Autonomous vehicle driving systems and methods for critical conditions

• US 10,725,470 B2
• Filed: 06/13/2017
• Issued: 07/28/2020
• 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: Mahabadi, Seyedalireza Kasaiezadeh, Jafari Tafti, Sayyed Rouhollah, Heil, Edward T., Moshchuk, Nikolai K., Litkouhi, Bakhtiar B.
• Primary Examiner(s): Smith, Isaac G
• Application Number:
  US15/621,221
• Publication Number:
  US 20180356819A1
• Time in Patent Office: 1,141 Days
• Field of Search: 701 26, 701301
• CPC Class Codes: B60W 2050/0075 Automatic parameter input, automatic initialising or calibrating means
• CPC Class Codes: B60W 2050/009 Priority selection
• CPC Class Codes: B60W 2554/00 Input parameters relating to objects
• CPC Class Codes: B60W 30/00 Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
• CPC Class Codes: B60W 30/08 Active safety systems predicting or avoiding probable or impending collision or attempting to minimise its consequences
• CPC Class Codes: B60W 30/09 Taking automatic action to avoid collision, e.g. braking and steering
• CPC Class Codes: G01C 21/3453 Special cost functions, i.e. other than distance or default speed limit of road segments
• 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 1/0212 with means for defining a desired trajectory involving a plurality of land vehicles G05D1/0287
• CPC Class Codes: G05D 1/0217 in accordance with energy consumption, time reduction or distance reduction criteria
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: G08G 1/202 Dispatching vehicles on the basis of a location, e.g. taxi dispatching

Abstract

A method is provided for autonomously operating a vehicle. The method includes receiving, at a processor, at least vehicle state data and vehicle object environment data; generating, with the processor, an optimal path for the vehicle with a cost function based on the vehicle state data and the vehicle object environment data; identifying, with the processor, at least one critical condition constraint based on at least one of the vehicle or vehicle environment; modifying, with the processor, at least a first portion of the optimal path based on the at least one critical condition constraint to result in a short-range trajectory portion; generating a resulting trajectory with the short-range trajectory portion; and implementing the resulting trajectory on the vehicle.

Claims

1. A method for autonomously operating a vehicle, the method comprising:

generating, by a processor, a search graph based on a reference trajectory, wherein the search graph includes a plurality of nodes that are offset in a lateral direction from centerline waypoint stations, and line segments that connect each node of the plurality of nodes to neighboring nodes;

generating, by the processor, a first path for the vehicle based on a cost function and the search graph, wherein the cost function is associated with possible collisions with static and dynamic objects on a road, a degree of offset from the reference trajectory, a required steering action, a degree of deviation from a previously generated trajectory;

generating, by the processor, a first trajectory based on the first path and a corridor, the corridor defines points associated with the first path and that represent safe distances from obstacles;

identifying, by the processor, at least one constraint;

modifying, by the processor, at least a first portion of the first trajectory using model predictive control that takes into account the at least one constraint to result in a second trajectory, wherein the portion is defined based on a pre-defined duration;

generating a resulting trajectory based on the first trajectory and the second trajectory; and

controlling the vehicle based on the resulting trajectory.

2. The method of claim 1 wherein the generating the resulting trajectory includes combining the first trajectory and the second trajectory, by smoothing an ending of the second trajectory with a beginning of the first trajectory to form the resulting trajectory.

3. The method of claim 1, wherein the at least one constraint is a safe zone constraint defined around the first portion of the first trajectory as an acceptable deviation.

4. The method of claim 1, wherein the at least one constraint is a stability constraint representing lateral motion of the vehicle in terms of side slope angle (β

) and yaw rate (r={dot over (φ

)}).

5. The method of claim 1, wherein the at least one constraint is an actuator constraint representing a limitation associated with at least one of a steering system, a propulsion system, or a braking system of the vehicle.

6. The method of claim 1, wherein the at least one constraint is based on a vehicle dynamics model.

7. The method of claim 1,

and wherein the search graph uses a coordinate system that indicates lateral offsets of objects relative to the reference trajectory.

8. The method of claim 7, wherein the objects include other vehicles in the vehicle environment.

9. The method of claim 8, wherein the search graph is one of a plurality of search graphs generated using the coordinate system to determine trajectory paths in different road scenarios.

14. The method of claim 1, wherein the model predictive control includes a linear parameter varying system.

10. An autonomous vehicle, comprising:

at least one sensor that provides sensor data about objects within a vehicle environment as vehicle object environment data and about a vehicle state as vehicle state data; and

a controller that, by a processor and based on the sensor data, is configured to;

generate, a search graph based on a reference trajectory, wherein the search graph includes a plurality of nodes that are offset in a lateral direction from centerline waypoint stations, and line segments that connect each node of the plurality of nodes to neighboring nodes;

generate a first path for the vehicle based on a cost function and the search graph, wherein the cost function is associated with possible collisions with static and dynamic objects on a road, a degree of offset from the reference trajectory, a required steering action, a degree of deviation from a previously generated trajectory;

generate a first trajectory based on the first path and a corridor, the corridor defines points associated with the first path and that represent safe distances from obstacles;

identify at least one critical condition constraint based on at least one of the vehicle or the vehicle environment;

modify at least a first portion of the first trajectory using model predictive control that takes into account the at least one critical condition constraint to result in a second trajectory, wherein the first portion is defined based on a pre-defined duration;

generate a resulting trajectory based on the first trajectory and the second trajectory; and

control the vehicle based on the resulting trajectory.

11. The autonomous vehicle of claim 10, wherein the controller is configured to generate the first trajectory without consideration of the at least one critical condition constraint.

12. The autonomous vehicle of claim 11, wherein the controller is configured to smooth a first end of the second trajectory to provide continuity with a second end of the first trajectory.

13. The autonomous vehicle of claim 12,

wherein the at least one critical condition constraint includes

a safe zone constraint defined around the first portion of the first trajectory as an acceptable deviation,

a stability constraint representing lateral motion of the vehicle in terms of side slope angle (β

) and yaw rate (r={dot over (φ

)}), or an actuator constraint representing a limitation associated with at least one of a steering system, a propulsion system, or a braking system of the vehicle.