System And Method For Low Speed Lateral Control Of A Vehicle

• US 20180354513A1
• Filed: 06/13/2017
• Published: 12/13/2018
• Est. Priority Date: 06/13/2017
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Moshchuk, Nikolai K., Chen, Shih-ken
• Granted Patent: US 10,427,678 B2
• Time in Patent Office: Days
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 30/12 Lane keeping
• 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 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence
• CPC Class Codes: G05D 1/0088 characterized by the autonomous decision making process, e.g. artificial intelligence, predefined behaviours using knowledge based models G06N5/00
• CPC Class Codes: G05D 1/0223 involving speed control of the vehicle vehicle fittings for automatically controlling, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator B60K31/00
• CPC Class Codes: G05D 1/0229 in combination with fixed guiding means

Abstract

A method for providing low speed lateral steering control for a vehicle is disclosed. The method includes receiving sensor data corresponding to a road wheel angle, determining a planned vehicle path of travel, defining a road wheel angle search range based on a maximum road wheel angle rate, determining a steering control goal using the road wheel angle that tracks and measures a difference between a current vehicle path and the planned vehicle path, determining an optimal steering control signal using the road wheel angle and the steering control goal and providing the control signal to a steering controller.

Claims

1. A method for providing low speed lateral steering control for an autonomously driven or semi-autonomously driven vehicle, the method comprising:

receiving, from at least one vehicle sensor, sensor data corresponding to a road wheel angle;

determining, by one or more data processors, a plurality of waypoints indicating a planned vehicle path of travel;

defining, by the one or more data processors, a road wheel angle search range based at least in part on a maximum road wheel angle rate;

determining, by the one or more data processors, a steering control goal using the road wheel angle that tracks and measures a difference between a current vehicle path and the planned vehicle path;

determining, by the one or more data processors, an optimal steering control signal using the road wheel angle and the steering control goal; and

providing the control signal to a steering controller.

2. The method of claim 1, wherein determining the optimal steering control signal includes using one-dimensional nonlinear optimization to minimize a path tracking error between the current vehicle path and the planned vehicle path.

3. The method of claim 2, wherein minimizing the path tracking error includes minimizing both a heading error and a radial error.

4. The method of claim 1, wherein determining a steering control goal includes defining a relationship between a steering command and a cost function.

5. The method of claim 4, wherein the cost function includes a cost associated with a radial error and a cost associated with a heading error.

6. The method of claim 5, wherein the cost function is defined by the equation:

J=J_L+J_φ

where J_L is the cost associated with the radial error and J_φ

is the cost associated with the heading error and J_L and J_φ

are expressed with the following equations;

7. An automotive vehicle, comprising:

a steering system;

at least one vehicle sensor;

a controller electrically connected to the steering system and the at least one vehicle sensor, the controller configured to

receive, from the at least one vehicle sensor, sensor data corresponding to a road wheel angle;

determine a plurality of waypoints indicating a planned vehicle path of travel;

define a road wheel angle search range based at least in part on a maximum road wheel angle rate;

determine a steering control goal using the road wheel angle that tracks and measures a difference between a current vehicle path and the planned vehicle path;

determine an optimal steering control signal using the road wheel angle and the steering control goal; and

provide the control signal to the steering system.

8. The automotive vehicle of claim 7, wherein determining the optimal steering control signal includes using one-dimensional nonlinear optimization to minimize a path tracking error between the current vehicle path and the planned vehicle path.

9. The automotive vehicle of claim 8, wherein minimizing the path tracking error includes minimizing both a heading error and a radial error.

10. The automotive vehicle of claim 7, wherein determining a steering control goal includes defining a relationship between a steering command and a cost function.

11. The automotive vehicle of claim 10, wherein the cost function includes a cost associated with a radial error and a cost associated with a heading error.

12. The automotive vehicle of claim 11, wherein the cost function is defined by the equation:

J=J_L+J_φ

where J_L is the cost associated with the radial error and J_φ

is the cost associated with the heading error and J_L and J_φ

are expressed with the following equations;

13. A method for providing low speed lateral control to an automotive vehicle, the method comprising:

receiving, from a vehicle sensor, sensor data corresponding to a road wheel angle;

determining, by one or more data processors, a plurality of waypoints indicating a planned vehicle path of travel;

defining, by the one or more data processors, a road wheel angle search range based on a maximum road wheel angle rate of change;

designing a steering control goal using a cost function that reduces a difference between a current vehicle path and the planned vehicle path, wherein the cost function includes a cost associated with a radial error and a cost associated with a heading error, and wherein the cost function can be expressed in a nonsingular form as a function of the road wheel angle, one or more vehicle geometric parameters, and the plurality of waypoints;

determining an optimal steering control signal by minimizing the cost function subject to a constraint driven by the maximum road wheel angle rate; and

providing the control signal to a steering controller.

14. The method of claim 13, wherein the cost function is defined by the equation:

J=J_L+J_φ

where J_L is the cost associated with the radial error and J_φ

is the cost associated with the heading error and J_L and J_φ

are expressed with the following equations;

15. The method of claim 13, wherein determining the optimal steering control signal includes using one-dimensional nonlinear optimization to minimize a path tracking error between the current vehicle path and the planned vehicle path.

16. The method of claim 15, wherein minimizing the path tracking error includes minimizing both the heading error and the radial error.

17. The method of claim 14, wherein the cost function has a resolvable singularity at z≡

tan δ

=0.

18. The method of claim 17, wherein J_L and J_φ

are expressed with the following equations;