Method And System For Forward Collision Avoidance In An Automotive Vehicle

• US 20070112514A1
• Filed: 04/28/2006
• Published: 05/17/2007
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Polestar Performance AB (Polestar Automotive Holding UK Plc)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Ekmark, Jonas, Jansson, Jonas
• Granted Patent: US 7,647,178 B2
• Time in Patent Office: Days
• US Class Current: 701/301
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 2420/403 Image sensing, e.g. optical camera
• CPC Class Codes: B60W 2554/4041 Position
• 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 30/12 Lane keeping
• CPC Class Codes: B60W 30/16 Control of distance between vehicles, e.g. keeping a distance to preceding vehicle
• CPC Class Codes: B60W 50/14 Means for informing the driver, warning the driver or prompting a driver intervention
• CPC Class Codes: G08G 1/161 Decentralised systems, e.g. inter-vehicle communication

Abstract

The present patent application relates to a method and system for autonomous action in multiple obstacle scenarios in an automotive vehicle forward collision avoidance system. Initially the presence of obstacles in front of a vehicle hosting the system is established. Thereafter the position, velocity and acceleration of the obstacles are estimated. The maneuvers which the vehicle is capable of performing that will lead to a collision with each respective obstacle is evaluated separately. The union of maneuvers which will lead to collision with any one of the obstacles is formed. The set of maneuvers which the vehicle is capable of performing through which collision with any of the obstacles may be avoided is established, and the set used for deciding how to avoid or mitigate collision with any one of the obstacles. Finally a collision avoidance maneuver based on said decision is executed autonomously.

Claims

1. A method for autonomous action in multiple obstacle scenarios in an automotive vehicle forward collision avoidance system, characterized in that it comprises the steps of:

establishing the presence of obstacles in front of a vehicle hosting said system;

estimating the position, velocity and acceleration of said obstacles;

evaluating for each respective one of said obstacles separately the maneuvers which the vehicle is capable of performing that will lead to a collision with said respective obstacle;

forming the union of maneuvers which will lead to collision with any one of said obstacles;

establishing the set of maneuvers which the vehicle is capable of performing through which collision with any of said obstacles may be avoided;

using said set for deciding how to avoid or mitigate collision with any one of said obstacles;

autonomously executing a collision avoidance maneuver based on said decision.

2. A method according to claim 1,

characterized in that it further comprises the steps of:

defining the set E of all the possible maneuvers that the driver and vehicle can perform;

defining, for each obstacle i={1, . . . , N}, a new set f_i, where f_i defines the set of maneuvers that lead to a collision with obstacle i;

forming the combined set of all maneuvers leading to a collision, which is given by F=f_i∪

. . . ∪

f_N, and where all maneuvers that do not lead to a collision are given by the set G=E\F, and a collision may be considered to be unavoidable if G=Ø

;

establishing a maneuver that avoids collision using min(G), which denotes the maneuver with the smallest effort that avoids collision.

3. A method according to any one of claims 1 or 2,

characterized in that it in order to realize a collision avoidance decision function for lateral vehicle maneuvers further comprises the step of:

calculating the lateral acceleration required to avoid collision with an obstacle.

4. A method according to claim 3,

characterized in that it the step of calculating the lateral acceleration required to avoid collision with an obstacle it is assumed that both the host and obstacle move with constant acceleration laterally, and the lateral acceleration required to avoid collision with an obstacle is calculated as:

${\stackrel{\mathrm{¨<br><br>}}{x}}_{\mathrm{needed}}={\stackrel{\mathrm{¨<br><br>}}{x}}_{\mathrm{lat},0}^{\mathrm{obstacle}}+\frac{-{\tilde{x}}_{\mathrm{lat},0}\pm <br><br>\frac{w^{\mathrm{host}}}{2}\pm <br><br>\frac{w^{\mathrm{obstacle}}}{2}-{\widetilde{\stackrel{.}{x}}}_{\mathrm{lat},0}<br><br>\mathrm{TTC}}{{\mathrm{TTC}}^2}$

where, in those cases where a solution exist the time to collision, TTC, is calculated as;

$\mathrm{TTC}=\{\begin{array}{c}\frac{{\tilde{x}}_{\mathrm{long},0}}{{\widetilde{\stackrel{.}{x}}}_{\mathrm{long},0}},\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}=0\\ \frac{-{\widetilde{\stackrel{.}{x}}}_{\mathrm{long},0}}{{\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}}_{\mathrm{long},0}}\pm <br><br>\frac{\sqrt{{\widetilde{\stackrel{.}{x}}}_{\mathrm{long},0}^2-2<br><br>{\tilde{x}}_{\mathrm{long},0}<br><br>{\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}}_{\mathrm{long},0}}}{{\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}}_{\mathrm{long},0}},\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}\ne <br><br>0\end{array}$

where;

{umlaut over (x)}_needed is the needed lateral acceleration (m/s²)

x_i,0^j is the lateral or longitudinal position for obstacle or host vehicle (m)

{dot over (x)}₀^j is the velocity for obstacle or host (m/s)

{umlaut over (x)}₀^j is the acceleration for obstacle or host (m/s²)

w^j is the vehicle width for obstacle or host (m)

and;

subscript “

lat” and

“

long”

denotes lateral and longitudinal motion respectively and superscript “

host” and

“

obstacle”

denotes the host and the obstacle vehicle, such that;

{tilde over (x)}=x^obstacle−

x^host is the relative distance (m)

{dot over ({tilde over (x)})}={dot over (x)}^obstacle−

{dot over (x)}^host is the relative velocity (m/s)

{umlaut over ({tilde over (x)})}={umlaut over (x)}^obstacle−

{umlaut over (x)}^host is the relative acceleration (m/s²)

5. An automotive vehicle forward collision avoidance system,

characterized in that it for autonomous action in multiple obstacle scenarios comprises:

means for establishing the presence of obstacles in front of a vehicle hosting said system;

means for estimating the position, velocity and acceleration of said obstacles;

means for evaluating for each respective one of said obstacles separately the maneuvers which the vehicle is capable of performing that will lead to a collision with said respective obstacle;

means for forming the union of maneuvers which will lead to collision with any one of said obstacles;

means for establishing the set of maneuvers which the vehicle is capable of performing through which collision with any of said obstacles may be avoided;

means for, using said set, deciding how to avoid or mitigate collision with any one of said obstacles;

means for autonomously executing a collision avoidance maneuver based on said decision.

6. A system according to claims 5,

characterized in that the means for establishing the presence of obstacles in front of said vehicle hosting said system comprises at least one of a RADAR system, a LIDAR system or a camera based system arranged to monitor the region in front of said host vehicle.

7. A system according to claim 6,

characterized in that it further comprises:

means for defining the set E of all the possible maneuvers that the driver and vehicle can perform;

means for defining, for each obstacle i={1, . . . , N}, a new set f_i, where f_i defines the set of maneuvers that lead to a collision with obstacle i;

means for forming the combined set of all maneuvers leading to a collision, which is given by F=f_i∪

. . . ∪

f_N., and where all maneuvers that do not lead to a collision are given by the set G=E\F, and a collision may be considered to be unavoidable if G=Ø

;

means for establishing a maneuver that avoids collision using min(G), which denotes the maneuver with the smallest effort that avoids collision.

8. A system according to claim 7,

characterized in that it further comprises:

means for calculating the lateral acceleration required to avoid collision with an obstacle under the assumption that both the host and obstacle move with constant acceleration laterally, and which means are arranged to calculate the lateral acceleration required to avoid collision with an obstacle as;

${\stackrel{\mathrm{¨<br><br>}}{x}}_{\mathrm{needed}}={\stackrel{\mathrm{¨<br><br>}}{x}}_{\mathrm{lat},0}^{\mathrm{obstacle}}+\frac{-{\tilde{x}}_{\mathrm{lat},0}\pm <br><br>\frac{w^{\mathrm{host}}}{2}\pm <br><br>\frac{w^{\mathrm{obstacle}}}{2}-{\widetilde{\stackrel{.}{x}}}_{\mathrm{lat},0}<br><br>\mathrm{TTC}}{{\mathrm{TTC}}^2}$

and, in those cases where a solution exist, arranged to calculate the time to collision, TTC, as;

$\mathrm{TTC}=\{\begin{array}{c}\frac{{\tilde{x}}_{\mathrm{long},0}}{{\widetilde{\stackrel{.}{x}}}_{\mathrm{long},0}},\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}=0\\ \frac{-{\widetilde{\stackrel{.}{x}}}_{\mathrm{long},0}}{{\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}}_{\mathrm{long},0}}\pm <br><br>\frac{\sqrt{{\widetilde{\stackrel{.}{x}}}_{\mathrm{long},0}^2-2<br><br>{\tilde{x}}_{\mathrm{long},0}<br><br>{\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}}_{\mathrm{long},0}}}{{\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}}_{\mathrm{long},0}},\widetilde{\stackrel{\mathrm{¨<br><br>}}{x}}\ne <br><br>0\end{array}$

where;

{umlaut over (x)}_needed is the needed lateral acceleration (m/s²)

x_i,0^j is the lateral or longitudinal position for obstacle or host vehicle (m)

{dot over (x)}₀^j is the velocity for obstacle or host (m/s)

{umlaut over (x)}₀^j is the acceleration for obstacle or host (m/s²)

w^J is the vehicle width for obstacle or host (m)

and;

subscript “

lat” and

“

long”

denotes lateral and longitudinal motion respectively and superscript “

host” and

“

obstacle”

denotes the host and the obstacle vehicle, such that;

{tilde over (x)}=x^obstacle−

x^host is the relative distance (m)

{dot over ({tilde over (x)})}={dot over (x)}^obstacle−

{dot over (x)}^host is the relative velocity (m/s)

{umlaut over ({tilde over (x)})}={umlaut over (x)}^obstacle−

{umlaut over (x)}^host is the relative acceleration (m/s²)

9. An automotive vehicle, characterized in that it comprises an automotive vehicle forward collision avoidance system according to any one of claims 5 to 8.