Method for Performing a Braking Maneuver Using a Vehicle Braking Assistant

Abstract

The invention relates to a method for performing a braking maneuver using a braking assistant (9) in a motor vehicle (3), wherein the braking assistant (9) initiates an automatic braking maneuver when a distance between the motor vehicle (3) and an object (5) located ahead of the motor vehicle (3) is less than a minimum distance a.sub.min, an acceleration signal of the decelerating vehicle (3) is ascertained, and if the acceleration signal is positive the braking maneuver initiated by the braking assistant (9) is automatically interrupted.

Claims

1. A method for performing a braking maneuver using a braking assistant (9) in a motor vehicle (3), wherein the braking assistant (9) initiates an automatic braking maneuver when a distance between the motor vehicle (3) and an object (5) located ahead of the motor vehicle (3) is less than a minimum distance a.sub.min, wherein an acceleration signal of the decelerating vehicle (3) is ascertained, and wherein if the acceleration signal is positive the braking maneuver performed by the braking assistant (9) is automatically interrupted.

2. The method according to claim 1, wherein the acceleration signal is ascertained by means of an onboard acceleration sensor (11).

3. The method according to claim 1, wherein the current change in speed of the vehicle (3) is ascertained based on the acceleration signal.

4. The method according to claim 1, wherein the current change in speed of the vehicle (3) is ascertained by integration of the acceleration signal.

5. The method according to claim 4, wherein, to ascertain the current change in speed of the vehicle (3), an acceleration integrator is used.

6. The method according to claim 5, wherein, as the acceleration integrator, a low-pass filter is used.

7. The method according to claim 3, wherein the current change in speed of the vehicle (3) is compared with a specified speed threshold.

8. The method according to claim 7, wherein, if the speed threshold is exceeded, the braking maneuver of the vehicle (3) is automatically interrupted.

9. A method of braking a motor vehicle with an automatic braking assistant system of the vehicle, comprising steps: a) initiating an automatic braking of the motor vehicle with the automatic braking assistant system; b) while the automatic braking is proceeding, with a sensor of the motor vehicle producing a sensor signal that is indicative of an acceleration of the motor vehicle, and evaluating the sensor signal to determine a sign of the acceleration; and c) when the sign of the acceleration is positive while the automatic braking is proceeding, then in response thereto automatically interrupting the automatic braking of the motor vehicle with the automatic braking assistant system.

10. The method according to claim 9, further comprising the step: d) when the sign of the acceleration is negative while the automatic braking is proceeding, then in response thereto automatically continuing the automatic braking of the motor vehicle with the automatic braking assistant system.

11. The method according to claim 9, wherein the step a) comprises detecting a spacing distance between the motor vehicle and an object located in front of the motor vehicle, comparing the detected spacing distance to a distance threshold, and when the detected spacing distance falls below the distance threshold then in response thereto performing the initiating of the automatic braking of the motor vehicle.

12. The method according to claim 9, excluding determining a direction of travel of the motor vehicle other than as indicated indirectly by the sign of the acceleration.

Description

[0023] In the following exemplary embodiments of the invention are explained in more detail using a drawing. This shows as follows:

[0024] FIG. 1 a first traffic situation with two vehicles following one behind the other and observing a specified minimum distance a.sub.min, and

[0025] FIG. 2 a second traffic situation with the two vehicles and where the distance is less than the minimum a.sub.min.

[0026] FIG. 1 shows a traffic situation 1, in which an ego-vehicle 3 and an object located ahead of the ego-vehicle 3, another vehicle 5, are travelling one behind the other in a lane 7 in the same direction of movement x, in forwards direction, at a distance a. The distance between the two vehicles is above a specified minimum distance a.sub.min (a>a.sub.min).

[0027] The ego-vehicle 3 is equipped with a braking assistant 9 with an acceleration sensor 11. By means of the braking assistant 9, in the event of an impending collision, when therefore the other vehicle 5 brakes, a braking maneuver of the ego-vehicle 3 is initiated. Here the acceleration sensor 11 ascertains the acceleration of the ego-vehicle 3. The braking assistant 9 uses the sign of the ascertained acceleration signal to ascertain the direction of movement of the ego-vehicle 3.

[0028] In this case, when the other vehicle 5 brakes, the distance a between the two vehicles 3,5 reduces and the braking assistant 9 initiates a braking maneuver, to restore the required minimum distance a.sub.min. The speed of the ego-vehicle 3 reduces in the forwards direction. The acceleration signal accordingly takes a negative value. The braking maneuver is accordingly continued until the minimum distance a.sub.min has been achieved again.

[0029] In the traffic situation 21 shown in FIG. 2, in addition to the two vehicles 3, 5 there is an obstruction in the form of a further vehicle 23 in the lane 7. The other vehicle 5 located ahead of the ego-vehicle 3 is accordingly travelling backwards to avoid the obstruction 23. At the same time the ego-vehicle 3 is also travelling backwards, to avoid a collision with the other vehicle 5.

[0030] In this case, however, the other vehicle is travelling backwards faster than the ego-vehicle 3, so that the distance a between the two vehicles 3, 5 falls to a level below the critical distance a.sub.min (a<a.sub.min). Because the level is below the minimum distance a.sub.min the braking assistant 9, which has no knowledge of the direction of travel, thus in this case the backwards direction, initiates a braking maneuver, to increase the distance between the two vehicles 3, 5.

[0031] The response by the braking assistant 9 would thus lead to the actual collision between the two vehicles 3, 5 that is to be avoided. Through further intervention of the braking assistant 9, however, such a collision is prevented. By ascertaining the acceleration, the starting direction of movement of the vehicle 3 is ascertained. The acceleration signal ascertained by means of the acceleration sensor 11 in this case takes a positive value during the braking maneuver. In this case the initiated braking maneuver is interrupted by the braking assistant 9 and thus a collision between the two vehicles 3,5 is avoided or at least the seriousness of the consequences of such a collision is reduced.

LIST OF REFERENCE NUMERALS

[0032] 1 Traffic situation

[0033] 3 Ego-vehicle

[0034] 5 Object

[0035] 7 Lane

[0036] 9 Braking assistant

[0037] 11 Acceleration sensor

[0038] 21 Traffic situation

[0039] 23 Obstacle