STEERING CONTROL METHOD AND SYSTEM FOR REAR-WHEEL STEERING

• US 20200130735A1
• Filed: 02/05/2019
• Published: 04/30/2020
• Est. Priority Date: 10/25/2018
• Status: Abandoned Application

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group), Industry-University Cooperation Foundation Hanyang University, Kia Motors Corporation (Kia Corp.)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group), Iucf-hyu, Kia Motors Corporation (Kia Corp.)
• Inventors: Chung, Rae Wook, Oh, Jun Wook, Heo, Jun Haeng, Kim, Seung Ki, Huh, Kun Soo, Park, Jang Hee
• Application Number:
  US16/267,602
• Publication Number:
  US 20200130735A1
• Time in Patent Office: Days
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 40/105 Speed
• CPC Class Codes: B60W 40/114 Yaw movement
• CPC Class Codes: B62D 15/021 Determination of steering angle
• CPC Class Codes: B62D 6/005 treating sensor outputs to obtain the actual yaw rate
• CPC Class Codes: B62D 7/1581 characterised by comprising an electrical interconnecting system between the steering control means of the different axles
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

The present disclosure provides a steering control method and system for rear-wheel steering that improves driving stability and yaw responsiveness of a vehicle by controlling rear wheels on the basis of a driving state of a vehicle. The method and system receives a vehicle speed and a front-wheel turning angle and calculates a rear-wheel same/inverse-phase control amount; estimates tire slip angles when the vehicle is driven such that the rear wheels are controlled with the same phase; calculates a final rear-wheel turn control value by reflecting a control weight proportioned to the tire slip angle estimation value to the rear-wheel same-phase control amount; and turns the rear wheels on the basis of the final rear-wheel turn control value.

Claims

1. A steering control method for rear-wheel steering, the method comprising:

a calculation step in which a controller receives a vehicle speed and a front-wheel turning angle and calculates a rear-wheel same/inverse-phase control amount;

an estimation step in which the controller estimates tire slip angles on the basis of factors showing a driving state of a vehicle when the vehicle is driven such that the rear wheels are controlled with the same phase;

a compensation step in which the controller calculates a final rear-wheel turn control value by reflecting a control weight proportioned to the tire slip angle estimation value to the rear-wheel same-phase control amount; and

a rear-wheel control step in which the controller turns the rear wheels by controlling a rear-wheel turn actuator on the basis of the final rear-wheel turn control value.

2. The method of claim 1, wherein the estimation step includes:

a step of receiving a vehicle speed, front-/rear-wheel turning angles, a yaw rate, a longitudinal acceleration, and a transverse acceleration;

a step of calculating and estimating a transverse slip angle of a car body using the input factors; and

a step of calculating and estimating tire slip angles using the factors and a transverse slip angle estimation value of the car body.

3. The method of claim 1, wherein the compensation step includes:

a step of determining a control weight in accordance with the tire slip angle estimation value; and

a step of calculating a final rear-wheel turn control value by multiplying the rear-wheel same-phase control amount by the control weight.

4. The method of claim 3, wherein the control weight is a value satisfying 0<

control weight≤

1 and is determined in proportion to the tire slip angle estimation value.

5. A steering control method for rear-wheel steering, the method comprising:

a calculation step in which a controller receives a vehicle speed and a front-wheel turning angle and calculates a rear-wheel same/inverse-phase control amount;

an estimation step in which the controller estimates tire slip angles on the basis of factors showing a driving state of a vehicle;

a compensation step in which the controller calculates a final rear-wheel turn control value by reflecting a control weight proportioned to a tire slip angle estimation value to the rear-wheel same-phase control amount; and

a rear-wheel control step in which the controller turns the rear wheels by controlling a rear-wheel turn actuator on the basis of the final rear-wheel turn control value.

6. A steering control system for rear-wheel steering, the system comprising:

a same/inverse-phase control amount calculator that receives a vehicle speed and a front-wheel turning angle and calculates a rear-wheel same/inverse-phase control amount;

a vehicle state estimator that estimates tire slip angles on the basis of factors showing a driving state of a vehicle when the vehicle is driven such that the rear wheels are controlled with the same phase; and

a rear-wheel turn controller that calculates a final rear-wheel turn control value by reflecting a control weight proportioned to a tire slip angle estimation value to the rear-wheel same-phase control amount and turns the rear wheels by controlling a rear-wheel turn actuator on the basis of the final rear-wheel turn control value.

7. The system of claim 6, wherein the vehicle state estimator includes:

a transverse slip angle estimator that receives a vehicle speed, front-/rear-wheel turning angles, a yaw rate, a longitudinal acceleration, and a transverse acceleration, and calculates and estimates a transverse slip angle of a car body using the input factors; and

a tire slip angle estimator that calculates and estimates tire slip angles using the factors and a transverse slip angle estimation value of the car body.

8. The system of claim 6, further comprising a distribution controller that determines a control weight in accordance with the tire slip angle estimation value,

wherein the rear-wheel turn controller calculates a final rear-wheel turn control value by multiplying the rear-wheel same-phase control amount by the control weight.