Obstacle avoidance guidance for ground vehicles

Patent metadata

Field	Value
Publication number	US-2021163068-A1
Application number	US-201917048285-A
Country	US
Kind code	A1
Filing date	Apr 16, 2019
Priority date	Apr 16, 2018
Publication date	Jun 3, 2021
Grant date	—

Abstract

Systems, methods, and computer program products for guiding vehicles. A vehicle control system detects obstacles and avoids contact between the vehicle, and the obstacles by solving a path planning problem using a four-phase system. In a parking scenario, switching control laws are used to drive the vehicle to a target line, and a forward path segment and a reverse path segment defined. The two path segments are connected along the target line to define a path for entering or exiting the parking space. Objects in a driving environment may be avoided by identifying an obstacle corner, defining an avoidance circle ( 62 ), ( 185 ) around the obstacle corner, and determining a path that allows the vehicle to avoid penetrating the avoidance circle. A line-of-sight guidance method may be used to follow the path by defining target points on the path at a lookout distance l, and steering the vehicle using the target points.

First claim

1 . A system comprising:
one or more processors; and a memory coupled to the one or more processors and including program code that, when executed by the one or more processors, causes the system to: define a virtual space including a vehicle, a parking space, an obstacle corner, and a target line; determine a ready position from which the vehicle can avoid the obstacle corner when moving between the ready position and the target line; move the vehicle between a first pose in the parking space and a second pose in the ready position; move the vehicle between the second pose and a third pose on the target line; determine a first path segment by tracing the vehicle as the vehicle is moved between the first pose, the second pose, and the third pose; move the vehicle between a fourth pose outside the parking space and a fifth pose on the target line; determine a second path segment by tracing the vehicle as the vehicle is moved between the fourth pose and the fifth pose; connect the first path segment to the second path segment to define a virtual path between the first pose and the fourth pose; and generate one or more control signals that cause a physical vehicle to move in a physical space using the virtual path in the virtual space.

2 . The system of claim 1 wherein the first pose is one of an initial pose or a final pose, the fourth pose is the other of the initial pose or the final pose, and the target line is in a drive aisle adjacent to the parking space.

3 . (canceled)

4 . The system of claim 1 wherein the program code causes the system to move the vehicle between the first pose in the parking space and the second pose in the ready position by moving the vehicle from the first pose to the second pose, and move the vehicle between the second pose and the third pose by moving the vehicle from the third pose to the second pose.

5 . (canceled)

6 . The system of claim 1 wherein the program code causes the system to define the virtual space to further include a bounded region, and the vehicle is kept within the bounded region.

7 . The system of claim 1 wherein the vehicle includes an orientation and a position, and when the vehicle is in the third pose, the orientation of the vehicle is within an orientation tolerance of the target line and the position of the vehicle is within a position tolerance of the target line.

8 . The system of claim 1 wherein the vehicle has a longitudinal axis and a width, and the program code causes the system to move the vehicle between the first pose and the second pose by:
defining an avoidance circle around the obstacle corner having a radius greater than half the width of the vehicle;
maneuvering the vehicle from the first pose until the longitudinal axis is pointing out of the parking space without hitting the avoidance circle;
straightening a steering angle of the vehicle; and
moving the vehicle forward to the second pose.

9 . The system of claim 8 wherein the vehicle has a rear axle having a midpoint, and the program code causes the system to maneuver the vehicle from the first pose until the longitudinal axis is pointing out of the parking space without hitting the avoidance circle by:
defining a line-of-sight that intersects the midpoint of the rear axle, points out of the parking space, and is tangent to the avoidance circle; and
alternately adjusting the steering angle and moving the vehicle backward and forward one or more times until an acute angle between the longitudinal axis of the vehicle and the line-of-sight is below an orientation threshold.

10 - 11 . (canceled)

12 . The system of claim 1 wherein the program code further causes the system to generate the one or more control signals by converting the virtual path to a trajectory that satisfies kinematics constraints of the vehicle, dynamics constraints of the vehicle, or both the kinematics constraints and the dynamics constraints of the vehicle.

13 . (canceled)

14 . The system of claim 12 wherein the virtual path includes one or more path segments, the program code causes the system to convert the virtual path to the trajectory by assigning a prespecified velocity profile to each path segment, and the prespecified velocity profile is selected from a plurality of prespecified velocity profiles based on a cost function that minimizes an error between the trajectory and the virtual path.

15 . (canceled)

16 . The system of claim 12 wherein the vehicle has a rear axle having a midpoint, and the program code causes the system to convert the virtual path to the trajectory by:
defining a line-of-sight that intersects the midpoint of the rear axle of the vehicle and a virtual target on the virtual path;
selecting a position of the virtual target on the virtual path that provides a lookout distance and a line-of-sight angle; and
determining a yaw rate for the vehicle based on the lookout distance, the line-of-sight angle, and a speed of the vehicle.

17 . The system of claim 16 wherein the speed for the vehicle is determined based on a curvature of the virtual path, the position of the virtual target is selected so that the lookout distance is inversely proportional to the curvature of the virtual path, the yaw rate for the vehicle and the speed for the vehicle are further determined based on a guidance constant, and the guidance constant is increased in response to a change in a sign of the curvature of the virtual path.

18 - 19 . (canceled)

20 . A method comprising:
defining a virtual space including a vehicle, a parking space, an obstacle corner, and a target line; determining a ready position from which the vehicle can avoid the obstacle corner when moving between the ready position and the target line; moving the vehicle between a first pose in the parking space and a second pose in the ready position; moving the vehicle between the second pose and a third pose on the target line; determining a first path segment by tracing the vehicle as the vehicle is moved between the first pose, the second pose, and the third pose; moving the vehicle between a fourth pose outside the parking space and a fifth pose on the target line; determining a second path segment by tracing the vehicle as the vehicle is moved between the fourth pose and the fifth pose; connecting the first path segment to the second path segment to define a virtual path between the first pose and the fourth pose; and generating one or more control signals that cause a physical vehicle to move in a physical space using the virtual path in the virtual space.

21 . The method of claim 20 wherein the first pose is one of an initial pose or a final pose, the fourth pose is the other of the initial pose or the final pose, and the target line is in a drive aisle adjacent to the parking space.

22 - 26 . (canceled)

27 . The method of claim 20 wherein the vehicle has a longitudinal axis and a width, and moving the vehicle between the first pose and the second pose includes:
defining an avoidance circle around the obstacle corner having a radius greater than half the width of the vehicle;
maneuvering the vehicle from the first pose until the longitudinal axis is pointing out of the parking space without hitting the avoidance circle;
straightening a steering angle of the vehicle; and
moving the vehicle forward to the second pose.

28 . The method of claim 27 wherein the vehicle has a rear axle having a midpoint, and maneuvering the vehicle from the first pose unti

Assignees

• Univ Ohio

Inventors

• Zhu Jianchao
• Lin Letian

Classifications

• B62D15/0285 Primary

  Parking performed automatically · CPC title

• G05D2201/02

  Physics · mapped topic

• G05D1/021

  specially adapted to land vehicles · CPC title

• G05D1/69

  Coordinated control of the position or course of two or more vehicles · CPC title