Vehicle trajectory planning for autonomous vehicles

Patent metadata

Field	Value
Publication number	US-9244462-B2
Application number	US-201414291802-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	May 30, 2014
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A method for controlling an autonomous vehicle includes obtaining, by one or more processors, information describing a current state of the autonomous vehicle and a goal state of the autonomous vehicle; determining, by the one or more processors, an initial vehicle trajectory from the current state of the autonomous vehicle to the goal state of the autonomous vehicle; determining, by the one or more processors, an optimized vehicle trajectory based the initial trajectory and a velocity profile by applying numerical minimization to minimize a trajectory length value and a lateral acceleration value; and controlling the autonomous vehicle to traverse the optimized vehicle trajectory.

First claim

What is claimed is:

1. A method for controlling an autonomous vehicle, comprising:
obtaining, by one or more processors, information describing a current state of the autonomous vehicle and a goal state of the autonomous vehicle;
determining, by the one or more processors, an initial vehicle trajectory from the current state of the autonomous vehicle to the goal state of the autonomous vehicle;
determining, by the one or more processors, an optimized vehicle trajectory using the initial vehicle trajectory and a velocity profile along the initial vehicle trajectory by applying numerical minimization that concurrently minimizes a trajectory length value and a lateral acceleration value; and
controlling the autonomous vehicle to traverse the optimized vehicle trajectory.

2. The method of claim 1 , wherein the optimized vehicle trajectory corresponds to a set of control inputs and reaches a maximum lateral acceleration value earlier than the initial vehicle trajectory.

3. The method of claim 2 , wherein the set of control inputs includes a plurality of steering angle values that are each associated with a discrete location along the optimized vehicle trajectory.

4. The method of claim 1 , wherein the velocity profile is predetermined, and determining the optimized vehicle trajectory does not include modifying the velocity profile.

5. The method of claim 1 , wherein the trajectory length value is a function of a length from the current state to the goal state and a trajectory length weighting factor, and the lateral acceleration value is a function of a maximum lateral acceleration value from the current state to the goal state and a lateral acceleration weighting factor.

6. The method of claim 1 , wherein the determining the initial vehicle trajectory comprises fitting a curve to the current state of the autonomous vehicle and the goal state of the autonomous vehicle using a vehicle dynamics model.

7. The method of claim 1 , wherein determining the optimized vehicle trajectory is performed by applying Levenberg-Marquardt minimization.

8. A control apparatus for an autonomous vehicle, comprising:
one or more processors; and
one or more memory devices for storing program instructions used by the one or more processors, wherein the program instructions, when executed by the one or more processors, cause the one or more processors to:
obtain information describing a current state of the autonomous vehicle and a goal state of the autonomous vehicle,
determine an initial vehicle trajectory from the current state of the autonomous vehicle to the goal state of the autonomous vehicle, and
determine an optimized vehicle trajectory using the initial vehicle trajectory and a velocity profile along the initial vehicle trajectory by applying numerical minimization that concurrently minimizes a trajectory length value and a lateral acceleration value; and
control the autonomous vehicle to traverse the optimized vehicle trajectory.

9. The control apparatus of claim 8 , wherein the optimized vehicle trajectory corresponds to a set of control inputs.

10. The control apparatus of claim 9 , wherein the set of control inputs includes a plurality of steering angle values that are each associated with a discrete location along the optimized vehicle trajectory.

11. The control apparatus of claim 8 , wherein the velocity profile is predetermined, and determining the optimized vehicle trajectory does not include modifying the velocity profile.

12. The control apparatus of claim 8 , wherein the trajectory length value is a function of a length from the current state to the goal state and a trajectory weighting factor, and the lateral acceleration value is a function of a maximum lateral acceleration value from the current state to the goal state and a lateral acceleration weighting factor.

13. The control apparatus of claim 8 , wherein the determining the initial vehicle trajectory comprises fitting a curve to the current state of the autonomous vehicle and the goal state of the autonomous vehicle using a vehicle dynamics model.

14. The control apparatus of claim 8 , wherein determining the optimized vehicle trajectory is performed by applying Levenberg-Marquardt minimization.

15. An autonomous vehicle, comprising:
a trajectory planning system that includes one or more processors and one or more memory devices for storing program instructions used by the one or more processors, wherein the program instructions, when executed by the one or more processors, cause the one or more processors to:
obtain information describing a current state of the autonomous vehicle and a goal state of the autonomous vehicle,
determine an initial vehicle trajectory from the current state of the autonomous vehicle to the goal state of the autonomous vehicle, and
determine an optimized vehicle trajectory using the initial vehicle trajectory and a velocity profile along the initial vehicle trajectory by applying numerical minimization that concurrently minimizes a trajectory length value and a lateral acceleration value;
a steering device that is operable to change a steering angle of at least one steered wheel; and
a steering control system operable to output a steering control signal to the steering device for controlling operation of the steering device, wherein the steering control system generates the steering control signal based on the optimized vehicle trajectory.

16. The autonomous vehicle of claim 15 , wherein the optimized vehicle trajectory corresponds to a set of control inputs.

17. The control apparatus of claim 16 , wherein the set of control inputs includes a plurality of steering angle values that are each associated with a discrete location along the optimized vehicle trajectory.

18. The autonomous vehicle of claim 15 , wherein the velocity profile is predetermined, and determining the optimized vehicle trajectory does not include modifying the velocity profile.

19. The autonomous vehicle of claim 15 , wherein the trajectory length value is a function of a length from the current state to the goal state and a trajectory weighting factor, and the lateral acceleration value is a function of a length from the current state to the goal state and a lateral acceleration weighting factor.

20. The autonomous vehicle of claim 15 , wherein the determining the initial vehicle trajectory fitting the trajectory to the current state of the autonomous vehicle and the goal state of the autonomous vehicle using a vehicle dynamics model.

21. The autonomous vehicle of claim 15 , wherein determining the optimized vehicle trajectory is performed by applying Levenberg-Marquardt minimization.

Assignees

• Nissan North America Inc

Inventors

• Pedersen Liam

Classifications

• G05D1/0088 Primary

  characterized by the autonomous decision making process, e.g. artificial intelligence, predefined behaviours (using knowledge based models G06N5/00) · CPC title

• B60W30/10

  Path keeping {(cruise control for automatically following a preceding vehicle B60W30/165)} · CPC title

• B60W60/001 Primary

  Planning or execution of driving tasks · CPC title

• G05D1/0217 Primary

  in accordance with energy consumption, time reduction or distance reduction criteria · CPC title