Method for operating a driver assistance system, concerning at least longitudinal guidance of a motor vehicle, for a motor vehicle

Abstract

The invention relates to a method for operating a driver assistance system (3) concerning at least longitudinal guidance of a motor vehicle (1), comprising: providing (S2) sensor information (22) describing at least one other motor vehicle (20) located ahead of the motor vehicle (1) in a direction of travel (18) of the motor vehicle (1); determining (S3) hazard warning light information (24) describing whether or not the at least one other motor vehicle (20) has an activated hazard warning light, by applying a hazard warning light recognition criterion (23) to the provided sensor information (22); if the at least one other motor vehicle (20) has the activated hazard warning light in accordance with the determined hazard warning light information (24), increasing (S5) a time difference value (25), describing a maximum time difference between a trigger time of a function of the driver assistance system (3) and a collision point of a predicted collision between the motor vehicle (1) and an obstacle in surroundings of the motor vehicle (1), by a predefined time interval (26); and operating (S6) the driver assistance system (3) taking into consideration the increased time difference value (25).

Description

[0001] Method for operating a driver assistance system for a motor vehicle relating to at least one longitudinal guidance of a motor vehicle

[0002] The invention relates to a method for operating a driver assistance system for a motor vehicle. The invention also relates to a motor vehicle, a control device for a motor vehicle, and a computer program product for implementing such a method.

[0003] A motor vehicle may have a driver assistance system relating to the longitudinal guidance of the motor vehicle. The driver assistance system may, for example, be designed to control the longitudinal guidance of the motor vehicle at least partially automatically, in particular fully automatically. The driver assistance system may therefore, for example, control a braking system of the motor vehicle. Such a driver assistance system is, for example, an autonomous emergency braking system (AEB). Alternatively or additionally, the driver assistance system may be designed to issue a warning of an obstacle in the vicinity of the motor vehicle and thus, for example, to indicate manual control of the longitudinal guidance by a driver of the motor vehicle.

[0004] The driver assistance system, which affects the longitudinal guidance of the motor vehicle, is typically controlled taking into account a predefined time difference value. This describes a time difference that can lie between a triggering time of the driver assistance system and a collision time at which a predicted collision of the motor vehicle with the obstacle occurs. The time difference can alternatively be referred to as time-to-collision (TTC). When an obstacle is detected with which the motor vehicle could collide, a continuous check is carried out to determine whether the time difference value has already been reached. As soon as it is reached, a function of the driver assistance system, such as autonomous emergency braking of the motor vehicle, is triggered and / or the warning message is issued. The time difference value is typically provided as a fixed, predefined value that can be stored in the driver assistance system.

[0005] However, a situation may arise in which, for example, the speed at which the vehicle is approaching the obstacle at the moment the obstacle is detected is too high for the driver assistance system to be able to prevent a collision with the obstacle, taking into account the specified time difference. Therefore, the driver assistance system cannot be used effectively in every situation.

[0006] US 2018 / 0257646 A1 shows a vehicle control device comprising a rear-end collision safety system that can perform safety control in the event of a risk of a rear-end collision.

[0007] It is the object of the invention to provide a solution by means of which a driver assistance system for a motor vehicle can be operated particularly effectively.

[0008] The problem is solved by the subject matter of the independent patent claims.

[0009] A first aspect of the invention relates to a method for operating a driver assistance system for a motor vehicle that relates to at least one longitudinal guidance system of a motor vehicle. The driver assistance system is preferably designed to control the longitudinal guidance system of the motor vehicle at least partially automatically, in particular fully automatically.

[0010] The invention is based at least on the realization that the driver assistance system cannot be operated effectively in every situation with a fixed time difference value (time-to-collision, TTC). Therefore, the time difference value should be variable, at least in certain situations. Increasing the time difference value depending on the situation is particularly useful in order to be able to prevent a collision with an obstacle even more reliably than when the driver assistance system is operated with a fixed time difference value.

[0011] The method comprises providing sensor information that describes at least one other motor vehicle located in front of the motor vehicle in a direction of travel of the motor vehicle. The other motor vehicle is, for example, another motor vehicle driving ahead of the motor vehicle. The other motor vehicle can be in a lane in which the motor vehicle itself is traveling and / or which is adjacent to the lane in which the motor vehicle is traveling. The other motor vehicle can be currently traveling or stationary. The sensor information describes, for example, all other motor vehicles that are within a detection range of a sensor device that detects and provides the sensor information. The detection range is, for example, at least part of the surroundings of the motor vehicle in a front region of the motor vehicle.It can be provided that the direction of travel of the other motor vehicle corresponds to the direction of travel of the motor vehicle, so that, for example, an oncoming motor vehicle that is also located in a different lane than the motor vehicle is not taken into account. This allows the method to be restricted to considering the sensor information that describes only other motor vehicles traveling ahead and / or stationary in front of the motor vehicle, and excludes, for example, oncoming vehicles. In general, however, any other motor vehicle described by the sensor information can be taken into account.

[0012] The sensor information is preferably transmitted to a control device of the motor vehicle and thus made available to the latter. The control device can then provide the sensor information. The control device is a computing device and is designed to evaluate the sensor information for the further method steps of the method. The method steps described below are preferably all carried out using the control device of the motor vehicle. The control device is also designed to operate the driver assistance system, i.e., to execute at least one function of the driver assistance system. The control device is therefore designed, for example, to generate at least one control command for, for example, the braking system of the motor vehicle and to provide it to the braking system.

[0013] The method comprises determining hazard warning light information by applying a hazard warning light detection criterion to the provided sensor information. The hazard warning light information describes whether or not the at least one other motor vehicle has activated hazard warning lights. A targeted check is therefore carried out to determine whether or not the respective other motor vehicle described by the sensor information currently has activated hazard warning lights. The hazard warning lights are implemented, for example, using lighting devices of the other motor vehicle. When the hazard warning light is activated, all indicators of the other motor vehicle are typically switched on and flashing simultaneously.The other motor vehicle drives with its hazard warning lights activated, for example, whenever a following road user needs to be alerted to an abrupt braking of the motor vehicle, the end of a traffic jam, the last vehicle in a convoy, an accident, the towing of another vehicle and / or an impending maneuver by a bus, in particular a school or public transport bus. There may be alternative or additional situations in which the other motor vehicle activates the hazard warning lights. The other motor vehicle driving and / or stationary with its hazard warning lights activated is therefore a clear indication of a possible obstacle for the motor vehicle. For this reason, the invention determines whether at least one other motor vehicle in the vicinity of the motor vehicle has activated its hazard warning lights.The hazard warning light detection criterion is, for example, an algorithm and / or a rule by which the sensor information is evaluated to determine which other motor vehicle described by the sensor information currently has the hazard warning light activated and which does not.

[0014] If, according to the determined hazard warning light information, at least one other motor vehicle has its hazard warning lights activated, a time difference value is increased by a predetermined time interval. The time difference value describes a maximum time difference that lies, in particular may lie, between a triggering time of a function of the driver assistance system and a collision time of a predicted collision of the motor vehicle with an obstacle in the vicinity of the motor vehicle. In connection with driver assistance systems, the time difference value is typically referred to as the time-to-collision (TTC) or time-to-collision value. The time difference value can be, for example, 1.4 seconds. In this case, the function of the driver assistance system is triggered at the latest 1.4 seconds before a calculated predicted time of the collision of the motor vehicle with the obstacle, i.e. 1.4 seconds before the collision time.The function of the driver assistance system includes, for example, at least partially automatic, in particular fully automatic, braking of the motor vehicle and / or issuing a warning message in the motor vehicle. The obstacle can be the other motor vehicle with the activated hazard warning lights and / or another object in the vicinity of the motor vehicle. Instead of the predicted collision of the motor vehicle with the obstacle, a predicted collision of the motor vehicle with the at least one other motor vehicle with the activated hazard warning lights can be assumed.

[0015] The specified time interval is a fixed time value. For example, the time interval is 0.5 seconds. In the above example, the time difference value is therefore increased by 0.5 seconds from the original 1.4 seconds to a total of 1.9 seconds.

[0016] The driver assistance system is then operated taking the increased time difference value into account. For example, the driver assistance system assumes 1.9 seconds as the specified time difference value and no longer the original 1.4 seconds. This extends the reaction time during which the driver assistance system function is activated, because, for example, at least partially automatic braking of the vehicle or another function of the driver assistance system begins earlier than with the original time difference value. The strength of the driver assistance system function can remain unchanged.

[0017] This method ensures that a potentially dangerous situation is recognized particularly quickly by taking the hazard warning light information into account, allowing, for example, braking or another function of the driver assistance system to be activated very early. This early activation is achieved by increasing the time difference value. This ensures particularly reliable operation of the driver assistance system.

[0018] An advantageous embodiment provides that the predetermined time interval is determined at least taking into account the vehicle's own speed. The time interval by which the time difference value is increased is therefore not constant, but depends at least on how fast the vehicle is currently traveling. The vehicle's own speed can be determined using a sensor designed for this purpose. The sensor records odometry data, for example. The faster the vehicle is traveling, i.e. the higher its own speed, the longer the predetermined time interval can be selected. Instead of the previously mentioned 0.5 seconds, the time interval can be increased to, for example, 0.7 seconds, 1 second, or even longer than 1 second. If the vehicle is traveling slowly, for example 30 kilometers per hour or less, the time interval can be reduced, for example to just 0.3 seconds.Time intervals other than those listed here as examples are possible. Depending on the situation, the time difference value that makes sense based on the current speed of the vehicle is always selected.

[0019] A further exemplary embodiment provides that the predetermined time interval is determined at least taking into account a relative speed of the motor vehicle to the at least one other motor vehicle. For example, not only the motor vehicle's own speed can influence the time interval, but also the speed difference between the motor vehicle and the other motor vehicle. Therefore, the speed of the motor vehicle compared to the other motor vehicle that has activated the hazard warning lights is taken into account. The relative speed therefore indicates the motor vehicle's own speed relative to a speed of the other motor vehicle. If the other motor vehicle is already at a standstill, for example, the relative speed is greater than in a situation in which the other motor vehicle is still moving and therefore has a speed greater than 0 kilometers per hour.The higher the relative speed, the longer the specified time interval typically is. To determine the relative speed, for example, the sensor information and / or the determined or measured speed of the vehicle can be evaluated. By taking the relative speed of the vehicle into account, a particularly useful specified time interval can be determined.

[0020] The determined time interval is always taken into account when increasing the time reference value. For this purpose, it can be stored, at least temporarily, in a memory unit of the control device.

[0021] In a preferred exemplary embodiment, if several other motor vehicles have the hazard warning light activated, distance information is determined for each of the several other motor vehicles. The distance information describes a distance between the motor vehicle and the respective other motor vehicle. The distance information can be determined, for example, taking sensor information into account. For this purpose, sensor information that describes a distance to a respective object in the surroundings of the motor vehicle can be evaluated, for example. The sensor information evaluated here can be detected 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 a camera image and thus from static and / or moving image data from a camera device.Known methods for determining a distance between the motor vehicle and an object in the vicinity of the motor vehicle, such as the other motor vehicle in this case, can be used.

[0022] The relative speed of the motor vehicle to the other motor vehicle for which the smallest distance information is determined is then taken into account. This check is carried out to determine which of the several other motor vehicles the smallest distance information was determined for. This other motor vehicle is then selected as the only other motor vehicle and taken into account within the process. The remaining other motor vehicles can then be neglected, for example. When determining the time interval, only the relative speed relative to the selected other motor vehicle is taken into account.Since the motor vehicle with the smallest distance information is the other motor vehicle closest to the motor vehicle, this ensures that the likely potential obstacle for the motor vehicle is taken into account, since the other motor vehicle closest to the motor vehicle with its hazard warning lights activated is most likely to represent the obstacle for the motor vehicle. This allows the risk of collision with the obstacle, i.e., with exactly one selected other motor vehicle, to be prevented particularly reliably.

[0023] In this exemplary embodiment, the other motor vehicle with the smallest distance information can be a motor vehicle that is traveling in an adjacent lane and thus not in the same lane as the motor vehicle. The selected other motor vehicle can be an obstacle that is located to the side of the motor vehicle and, in particular, not on its predicted travel trajectory. It is assumed that, in a motor vehicle that is moving or stationary with its hazard warning lights activated, it can be the case that an occupant leaves the vehicle, particularly suddenly, and becomes an obstacle for the motor vehicle. By taking into account the other motor vehicle with its hazard warning lights activated in the adjacent lane, the time difference value is increased as a precautionary measure with regard to such a situation.This can be particularly useful in an inner-city area where it is relatively likely that an occupant of the other vehicle will leave it.

[0024] A further exemplary embodiment provides that if several other motor vehicles have their hazard warning lights activated, it is determined which of these other motor vehicles are in the same lane as the motor vehicle. The lane in this case is a lane of a road on which both the motor vehicle and the several other motor vehicles are traveling. Distance information is only determined for the other motor vehicle determined in this case. The distance information is therefore only determined for the other motor vehicles or for at least one other motor vehicle that is in the same lane as the motor vehicle. The distance information describes a distance between the motor vehicle and the determined other motor vehicle, analogous to what was described above.The relative speed of the motor vehicle to the other motor vehicle detected is taken into account for which the smallest distance information was determined. So here too, if distance information was determined for several other motor vehicles in the same lane, the smallest distance information is selected and the associated other motor vehicle is taken into account as the only motor vehicle. So typically the motor vehicle traveling in the same lane directly in front of the motor vehicle is identified. This means that motor vehicles in adjacent lanes, particularly in the case of a motorway with multiple lanes, are not taken into account; only the other motor vehicle that the motor vehicle is traveling directly towards because it is in the same lane.This means that the procedure is specifically tailored to a potentially impending frontal collision between the motor vehicle and the other motor vehicle in front and thus to a collision situation typical in road traffic.

[0025] A particularly preferred embodiment provides that the predefined time interval is determined at least taking into account the smallest distance information determined. Thus, for example, in addition to or as an alternative to the vehicle's own speed and / or relative speed, the distance from the nearest other motor vehicle of the plurality of motor vehicles can be taken into account. Depending on how far away this other motor vehicle is from the motor vehicle, the time interval can be specified to be longer or shorter. This results in a time interval that is particularly tailored to the situation.

[0026] According to an additional exemplary embodiment, it is provided that a check is carried out to determine whether the vehicle's own speed is greater than a predefined speed difference value. The speed difference value is a value predefined for the driver assistance system. It describes a speed difference by which the vehicle's own speed can be reduced by the driver assistance system. It is assumed here that the driver assistance system cannot brake the vehicle at least partially automatically from any arbitrary own speed down to a standstill, but that the at least partially automatic speed reduction that can be achieved by the driver assistance system is limited to a maximum speed difference. This is described by the speed difference value. This can be, for example, 60 kilometers per hour.

[0027] If the vehicle's own speed is greater than the specified speed difference value, the time difference value is increased by a specified time interval that is greater than the specified time interval. It may therefore be the case that, for a motor vehicle traveling at 120 kilometers per hour, for example, a speed difference value is predefined that is below the vehicle's own speed, for example, 60 kilometers per hour. In this example, the driver assistance system reduces the current vehicle's own speed of 120 kilometers per hour to a maximum of 60 kilometers per hour, semi-automatically, or in particular fully automatically.After that, for example, any remaining braking down to a standstill or down to a speed of less than 60 kilometers per hour must be done manually, for example by the driver pressing the brake pedal of the vehicle. To take into account that the driver may react with a delay because they are relying on the driver assistance system, the time difference value is increased by an even larger time interval than previously provided. For example, instead of the example 0.5 seconds, the time interval is set to 1 second, 1.5 seconds, 2 seconds or even longer. It is intended that the time difference value here is increased by the other specified time interval instead of the specified time interval. This means that if the braking function of the driver assistance system is restricted, a sensible additional increase in the time difference value can be made.

[0028] In a further exemplary embodiment, the predetermined other time interval is determined at least taking into account a reaction time for a reaction of the driver of the motor vehicle. For example, a driver-specific or driver-dependent reaction time can be known and taken into account. This can, for example, be stored in a user profile of the driver, which can be stored in the motor vehicle and / or loaded into it if provided by an external computing device. Alternatively or additionally, the reaction time is generally predetermined. The generally predetermined reaction time can, for example, be between 1 second and 3 seconds.The time interval is then, for example, at least the reaction time; in particular, it is the time interval determined taking into account the vehicle's own speed, the relative speed, and / or the smallest distance information plus the reaction time. This provides additional security by taking the driver's reaction time into account.

[0029] In an additional exemplary embodiment, it is provided that the hazard warning light information is continuously determined and checked. Checking is understood to mean that a check is carried out to determine whether, according to the hazard warning light information, at least one other motor vehicle with activated hazard warning lights has been detected or whether, for example, no other motor vehicle with activated hazard warning lights has been detected. As soon as it is determined that, according to the determined hazard warning light information, no other motor vehicle has the hazard warning lights activated, the time difference value is reduced again by the predetermined time interval and the driver assistance system is again operated taking the reduced time difference value into account. In other words, the increase in the time difference value is only maintained as long as at least one other motor vehicle with activated hazard warning lights is detected by evaluating the sensor information.As soon as no other motor vehicle within the detection range of the motor vehicle's sensor device that provides the sensor information has activated its hazard warning lights, the previously increased time difference value is reduced back to its initial value. The time difference value is thus reset to the original time difference value. This makes it clear that the method according to the invention is intended only for special situations and is not intended to change the specified time difference value indefinitely.

[0030] According to an additional exemplary embodiment, the function of the driver assistance system comprises warning of the predicted collision, braking preparation of at least one brake of a braking system of the motor vehicle, and / or braking using the at least one brake of the braking system. The driver assistance system can therefore be designed only to warn of a collision and thus, for example, indicate to the driver of the motor vehicle a point in time from which braking should be applied. The warning issued in this context is provided taking into account the increased time difference value. For example, an output device can be provided in the motor vehicle for the warning. The output device can be designed for acoustic and / or visual output.The output device is, for example, a display device, such as a screen, in particular a touch-sensitive screen, and / or a head-up display on the one hand, and / or a loudspeaker device with at least one loudspeaker on the other. The output device can be a component of the motor vehicle and / or comprised of a mobile terminal positioned in the motor vehicle, in particular a smartphone or tablet. The control device transmits, for example, the warning measure, such as the warning message, to the output device.

[0031] Braking preparation as a function can, for example, involve preparing for an upcoming braking maneuver using at least one brake of the braking system. For this purpose, the brake can be brought into a pre-braking state, for example, using at least one mechanical, pneumatic, and / or hydraulic measure. This has the effect that particularly rapid subsequent braking using the brake is possible, if necessary. It is preferably provided that the driver assistance system can actually control at least one brake of the braking system and thus actually perform braking, in particular braking to a standstill. The driver assistance system is therefore a driver assistance system that affects the longitudinal guidance of the motor vehicle in various ways.

[0032] Another embodiment provides for the driver assistance system to be an autonomous emergency braking system and / or an adaptive cruise control system. The autonomous emergency braking system is often referred to as Autonomous Emergency Breaking (AEB). The adaptive cruise control system can alternatively be referred to as adaptive cruise control (ACC). Thus, driver assistance systems are preferably provided that are actually designed to control at least one brake of the braking system at least partially automatically, in particular fully automatically.

[0033] Furthermore, one exemplary embodiment provides that the sensor information is acquired by means of a sensor device of the motor vehicle. The sensor device is, in particular, a camera and / or a lidar device. The sensor device is therefore preferably an imaging sensor designed to generate a static and / or moving or dynamic image of the surroundings. The sensor information therefore comprises, for example, image data in the case of the camera. The sensor device is preferably the front camera of the motor vehicle. Alternatively or additionally, the sensor information can be provided by an external device, in particular by another motor vehicle, a traffic observation camera and / or a traffic monitoring computing device, such as a backend, a server and / or a cloud server.The transmission of sensor information to the motor vehicle can, for example, be based on vehicle-to-vehicle and / or vehicle-to-infrastructure communication.

[0034] A further aspect of the invention relates to a motor vehicle for carrying out the described method. The motor vehicle is thus designed to carry out the method described above. The motor vehicle is, for example, a passenger car, a truck, a bus, a motorcycle, and / or a moped. The motor vehicle can have a control device.

[0035] A further aspect of the invention relates to a control device for a motor vehicle, which is designed to carry out the method described above. The control device carries out the described method, in particular an exemplary embodiment or a combination of exemplary embodiments of the described method. The control device has a processor device. The processor device can have 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 processor device can have program code, which can alternatively be referred to as a computer program product. The program code can be stored in a data memory of the processor device.

[0036] A further aspect of the invention relates to a computer program product. The computer program product is a computer program. The computer program product comprises instructions that, when executed by a computer, such as the control devices of the motor vehicle, cause the computer to perform the steps of the method according to the invention.

[0037] The exemplary embodiments described in connection with the method according to the invention, both individually and in combination with one another, apply accordingly, to the motor vehicle according to the invention, the control device according to the invention, and the computer program product according to the invention, as applicable. The invention encompasses combinations of the described exemplary embodiments.

[0038] Showing:

[0039] Fig. 1 is a schematic representation of a motor vehicle with a sensor device;

[0040] Fig. 2 is a schematic representation of several motor vehicles on a road; Fig. 3 is a schematic representation of a signal flow graph of a method for operating a driver assistance system relating to at least one longitudinal guidance of the motor vehicle; and

[0041] Fig. 4 shows a schematic representation of a signal flow graph of further method steps of a method according to Fig. 3.

[0042] Fig. 1 shows a motor vehicle 1 having a control device 2. The control device 2 is a computing device of the motor vehicle 1 and can, for example, have a driver assistance system 3 that has at least one function. The driver assistance system 3 relates to at least one longitudinal guidance of the motor vehicle 1. The driver assistance system 3 is, for example, an autonomous emergency braking system and / or an adaptive cruise control system. The function of the driver assistance system 3 can warn of a predicted collision of the motor vehicle 1 with an obstacle. Alternatively or additionally, the function of the driver assistance system 3 can prepare the braking of at least one brake of a braking system 12 of the motor vehicle 1.Alternatively or additionally, the function of the driver assistance system 3 can carry out at least partially automatic, in particular fully automatic, braking by means of the at least one brake of the braking system 12.

[0043] The motor vehicle 1 has a sensor device 4. The surroundings of the motor vehicle 1 can be detected by means of the sensor device 4. The sensor device 4 can, as shown here by way of example, comprise a plurality of cameras, such as a front camera 5, a side camera 6 and / or a rear camera 7. The sensor device 4 preferably comprises at least the front camera 5. Alternatively or additionally, the sensor device 4 can have a lidar device 8, a radar device 9 and / or an ultrasonic sensor (not sketched here). The side cameras 6 are arranged here in side mirrors 10 of the motor vehicle 1. The front camera 5 is arranged in an area of ​​a windshield 11 of the motor vehicle 1 that is located at the top in a vertical direction of the motor vehicle 1. Several radar devices 9 and / or lidar devices 8 and / or ultrasonic sensors can be arranged in the motor vehicle 1.Here, purely by way of example, several such sensors for a front area of ​​the motor vehicle 1 are sketched, which can be arranged in a bumper of the motor vehicle. By means of these, at least one surrounding area of ​​the motor vehicle 1 in the front area of ​​the motor vehicle 1 can be detected. An output device 13 can be arranged in the motor vehicle 1, such as a screen, in particular a touch-sensitive screen, a head-up display and / or a loudspeaker device comprising at least one loudspeaker. The output device 13 can be a component of the motor vehicle 1 and / or be comprised of a mobile device positioned in the motor vehicle 1. The mobile device is, for example, a smartphone and / or tablet. If the function of the driver assistance system 3 provides for warning of the predicted collision, a warning can be output by means of the output device 13.

[0044] Fig. 2 shows a road 14 on which the motor vehicle 1 is traveling. The road 14 has a right-hand lane 15 and a left-hand lane 16. The same direction of travel 18 applies to both lanes 15, 16. In addition to the motor vehicle 1, there are two other motor vehicles 20 on the road 14, purely as an example. These are traveling in the direction of travel 18 in front of the motor vehicle 1 on the road 14. One of the two other motor vehicles 20 is traveling in the same lane 15, 16 as the motor vehicle 1, i.e. in the right-hand lane 15. The other motor vehicle 20 is traveling in the adjacent left-hand lane 16. Both other motor vehicles 20 have activated hazard warning lights, i.e. all lighting devices 21 of the respective other motor vehicle 20 are flashing, for example to warn of a potential obstacle, such as the end of a traffic jam.

[0045] Fig. 3 shows steps of a method for operating the driver assistance system 3 relating at least to the longitudinal guidance of the motor vehicle 1. In a method step S1, the sensor information 22 can be acquired by means of the sensor device 4. The sensor device 4 in method step S1 preferably comprises at least the front camera 5, in particular also the side cameras 6 and / or the lidar device 8. The sensor information 22 is provided in a method step S2 by means of the control device 2. The sensor information 22 describes at least one other motor vehicle 20 located in front of the motor vehicle 1 in the direction of travel 18 of the motor vehicle 1.

[0046] In a method step S3, a hazard warning light detection criterion 23 is applied to the provided sensor information 22. This determines hazard warning light information 24 that describes whether or not the at least one other motor vehicle 20 has an activated hazard warning light. In a method step S4, it is checked whether or not at least one other motor vehicle 20 with activated hazard warning lights has been detected. If this is the case, a time difference value 25 is incremented in a method step S5. The time difference value 25 describes a maximum time difference between a triggering time of the function of the driver assistance system 3 and a collision time of a predicted collision of the motor vehicle 1 with an obstacle, such as in particular the other motor vehicle 20. The time difference value 25 is incremented here by a predetermined time interval 26.In a method step S6, the driver assistance system 3 is then operated 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.

[0047] It can be provided that the predetermined time interval 26 is first determined and, in doing so, an own speed 27 of the motor vehicle 1 is taken into account. This is determined, for example, in the motor vehicle 1, in particular by means of a sensor of the motor vehicle 1 designed for this purpose. Alternatively or additionally, a relative speed 28 can be taken into account when determining the time interval 26, which describes the relative speed of the motor vehicle 1 to the at least one other motor vehicle 20. The relative speed 28 is therefore a deviation of the own speed 27 from a speed of the other motor vehicle 20. The relative speed 28 can be determined, for example, taking into account data from the radar device 9, the ultrasonic sensor and / or the lidar device 8.

[0048] Furthermore, after method step S4, a check can be carried out in a method step S7 to determine whether several other motor vehicles 20 have their hazard warning lights activated. Three other motor vehicles 20 are shown here as examples, each driving or stationary with its hazard warning lights activated. Distance information 29 is then determined for each of the several other motor vehicles 20. This occurs in a method step S8. The respective distance information 29 describes a distance between motor vehicle 1 and the other motor vehicle 20. Only those other motor vehicles 20 with activated hazard warning lights are taken into account. Therefore, in the example shown here, three distance information items 29 are determined.

[0049] A smallest distance information item 30 is then selected from the determined distance information items 29. The relative speed 28 of motor vehicle 1 to precisely the other selected motor vehicle 20 for which the smallest distance information item 30 was determined is then taken into account. It can therefore be provided that the determined smallest distance information item 30 is taken into account when determining the predetermined time interval 26.

[0050] Instead of taking into account all other motor vehicles 20 described by the sensor information 22, it can be provided in a method step S10 that, after method step S7, it is determined which of the other motor vehicles 20 that has the activated hazard warning light is located in the same lane 15, 16 as motor vehicle 1. Here, for example, this is precisely one other motor vehicle 20, which is sketched here as the identified other motor vehicle 31. In a method step S11, the distance information 29, which describes the distance between motor vehicle 1 and the identified other motor vehicle 31, is determined only for the identified other motor vehicle 31.If several other motor vehicles 31 are determined, the relative speed 28 of the motor vehicle 1 is taken into account exactly with respect to the other motor vehicle 31 for which the smallest distance information 30 was determined, i.e. method step S9 is carried out.

[0051] In method steps S8 and S9, however, any other motor vehicle 20 can in principle be taken into account without method steps S10 and S11, even if it is, for example, located in the adjacent lane 15, 16 to the lane 15, 16 of motor vehicle 1. Referring to Fig. 2, the relative speed 28 to the other motor vehicle 20 traveling in the left lane 16 can therefore be taken into account, since this other motor vehicle 20 is at a smaller distance from motor vehicle 1 than the other motor vehicle 20 traveling directly in front of motor vehicle 1 in the right lane 15. In method steps S10, S11, and subsequently S9, however, this other motor vehicle 20 is not taken into account at all, but only the other motor vehicle 20 traveling directly ahead and thus also traveling in the right lane 15.

[0052] It can further be provided that the hazard warning light information 24 is continuously checked. As soon as it is determined that, according to the determined hazard warning light information 24, no other motor vehicle 20 has the hazard warning light activated, the time difference value 25 is reduced again by the predetermined time interval 26. The driver assistance system 3 is then operated again taking into account the reduced time difference value 25 and thus taking into account the original time difference value 25. It can be provided that if it is determined in method step S4 that, according to the determined hazard warning light information 24, no other motor vehicle 20 with the hazard warning light activated was detected, method step S1 is immediately carried out again.

[0053] A method step S12 can also be provided in which it is checked whether the driver assistance system 3 is currently being operated according to the increased time difference value 25. If this is the case, the time difference value 25 can be reduced again by the time interval 26 in a method step S13. If the check determines that the driver assistance system 3 is not currently being operated with the increased time difference value 25 at all, method step S1 is also performed again. If, for example, it is determined in method step S7 that several other motor vehicles 20 do not have the hazard warning lights activated, method step S5 can be performed.

[0054] Fig. 4 outlines two optional method steps S14 and S15. In method step S14, a check is carried out to determine whether the own speed 27 of the motor vehicle 1 is greater than a predefined speed difference value 32. The speed difference value 32 is fixed for the driver assistance system 3. It describes a speed difference by which the own speed 27 of the motor vehicle 1 can be reduced to a maximum by means of the driver assistance system 3. Thus, the case described here is that the driver assistance system 3 cannot decelerate from any arbitrary own speed 27 to a standstill, but only by, for example, the speed difference of 60 kilometers per hour. If this is the case, in a method step S15, the time difference value 25 is increased by a predefined other time interval 26', which is greater than the predefined time interval 26.For the specified other time interval 26', at least one reaction time 33 for a reaction of a driver of motor vehicle 1 is taken into account. The reaction time 33 can be specified for this purpose on a driver-specific basis. If the vehicle's own speed 27 is less than or equal to the speed difference value 32, the method can be terminated or method step S5 can be performed. It is therefore possible to perform method steps S14 after method steps S4 or S7 and to replace method step S5 with method step S15. After method step S15, method step S6 is preferably performed, but taking into account the time difference value 25, which has been increased by the specified other time interval 26'. Overall, the examples show a time difference value threshold adjustment by detecting the hazard warning lights of the other motor vehicle 20 in front.The ego vehicle (motor vehicle 1) detects the hazard warning lights of the other motor vehicles 20 ahead using optical sensors, such as the front camera 5 or the lidar device 8. Motor vehicle 1 increases the time difference value 25 (TTC thresholds) of the driver assistance system 3 (for example, for FCW (Forward Collision Warning), prefill, and brake). The increase can occur dynamically depending on the vehicle's own speed 27 and / or the relative speed 28 to the most critical other motor vehicle 20.

[0055] Motor vehicle 1 is traveling on a highway at 120 kilometers per hour. In front of it, several other motor vehicles 20 have their hazard lights on and are not moving, indicating a traffic jam. A typical driver assistance system configuration has a time difference value 25 (TTC threshold) of 1.4 seconds. With this own speed 27 and relative speed 28, and a typical deceleration on dry roads of 9 meters per square second, this results in motor vehicle 1 braking when the distance to the other motor vehicle 20 in front is 46.66 meters. However, for motor vehicle 1 to come to a stop without a collision, it needs 61.67 meters, which means that the collision cannot be avoided here.However, if the time difference value 25 (TTC threshold) is increased to 1.9 seconds (an increase of 0.5 s), motor vehicle 1 brakes when the distance to the other motor vehicle 20 in front is still 63.33 meters and comes to a stop when the distance is 1.66 meters. The collision is therefore avoided.

Claims

Patent claims 1 . Method for operating a driver assistance system (3) relating to at least one longitudinal guidance of a motor vehicle (1), comprising: - Providing (S2) sensor information (22) which describes at least one other motor vehicle (20) located in front of the motor vehicle (1) in a direction of travel (18) of the motor vehicle (1); - determining (S3) hazard warning light information (24) describing whether or not the at least one other motor vehicle (20) has an activated hazard warning light by applying a hazard warning light detection criterion (23) to the provided sensor information (22); - if, according to the determined hazard warning light information (24), the at least one other motor vehicle (20) has the activated hazard warning light, increasing (S5) a time difference value (25), which describes a time difference that lies at most between a triggering time of a function of the driver assistance system (3) and a collision time of a predicted collision of the motor vehicle (1) with an obstacle in an environment of the motor vehicle (1), by a predetermined time interval (26); and - Operating (S6) the driver assistance system (3) taking into account the increased time difference value (25).

2. Method according to claim 1, wherein the predetermined time interval (26) is determined at least taking into account an own speed (27) of the motor vehicle (1).

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

4. The method according to claim 3, wherein if several other motor vehicles (20) have the activated hazard warning light, distance information (29) is determined (S8) for each of the several other motor vehicles (20), which distance information (29) indicates a distance between the motor vehicle (1) and the other motor vehicle (20), and the relative speed (28) of the motor vehicle (1) to exactly the other motor vehicle (20) for which the smallest distance information (30) was determined is taken into account.

5. The method according to claim 3, wherein, if several other motor vehicles (20) have the activated hazard warning light, it is determined (S10) which of these other motor vehicles (20) are located in the same lane (15, 16) as the motor vehicle (1); distance information (29) is determined (S11) only for the respective other motor vehicle (31) determined, which distance information describes a distance between the motor vehicle (1) and the other motor vehicle (31) determined, and the relative speed (28) of the motor vehicle (1) to precisely the other motor vehicle (31) determined for which the smallest distance information (30) was determined is taken into account.

6. Method according to one of claims 4 or 5, wherein the predetermined time interval (26) is determined at least taking into account the determined smallest distance information (30).

7. Method according to one of the preceding claims, in which references back to claim 2, wherein it is checked (S14) whether the own speed (27) of the motor vehicle (1) is greater than a predetermined speed difference value (32) which is predetermined for the driver assistance system (3) and describes a speed difference by which the own speed (27) can be maximally reduced by means of the driver assistance system (3), wherein if the own speed (27) is greater than the predetermined speed difference value (32), the time difference value (25) is increased (S15) by a predetermined other time interval (26') which is greater than the predetermined time interval (26).

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

9. Method according to one of the preceding claims, wherein the hazard warning light information (24) is continuously determined and checked, wherein as soon as it is determined that according to the determined hazard warning light information (24) no other motor vehicle (20) has the activated hazard warning light, the time difference value (25) is reduced again by the predetermined time interval (26) and the driver assistance system (3) is operated again taking into account the reduced time difference value (25) (S13).

10. Method according to one of the preceding claims, wherein the function of the driver assistance system (3) comprises a warning of the predicted collision, a braking preparation of at least one brake of a braking system (12) of the motor vehicle (1) and / or braking by means of the at least one brake.

11. Method according to one of the preceding claims, wherein the driver assistance system (3) is an autonomous emergency braking system and / or an adaptive cruise control system.

12. Method according to one of the preceding claims, wherein the sensor information (22) is detected by means of a sensor device (4) of the motor vehicle (1), in particular by means of a camera and / or a lidar device as the sensor device (4).

13. Motor vehicle (1) designed to carry out a method according to one of the preceding claims.

14. Control device (2) for a motor vehicle (1), which is designed to carry out the steps of a method according to one of claims 1 to 12 provided for the control device (2).

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

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