Vehicle steering control

• US 7,900,742 B2
• Filed: 12/05/2006
• Issued: 03/08/2011
• 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
• Primary Examiner(s): Boehler; Anne Marie M
• Application Number:
  US11/633,646
• Publication Number:
  US 20070131476A1
• Time in Patent Office: 1,554 Days
• Field of Search: 180/402, 180/403, 180/405, 180/407, 180/443, 180/444, 180/446
• US Class Current: 180/402
• 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 including a first shaft, a second shaft, and a steering mechanism disposed between the first and second shafts;

a backup mechanism selectively operable to mechanically connect the driver operating unit to the turning unit via the first shaft to transmit a mechanical input torque from the driver operating unit to the turning unit when the driver operating unit and the turning unit are mechanically connected, the backup mechanism being arranged with respect to the driver operating unit and the turning unit such that a mechanical input torque from the driver operating unit cannot be transmitted to the turning unit via the second shaft;

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

a first wheel turning actuator mechanically connected to the backup mechanism and operable to apply a wheel turning torque to the turning unit via the first shaft; and

a second wheel turning actuator laterally spaced from the first wheel turning actuator along the turning unit with respect to a lateral direction of the vehicle and operable to apply a wheel turning torque to the turning unit via the second shaft which is parallel to and laterally spaced from the first shaft along the turning unit with respect to the lateral direction of the vehicle, with a non-mechanical torque command being non-mechanically transmitted to the second wheel turning actuator,

the second wheel turning actuator being mechanically connected to the backup mechanism only via the second shaft through the steering mechanism and being configured to provide an operating parameter that is less affected by an external disturbance within the backup mechanism than an operating parameter provided by the first wheel turning actuator which is mechanically connected to the backup mechanism; and

a controller operable to control the first and second wheel turning actuators and the steering reaction actuator, the controller being configured to control the steering reaction actuator based on the operating parameter of the second wheel turning actuator and not based on the operating parameter of the first wheel turning actuator while at least the second wheel turning actuator is determined to be operating normally,

the controller being further configured to compute a current command value based on angle information pertaining to the second wheel turning actuator, and not based on angle information pertaining to the first 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, the second wheel turning actuator being arranged relative to the first wheel turning actuator such that the current command value based on angle information pertaining to the second wheel turning actuator is less affected by an external disturbance within the backup mechanism than a current command value based on angle information pertaining to the first wheel turning actuator which is mechanically connected to the backup mechanism.

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 second 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 wheel turning actuators comprise 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.

4. 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.

5. The steering apparatus according to claim 1, 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.

6. 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.

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

8. A steering apparatus comprising:

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

turning means for turning at least one steered wheel, the turning means including a first transmission path, a second transmission path, and a steering mechanism disposed between the first and second transmission paths;

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

second torque applying means for applying a second wheel turning torque to the turning means via the second transmission path which is parallel to and laterally spaced from the first transmission path along the turning means with respect to a lateral direction of a vehicle having the steering apparatus, the second torque applying means being laterally spaced from the first torque applying means along the turning means with respect to the lateral direction of the vehicle;

backup means for mechanically connecting the steering input means to the turning means via the first transmission path to mechanically transmit a mechanical input torque from the steering input means to the turning means when the steering input means and the turning means are mechanically connected by the backup means, with a non-mechanical torque command being non-mechanically transmitted to the second second torque applying means when the steering input means and the turning means are not mechanically connected by the backup means, and with the first torque applying means being mechanically connected to the backup means, and with the second torque applying means being mechanically connected to the backup means only via the second transmission path through the steering mechanism and being configured to provide an operating parameter that is less affected by an external disturbance within the backup means than an operating parameter provided by the first torque applying means which is mechanically connected to the backup means,

the backup means beings arranged with respect to the steering input means and the turning means such that the mechanical input torque from the steering input means cannot be transmitted to the turning means via the second transmission path;

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 the operating parameter of the second torque applying means and not based on the operating parameter of the first torque applying means

the control means being further configured to compute a current command value based on angle information pertaining to the second torque applying means, and not based on angle information pertaining to the first torque applying means, so as to obtain an angle command value corresponding to an operating state of the steering input means and to drive the first and second torque applying means accordingly, the second torque applying means being arranged relative to the first torque applying means such that the current command value based on angle information pertaining to the second torque applying means is less affected by an external disturbance within the backup means than a current command value based on angle information pertaining to the first torque applying means which is mechanically connected to the backup means.

9. The steering apparatus according to claim 8, 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.

10. A vehicle equipped with the steering apparatus according to claim 8.

11. 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 not based on a mechanical input torque transmitted to the turning unit via a second transmission path, with a non-mechanical torque command being non-mechanically transmitted to the first transmission path, the turning unit including the first transmission path, the second transmission path, and a steering mechanism disposed between the first and second transmission paths; and

a second mode control section configured to selectively control a clutch disposed in the second transmission path which is parallel to and laterally spaced from the first transmission path along the turning unit with respect to a lateral direction of a vehicle having the steering controller, the second transmission path being formed between the driver operating unit and the turning unit such that the mechanical input torque from the driver operating unit cannot be transmitted to the turning unit via the first transmission path, the clutch disposed so as to selectively connect and disconnect mechanically the driver operating unit to the turning unit through the second transmission path such that the mechanical input torque of the driver operating unit is transmitted to the turning unit via the second transmission path while the driver operating unit and the turning unit are mechanically connected,

the first transmission path being mechanically connected to the clutch only via the first transmission path through the steering mechanism such that a measurement of the wheel turning torque transmitted to the turning unit via the first transmission path is less affected by an external disturbance within the clutch than a measurement of the mechanical input torque transmitted to the turning unit via the second transmission path which is mechanically connected to the clutch, and

the first mode control section being further configured to compute a current command value based on angle information pertaining to the first transmission path, and not based on angle information pertaining to the second transmission path, so as to obtain an angle command value corresponding to an operating state of the driver operating unit and to transfer torque to the turning unit via the first and second transmission paths accordingly, the first transmission path being arranged relative to the second transmission path such that the current command value based on angle information pertaining to the first transmission path is less affected by an external disturbance within the clutch than a current command value based on angle information pertaining to the second transmission path which is mechanically connected to the backup mechanism.

12. A vehicle equipped with the steering controller according to claim 11.

13. 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, the first wheel turning actuator being mechanically connected to the backup mechanism;

a second wheel turning actuator control section configured to control a second wheel turning actuator laterally spaced from the first wheel turning actuator along the turning unit with respect to a lateral direction of a vehicle having the controller so as to apply a second wheel turning torque to the turning unit via a second torque transmission path which is parallel to and laterally spaced from the first transmission path along the turning unit with respect to the lateral direction of the vehicle, with a non-mechanical torque command being non-mechanically transmitted to the second wheel turning actuator,

the turning unit including the first torque transmission path, the second torque transmission path, and a steering mechanism disposed between the first and second torque transmission paths, and the backup mechanism being arranged with respect to the driver operating unit and the turning unit such that a mechanical input torque from the driver operating unit cannot be transmitted to the turning unit via the second torque transmission path,

the second wheel turning actuator being mechanically connected to the backup mechanism only via the second torque transmission path through the steering mechanism and being configured to provide an operating parameter based on the second wheel turning torque that is less affected by an external disturbance within the backup mechanism than an operating parameter provided by the first wheel turning actuator based on the first wheel turning torque which is mechanically connected to the backup mechanism; 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 operating parameter based on the second wheel turning torque applied to the turning unit by the second wheel turning actuator and not based on the operating parameter based on the first wheel turning torque applied to the turning unit by the first wheel turning actuator while at least the second wheel turning actuator is determined to be operating normally,

the steering reaction actuator control section being further configured to compute a current command value based on angle information pertaining to the second wheel turning actuator, and not based on angle information pertaining to the first 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, the second wheel turning actuator being arranged relative to the first wheel turning actuator such that the current command value is less affected by an external disturbance within the backup mechanism than a current command value based on angle information pertaining to the first wheel turning actuator which is mechanically connected to the backup mechanism.

14. The vehicle steering system controller according to claim 13, 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.

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

16. A steering method comprising:

applying a wheel turning torque to a turning unit using a first wheel turning actuator based on a driver input to a driver operating unit via a first transmission path including a first shaft;

applying a wheel turning torque to the turning unit using a second wheel turning actuator laterally spaced from the first wheel turning actuator along the turning unit with respect to a lateral direction of a vehicle in which the steering method is performed to apply a wheel turning torque to the turning unit via a second transmission path including a second shaft which is parallel to and laterally spaced from the first shaft along the turning unit with respect to the lateral direction of the vehicle, with a non-mechanical torque command being non-mechanically transmitted to the second wheel turning actuator, and with the turning unit including the first shaft, the second shaft, and a steering mechanism disposed between the first and second shafts;

mechanically connecting the driver operating unit to the turning unit via a backup mechanism, when at least one of the driver operating unit and the turning unit malfunctions, to transmit a mechanical input torque from the driver operating unit to the turning unit via the first transmission path such that the first wheel turning actuator is mechanically connected to the backup mechanism, the backup mechanism being arranged with respect to the driver operating unit and the turning unit such that the mechanical input torque from the driver operating unit cannot be transmitted to the turning unit via the second shaft,

applying a steering reaction torque to the driver operating unit based on a measurement of the wheel turning torque applied using the second wheel turning actuator and not based on a measurement of the wheel turning torque applied using the first wheel turning actuator,

the second wheel turning actuator being mechanically connected to the backup mechanism only via the second shaft through the steering mechanism such that the measurement of the wheel turning torque applied using the second wheel turning actuator is less affected by an external disturbance within the backup mechanism than the measurement of the wheel turning torque applied using the second wheel turning actuator which is mechanically connected to the backup mechanism; and

computing a current command value based on angle information pertaining to the second wheel turning actuator, and not based on angle information pertaining to the first 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, the second wheel turning actuator being arranged relative to the first wheel turning actuator such that the current command value based on angle information pertaining to the second wheel turning actuator is less affected by an external disturbance within the backup mechanism than a current command value based on angle information pertaining to the first wheel turning actuator which is mechanically connected to the backup mechanism.