Automatic crab steering on side hills

Patent metadata

Field	Value
Publication number	US-11440551-B2
Application number	US-201916560475-A
Country	US
Kind code	B2
Filing date	Sep 4, 2019
Priority date	Sep 4, 2019
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

Steering a vehicle in an electronic steering mode of operation that includes a front axle steering system, a rear axle steering system, one or more vehicle environment sensors, and a controller operatively coupled with the front axle steering system, the rear axle steering system, and the vehicle environment sensors. Commanding the vehicle to operate at a desired vehicle speed, detecting a lateral force acting on the vehicle in response to input from the vehicle environment sensors, and determining an actual lateral acceleration of the vehicle and a predicted lateral acceleration of the vehicle from the desired vehicle speed. Determining a lateral acceleration error by comparing the predicted lateral acceleration to the actual lateral acceleration, and determining if the lateral acceleration error exceeds a lateral acceleration limit, then turning both of the front axle steering system and the rear axle steering system to a crab steering correction angle.

First claim

The invention claimed is:

1. A system comprising:
a vehicle including a front axle steering system, a rear axle steering system, one or more vehicle environment sensors, and a controller operatively coupled with the front axle steering system, the rear axle steering system, and the one or more vehicle environment sensors, wherein the controller is configured to:
operate the vehicle in an electronic steering mode of operation at a desired vehicle speed;
detect presence of a lateral force on the vehicle in response to input from the one or more vehicle environment sensors;
in response to detection of the lateral force on the vehicle and in response to the desired vehicle speed, determine an actual lateral acceleration of the vehicle and a predicted lateral acceleration of the vehicle;
determine a lateral acceleration error by comparing the predicted lateral acceleration to the actual lateral acceleration; and
in response to the determination of the lateral acceleration error, determine if the lateral acceleration error exceeds a lateral acceleration limit, then compensate for the lateral force acting on the vehicle by turning both of the front axle steering system and the rear axle steering system to a crab steering correction angle.

2. The system of claim 1 , wherein the crab steering correction angle is adjusted by an operator correction factor.

3. The system of claim 1 , wherein the crab steering correction angle includes a front axle steering angle and a rear axle steering angle, the front axle steering system configured to adjust to the front axle steering angle and the rear axle steering system configured to adjust to the rear axle steering angle.

4. The system of claim 3 , wherein the front axle steering angle is different from the rear axle steering angle.

5. The system of claim 1 , wherein the vehicle includes an articulated steering system between the rear and the front axle steering systems configured to laterally offset the rear axle steering system from the front axle steering system.

6. The system of claim 1 , wherein the one or more sensors measure a yaw rate and an actual vehicle speed.

7. The system of claim 1 , wherein the one or more sensors include a lateral accelerometer.

8. The system of claim 1 , wherein the one or more sensors measure a vehicle roll angle; and
adjusting the crab steering correction angle based on the vehicle roll angle.

9. The system of claim 1 , wherein the front axle steering system includes at least two wheels, the rear axle steering system includes at least two wheels,
wherein the one or more sensors measures a wheel slip condition of each of the wheels of the front axle steering system and the rear axle steering system; and
adjusting the crab steering correction angle based on the wheel slip condition being satisfied for any of the wheels.

10. The system of claim 1 , wherein the crab steering correction angle is between 0 and 15 degrees as measured relative to a longitudinal axis of each of the front axle steering system and the rear axle steering system.

11. A method of steering a vehicle, comprising:
operating the vehicle in an electronic steering mode of operation wherein the vehicle includes a front axle steering system, a rear axle steering system, one or more vehicle environment sensors, and a controller operatively coupled with the front axle steering system, the rear axle steering system, and the one or more vehicle environment sensors;
commanding the vehicle to operate at a desired vehicle speed;
detecting a lateral force acting on the vehicle in response to input from the one or more vehicle environment sensors;
in response to detecting the lateral force and the desired vehicle speed, determining an actual lateral acceleration of the vehicle and a predicted lateral acceleration of the vehicle from the desired vehicle speed;
determining a lateral acceleration error by comparing the predicted lateral acceleration to the actual lateral acceleration; and
in response to the determination of the lateral acceleration error, determining if the lateral acceleration error exceeds a lateral acceleration limit, then turning both of the front axle steering system and the rear axle steering system to a crab steering correction angle.

12. The method of claim 11 , wherein the crab steering correction angle is adjusted by an operator correction factor.

13. The method of claim 11 , wherein the crab steering correction angle includes a front axle steering angle and a rear axle steering angle;
adjusting the front axle steering system to the front axle steering angle; and
adjusting the rear axle steering system to the rear axle steering angle.

14. The method of claim 13 , wherein the front axle steering angle is different from the rear axle steering angle.

15. The method of claim 11 , wherein the vehicle includes an articulated joint between the rear and the front axle steering systems; and
offsetting laterally the rear axle steering system from the front axle steering system.

16. The method of claim 11 , further comprising:
measuring a yaw rate and an actual vehicle speed with the one or more sensors; and
determining the actual lateral acceleration with the yaw rate and actual vehicle speed.

17. The method of claim 11 , wherein the one or more sensors include a lateral accelerometer for measuring the actual lateral acceleration.

18. The method of claim 11 , wherein the one or more sensors measure a vehicle roll angle; and
adjusting the crab steering correction angle based on the vehicle roll angle.

19. The method of claim 11 , wherein the front axle steering system includes at least two wheels, the rear axle steering system includes at least two wheels,
measuring a wheel slip condition of each of the wheels of the front axle steering system and the rear axle steering system with one or more sensors; and
adjusting the crab steering correction angle based on the wheel slip condition being satisfied for any of the wheels.

20. The method of claim 11 , wherein the crab steering correction angle is between 0 and 15 degrees as measured relative to a longitudinal axis of each of the front axle steering system and the rear axle steering system.

Assignees

• Deere & Co

Inventors

• Hudson Scott A
• Tott Jeffrey M
• Kreis Edwin R
• Bowman Dennis A

Classifications

• B60W2520/18

  Roll · CPC title

• B62D11/20

  Endless-track steering having pivoted bogie carrying track (B62D11/02 takes precedence) · CPC title

• B62D7/1545

  provided with electrical assistance · CPC title

• B62D6/00 Primary

  Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits (means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00) · CPC title

• B62D7/14

  the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering · CPC title