Steering Assist in Driver Initiated Collision Avoidance Maneuver

• US 20140032049A1
• Filed: 07/24/2012
• Published: 01/30/2014
• Est. Priority Date: 07/24/2012
• 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, Zagorski, Chad T., Chatterjee, Aamrapali
• Granted Patent: US 8,849,515 B2
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B62D 15/0265 Automatic obstacle avoidance by steering
• CPC Class Codes: G08G 1/165 for passive traffic, e.g. including static obstacles, trees
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

A collision avoidance system for assisting a driver in avoiding a collision between a host vehicle and obstacle. A processor recursively calculates a time-to-collision with the obstacle and an optimal collision avoidance path for avoiding the collision. The optimum collision avoidance path is recursively generated based on a position and speed of the host vehicle relative to the obstacle and an updated calculated time-to-collision. A sensing device determines whether the driver of the vehicle has initiated a steering maneuver to avoid the obstacle. A steering assist mechanism maintains the host vehicle along the optimum collision avoidance path. The steering assist mechanism applies a steering assist torque for producing steering adjustments to assist in guiding the host vehicle along the optimum collision avoidance path to the target lane. The steering assist torque generated by the steering assist mechanism is recursively adjusted based on a recent updated optimum collision avoidance path.

Claims

1. A method of assisting a driver in avoiding a collision between a host vehicle and an obstacle in a lane of travel, the method comprising the steps of:

identifying a collision threat with the obstacle;

recursively calculating a time-to-collision;

recursively generating an optimal collision avoidance path to a target lane for avoiding a collision with the forward driven vehicle, wherein recursively generating the optimum collision avoidance path is determined by a processor and is based on a position and a speed of the host vehicle relative to the obstacle and an updated calculated time-to-collision;

determining whether the driver of the vehicle has initiated a steering maneuver to avoid the obstacle;

enabling steering assist for maintaining the host vehicle along the optimum collision avoidance path, the steering assist applying a torque by a steering mechanism for producing steering adjustments to assist in guiding the host vehicle along the optimum collision avoidance path to the target lane; and

recursively adjusting the steering assist torque by the steering mechanism based on a recent updated optimum collision avoidance path.

2. The method of claim 1 wherein enabling steering assist for maintaining the host vehicle along the optimum collision avoidance path further includes determining whether the optimum collision avoidance path is feasible, wherein the steering assist torque is recursively adjusted if the optimum collision avoidance path is feasible, and wherein the steering assist is disabled in response to the collision avoidance path being infeasible.

3. The method of claim 1 wherein enabling steering assist for maintaining the host vehicle along the optimum collision avoidance path further includes determining whether the target lane is clear for making a lane change, wherein the steering assist torque is recursively adjusted if the target lane is clear for making the lane change, and wherein the steering assist is disabled in response to the target lane becoming not clear for making the lane change.

4. The method of claim 1 wherein enabling steering assist is based on whether collision imminent braking is initiated by a vehicle control unit, wherein the steering assist is enabled if the collision imminent braking is initiated.

5. The method of claim 1 wherein enabling steering assist for maintaining the host vehicle along the optimum collision avoidance path further includes determining that the driver'"'"'s self-initiated steering maneuver is insufficient for avoiding the collision based on the optimum collision avoidance path.

6. The method of claim 1 wherein the determining whether the optimum collision avoidance path is feasible includes determining when the maximum allowable lateral acceleration is less than 5.0 m/sec².

7. The method of claim 1 wherein steering assist is disabled if a driver overrides the torque applied by the steering assist to the steering mechanism.

8. The method of claim 1 wherein the optimum collision avoidance path includes a lane change to an adjacent target lane, and wherein the steering assist is disabled if the adjacent target lane is unavailable.

9. The method of claim 1 wherein steering assist is disabled when the host vehicle successfully completes a lane change maneuver to the target lane.

10. The method of claim 1 wherein a steering assist adjustment threshold is estimated that is a function of a time required for the host vehicle to move from a current position to the target lane utilizing the optimum collision avoidance path, and wherein a steering assist adjustment threshold is compared to an updated time-to-collision estimation, and wherein the steering assist is enabled as a function of the time-to-collision estimation being less than the steering assist adjustment threshold.

11. The method of claim 10 wherein the steering assist adjustment threshold TH_SAA is represented by the following formula:

TH_SAA=x_h/V_x+τ

wherein V_x is a velocity of the host vehicle, x_h is a distance from the host vehicle to a position along the optimum collision avoidance path in the target lane, and τ

is the steering actuator delay.

12. The method of claim 11 wherein the position along the optimum collision avoidance path to the target is a respective distance from a centerline of the obstacle into the target lane.

13. The method of claim 12 wherein distance form the centerline of the obstacle into the target lane is determined by the following formula:

14. The method of claim 1 wherein the obstacle is a remote vehicle.

17. The collision avoidance system of claim 10 wherein the steering assist adjustment threshold TH_SAA is represented by the following formula:

TH_SAA=x_h/V_x+τ

wherein V_x is a velocity of the host vehicle, and x_h is a distance from the host vehicle to a position along the optimum collision avoidance path in the target lane.

18. The collision avoidance system of claim 11 wherein the position along the optimum collision avoidance path to the target lane is a respective distance from a centerline of the obstacle into the target lane.

19. The collision avoidance system of claim 12 wherein distance form the centerline of the obstacle into the target lane is determined by the following formula:

15. A collision avoidance system for assisting a driver in avoiding a collision between a host vehicle and obstacle, the system comprising:

a memory for retaining position and speed of the host vehicle and the obstacle;

a processor for recursively calculating a time-to-collision with the obstacle, the processor recursively generating an optimal collision avoidance path to a target lane for avoiding a collision with the obstacle, wherein recursively generating an optimum collision avoidance path is based on a position and a speed of the host vehicle relative to the obstacle and an updated calculated time-to-collision;

a sensing device for determining whether the driver of the vehicle has initiated a steering maneuver to avoid the obstacle; and

a steering assist mechanism for maintaining the host vehicle along the optimum collision avoidance path, the steering assist mechanism applying a steering assist torque for producing steering adjustments to assist in guiding the host vehicle along the optimum collision avoidance path to the target lane;

wherein the steering assist torque generated by the steering assist mechanism is recursively adjusted based on a recent updated optimum collision avoidance path.

16. The collision avoidance system of claim 15 wherein a steering assist adjustment threshold by the processor is estimated that is a function of a time required for the host vehicle to move from a current position to the target lane utilizing the optimum collision avoidance path, and wherein a steering assist adjustment threshold is compared to an updated time-to-collision estimation, and wherein the steering assist torque is enabled as a function of the time-to-collision estimation being less than the steering assist adjustment threshold.

20. The collision avoidance system of claim 15 wherein enabling the steering assist torque for maintaining the host vehicle along the optimum collision avoidance path further includes determining whether the optimum collision avoidance path is feasible, wherein the steering assist torque is recursively adjusted if the optimum collision avoidance path is feasible, and wherein the steering assist torque is disabled in response to the collision avoidance path being infeasible.