3. The steering apparatus according to claim 1, wherein

the first and second shafts are connected to the turning unit in parallel to one another.

4. The steering apparatus according to claim 1, further comprising

an additional wheel turning actuator operable to apply an additional wheel turning torque to the turning unit via the first shaft, with the additional wheel turning actuator constituting a first wheel turning actuator and the wheel turning actuator that applies the wheel turning torque to the turning unit via the second shaft constituting a second wheel turning actuator.

5. The steering apparatus according to claim 4, wherein

the first and second wheel turning actuators comprises first and second wheel turning motors, respectively, with the first wheel turning motor being operable to apply a first wheel turning torque to the turning unit via the first shaft, the second wheel turning motor being operable to apply a second wheel turning torque to the turning unit via the second shaft, and the controller being configured to control the steering reaction actuator based on a driving current of the second wheel turning motor.

6. The steering apparatus according to claim 1, wherein

the turning unit comprises a steering rack, a first pinion gear and a second pinion gear;

the first shaft comprises at least a part of a pinion shaft of the first pinion gear connected at least near a first end part of the steering rack thereof; and

the second shaft comprises at least a part of a pinion shaft of the second pinion gear connected at least near a second end part the steering rack.

7. The steering apparatus according to claim 4, wherein

the controller is further configured to control the steering reaction actuator based on the wheel turning torque of the first wheel turning actuator when the second wheel turning actuator malfunctions or fails.

8. The steering apparatus according to claim 1, wherein

the backup mechanism includes a clutch operable to connect and disconnect the driver operating unit to and from the turning unit, and a cable column connected between the clutch and the turning unit.

9. The steering apparatus as claimed in claim 4, wherein

the controller is configured to compute a current command value based on angle information pertaining to the second wheel turning actuator so as to obtain an angle command value corresponding to an operating state of the driver operating unit and to drive the first and second wheel turning actuators accordingly.

10. A vehicle equipped with the steering apparatus according to claim 1.

11. A steering apparatus comprising:

steering input means for receiving a steering operation from a driver;

turning means for turning at least one steered wheel;

first torque applying means for applying a first wheel turning torque to the turning means via a first transmission path;

second torque applying means for applying a second wheel turning torque to the turning means via a second transmission path;

backup means for mechanically connecting the steering input means to the turning means via the first torque applying means to mechanically transmit an input torque from the steering input means to the turning means via at least part of the second transmission path when the steering input means and the turning means are mechanically connected by the backup means;

steering reaction means for applying a steering reaction torque to the steering input means; and

control means for controlling the steering reaction means based on an operating parameter of the second torque applying means.

12. The steering apparatus according to claim 11, wherein

the control means is configured to control the steering reaction means based on the second wheel turning torque applied to the turning means by the second torque applying means.

13. A vehicle equipped with the steering apparatus according to claim 11.

14. A steering controller comprising:

a first mode control section configured to selectively apply a wheel turning torque to a turning unit for turning at least one wheel via a first transmission path and apply a steering reaction torque to a driver operating unit based on the wheel turning torque transmitted to the turning unit via the first transmission path; and

a second mode control section configured to selectively control a clutch disposed in a second transmission path formed between the driver operating unit and the turning unit to selectively connect and disconnect mechanically the driver operating unit to the turning unit such that a steering torque input of the driver operating unit is transmitted to the turning unit via the second transmission path.

15. A vehicle equipped with the steering controller according to claim 14.

16. A vehicle steering system controller comprising:

a first wheel turning actuator control section configured to control a first wheel turning actuator so as to apply a first wheel turning torque to a turning unit via a first torque transmission path in which a backup mechanism is selectively operable to mechanically connect a driver operating unit to the turning unit;

a second wheel turning actuator control section configured to control the second wheel turning actuator so as to apply a second wheel turning torque to the turning unit via a second torque transmission path; and

a steering reaction actuator control section configured to control a steering reaction actuator of the driver operating unit so as to apply a steering reaction torque to the driver operating unit based only on the second wheel turning torque applied to the turning unit by the second wheel turning actuator when at least the second wheel turning actuator is determined to be operating normally.

17. The vehicle steering system controller according to claim 16, wherein

the steering reaction actuator control section is further configured to control the steering reaction actuator to apply the steering reaction torque to the driver operating unit based on the first wheel turning torque applied to the turning unit by the first wheel turning actuator when the second wheel turning actuator is determined to be malfunctioning.

18. A vehicle equipped with the steering apparatus according to claim 16.

19. A steering method comprising:

applying a wheel turning torque to a turning unit based on a driver input to a driver operating unit via a first transmission path in which the driver input is at least partially non-mechanically transmitted to the turning unit;

applying a steering reaction torque to the driver operating unit in based on the wheel turning torque; and

mechanically connecting the driver operating unit to the turning unit via a backup mechanism forming at least a part of a mechanical transmission path, when at least one of the driver operating unit and the turning unit malfunctions, to transmit a wheel turning torque from the driver operating unit to the turning unit via a mechanical transmission path.

20. The method according to claim 19, wherein

the mechanical transmission path is configured in parallel with the first transmission path.