Vehicle steering control device and vehicle steering control method

• US 9,381,939 B2
• Filed: 12/27/2013
• Issued: 07/05/2016
• Est. Priority Date: 02/21/2013
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Chai, Yu wun, Igarashi, Kazuhiro
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): Lee, Tyler J
• Application Number:
  US14/768,283
• Publication Number:
  US 20150375780A1
• Time in Patent Office: 921 Days
• Field of Search: 701 41- 44
• US Class Current: 1/1
• CPC Class Codes: B62D 15/021 Determination of steering angle
• CPC Class Codes: B62D 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence
• 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 vehicle steering control device and a vehicle steering control method achieve an ideal steering feeling. A turning controller is configured to set as a target turning angle of a turning wheel an addition value obtained by adding a steady steer control amount that is a control amount depending on a steering angle and a differential steer control amount that is a control amount depending on a steering angular velocity. In this situation, when a driver is increasingly turning a steering wheel, the differential steer control amount is computed to be smaller than the differential steer control amount when the driver is not increasingly turning the steering wheel. Accordingly, the phase of the turning angle with respect to the steering angle in the steering returning operation can be delayed as compared to the phase in the steering increasing operation.

Claims

1. A vehicle steering control device, comprising:

a turning controller configured to control turning of a turning wheel at a target turning angle depending on a steering state of a steering wheel, the steering wheel being mechanically separated from the turning wheel; and

a steering returning operation detector configured to detect a steering returning operation with the steering wheel operated by a driver,

wherein the turning controller comprises;

a steady steer control amount computation unit configured to compute a steady steer control amount that is a control amount depending on a steering angle of the steering wheel;

a differential steer control amount computation unit configured to compute a differential steer control amount that is a control amount depending on a steering angular velocity of the steering wheel; and

a target turning angle setting unit configured to set as a target turning angle an addition value obtained by adding the steady steer control amount computed by the steady steer control amount computation unit and the differential steer control amount computed by the differential steer control amount computation unit,

wherein the differential steer control amount computation unit comprises;

a reference value computation unit configured to compute a reference value of the differential steer control amount based on the steering angular velocity of the steering wheel; and

a gain multiplication unit configured to compute the differential steer control amount obtained by multiplying the reference value of the differential steer control amount computed by the reference value computation unit by a gain depending on a detection result of the steering returning operation detector, and

wherein when the steering returning operation detector detects the steering returning operation with the steering wheel operated by the driver, the gain multiplication unit is configured to make the gain smaller than the gain generated when the steering returning operation detector detects the steering increasing operation.

2. The vehicle steering control device according to claim 1, wherein the reference value computation unit is configured to compute the reference value of the differential steer control amount from the steering angular velocity of the steering wheel and a differential steer map in which the steering angular velocity of the steering wheel and the reference value of the differential steer control amount are associated with each other.

3. The vehicle steering control device according to claim 2, wherein the differential steer map is configured to compute the reference value of the differential steer control amount to be larger as a vehicle speed is higher.

4. A vehicle steering control device, comprising:

a turning controller configured to control turning of a turning wheel at a target turning angle depending on a steering state of a steering wheel, the steering wheel being mechanically separated from the turning wheel; and

a steering returning operation detector configured to detect a steering returning operation with the steering wheel operated by a driver,

wherein the turning controller comprises;

a steady steer control amount computation unit configured to compute a steady steer control amount that is a control amount depending on a steering angle of the steering wheel;

a differential steer control amount computation unit configured to compute a differential steer control amount that is a control amount depending on a steering angular velocity of the steering wheel; and

a target turning angle setting unit configured to set as a target turning angle an addition value obtained by adding the steady steer control amount computed by the steady steer control amount computation unit and the differential steer control amount computed by the differential steer control amount computation unit,

wherein the differential steer control amount computation unit is configured to compute the differential steer control amount from the steering angular velocity of the steering wheel and a differential steer map in which the steering angular velocity of the steering wheel and the differential steer control amount are associated with each other, and

wherein when the steering returning operation detector detects the steering returning operation with the steering wheel operated by the driver, the differential steer control amount computation unit is configured to compute the differential steer control amount to be smaller, by reference to the differential steer map that is different from another differential steer map when the steering returning operation detector detects the steering increasing operation, than the differential steer control amount generated when the steering returning operation detector detects the steering increasing operation.

5. A vehicle steering control method, comprising:

setting as a target turning angle an addition value obtained by adding a steady steer control amount that is a control amount depending on a steering angle of a steering wheel and a differential steer control amount that is a control amount depending on a steering angular velocity of the steering wheel, the steering wheel being mechanically separated from a turning wheel;

controlling turning of the turning wheel at the target turning angle that has been set;

computing a reference value of the differential steer control amount based on the steering angular velocity of the steering wheel;

computing the differential steer control amount obtained by multiplying the reference value of the differential steer control amount that has been computed by a gain; and

when a steering returning operation with the steering wheel operated by a driver is detected, making the gain smaller than the gain generated when a steering increasing operation is detected.

6. A vehicle steering control method, comprising:

setting as a target turning angle an addition value obtained by adding a steady steer control amount that is a control amount depending on a steering angle of a steering wheel and a differential steer control amount that is a control amount depending on a steering angular velocity of the steering wheel, the steering wheel being mechanically separated from a turning wheel;

controlling turning of the turning wheel at the target turning angle that has been set;

computing the differential steer control amount from the steering angular velocity of the steering wheel and a differential steer map in which the steering angular velocity of the steering wheel and the differential steer control amount are associated with each other; and

when a steering returning operation with the steering wheel operated by a driver is detected, computing the differential steer control amount to be smaller, by reference to the differential steer map that is different from another differential steer map when a steering increasing operation is detected, than the differential steer control amount when the steering increasing operation is detected.