DE102022133406A1 - Method for operating a driver assistance system for a motor vehicle relating to at least one longitudinal guidance of a motor vehicle - Google Patents

Abstract

The invention relates to a 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) which describes 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 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).

Description

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 carrying out such a method.

A motor vehicle can have a driver assistance system that relates to a longitudinal guidance of the motor vehicle. The driver assistance system can, for example, be designed to control a longitudinal guidance of the motor vehicle at least partially automatically, in particular fully automatically. The driver assistance system can therefore, for example, control a braking system of the motor vehicle. Such a driver assistance system is, for example, an autonomous emergency braking system (Autonomous Emergency Breaking, AEB). Alternatively or additionally, the driver assistance system can be designed to issue a warning about 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.

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). If 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 value that can be stored in the driver assistance system.

However, a situation may arise in which, for example, the speed at which the motor vehicle approaches 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 value. The driver assistance system cannot therefore be used effectively in every situation.

The US 2018/0257646 A1 shows a vehicle control device including a rear collision safety system that can perform safety control in the event of a danger of a rear collision.

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.

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

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

The invention is based at least on the knowledge that the driver assistance system cannot be operated sensibly in every situation with a fixed time difference value (time-to-collision, TTC). The time difference value should therefore be changeable at least in certain situations. It is particularly useful to increase the time difference value depending on the situation 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.

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 on which the motor vehicle itself is traveling and/or which is adjacent to the lane on which the motor vehicle is traveling. The other motor vehicle can currently be traveling or stationary. The sensor information describes, for example, all other motor vehicles that are in a detection range of a sensor device that detects and provides the sensor information. The detection range is, for example, at least part of an environment of the motor vehicle in a front area 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 other motor vehicle that is also, for example, in a different lane than the motor vehicle is not taken into account. This allows the method to be restricted to taking into account the sensor information that only describes other motor vehicles driving ahead and/or stationary in front of the motor vehicle and excludes, for example, motor vehicles in oncoming traffic. In general, however, any other motor vehicle described by the sensor information can be taken into account.

The sensor information is preferably transmitted to a control device of the motor vehicle and thus made available to it. 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 carry out 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 make it available to the braking system.

The method includes determining hazard warning light information by applying a hazard warning light recognition criterion to the sensor information provided. The hazard warning light information describes whether or not the at least one other motor vehicle has an activated hazard warning light. It is therefore specifically checked whether the respective other motor vehicle described by the sensor information currently has an activated hazard warning system or not. The hazard warning light is implemented, for example, using lighting devices of the other motor vehicle. When the hazard light is activated, all indicators of the other motor vehicle are typically switched on and flashing at the same time. The other motor vehicle drives with the hazard warning light activated, for example, whenever a following road user should be informed of, for example, 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 driving maneuver of a bus, in particular a school or public bus. There may be alternative or additional situations in which the other motor vehicle activates the hazard warning light. The other motor vehicle that is driving and/or standing with its hazard warning lights activated is therefore a clear indication of a possible obstacle for the motor vehicle. For this reason, according to the invention, it is determined 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 based on which the sensor information is evaluated in order to determine which other motor vehicle described by the sensor information currently has the hazard warning lights activated and which does not.

If, according to the determined hazard warning light information, the at least one other motor vehicle has the hazard warning light activated, a time difference value is increased by a predetermined time interval. The time difference value describes a time difference that is, in particular may be, a maximum 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 an environment of the motor vehicle. In connection with driver assistance systems, the time difference value is typically referred to as 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 light 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 at least one other motor vehicle that has the activated hazard warning light can be assumed.

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

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 means that the reaction time in which the driver assistance system function is activated is extended, since the at least partially automatic braking begins earlier than with the original time difference value, for example. of the motor vehicle or another function of the driver assistance system is started. A strength of the function of the driver assistance system can remain unchanged.

The process ensures that a potentially dangerous situation is recognized particularly quickly by taking the hazard warning light information into account, so that braking or another function of the driver assistance system can be activated particularly early. This early activation is achieved by increasing the time difference value. This ensures that the driver assistance system can be operated particularly reliably.

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 travels, 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 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. Other time intervals than those mentioned here as examples are possible. This means that, depending on the situation, the time difference value that makes sense based on the current speed of the vehicle is always selected.

Another 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. It is therefore taken into account how fast the motor vehicle is traveling compared to the other motor vehicle that has activated the hazard warning lights. The relative speed therefore indicates the 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 traveling and thus has a speed greater than 0 kilometers per hour. The higher the relative speed, the longer the predetermined time interval is typically. To determine the relative speed, for example, the sensor information and/or the determined or measured own speed of the motor vehicle can be evaluated. By taking the relative speed of the motor vehicle into account, a particularly useful predetermined time interval is determined.

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.

In a preferred embodiment, if several other motor vehicles have the activated hazard warning lights, 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 the sensor information into account. For this purpose, for example, sensor information can be evaluated that describes a distance to a respective object in the vicinity of the motor vehicle. The sensor information evaluated here can, for example, be recorded and provided 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 here, can be used.

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. It is therefore checked for which of the several other motor vehicles the smallest distance information was determined. This other motor vehicle is then selected as the only other motor vehicle and taken into account in the process. The remaining other motor vehicles can then be neglected, for example. When determining the time interval, only the relative speed in relation to the selected other motor vehicle is taken into account. Since the motor vehicle with the smallest distance information is the other motor vehicle located closest to the motor vehicle, this ensures that the expected potential distance obstacle for the motor vehicle is taken into account, since the other motor vehicle closest to the motor vehicle with activated hazard warning lights is particularly likely to represent the obstacle for the motor vehicle. This makes it particularly reliable to prevent the risk of collision with the obstacle, i.e. with exactly one other selected motor vehicle.

In this exemplary embodiment, the other motor vehicle with the smallest distance information can be a motor vehicle that is driving 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 arranged 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 driving or stationary with the hazard warning lights activated, it can be the case that an occupant leaves the vehicle, in particular suddenly, and becomes an obstacle for the motor vehicle. By taking into account the other motor vehicle with the hazard warning lights activated in the adjacent lane, the time difference value is increased as a precaution with regard to such a situation. This can be particularly useful in an inner-city area in which it is relatively likely that an occupant of the other motor vehicle will leave it.

Another embodiment provides that if several other motor vehicles have the hazard warning lights activated, it is determined which of these other motor vehicles are in the same lane as the motor vehicle. The lane 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 here. 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, analogously to what was described above, a distance between the motor vehicle and the other motor vehicle determined. The relative speed of the motor vehicle to the other motor vehicle determined 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 distance information that is the smallest is selected and the associated other motor vehicle is taken into account as the only motor vehicle. The motor vehicle that is driving in the lane of the motor vehicle directly in front of the motor vehicle is typically identified here. This means that motor vehicles on adjacent lanes are not taken into account, particularly in the case of a motorway with several lanes, but only the other motor vehicle that the vehicle is driving 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 driving ahead and thus to a collision situation that is typical in road traffic.

A particularly preferred embodiment provides that the predefined time interval is determined at least taking into account the smallest distance information determined. For example, in addition to or as an alternative to the vehicle's own speed and/or the relative speed, it is possible to take into account how far the next other motor vehicle of the several motor vehicles is from the motor vehicle. Depending on how far away this other motor vehicle is from the motor vehicle, the time interval can be specified to be larger or smaller. This leads to a time interval that is particularly differentiated and adapted to the situation.

According to an additional embodiment, it is provided that a check is carried out to determine whether the speed of the motor vehicle 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 speed of the vehicle can be reduced to a maximum by means of the driver assistance system. It is assumed here that the driver assistance system cannot brake the motor vehicle at least partially automatically from any speed of the vehicle to a standstill, but that the at least partially automatic speed reduction that can be achieved by means of 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.

If the vehicle's own speed is greater than the specified speed difference value, the time difference value is increased by a specified other time interval that is greater than the specified time interval. It may therefore be the case that for a motor vehicle that is traveling at 120 kilometers per hour, for example, a speed difference value is specified that is below the vehicle's own speed, for example 60 kilometers per hour. In this example, the driver assistance system limits the current vehicle's own speed of 120 kilometers per hour to a maximum of reduced to the vehicle's own speed of 60 kilometers per hour partially automatically, in particular fully automatically. After that, for example, the rest of the 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. In order to take into account that the driver may react with a delay because he is relying on the driver assistance system, the time difference value is increased by an even larger time interval than was previously provided. For example, instead of the example of 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 be 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.

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 be stored, for example, in a user profile of the driver, which can be stored in the motor vehicle and/or loaded into it if it is 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.

In an additional embodiment, it is provided that the hazard warning light information is continuously determined and checked. Checking is to be understood as checking whether, according to the hazard warning light information, at least one other motor vehicle with activated hazard warning light was detected or whether, for example, no other motor vehicle with activated hazard warning light was detected. As soon as it is determined that, according to the determined hazard warning light information, no other motor vehicle has the activated hazard warning light, 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 light is detected by evaluating the sensor information. As soon as no other motor vehicle that is in the detection range of the sensor device of the motor vehicle that provides the sensor information has activated its hazard warning light, the previously increased time difference value is reduced back to its initial value. The time difference value is therefore reset to the original time difference value. This makes it clear that the method according to the invention is only intended for special situations and that no unlimited change of the predetermined time difference value is intended.

According to an additional embodiment, it is provided that the function of the driver assistance system includes warning of the predicted collision, braking preparation of at least one brake of a braking system of the motor vehicle and/or braking by means of the at least one brake of the braking system. The driver assistance system can therefore only be designed to warn of a collision and thus, for example, indicate a point in time from which braking should be applied to the driver of the motor vehicle. 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 optical output. The output device is therefore, 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 be included in 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, to the output device.

The braking preparation function can, for example, involve preparing 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 using at least one mechanical, pneumatic and/or hydraulic measure. This means that, if necessary, a particularly rapid braking is possible using the brake. Preferably, the driver assistance system can actually control at least one brake of the braking system and thus actually carry out 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.

Another embodiment provides that the driver assistance system is 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 distance control or Adaptive Cruise Control (ACC). Driver assistance systems are therefore preferably provided that are actually designed to control at least one brake of the braking system at least partially automatically, in particular fully automatically.

In addition, one embodiment provides that the sensor information is recorded 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 that is designed to generate a static and/or moving or dynamic image of the environment. The sensor information therefore includes, 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 the sensor information to the motor vehicle can be based, for example, on vehicle-to-vehicle and/or vehicle-to-infrastructure communication.

A further aspect of the invention relates to a motor vehicle for carrying out the method described. The motor vehicle is therefore 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.

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 embodiment or a combination of 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.

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 which, when the program is executed by a computer, such as by the control devices of the motor vehicle, cause the computer to carry out the steps of the method according to the invention.

The embodiments described in connection with the method according to the invention, each individually and in combination with one another, apply accordingly, where applicable, to the motor vehicle according to the invention, the control device according to the invention and the computer program product according to the invention. The invention includes combinations of the described embodiments.

• 1 eine schematische Darstellung eines Kraftfahrzeugs mit einer Sensoreinrichtung;
• 2 eine schematische Darstellung mehrerer Kraftfahrzeuge auf einer Straße;
• 3 in schematischer Darstellung einen Signalflussgraphen eines Verfahrens zum Betreiben eines zumindest eine Längsführung des Kraftfahrzeugs betreffenden Fahrerassistenzsystems; und
• 4 in schematischer Darstellung einen Signalflussgraphen weiterer Verfahrensschritte eines Verfahrens gemäß 3.

Showing:

• 1 a schematic representation of a motor vehicle with a sensor device;
• 2 a schematic representation of several motor vehicles on a road;
• 3 in schematic representation 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
• 4 in schematic representation a signal flow graph of further process steps of a method according to 3 .

In 1 a motor vehicle 1 is outlined which has 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 which has at least one function. The driver assistance system 3 relates to at least a longitudinal guidance of the motor vehicle 1. The driver assistance system 3 is, for example, an auto nomes emergency braking system and/or an adaptive cruise control system. The function of the driver assistance system 3 can carry out a warning of a predicted collision of the motor vehicle 1 with an obstacle. Alternatively or additionally, the function of the driver assistance system 3 can carry out braking preparation 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.

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 several 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 comprise 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 are sketched for a front area of the motor vehicle 1, which can be arranged in a bumper of the motor vehicle. By means of this, at least one environment 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 that includes at least one loudspeaker. The output device 13 can be a component of the motor vehicle 1 and/or can be included in a mobile terminal that is positioned in the motor vehicle 1. The mobile terminal 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 issued by means of the output device 13.

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 other two 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 an activated hazard warning light, i.e. all lighting devices 21 of the respective other motor vehicle 20 flash, for example to warn of a potential obstacle, such as the end of a traffic jam.

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 recorded by means of the sensor device 4. The sensor device 4 in the 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.

In a method step S3, a hazard warning light detection criterion 23 is applied to the sensor information 22 provided. This determines hazard warning light information 24 which 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 was detected. If this is the case, a time difference value 25 is increased in a method step S5. The time difference value 25 describes a time difference which lies at most 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 increased 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, that is, the sum of the original time difference value 25 and the predetermined time interval 26.

It can be provided that the predetermined time interval 26 is first determined and that 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 designed for this purpose by a sensor of the motor vehicle 1. Alternatively or additionally, when determining the time interval 26, a relative speed 28 can be taken into account, 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 vehicle's 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.

After method step S4, it can also be checked in a method step S7 whether several other motor vehicles 20 have the hazard warning lights activated. Three other motor vehicles 20 are shown here as examples, which are driving or standing with the hazard warning lights activated. Distance information 29 is then determined for each of the several other motor vehicles 20. This takes place in a method step S8. The respective distance information 29 describes a distance between the motor vehicle 1 and the other motor vehicle 20. Only the other motor vehicles 20 that have an activated hazard warning light are taken into account here. In the example outlined here, three distance information 29 are therefore determined.

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

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 in the same lane 15, 16 as motor vehicle 1. Here, for example, this is exactly one other motor vehicle 20, which is sketched here as an identified other motor vehicle 31. In a method step S11, the distance information 29 that 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 identified other motor vehicles 31 are determined, the relative speed 28 of motor vehicle 1 is taken into account exactly in relation to the identified other motor vehicle 31 for which the smallest distance information 30 was determined, i.e. method step S9 takes place.

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 located, for example, on the lane 15, 16 adjacent to lane 15, 16 of motor vehicle 1. In relation to 2 the relative speed 28 to the other motor vehicle 20 driving in the left lane 16 can therefore be taken into account, since this has a smaller distance to the motor vehicle 1 than the other motor vehicle 20 driving directly in front of the motor vehicle 1 in the right lane 15. In the method steps S10, S11 and then S9, however, this other motor vehicle 20 is not taken into account at all, but only the other motor vehicle 20 driving directly ahead and thus also driving in the right lane 15.

It can also 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 activated hazard warning lights was detected, method step S1 is carried out again directly.

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 it is determined during the check that the driver assistance system 3 is not currently being operated with the increased time difference value 25 at all, the method step S1 is also carried out again. If, for example, it is determined in the method step S7 that several other motor vehicles 20 do not have the activated hazard warning lights at all, the method step S5 can take place.

In 4 Two optional process steps S14 and S15 are outlined. In process step S14, it is checked whether the airspeed 27 of the motor vehicle 1 is greater than a predetermined 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. The case described here is therefore that the driver assistance system 3 cannot brake from any own speed 27 to a standstill, but only by, for example, the speed difference of, for example, 60 kilometers per hour. If this is the case, in a 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 a reaction of a driver of the motor vehicle 1 is taken into account. The reaction time 33 can be predetermined for this purpose on a driver-specific basis. If the 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 carried out. It is therefore possible to carry out method steps S14 after method step S4 or S7 and to replace method step S5 with method step S15. After method step S15, method step S6 is preferably carried out, 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 in front with 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 be dynamic depending on the own speed 27 and/or the relative speed 28 to the most critical other motor vehicle 20.

Motor vehicle 1 is travelling on a highway at 120 kilometres per hour. Ahead 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 metres per square second, this results in motor vehicle 1 braking when the distance to the other motor vehicle 20 in front is 46.66 metres. However, for motor vehicle 1 to come to a stop without a collision, it needs 61.67 metres, 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 here.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 20180257646 A1 [0005]

Claims (15)

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) which describes whether the at least one other motor vehicle (20) has an activated hazard warning light or not, by applying a hazard warning light recognition 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). Procedure 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). Procedure 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). Procedure 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 describes 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. Procedure 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 in the same lane (15, 16) as the motor vehicle (1); only for the respective other motor vehicle (31) determined, distance information (29) is determined (S11), which 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 exactly the other motor vehicle (31) determined for which the smallest distance information (30) was determined is taken into account. Method according to one of the Claims 4 or 5 , wherein the predetermined time interval (26) is determined at least taking into account the determined smallest distance information (30). Method according to one of the preceding claims, in whose references 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). Procedure 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). 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 again operated taking into account the reduced time difference value (25) (S13). 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. 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. 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). Motor vehicle (1) designed to carry out a method according to one of the preceding claims. Control device (2) for a motor vehicle (1), which is designed to carry out the steps of a method according to one of the Claim 1 until 12 to carry out. Computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out a method according to one of the Claims 1 until 12 to execute.

Images