Methods and apparatuses for determining estimates of a vehicle's wheel angle and the vehicle's steering ratio

• US 10,124,827 B2
• Filed: 08/31/2016
• Issued: 11/13/2018
• Est. Priority Date: 08/31/2016
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Nykamp, Alex, Lawson, Joshua
• Primary Examiner(s): Cheung, Calvin
• Application Number:
  US15/252,809
• Publication Number:
  US 20180057046A1
• Time in Patent Office: 804 Days
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids
• CPC Class Codes: B62D 15/022 on or near the connection between the steering wheel and steering column
• CPC Class Codes: B62D 15/025 Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation B62D1/28 takes precedence
• 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 5/046 Controlling the motor
• CPC Class Codes: B62D 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence
• CPC Class Codes: B62D 6/005 treating sensor outputs to obtain the actual yaw rate
• CPC Class Codes: G05D 1/021 specially adapted to land vehicles

Abstract

In an example embodiment, a vehicle guidance system includes a memory including computer-readable instructions stored therein and a processor. The processor is configured to execute the computer-readable instructions to estimate a wheel angle of a vehicle based on at least a first value, the first value being a hand wheel based estimate of the wheel angle, and adjust steering commands for steering the vehicle based on the estimated wheel angle to permit the vehicle to move along a set path.

Claims

1. A vehicle guidance system comprising:

a memory including computer-readable instructions stored therein; and

a processor configured to execute the computer-readable instructions to,

determine a vehicle steering ratio based on a position of a hand wheel and a yaw rate of the vehicle,

determine a first value based on an angle of the hand wheel and the vehicle steering ratio,

estimate a wheel angle of the vehicle based on at least the first value, the first value being a hand wheel based estimate of the wheel angle, and

adjust steering commands for steering the vehicle based on the estimated wheel angle to permit the vehicle to move along a set path.

2. The vehicle guidance system of claim 1, wherein the processor is further configured to execute the computer-readable instructions to receive information on the angle of the hand wheel from an encoder installed on the hand wheel.

3. The vehicle guidance system of claim 1, wherein the processor is further configured to execute the computer-readable instructions to receive the yaw rate from a positioning sensor.

4. The vehicle guidance system of claim 3, wherein the processor is further configured to execute the computer-readable instructions to,

determine a second value based on the received yaw rate, a vehicle wheel base value and a speed of the vehicle, the second value being a yaw rate based estimate of the wheel angle, and

estimate the wheel angle based on the first value and the second value.

5. The vehicle guidance system of claim 4, wherein the processor is further configured to execute the computer-readable instructions to determine the vehicle steering ratio as a ratio of a change in the position of the hand wheel and a change in the second value.

6. A vehicle guidance system comprising:

a memory including computer-readable instructions stored therein; and

a processor configured to execute the computer-readable instructions to,

determine a system bias value based on a first value and a second value, the first value being a hand wheel based estimate of a wheel angle of a vehicle, and

estimate the wheel angle as a sum of the first value and the determined system bias value, and

adjust steering commands for steering the vehicle based on the estimated wheel angle to permit the vehicle to move along a set path.

7. The vehicle guidance system of claim 6, wherein the processor is further configured to execute the computer-readable instructions to determine the system bias value by,

determining a difference between the first value and the second value, and

determining the system bias value as a ratio of the difference to a bias factor.

8. The vehicle guidance system of claim 6, wherein the processor is further configured to execute the computer-readable instructions to,

determine if a yaw rate of the vehicle is accurate,

determine the system bias value if the yaw rate is accurate, and

determine the wheel angle to be equal to the first value if the yaw rate is not accurate.

9. A method comprising:

determining a vehicle steering ratio based on a position of a hand wheel and a yaw rate of a vehicle;

determining a first value based on an angle of the hand wheel and the vehicle steering ratio;

estimating a wheel angle of the vehicle based on at least the first value, the first value being a hand wheel based estimate of the wheel angle; and

adjusting steering commands for steering the vehicle based on the estimated wheel angle to permit the vehicle to move along a set path.

10. The method of claim 9, further comprising:

receiving information on the angle of the hand wheel from an encoder installed on the hand wheel.

11. The method of claim 9, further comprising:

receiving the yaw rate from a positioning sensor.

12. The method of claim 11, further comprising:

determining a second value based on the received yaw rate, a vehicle wheel base value and a speed of the vehicle, the second value being a yaw rate based estimate of the wheel angle, wherein the estimating includes estimating the wheel angle based on the first value and the second value.

13. The method of claim 12, wherein the determining of the vehicle steering ratio includes determining the vehicle steering ratio as a ratio of a change in the position of the hand wheel and a change in the second value.

14. A method comprising:

determining a system bias value based on a first and a second value, the first value being a hand wheel based estimate of a wheel angle,

estimating the wheel angle as a sum of the first value and the determined system bias value; and

adjusting steering commands for steering the vehicle based on the estimated wheel angle to permit the vehicle to move along a set path.

15. The method of claim 14, wherein the determining the system bias includes,

determining a difference between the first value and the second value, and

determining the system bias value as a ratio of the difference to a bias factor.

16. The method of claim 14, further comprising:

determining if a yaw rate of the vehicle is accurate, the determining the system bias value determining the system bias value if the yaw rate is accurate, and

determining the wheel angle to be equal to the first value if the yaw rate is not accurate.