Steering control device

• US 9,567,003 B2
• Filed: 10/28/2013
• Issued: 02/14/2017
• Est. Priority Date: 11/07/2012
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kageyama, Yusuke
• Primary Examiner(s): MUSTAFA, IMRAN K
• Application Number:
  US14/437,894
• Publication Number:
  US 20150291210A1
• Time in Patent Office: 1,205 Days
• US Class Current: 1/1
• CPC Class Codes: B60T 2260/02 Active Steering, Steer-by-Wire
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60W 10/188 hydraulic brakes
• CPC Class Codes: B60W 10/196 acting within the driveline, e.g. retarders
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 10/22 including control of suspension systems
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60W 2710/18 Braking system
• CPC Class Codes: B60W 2710/20 Steering systems
• CPC Class Codes: B60W 2720/14 Yaw
• CPC Class Codes: B60W 30/045 Improving turning performance
• CPC Class Codes: B62D 5/04 electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
• CPC Class Codes: B62D 6/003 in order to control vehicle yaw movement, i.e. around a vertical axis B62D6/007 takes precedence
• CPC Class Codes: B62D 6/02 responsive only to vehicle speed
• CPC Class Codes: B62D 6/08 responsive only to driver input torque

Abstract

A steering control device suppresses response delay to stabilize a behavior of a vehicle during turning braking. The steering control device includes a steer-by-wire system that controls an actuator that detects displacement of a steering angle when a steering wheel is steered and operates a turning mechanism that turns a turning wheel separated from the steering wheel based on a detection result; a vehicle yaw angle detector; a steering angle detector; a turning state detector that detects a turning state of the vehicle based on the yaw angle; a braking state detector that detects a braking state of the vehicle; and a yaw angle controller that controls the actuator to suppress a yaw angle deviation before and after braking when the turning state of the vehicle is detected by the turning state detector and when the braking state of the vehicle is detected by the braking state detector.

Claims

1. A steering control device comprising:

a steer-by-wire system configured to control an actuator configured to detect displacement of a steering angle when a steering wheel is steered and to operate a turning mechanism that turns a turning wheel separated from the steering wheel based on a detection result;

a yaw angle detector configured to detect a yaw angle of a vehicle;

a steering angle detector configured to detect the steering angle of the steering wheel;

a turning state detector configured to detect a turning state of the vehicle;

a traveling state detector configured to detect a braking state or an acceleration state of the vehicle; and

a yaw angle controller configured to control the actuator to suppress a yaw angle deviation before and after braking or acceleration in a state where the steering wheel maintains steering, when the turning state of the vehicle is detected by the turning state detector and when the braking state or the acceleration state of the vehicle is detected by the traveling state detector,

wherein the yaw angle controller including a target turning amount calculator configured to select, when the turning state of the vehicle is detected by the turning state detector and when the state change due to the acceleration state or braking state is detected, a corresponding target turning amount characteristic line from among a plurality of target turning amount characteristic lines indicating the relationship between the vehicle velocity and the yaw angle where a target turning amount of the actuator is used as a parameter, based on the vehicle velocity after state change and the yaw angle after state change after detecting the state change, and calculates the target turning amount depending on the state change based on the selected target turning amount characteristic line, and to control the actuator so that a turning amount of the turning wheel due to the actuator becomes the target turning amount.

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

a vehicle velocity detector configured to detect the vehicle velocity of the vehicle,

wherein the yaw angle controller is operated when the vehicle velocity is equal to or greater than a setting vehicle velocity.

3. The steering control device according to claim 1,

wherein the yaw angle controller comprises the target yaw angle calculator configured to calculate a target yaw angle depending on the state change based on the vehicle velocity and the yaw angle after the state change due to the acceleration state or the brake state is detected,

wherein the yaw angle controller continues the control of the actuator for causing the control amount to become the target control amount until the yaw angle of the vehicle detected by the vehicle yaw angle detector becomes a value close to the target yaw angle.

4. The steering control device according to claim 1,

wherein the yaw angle controller stops the control of the actuator when the acceleration state of the vehicle is detected by the travel state detector, and when a steering angle deviation before and after acceleration state detected by the steering angle detector is equal to or greater than a predetermined value.

5. A steering control device according to claim 1 comprising:

wherein the yaw angle controller includes a yaw angle control start delaying section configured to delay control start of the yaw angle controller by a predetermined time when a change from a straight traveling state of the vehicle to the turning state of the vehicle is detected by the turning state detector.

6. The steering control device according to claim 1,

wherein a suspension device configured to support the turning wheel, includes a plurality of link members configured to support the turning wheel to a vehicle body, and a king pin axis configured to pass through an upper pivot point and a lower pivot point of the link members is set to pass through the inside of a tire contact surface at a neutral position of the steering wheel.

7. The steering control device according to claim 1,

wherein the actuator is a turning actuator configured to drive a rack mechanism of the steer-by-wire system, and the target turning amount is a target rack stroke.

8. The steering control device according to claim 1,

wherein the actuator is a yaw angle control actuator for giving a speed difference to the right and left turning wheels for steering.