Method of operating a driving assistance system for a motor vehicle, at least with respect to longitudinal guidance of the motor vehicle

Abstract

The present invention relates to a method for operating a driver assistance system (3) for at least longitudinal guidance of a vehicle (1), the method comprising: providing (S2) sensor information (22) describing at least one other vehicle (20) located ahead of the vehicle (1) in the direction of travel (18) of the vehicle (1); determining (S3) hazard warning light information (24) describing whether the at least one other vehicle (20) has activated a hazard warning light by applying hazard warning light recognition criteria (23) to the provided sensor information (22); if the at least one other vehicle (20) has activated a hazard warning light according to the determined hazard warning light information (24), increasing (S5) by a predetermined time interval (26) a time difference value (25) describing a maximum time difference between an activation time of a function of the driver assistance system (3) and a collision time of a predicted collision between the vehicle (1) and an obstacle in the vehicle's surroundings (1); and operating (S6) the driver assistance system (3) taking into account the increased time difference value (25).

Description

[Technical Field]

[0001] The present invention relates to a method for operating a driver assistance system for a motor vehicle, and also to a motor vehicle, a control device for the motor vehicle, and a computer program product for implementing the same. [Background technology]

[0002] The motor vehicle may have a driving assistance system for longitudinal guidance of the motor vehicle. The driving assistance system may, for example, be designed to activate the longitudinal guidance of the motor vehicle at least semi-automatically, in particular fully automatically. The driving assistance system may, for example, activate the braking system of the motor vehicle. Such a driving assistance system is, for example, an automatic emergency braking system (AEB). Alternatively or additionally, the driving assistance system may be designed to output a warning about obstacles in the surroundings of the motor vehicle and thus, for example, to suggest manual activation of the longitudinal guidance by the driver of the motor vehicle.

[0003] A driving assistance system for longitudinal guidance of a vehicle is typically activated taking into account a predetermined time difference value. This time difference value indicates the time difference that may exist between the activation time of the driving assistance system and the predicted collision time of the vehicle with an obstacle. This time difference is also sometimes called the time to collision (TTC). When an obstacle with which the vehicle may collide is detected, it is continuously checked whether the time difference value has been reached. As soon as the time difference value is reached, a function of the driving assistance system, such as the vehicle's collision mitigation braking, is activated and / or a warning message is output. The time difference value is typically provided as a constant predetermined value and can be stored in the driving assistance system.

[0004] However, there may be a situation where the speed at which the vehicle approaches the obstacle at the moment the obstacle is detected is too high, and the driving assistance system is unable to prevent a collision with the obstacle by taking into account the predetermined time difference value, and therefore the driving assistance system cannot operate appropriately in all situations.

[0005] US Patent Application Publication No. 2018 / 0257646(A1) discloses a vehicle control device including a rear-end collision impact safety system that can implement safety control when there is a risk of a rear-end collision. Summary of the Invention

[0006] The object of the invention is to provide a solution that allows particularly suitable operation of driver assistance systems in motor vehicles.

[0007] This object is achieved by the subject matter of the independent claims.

[0008] A first aspect of the invention relates to a method for operating a driving assistance system for a motor vehicle, at least with respect to longitudinal guidance of the motor vehicle, the driving assistance system being preferably designed for at least semi-automatically, in particular fully automatically, operating the longitudinal guidance of the motor vehicle.

[0009] The present invention is based at least on the finding that a driving assistance system cannot operate appropriately in all situations with a constant, predetermined time difference value (Time to Collision, TTC). Therefore, the time difference value should be changeable, at least in certain situations. In particular, increasing the time difference value depending on the situation is appropriate for more reliably preventing a collision with an obstacle, compared to operation of a driving assistance system using a constant, predetermined time difference value.

[0010] The method includes providing sensor information describing at least one other vehicle located ahead of the vehicle in the direction of travel of the vehicle. The other vehicle may be, for example, another vehicle traveling ahead of the vehicle. The other vehicle may be located in the lane in which the vehicle itself is traveling and / or in a lane adjacent to the lane in which the vehicle is traveling. The other vehicle may be currently traveling or stationary. The sensor information may, for example, describe all other vehicles located within a capture area of ​​a sensor device capturing and providing the sensor information. The capture area may, for example, be at least a portion of the vehicle's surroundings in the area ahead of the vehicle. The direction of travel of the other vehicles may correspond to the direction of travel of the vehicle, such that oncoming vehicles located in a different lane from the vehicle are not considered. In this way, the method may be limited to considering sensor information that describes only other vehicles traveling ahead of the vehicle and / or stationary in front of the vehicle, excluding, for example, vehicles in oncoming traffic. However, in general, any other vehicle described by the sensor information may be considered.

[0011] The sensor information is preferably transmitted to and provided to a control device of the vehicle, i.e., the control device can provide the sensor information. The control device is a computing device and is designed to evaluate the sensor information in further method steps of the method. All method steps described below are preferably executed by the control device of the vehicle. The control device is further designed to operate the driver assistance system, i.e., to perform at least one function of the driver assistance system. Thus, for example, the control device is designed to generate and provide at least one control command for a braking system of the vehicle.

[0012] The method includes determining hazard warning light information by applying hazard warning light detection criteria to the provided sensor information. The hazard warning light information describes whether at least one other vehicle has activated its hazard warning light. Accordingly, each other vehicle described by the sensor information is carefully checked to see if it currently has its hazard warning light system activated. The hazard warning light may be implemented, for example, as a lighting unit on the other vehicle. Activation of the other vehicle's hazard warning light typically results in all turn signals being activated simultaneously and flashing. The other vehicle operates its hazard warning light when it needs to notify following road users, for example, of a sudden vehicle deceleration, the end of a traffic jam, the last vehicle in a queue, an accident, a tow, and / or an upcoming maneuver by a bus, particularly a school bus or transit bus. There may also be other or additional circumstances in which the other vehicle activates its hazard warning light. Accordingly, another vehicle operating and / or stopping with its hazard warning light activated provides a clear indication to the vehicle of a possible obstacle. Thus, the present invention determines whether at least one other vehicle in the vicinity of the vehicle has activated its hazard warning lights. The hazard warning light detection criteria are, for example, algorithms and / or rules based on which the sensor information is evaluated to determine which other vehicles described by the sensor information currently have their hazard warning lights activated and which do not.

[0013] If, according to the determined hazard warning light information, at least one other vehicle activates its hazard warning light, the time difference value is increased by a predetermined time interval. The time difference value describes the maximum, particularly acceptable, time difference between the activation time of the function of the driving assistance system and the impact time of a predicted collision between the vehicle and an obstacle in its surroundings. In the context of driving assistance systems, the time difference value is usually designated as a time to collision (TTC) or time to collision value. The time difference value may be, for example, 1.4 seconds. In this case, the function of the driving assistance system is activated at the latest 1.4 seconds before the calculated predicted collision time between the vehicle and the obstacle, i.e., 1.4 seconds before the impact time. The function of the driving assistance system may, for example, at least semi-automatically brake the vehicle, particularly fully automatically brake the vehicle, and / or output a warning message to the vehicle. The obstacle may be the other vehicle that activated its hazard warning light and / or another object in the vehicle's surroundings. Therefore, instead of a predicted collision between the vehicle and the obstacle, a predicted collision between the vehicle and at least one other vehicle that activated its hazard warning light may be assumed.

[0014] The predetermined time interval is a fixed time value. For example, the time interval is 0.5 seconds. Therefore, in the above example, the time difference value is increased by 0.5 seconds from the original 1.4 seconds to a total of 1.9 seconds.

[0015] The driving assistance system then operates taking this increased time difference into account. That is, for example, the driving assistance system no longer assumes the original 1.4 seconds but now assumes 1.9 seconds as the predetermined time difference. Therefore, at least semi-automatic deceleration of the vehicle or another function of the driving assistance system is initiated earlier than the original time difference value, thereby extending the reaction time for the function of the driving assistance system to be activated. The intensity of the function of the driving assistance system does not need to be changed.

[0016] By taking into account the hazard warning light information in this manner, potentially dangerous situations can be detected particularly quickly, and thus, for example, braking or another function of the driver assistance system can be activated particularly early. Early activation can be achieved by increasing the time difference value. In this way, particularly reliable operation of the driver assistance system can be achieved.

[0017] In one advantageous exemplary embodiment, the predetermined time interval is determined taking into account at least the vehicle's inherent speed. That is, the time interval over which the time difference value increases is not constant but depends at least on the vehicle's current speed. The inherent speed can be determined by a vehicle sensor designed for this purpose. The sensor captures, for example, odometer data. The faster the vehicle is traveling, i.e., the higher the inherent speed, the larger the predetermined time interval can be selected. Instead of the aforementioned 0.5 seconds, the time interval can be increased, for example, to 0.7 seconds, 1 second, or even more than 1 second. If the vehicle is traveling slowly, for example, at a speed of 30 km / h or less, the time interval can be reduced, for example, to just 0.3 seconds. Time intervals other than those given as examples are also possible. In this way, an appropriate time difference value can always be selected depending on the situation and based on the vehicle's current speed.

[0018] In a further exemplary embodiment, the predetermined time interval is determined taking into account the relative speed of the vehicle with respect to at least one other vehicle. That is, for example, not only the vehicle's intrinsic speed but also the speed difference between the vehicle and the other vehicle may affect the time interval. Therefore, the speed at which the vehicle is traveling compared to the other vehicle that activated the hazard warning light is taken into account. The relative speed thus specifies the intrinsic speed relative to the speed of the other vehicle. For example, if the other vehicle is already stopped, the relative speed will be greater than if the other vehicle is still moving and its speed is greater than 0 km / h. The higher the relative speed, the longer the predetermined time interval will typically be. To determine the relative speed, for example, sensor information and / or the determined or measured intrinsic speed of the vehicle can be evaluated. Taking the relative speed of the vehicle into account allows a particularly suitable predetermined time interval to be determined.

[0019] The determined time interval is always taken into account when increasing the time reference value and can be stored at least temporarily in a memory of the control device for this purpose.

[0020] In a preferred exemplary embodiment, when multiple other vehicles have activated their hazard warning lights, distance information is determined for each of the multiple other vehicles. The distance information describes the distance between the vehicle and each of the other vehicles. The distance information can be determined, for example, taking into account sensor information. For this purpose, for example, sensor information describing the distance to each object in the vehicle's surroundings can be evaluated. The evaluated sensor information can be acquired and provided, for example, by a radar device, a lidar device, and / or an ultrasonic sensor. Alternatively or additionally, the distance information can be determined from camera images, i.e., from still and / or video image data from the camera unit. Known methods for determining the distance between a vehicle and objects, such as other vehicles, in the vehicle's surroundings can be used.

[0021] The relative speed of the vehicle with respect to the other vehicle for which the minimum distance information was determined is then considered. That is, it is determined which of the multiple other vehicles for which the minimum distance information was determined. This other vehicle is then selected as the single other vehicle and considered within the scope of the method. The remaining other vehicles can, for example, be ignored. Once the time interval is determined, only the relative speed with respect to the selected other vehicle is considered. The vehicle with the minimum distance information is the other vehicle located closest to the vehicle. Since the other vehicle located closest to the vehicle and having its hazard warning light activated is a particular obstacle for the vehicle, in this way, expected potential obstacles for the vehicle are taken into account. In this way, the risk of a collision with an obstacle, i.e., the precisely selected one other vehicle, can be particularly reliably prevented.

[0022] In this exemplary embodiment, the other vehicle with the smallest distance information may be a vehicle traveling in an adjacent lane, and therefore may not be a vehicle traveling in the same lane as the vehicle. The selected other vehicle may also be an obstacle located laterally relative to the vehicle, particularly one that is not on the vehicle's predicted driving trajectory. When a vehicle with a hazard warning light activated is moving or stopped, it is particularly likely that an occupant may suddenly leave the vehicle and become an obstacle to the vehicle. Here, other vehicles with hazard warning lights activated that are located in adjacent lanes are taken into consideration, and the time difference value is increased to prepare for such an event. This may be particularly appropriate in urban areas where the occupants of other vehicles are relatively likely to leave the vehicle.

[0023] In a further exemplary embodiment, when multiple other vehicles have activated their hazard warning lights, it is determined which of these other vehicles is located in the same lane as the vehicle. In this case, the lane is a lane of the road on which both the vehicle and the multiple other vehicles are traveling. Distance information is determined only for the other vehicle determined in this case. That is, distance information is determined only for the multiple other vehicles or at least one other vehicle that is located in the same lane as the vehicle. The distance information describes the distance between the vehicle and the determined other vehicle, as in the above-mentioned method. The relative speed of the vehicle with respect to the other vehicle for which the smallest distance information has been determined is taken into account. Therefore, when distance information has been determined for multiple other vehicles in the same lane, the smallest distance information is selected, and the relevant other vehicle is considered as the only vehicle. That is, in this case, the vehicle traveling in the same lane immediately before the vehicle is usually identified. Therefore, particularly in the case of a highway with multiple lanes, vehicles in adjacent lanes are not considered, but only other vehicles in the same lane that the vehicle is directly following are considered. In this way, the method is purposefully tailored to typical collision situations in road traffic, since a frontal collision of the vehicle with another vehicle traveling ahead may be imminent.

[0024] In a particularly preferred exemplary embodiment, the predetermined time interval is determined taking into account at least the determined minimum distance information. That is, for example, in addition to or instead of the specific speed and / or the relative speed, the distance from the vehicle of the nearest other vehicle among the plurality of vehicles can be taken into account. Depending on the distance from the other vehicle, a larger or smaller time interval can be predetermined. This results in a time interval that is specifically tailored to the situation.

[0025] According to an additional exemplary embodiment, it is checked whether the vehicle's intrinsic speed is greater than a predetermined speed difference value. The speed difference value is a value preset in the driving assistance system. The speed difference value indicates a speed difference by which the intrinsic speed can be reduced by the driving assistance system at a maximum. It is assumed that the driving assistance system cannot semi-automatically slow the vehicle from any intrinsic speed to a standstill, and that the at least semi-automatic speed reduction achievable by the driving assistance system is limited to a maximum speed difference, which is represented by the speed difference value. This may be, for example, 60 km / h.

[0026] If the specific speed is greater than the predetermined speed difference value, the time difference value is increased by a predetermined other time interval greater than the predetermined time interval. Thus, for example, in a vehicle traveling at a speed of 120 km / h, a speed difference value lower than the specific speed of the vehicle, such as 60 km / h, may be preset to a constant value. In this example, the current specific speed of 120 km / h is semi-automatically, particularly fully automatically, reduced by the driving assistance system to a maximum specific speed of 60 km / h. After that, the remaining braking, for example, to stop or reduce the speed to less than 60 km / h, must be performed manually, for example, by the driver of the vehicle operating the vehicle's brake pedal. Considering the possibility of a delayed reaction due to the driver's reliance on the driving assistance system, the time difference value is increased by a longer time interval than before. For example, the time interval may be defined as 1 second, 1.5 seconds, 2 seconds, or more, instead of the exemplary 0.5 second. Here, the time difference value is increased by a predetermined other time interval instead of the predetermined time interval. If the braking function of the driving assistance system is limited, the time difference value can be increased further appropriately.

[0027] In a further exemplary embodiment, the predetermined other time interval is determined taking into account at least the reaction time required for the vehicle driver to react. Driver-specific or driver-dependent reaction times may be known and may be taken into account, for example. The reaction time may be stored in the driver's user profile, for example, and if this profile is provided by an external computing device, may be stored in the vehicle and / or loaded into the vehicle. Alternatively or additionally, the reaction time may be typically preset. The typically preset reaction time may be, for example, between 1 and 3 seconds. The time interval may then be, for example, at least the reaction time, in particular the time interval determined taking into account the intrinsic speed, relative speed, and / or minimum distance information, plus the reaction time. In this way, additional protection is achieved by taking into account the driver's reaction time.

[0028] In an additional exemplary embodiment, the hazard warning light information is continuously determined and verified. Verification should be understood to mean that it is determined, according to the hazard warning light information, whether at least one other vehicle has activated its hazard warning light or, for example, whether it has been detected that the other vehicle does not have its hazard warning light activated. As soon as it is determined, according to the determined hazard warning light information, that the other vehicle does not have its hazard warning light activated, the time difference value is again reduced by a predetermined time interval, and the driving assistance system operates again taking the reduced time difference value into account. In other words, the increased time difference value is maintained only as long as at least one other vehicle with an activated hazard warning light is detected by evaluating the sensor information. As soon as the other vehicle within the capture area of ​​the sensor device of the vehicle providing the sensor information does not have its hazard warning light activated, the previously increased time difference value is again reduced to its starting value. Thus, the time difference value is reset again to the original time difference value. It is thus clear that the method according to the present invention is intended only for special situations and is not intended to change the predetermined time difference value indefinitely over time.

[0029] According to additional exemplary embodiments, the functions of the driver assistance system include warning of a predicted collision, preparing at least one brake of the vehicle's braking system for braking, and / or braking with at least one brake of the braking system. That is, the driver assistance system can be designed solely for collision warning and, therefore, for example, indicate to the vehicle driver the time to brake. The warning message output in this context is provided taking into account an increased time difference value. For example, an output unit for the warning can be provided in the vehicle. The output unit can be designed for acoustic and / or optical output. That is, the output unit can be, for example, a display unit, such as a display screen, in particular a touch-sensitive display screen and / or a head-up display, and / or a speaker unit with at least one speaker. The output unit can be a component of the vehicle and / or can consist of a mobile terminal, in particular a smartphone or tablet, arranged in the vehicle. The control device transmits a warning, for example, a warning message, to the output unit.

[0030] Braking preparation as a function is, for example, the preparation of at least one brake of the braking system for an upcoming braking operation. For the purpose of braking preparation, the brakes can be brought into a braking readiness state, for example, by at least one mechanical, pneumatic, and / or hydraulic means. This has the effect of enabling particularly rapid braking by the subsequent brakes, if required. Preferably, the driver assistance system can actually activate at least one brake of the braking system, thus actually performing braking, in particular braking to a standstill. In this way, the driver assistance system is a driver assistance system that is involved in the longitudinal guidance of the vehicle in various ways.

[0031] In further exemplary embodiments, the driver assistance system is an automatic emergency braking system and / or an adaptive cruise control system. An automatic emergency braking system is often called automatic emergency braking (AEB). An adaptive cruise control system may alternatively be called adaptive cruise control (ACC). Therefore, the driver assistance system is preferably designed to activate at least one brake of the braking system at least semi-automatically, in particular fully automatically.

[0032] Furthermore, in an exemplary embodiment, the sensor information is captured by a sensor device of the motor vehicle. The sensor device is, in particular, a camera and / or a lidar device. Thus, the sensor device is preferably an imaging sensor designed to generate a static and / or moving or dynamic representation of the surroundings. That is, the sensor information comprises image data, for example, in the case of a camera. The sensor device is preferably a front camera of the motor vehicle. Alternatively or additionally, the sensor information can be provided by an external device, in particular another motor vehicle, a traffic observation camera, and / or a traffic monitoring computing device such as a back-end server and / or a cloud server. The transmission of the sensor information to the motor vehicle can be, for example, based on vehicle-to-vehicle and / or vehicle-to-infrastructure communication.

[0033] A further aspect of the invention relates to a motor vehicle that implements the above-mentioned method. Thus, the motor vehicle is designed to implement the above-mentioned method. The motor vehicle may be, for example, a car, a truck, a bus, a motorcycle and / or a moped. The motor vehicle may have a control device.

[0034] A further aspect of the present invention relates to a control device for a motor vehicle designed to implement the above-mentioned method. The control device implements the above-mentioned method, in particular an exemplary embodiment or a combination of exemplary embodiments of the above-mentioned method. The control device has a processing unit. The processing unit may include at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). Furthermore, the processing unit may have program code, which may alternatively be referred to as a computer program product. The program code may be stored in a data memory of the processing unit.

[0035] Another aspect of the invention relates to a computer program product, which is a computer program comprising instructions that, when the program is executed by a computer, for example a control unit of a motor vehicle, cause the computer to carry out the steps of the method according to the invention.

[0036] The exemplary embodiments described above in connection with the method according to the invention apply, individually and in combination with one another, to the motor vehicle according to the invention, to the control device according to the invention and to the computer program product according to the invention, where applicable. The invention includes combinations of the exemplary embodiments described above. [Brief explanation of the drawings]

[0037] In the figure [Figure 1] FIG. 1 shows a schematic diagram of a motor vehicle with a sensor device. [Figure 2] Figure 2 shows a schematic diagram of several cars on a road. [Figure 3] FIG. 3 shows a schematic signal flow diagram of a method for activating a driving assistance system that is at least related to the longitudinal guidance of a motor vehicle. [Figure 4] FIG. 4 shows a schematic signal flow diagram of further method steps of the method according to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0038] FIG. 1 shows a schematic diagram of a motor vehicle 1 having a control device 2. The control device 2 is a computing device of the motor vehicle 1 and can have, for example, a driving assistance system 3 with at least one function. The driving assistance system 3 is at least related to the longitudinal guidance of the motor vehicle 1. The driving assistance system 3 can be, for example, an automatic emergency braking system and / or an adaptive cruise control system. The function of the driving assistance system 3 can provide a warning before a predicted collision between the motor vehicle 1 and an obstacle. Alternatively or additionally, the function of the driving assistance system 3 can provide braking preparation for at least one brake of a braking system 12 of the motor vehicle 1. Alternatively or additionally, the function of the driving assistance system 3 can provide at least semi-automatic, in particular fully automatic, braking by at least one brake of the braking system 12.

[0039] The automobile 1 has a sensor device 4. The sensor device 4 can capture the surroundings of the automobile 1. The sensor device 4 can include multiple cameras, such as a front camera 5, a side camera 6, and / or a rear camera 7, as shown by way of example herein. Preferably, the sensor device 4 includes at least the front camera 5. Alternatively or additionally, the sensor device 4 can include a lidar device 8, a radar device 9, and / or an ultrasonic sensor (not shown). The side cameras 6 are arranged in the side mirrors 10 of the automobile 1 here. The front camera 5 is arranged in the area of ​​the windshield 11 of the automobile 1, which is arranged at the vertical upper part of the automobile 1. Multiple radar devices 9 and / or lidar devices 8 and / or ultrasonic sensors can be arranged in the automobile 1. As an example, multiple such sensors are shown schematically in the present specification for the area in front of the automobile 1, and the sensors can be arranged in the bumper of the automobile. The surroundings of the automobile 1, at least in the area in front of the automobile 1, can be captured by these sensors.

[0040] An output unit 13, such as a display screen, in particular a touch-sensitive display screen, a head-up display, and / or a speaker unit consisting of at least one speaker, can be arranged in the vehicle 1. The output unit 13 can be a component of the vehicle 1 and / or can be constituted by a mobile terminal arranged in the vehicle 1. The mobile terminal is, for example, a smartphone and / or a tablet. If a function of the driver assistance system 3 issues a warning before a predicted collision, a warning message can be output by the output unit 13.

[0041] FIG. 2 shows a road 14 on which a car 1 is traveling. The road 14 has a right lane 15 and a left lane 16. Both lanes 15, 16 have the same direction of travel 18. In FIG. 2, as an example, in addition to the car 1, two other cars 20 are also located on the road 14. These cars are traveling ahead of the car 1 on the road 14 in the direction of travel 18. One of the two other cars 20 is traveling in the same lane 15, 16 as the car 1, i.e., the right lane 15. The other other car 20 is traveling in the adjacent left lane 16. Both other cars 20 have their hazard warning lights activated, i.e., all light units 21 of each other car 20 are flashing to warn of a potential obstacle, such as the end of a traffic jam.

[0042] 3 shows the steps of the method for operating the driver assistance system 3 that are relevant to at least the longitudinal guidance of the motor vehicle 1. In method step S1, sensor information 22 can be captured by the sensor device 4. The sensor device 4 in method step S1 preferably includes at least a front camera 5, in particular also a side camera 6 and / or a lidar device 8. The sensor information 22 is provided by the control device 2 in method step S2. The sensor information 22 describes at least one other motor vehicle 20 that is located ahead of the motor vehicle 1 in the direction of travel 18 of the motor vehicle 1.

[0043] In method step S3, hazard warning light detection criteria 23 are applied to the provided sensor information 22. In this way, hazard warning light information 24 is determined, which describes whether at least one other vehicle 20 has activated its hazard warning light. In method step S4, it is checked whether it has been determined that at least one other vehicle 20 has activated its hazard warning light. If at least one other vehicle 20 has activated its hazard warning light, a time difference value 25 is increased in method step S5. The time difference value 25 describes the maximum time difference between the activation time of the function of the driver assistance system 3 and the predicted time of collision of the vehicle 1 with an obstacle, in particular another vehicle 20. In FIG. 3, the time difference value 25 is increased by a predetermined time interval 26. In method step S6, the driver assistance system 3 operates taking into account the increased time difference value 25, i.e., the sum of the original time difference value 25 and the predetermined time interval 26.

[0044] A predetermined time interval 26 is first determined, during which an intrinsic speed 27 of the vehicle 1 can be taken into account. This speed can be determined, for example, in the vehicle 1 by sensors of the vehicle 1 that are specifically designed for this purpose. Alternatively or additionally, a relative speed 28, which represents the relative speed of the vehicle 1 with respect to at least one other vehicle 20, can be taken into account in determining the time interval 26. That is, the relative speed 28 is the deviation of the intrinsic speed 27 from the speeds of the other vehicles 20. The relative speed 28 can be determined, for example, by taking into account data from a radar device 9, an ultrasonic sensor, and / or a lidar device 8.

[0045] Furthermore, after method step S4, in method step S7 it can be checked whether a plurality of other vehicles 20 have activated their hazard warning lights. In FIG. 3 three other vehicles 20 are shown schematically as an example, and these vehicles are moving or stationary with their hazard warning lights activated. Distance information 29 is then determined for each of the plurality of other vehicles 20. This is carried out in method step S8. Each distance information 29 describes the distance between vehicle 1 and the other vehicles 20. In FIG. 3 only other vehicles 20 that have activated their hazard warning lights are taken into account. Thus, in the example outlined in FIG. 3 three distance information 29 are determined.

[0046] From the determined distance information 29, the smallest distance information 30 is selected. Next, the relative speed 28 of the vehicle 1 with respect to the selected other vehicle 20 for which the smallest distance information 30 was determined is taken into account. Thus, the determined smallest distance information 30 can be taken into account in determining the predetermined time interval 26.

[0047] Instead of considering all other vehicles 20 described by the sensor information 22, in method step S10 after method step S7, it can be determined which of the other vehicles 20 that have activated their hazard warning lights are located in the same lane 15, 16 as vehicle 1. This is, for example, exactly one other vehicle 20 in FIG. 3, which is diagrammatically shown as determined other vehicle 31 in FIG. 3. In method step S11, distance information 29 describing the distance between vehicle 1 and the determined other vehicle 31 is determined only for the determined other vehicle 31. If several determined other vehicles 31 are determined, the relative speed 28 of vehicle 1 with respect to the other vehicle 31 with the smallest distance information 30 is taken into account, i.e. method step S9 is executed.

[0048] However, in method steps S8 and S9, any other vehicle 20 can in principle be taken into account without going through method steps S10 and S11, even if it is, for example, located in a lane 15, 16 adjacent to the lane 15, 16 of vehicle 1. With reference to Figure 2, the relative speed 28 of vehicle 1 relative to another vehicle 20 traveling in the left lane 16 can be taken into account because the distance to vehicle 1 is smaller than that of another vehicle 20 traveling just in front of vehicle 1 traveling in the right lane 15. However, in method steps S10, S11 and S9, this other vehicle 20 is not taken into account at all, but rather only the other vehicle 20 traveling directly ahead, i.e. also traveling in the right lane 15, is taken into account.

[0049] Furthermore, the hazard warning light information 24 can be continuously checked. As soon as it is determined according to the determined hazard warning light information 24 that the other vehicle 20 still has not activated its hazard warning light, the time difference value 25 is reduced again by a predetermined time interval 26. The driving assistance system 3 then operates again taking into account the reduced time difference value 25 and therefore the original time difference value 25.

[0050] If in method step S4 it is determined according to the determined hazard warning light information 24 that the other motor vehicle 20 has not activated its hazard warning light, method step S1 can be directly carried out again.

[0051] Furthermore, a method step S12 can be provided, in which it is checked whether the driving assistance system 3 is currently operating according to the increased time difference value 25. If the driving assistance system 3 is currently operating according to the increased time difference value 25, then in method step S13 the time difference value 25 can be decreased again by the time interval 26. If in the check it is determined that the driving assistance system 3 is not currently operating using the increased time difference value 25, then method step S1 is likewise performed again. For example, if in method step S7 it is determined that a plurality of other vehicles 20 do not have their hazard warning lights activated, method step S5 can be performed.

[0052] FIG. 4 shows two optional method steps S14 and S15. In method step S14, it is determined whether the specific speed 27 of the vehicle 1 is greater than a predetermined speed difference value 32. The speed difference value 32 is always preset constant in the driving assistance system 3. The speed difference value 32 describes the maximum speed difference by which the specific speed 27 of the vehicle 1 can be reduced by the driving assistance system 3. Here, it is assumed that the driving assistance system 3 cannot decelerate from any specific speed 27 to a standstill, but rather decelerates by a speed difference of, for example, 60 km / h. In this case, in method step S15, the time difference value 25 is increased by a predetermined other time interval 26' that is greater than the predetermined time interval 26. For the predetermined other time interval 26', at least one reaction time 33 for the reaction of the driver of the vehicle 1 is taken into account. The reaction time 33 can be specifically predetermined by the driver for this purpose. If the specific speed 27 is equal to or less than the speed difference value 32, the method can be terminated or method step S5 can be performed. That is, it is possible to carry out method step S14 after method step S4 or S7 and to replace method step S5 by method step S15. After method step S15, method step S6 is preferably carried out, but taking into account the time difference value 25 increased by another predetermined time interval 26'.

[0053] Overall, the example illustrates a time difference value threshold adjustment by detecting the hazard warning light system of another vehicle 20 ahead. The host vehicle (vehicle 1) detects the hazard warning light system of the other vehicle 20 ahead using optical sensors such as the front camera 5 and the lidar device 8. The vehicle 1 increases the time difference value 25 (TTC threshold) of the driver assistance system 3 (e.g., due to FCW (Forward Collision Warning), brake prefill, braking). This increase can be performed dynamically depending on the specific speed 27 and / or relative speed 28 with respect to the most important other vehicle 20.

[0054] On a highway, car 1 is traveling at 120 km / h. In front of car 1, there is another car 20 that has its hazard warning light system on and is stationary, indicating a traffic jam. In a typical driver assistance system configuration, the time difference value 25 (TTC threshold) is 1.4 seconds. Considering the specific speed 27, relative speed 28, and the typical deceleration of 9 meters per second on a dry road, car 1 will brake when the distance to the other car 20 ahead is 46.66 meters. However, car 1 will need 61.67 meters to stop without colliding, which means that a collision cannot be avoided. However, if the time difference value 25 (TTC threshold) is set to 1.9 seconds (adding 0.5 seconds), car 1 will brake when the distance to the other car 20 ahead is 63.33 meters and stop when the distance is 1.66 meters. Thus, a collision is avoided.

Claims

1. A method for operating a driving assistance system (3) at least for longitudinal guidance of a motor vehicle (1), comprising: providing (S2) sensor information (22) describing at least one other vehicle (20) located ahead of the vehicle (1) in the direction of travel (18) of the vehicle (1); determining (S3) hazard warning light information (24) describing whether the at least one other vehicle (20) has activated a hazard warning light by applying hazard warning light detection criteria (23) to the provided sensor information (22); Increasing (S5) by a predetermined time interval (26) a time difference value (25) describing the maximum time difference between the activation time of a function of the driving assistance system (3) and the impact time of a predicted collision between an obstacle around the vehicle (1) and the vehicle (1) if the at least one other vehicle (20) has activated its hazard warning light according to the determined hazard warning light information (24); and and operating (S6) said driving assistance system (3) taking into account said increased time difference value (25).

2. 2. The method according to claim 1, wherein the predetermined time interval (26) is determined taking into account at least the intrinsic speed (27) of the vehicle (1).

3. 3. The method according to claim 1 or 2, wherein the predetermined time interval (26) is determined taking into account the relative speed (28) of the vehicle (1) with respect to the at least one other vehicle (20).

4. 4. The method of claim 3, further comprising determining (S8) for each of the plurality of other motor vehicles (20) distance information (29) describing the distance between the motor vehicle (1) and the other motor vehicle (20) if the plurality of other motor vehicles (20) have activated the hazard warning light, and taking into account the relative speed (28) of the motor vehicle (1) relative to the other motor vehicle (20) for which the smallest distance information (30) is determined.

5. 4. The method of claim 3, further comprising: if a plurality of other motor vehicles (20) have activated their hazard warning lights, determining (S10) which of these other motor vehicles (20) are located in the same lane (15, 16) as the motor vehicle (1); determining (S11) for each of the determined other motor vehicles (31) an item of distance information (29) describing the distance between the motor vehicle (1) and the determined other motor vehicle (31); and taking into account the relative speed (28) of the motor vehicle (1) relative to the determined other motor vehicle (31) for which the smallest distance information (30) is determined.

6. 6. The method according to claim 4, wherein the predetermined time interval (26) is determined taking into account at least the determined minimum distance information (30).

7. 7. The method according to claim 1, further comprising checking (S14) whether the intrinsic speed (27) of the vehicle (1) is greater than a predetermined speed difference value (32), which is preset in the driving assistance system (3) and describes a speed difference by which the intrinsic speed (27) can be maximally reduced by the driving assistance system (3), and if the intrinsic speed (27) is greater than the predetermined speed difference value (32), increasing (S15) the time difference value (25) by another predetermined time interval (26') greater than the predetermined time interval (26).

8. 8. The method according to claim 7, wherein the predetermined other time interval (26') is determined taking into account at least the reaction time of the driver of the motor vehicle (1).

9. 9. The method according to claim 1, wherein the hazard warning light information (24) is continuously determined and checked, and as soon as it is determined that no other motor vehicle (20) has activated its hazard warning light according to the determined hazard warning light information (24), the time difference value (25) is reduced again by the predetermined time interval (26) and the driving assistance system (3) is operated again taking into account the reduced time difference value (25).

10. 10. The method according to claim 1, wherein the function of the driver assistance system (3) comprises warning of the predicted collision, preparing at least one brake of the braking system (12) of the motor vehicle (1) for braking, and / or applying the at least one brake.

11. The method according to any one of claims 1 to 10, wherein the driver assistance system (3) is an automatic emergency braking system and / or an adaptive cruise control system.

12. The method according to any one of claims 1 to 11, wherein the sensor information (22) is captured by a sensor device (4) of the motor vehicle (1), in particular by a camera and / or a lidar device as the sensor device (4).

13. A motor vehicle (1) designed to implement the method according to any one of claims 1 to 12.

14. A control device (2) for a motor vehicle (1), the control device (2) being designed to carry out the steps of the method according to any one of claims 1 to 12 and provided for said control device (2).

15. A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the method of any one of claims 1 to 12.

Images