Method for automatic emergency braking of motor vehicle

Abstract

The invention relates to a method for automatic emergency braking (54) of a motor vehicle (10), in which a detection system (13) arranged on the motor vehicle (10) detects a traveling obstacle (20) and transmits the detected obstacle to an electronic control unit (14) of the motor vehicle (10). According to the invention, an automatic emergency braking (54) of the motor vehicle (10) is triggered only if an imminent collision of the motor vehicle (10) with an obstacle (20) is determined by the controller (14), which collision can no longer be avoided by a driving impact on the obstacle (20).

Description

Technical Field

[0001] The invention relates to a method for automatic emergency braking of a motor vehicle. In addition, the invention relates to a computer program product which is designed to carry out each step of the method according to the invention and to a machine-readable storage medium on which the computer program product according to the invention is stored. In addition, the invention relates to an electronic control unit which is designed to carry out automatic emergency braking of a motor vehicle by means of the method according to the invention. Background Art

[0002] If a driver assistance system for a motor vehicle detects a serious risk of a collision between the motor vehicle and an obstacle, it can trigger automatic emergency braking. In this way, accidents are to be avoided that the driver of the motor vehicle is unable to avoid independently due to driving error, inattention or insufficient reaction to the dangerous situation.

[0003] DE 197 38 611 A1 describes a method of this type which enables the driver to have maximum decision-making autonomy when avoiding, braking or accelerating with respect to an obstacle, without having to dispense with the advantages of a system that supports the driver for collision avoidance or accident severity reduction in the event of an actual collision situation. For this purpose, it is provided that automatic emergency braking is triggered only if the driver assistance system determines that a collision with an obstacle can no longer be avoided by the driver's driving influence by means of steering and / or braking in terms of driving physics.

[0004] Driver assistance systems use environmental detection sensors to identify obstacles. However, due to the inaccuracy of these sensors, such as radar sensors, and due to the reflection of radar waves emitted by radar sensors on the surrounding infrastructure, it may happen that the driver assistance system mistakenly identifies obstacles that do not actually exist. Such non-existent obstacles are called phantom objects. If emergency braking is triggered due to the detection of phantom objects, this will cause the driver to lose comfort in the best case. However, in the worst case, the motor vehicle stops in the driving path of other real vehicles, or arrives at the driving path of real vehicles slightly later due to the reduction in speed, which leads to a collision that would not occur without emergency braking. Summary of the invention

[0005] A method for automatic emergency braking of a motor vehicle is proposed, wherein a detection system arranged on the motor vehicle detects a moving obstacle and transmits this information to an electronic control unit of the motor vehicle. Automatic emergency braking of the motor vehicle is triggered only when the control unit detects an imminent collision of the motor vehicle with the obstacle, which collision can no longer be avoided by driving the obstacle.

[0006] The method has the advantage that the risk of unnecessary emergency braking due to the presence of a phantom object is minimized. That is, as the distance to the obstacle decreases, the reliability of the detection system, which in particular has at least one radar sensor, in detecting the obstacle increases. Since the method triggers the emergency braking as late as possible, the probability increases that the phantom object itself is detected before the automatic emergency braking is triggered and that an unnecessary automatic emergency braking does not occur in this case.

[0007] When determining an impending collision, a cooperative behavior of the obstacle is preferably assumed. This is to be understood as assuming a driving behavior of the obstacle that is designed to increase the total utility and / or minimize the total costs for all road users, rather than to maximize the utility and / or minimize the costs for the obstacle itself without taking into account other road users.

[0008] In principle, all conceivable driving maneuvers can be taken into account in the method, which as driving influences on an obstacle can avoid a collision with the motor vehicle. However, since it is particularly difficult to calculate the effects of an evasive maneuver, it is preferred that only driving influences on an obstacle by a braking maneuver of the obstacle are taken into account in the method. In order to ensure that the automatic emergency braking of the motor vehicle is not irresponsibly delayed for a long time, it is also preferred that a predeterminable safety distance be added to the braking distance of the obstacle when determining an impending collision.

[0009] In order to be able to determine an impending collision, various parameters of the obstacle and of the driver of the obstacle need to be known. The reaction time of the driver of the obstacle, the braking intensity of the driver of the obstacle, and the braking power of the brake system, with which the driver actuates the braking system of his vehicle, are particularly relevant. Since the actual values ​​of these parameters cannot be determined in an impending collision scenario, it is preferred to assume values ​​stored in the electronic control unit for these parameters. In this case, preferably the following values ​​are stored, which have been proven to be average for road traffic participants based on experience with respect to the reaction time and braking intensity of the driver of the obstacle. For the braking power of the brake system of the obstacle, in particular values ​​are stored, which are average for a fleet of vehicles in the region (Land) in whose road network the method is to be used.

[0010] In order to reliably bring the motor vehicle to a stopped state before a collision occurs, the emergency brake is preferably automatically performed with maximum brake pressure. Here, the maximum brake pressure is maintained until the motor vehicle stops.

[0011] At low and medium speeds, emergency braking is suitable for avoiding collisions. At high speeds, as occur in particular on national roads and motorways, it is known from the analysis of accident data that collisions can be avoided in an optimized manner by changing lanes. Emergency braking generally no longer results in a significant reduction in the consequences of an accident. The method is therefore preferably used only at a maximum speed of 70 km / h and particularly preferably only at a maximum speed of 60 km / h.

[0012] The computer program product is configured to execute each step of the method when the computer program product is run on an electronic controller. To this end, the computer program product is stored on a machine-readable storage medium.

[0013] By uploading the computer program product to a conventional electronic controller, an electronic controller is obtained which is designed to perform automatic emergency braking of a motor vehicle by means of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0015] Figure 1 An unnecessary emergency braking is schematically shown, which can be avoided by means of an exemplary embodiment of the method according to the invention.

[0016] Figure 2A collision of a motor vehicle with other road users due to emergency braking triggered by a phantom object is schematically shown, which can be avoided by means of an exemplary embodiment of the method according to the invention.

[0017] Figure 3 A further collision of a motor vehicle with other road users due to emergency braking triggered by a phantom object is schematically shown, which can be avoided by means of an exemplary embodiment of the method according to the invention.

[0018] Figure 4 The determination of a possible imminent collision of a motor vehicle with an obstacle in a method according to an exemplary embodiment of the present invention is schematically shown.

[0019] Figure 5 A motor vehicle is schematically shown, the automatic emergency braking of which can be triggered by means of a method according to an exemplary embodiment of the present invention.

[0020] Figure 6 A flow chart showing an embodiment of the method according to the invention is shown. DETAILED DESCRIPTION

[0021] Driver assistance systems of the prior art are designed to bring motor vehicle 10 to a standstill as early as possible when a collision with an obstacle is imminent or to reduce the speed until a collision is avoided. Figure 1 , how the driving path 11 of the motor vehicle 10 intersects the driving path 21 of another motor vehicle, which may constitute a potential obstacle 20 for the first motor vehicle 10. The driver assistance system of the motor vehicle 10 triggers an automatic emergency brake, by which the motor vehicle 10 stops or reduces its speed so early that a safety distance a is always maintained between its front side 12 and the edge 22 of the driving path 21 of the obstacle 20 facing the motor vehicle 10. However, in Figure 1 In the illustrated situation, the driver of the second motor vehicle has recognized the impending collision itself and braked his vehicle to avoid the collision. At the time when the first motor vehicle 10 stops, the potential obstacle 20 has stopped in front of the possible deflection point. Therefore, emergency braking is unnecessary.

[0022] exist Figure 1 The unnecessary emergency braking shown in FIG. 1 is merely unpleasant for the driver of the motor vehicle 10 and is not Figure 2, which is dangerous for the driver. Here, the driver of a motor vehicle 10 is turning left at an intersection. Due to the reflection of the radar waves of the radar sensor of the motor vehicle 10 on the surrounding infrastructure elements, the driver assistance system of the motor vehicle mistakenly believes that there is another motor vehicle, which is interpreted as a potential obstacle 20. The driving path 21 of the obstacle intersects with the driving path 11 of the motor vehicle 10. The emergency brake is triggered, which stops the motor vehicle 10 at the collision point k in the center of the intersection. There, the motor vehicle collides with an oncoming third motor vehicle 30, whose driving path 31 intersects with the driving path 11 of the motor vehicle 10. This would not be a problem if the first motor vehicle 10 continued to drive immediately, but a collision occurs due to the emergency brake.

[0023] exist Figure 3 2 shows an even more dangerous situation. Motor vehicle 10 is stopped by emergency braking because its radar sensor inadvertently interprets a phantom object as an obstacle 20, the path 21 of which would intersect the path of travel of motor vehicle 10. However, motor vehicle 10 thus enters the path 31 of another motor vehicle 30 approaching from the left, whereby a life-threatening collision occurs on the driver's side at the level of the passenger compartment of motor vehicle 10 due to the impact of motor vehicle 30 approaching from the left, with the attendant risk of severe or life-threatening injuries to the vehicle occupants.

[0024] In order to minimize the risk of unnecessary and partially dangerous collisions of this type, it is provided in an exemplary embodiment of the method according to the invention that, before initiating the automatic emergency braking, it is first assessed whether the motor vehicle constituting a potential obstacle 20 can independently avoid a potential collision through the driving influence of its driver. Figure 1 Unnecessary emergency braking is avoided. Figure 2 and 3In the case of the phantom object shown, emergency braking is delayed until the phantom object itself can be identified with a high probability so that emergency braking does not occur. For this purpose, it is determined whether the obstacle 20 is still located in the first area 41 on its driving path 21, in which a potential collision can still be avoided by the braking process, or whether the obstacle is already in the second area 42, in which this type of collision avoidance is no longer possible. For this purpose, the safety distance s is added to the braking distance b of the obstacle 20. If the driving path 21 predicted from the front (Vorderfront) of the obstacle 20 intersects the driving path 11 of the motor vehicle at the sum of the braking distance b and the safety distance s, the emergency braking of the motor vehicle 10 is triggered when all the necessary conditions for triggering are met. For this prediction, the cooperative behavior of the driver of the obstacle 20 is assumed. In order to estimate the braking distance b, typical values ​​of the driver's reaction time, his braking intensity and the braking power of the braking system of the motor vehicle are assumed.

[0025] In order to be able to perform the method according to the invention, Figure 5 The motor vehicle 10 shown has a detection system 13 arranged on its front side. In the present embodiment, the detection system has at least one radar sensor. The detection system is connected to an electronic control unit 14 of the motor vehicle 10. In addition, the electronic control unit 14 controls the braking system (not shown) of the motor vehicle and can thus trigger an automatic emergency brake.

[0026] exist Figure 6 . The process of an embodiment of the method according to the invention is shown in FIG. 5 . The start 50 of the method is carried out when the motor vehicle 10 is traveling at a maximum speed of 70 km / h. Then, based on the input data of the detection system 13, the following decision 51 is made in the electronic control unit 14: whether a collision with an obstacle 20 is imminent, wherein the obstacle 20 is a moving obstacle, and whether the collision can still be avoided by the driver of the obstacle 20 in terms of driving physics by a braking maneuver. If the first check 52 shows that there is no risk of collision, the method is terminated 55. Otherwise, the following second check 53 is made: whether the collision with the obstacle can still be avoided by the driver of the obstacle by a braking maneuver. If this condition is met, the monitoring and decision of the traffic situation are continued in step 51 with the aid of the two subsequent checks 52, 53. However, if the second check 53 shows that the driver of the obstacle can no longer avoid the impending collision, emergency braking 54 of the motor vehicle 10 is triggered and the method is then terminated 55.

Claims

1. A method for automatic emergency braking (54) of a motor vehicle (10), wherein: A detection system (13) arranged on the motor vehicle (10) detects a moving obstacle (20) and transmits it to an electronic control unit (14) of the motor vehicle (10), characterized in that automatic emergency braking (54) of the motor vehicle (10) is triggered only when the following situation occurs: an imminent collision between the motor vehicle (10) and the obstacle (20) is determined by the control unit (14), and the collision can no longer be avoided by driving the obstacle (20).

2. The method according to claim 1, characterized in that In determining the impending collision, cooperative behavior of the obstacles (20) is assumed.

3. The method according to claim 1 or 2, characterized in that: The driving influence is a braking maneuver.

4. The method according to claim 3, characterized in that When determining the impending collision, a predeterminable safety distance (s) is added to the braking distance (b) of the obstacle (20).

5. The method according to claim 3 or 4, characterized in that: When determining the impending collision, values ​​are assumed to be saved (14) in the electronic controller for the reaction time of the driver of the obstacle (20), the braking intensity of the driver of the obstacle (20) and the braking power of the braking system of the obstacle (20).

6. The method according to any one of claims 1 to 5, characterized in that The emergency braking (54) is performed at maximum brake pressure.

7. The method according to any one of claims 1 to 6, characterized in that The method is used only when the speed of the motor vehicle (10) is a maximum of 70 km / h. 8 . A computer program product, which is designed to carry out each step of the method according to claim 1 .

9. A machine-readable storage medium on which the computer program product according to claim 8 is stored.

10. An electronic control unit (14) which is designed to carry out automatic emergency braking (54) of a motor vehicle (10) by means of a method according to any one of claims 1 to 7.

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