Method for operating a driver assistance system for a motor vehicle, driver assistance system and motor vehicle having a driver assistance system

Abstract

The invention relates to a method for operating a driver assistance system (12) for a motor vehicle (10), wherein a predetermined safety measure for the motor vehicle (10) is triggered by the driver assistance system (12) when a predetermined warning threshold value is reached during a journey of the motor vehicle (10). According to the invention, a first triggering event is detected, wherein the first triggering event comprises a first triggering of the predetermined safety measure within a first journey portion of the journey. A reaction and / or a reaction speed of a driver of the motor vehicle (10) to the first triggering event is then observed. An attention value of the driver is then adjusted depending on the observed reaction and / or the observed reaction speed. Finally, the warning threshold is adjusted depending on the adjusted attention value.

Description

[0001] Method for operating a driver assistance system for a motor vehicle, driver assistance system and motor vehicle with a driver assistance system

[0002] The invention relates to a method for operating a driver assistance system for a motor vehicle, wherein the driver assistance system triggers a predetermined safety measure for the motor vehicle upon reaching a predetermined warning threshold during the course of a journey of the motor vehicle. The invention also relates to such a driver assistance system and to a motor vehicle with such a driver assistance system.

[0003] It is known that a lack of or declining attention on the part of a motor vehicle driver in road traffic can lead to an increased number of incidents, such as rear-end collisions. Many motor vehicles are therefore equipped with driver assistance systems that can independently intervene in the vehicle's current driving behavior and, for example, initiate braking if the driver is inattentive (AEB - autonomous emergency braking). In most cases, the driver assistance system issues a corresponding collision warning (FCW - forward collision warning) prior to such automatically initiated braking. Thresholds or warning thresholds can be specified for triggering braking and / or the preceding warning, with the corresponding action being triggered when the associated warning threshold is exceeded.Such a warning threshold can describe the remaining time, for example, in seconds, until the impending collision (TTC - time to collision). A corresponding warning threshold can be referred to as a TTC threshold.

[0004] DE 10 2015 117 976 A1 discloses adapting a TTC threshold to the current speed of a motor vehicle and / or to the current relative speed of the motor vehicle to a potential collision obstacle. This requires complex recording and processing of the current speed of the motor vehicle and other road users.

[0005] CN 11 20 46 454 A discloses adjusting a TTC threshold depending on current environmental conditions, such as road gradient and / or slippery road surfaces. In other words, the warning threshold can be increased if a downhill road layout and / or a slippery road surface leads to an increased or longer braking distance. To implement the described method, current data on the road layout, road conditions, and / or current weather conditions must be maintained and processed, which is also very complex.

[0006] Another known way to reduce the likelihood of a road traffic incident being caused by a motor vehicle driver's lack of attention is to continuously monitor the driver's current level of attention using sensors, such as camera sensors, in the vehicle interior and to warn the driver accordingly if a decrease in attention is detected (DMS - Driver Monitoring System). In this case, there is no automated or autonomous intervention by systems in the vehicle's current driving mode; instead, the warning is intended to encourage the driver to regain increased attention. However, such monitoring systems are disadvantageously complex to install because they rely on a large number of sensors. These sensors collect and process a large amount of data, which makes the implementation of such systems in the motor vehicle context complex.Furthermore, such monitoring systems are unreliable. If, for example, the lighting conditions inside the vehicle are poor, the camera sensors may not be able to reliably detect the driver's waning attention.

[0007] Even if a DMS warns the driver of their declining attention, they may ignore the warning and continue to participate in traffic despite their lack of attention. Driver monitoring systems therefore only increase overall road safety to a limited extent.

[0008] An object of the present invention is to provide an efficient and reliable way to increase general road safety.

[0009] The problem is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are described by the dependent patent claims, the following description, and the figures.

[0010] The invention is based on the finding that the extent and / or frequency of the above-described intervention of driver assistance functions, for example the triggering of an FCW or an AEB, during the course of a journey of a motor vehicle also allow a conclusion to be drawn about the current attention of a driver of the motor vehicle.

[0011] The invention provides a method for operating a driver assistance system for a motor vehicle, wherein the driver assistance system triggers a predetermined safety measure for the motor vehicle upon reaching a predetermined warning threshold during the course of a journey of the motor vehicle. The warning threshold can be the TTC warning threshold described above. The predetermined safety measure can, for example, be the issuance of a collision warning and / or the intervention of an autonomous braking function of the motor vehicle. If the warning threshold is preset to 3 seconds, for example, the safety measure is triggered as soon as the driver assistance system detects that, without the safety measure taken, a collision of the motor vehicle with an external object is to be expected within 3 seconds.A typical warning threshold for the intervention of an autonomous braking function can be 1.3 seconds.

[0012] According to the invention, such a triggering is detected as a triggering event, wherein a first triggering event comprises a first triggering of the predetermined safety measure within a first section of the journey. In addition, a reaction and / or a reaction speed of a driver of the motor vehicle to the first triggering event is observed. For example, a brake pedal sensor of the motor vehicle can detect when the driver brakes the motor vehicle in response to the issued collision warning. In this case, it can be detected not only whether such a reaction occurs at all, but also at what point in time. In other words, it can be detected whether the driver reacts by braking immediately after the collision warning is triggered, or only when the motor vehicle is already being braked autonomously.

[0013] According to the invention, the driver's attention level is adjusted depending on the observed reaction and / or the observed reaction speed. For example, if no reaction is observed when the safety measure is triggered, the attention level can be set from an initial value of 1 to 0. If a reaction is detected immediately after a collision warning is triggered, the attention level can be reduced to a value greater than zero, for example 0.8. If there is no reaction when the collision warning is triggered, but only during the course of an automatic braking maneuver following the warning, the attention level can be set to 0.4. If the driver does not brake immediately, but only when the autonomous braking system has already been activated or triggered, the attention level will be reduced more sharply than if the driver has already reacted to the collision warning by braking.The values ​​mentioned here are purely exemplary and should not be understood as limiting.

[0014] According to the invention, the warning threshold is adjusted depending on the adjusted attention level. Thus, the warning threshold can be increased if the attention level is reduced, so that the predetermined safety measure for the motor vehicle is triggered sufficiently in advance of the detected impending collision, giving the inattentive driver more time to react.

[0015] The method according to the invention offers the advantage of utilizing existing vehicle functions to determine the driver's attention level. This leads to particularly efficient attention monitoring. At the same time, the inventive determination of the attention level is particularly reliable. Accordingly, the warning threshold can also be adjusted very reliably. The invention thus advantageously increases general road safety.

[0016] The invention also includes embodiments which provide additional advantages.

[0017] One embodiment provides that, if at least one further triggering event is detected during subsequent sections of the journey, the driver's reaction and / or reaction speed to the at least one further triggering event is observed, and the driver's adjusted attention value is updated based on the observed reaction and / or the observed reaction speed to the at least one further triggering event, and the adjusted warning threshold is adjusted again depending on the updated attention value. In other words, according to the embodiment described here, the warning threshold is dynamically adjusted to a changing attention value as the journey progresses.In other words, the driver's reactions to several consecutive trigger events can be accumulated, with a continuously updated driver attention score being determined from the accumulated reactions. For example, several consecutive trigger events and the driver's observed reactions and / or reaction speeds can be accumulated until a critical threshold is reached. Upon reaching the threshold, the warning threshold can be increased by a specified increment or by a specified step, for example, by one second.

[0018] The embodiment described here can be based on the situation that the driver's attention level is 100 percent at the beginning of the motor vehicle's journey. For example, if a first triggering event occurs after 70 minutes of driving, triggering a warning of an impending collision, and the driver reacts to this warning by braking, so that no automatic braking is initiated by the motor vehicle, 5 percent can be deducted from the initial 100 percent attention level. Thus, after 70 minutes of driving, the attention level is 95 percent.

[0019] Further along the journey, for example, after 75 minutes, another triggering event may occur. In this case, a collision warning may be issued again, but the driver fails to brake in time for the next triggering event. Therefore, the vehicle's autonomous braking system intervenes. If the driver brakes with a delay, for example, while the autonomous braking system is still braking, 15 percent is deducted from the attention score. In this example, the attention score after 75 minutes of driving is 80 percent.

[0020] As the journey progresses, for example, after 80 minutes, a third trigger event may occur. During this trigger event, the driver may no longer react at all. In other words, a collision warning is initially issued, followed by the vehicle's autonomous braking. No driver reaction is observed either to the collision warning or during the automatic braking process. In this example, 20 percent can be deducted from the attention score. Thus, after 80 minutes of driving, the attention score is only 60 percent.

[0021] For example, an initial threshold for the attention level is 75 percent. If this initial threshold is exceeded, one second can be added to the warning threshold. A distinction can be made between the warning threshold for triggering the collision warning and the warning threshold for automatically performing the braking action. By increasing the warning threshold, for example, it can be achieved that the collision warning is triggered as a predetermined safety measure when an impending collision occurs in 11 seconds instead of 10. At the same time, the triggering of the automatic braking action as a safety measure can be defined so that it is triggered in five and a half seconds when an impending collision occurs, and not only when a collision occurs in five seconds.These examples illustrate that the predetermined safety measure for the motor vehicle is triggered earlier when the warning threshold is increased, giving the driver more time to react. This dynamic adjustment of the warning threshold during the journey has the advantage of allowing a flexible response to the driver's current level of attention or attention level.

[0022] A further embodiment provides that the time interval between consecutive triggering events during the journey and / or the frequency of triggering events during the journey are taken into account when adjusting the attention value and / or the warning threshold. For example, if a particularly large number of triggering events occur in a short period of time, for example, more than 10 triggering events in less than 10 minutes, an additional factor can be taken into account when lowering the attention value and / or raising the warning threshold.

[0023] A further embodiment provides that at a predetermined point in time after a predetermined duration of the journey, the driver's attention level is updated by discarding the triggering event that occurred most recently at that point in time and the driver's observed reaction and / or reaction speed. The warning threshold is then adjusted again depending on the updated attention level. In other words, the triggering event that occurred most recently is no longer taken into account when adjusting the warning threshold. In other words, a driver can improve their attention level again over the course of the journey.

[0024] For the example described above, this could mean that after a driving time of 100 minutes, the 5 percent initially deducted from the attention level is added back to the alertness level. The alertness level after 100 minutes is therefore back to 65 percent. Preferably, the trigger events are finally discarded at the end of the current journey. In other words, the driver can start the next journey with the original alertness level of 100 percent. This has the advantage that an unnecessarily long advance warning period is not selected when the driver's alertness is increased again.

[0025] A further embodiment provides that the predetermined safety measure comprises successive individual measures, wherein the individual measures are classified based on predefined measure classes. In the embodiment described here, the attention value and / or the warning threshold are adjusted depending on which of the successive individual measures the driver reacts during. To stay with the example described above, the driver can, for example, already react while the collision warning is being issued. This leads to a smaller deduction in the attention value than if the driver only intervenes during the subsequent autonomous braking of the motor vehicle. This advantageously results in increased granularity in the adjustment of the attention value and thus also in the adjustment of the warning threshold.

[0026] A further embodiment provides that the predetermined safety measure comprises issuing a warning, in particular a collision warning, about an impending collision to the driver of the motor vehicle and / or a subsequent intervention by at least one autonomous safety system, for example an autonomous braking system, of the motor vehicle. In other words, the safety measure preferably comprises the intervention of an autonomous safety system of the motor vehicle, in particular an autonomous execution of a braking operation.

[0027] The driver’s reaction preferably includes a steering intervention and / or a braking operation.

[0028] A further embodiment provides that data from a driver monitoring system (DMS) is acquired and additionally taken into account to adjust the driver's attention level and / or to adjust the warning threshold. In other words, the DMS can determine its own attention level, for example, based on camera monitoring of the driver. The attention levels from the DMS and from the driver assistance system described here can be calculated to produce a common attention level. Preferably, it can be provided that the DMS attention level is classified as less credible than the attention level resulting from the inventive observation of the driver's reactions. In other words, the DMS attention level can be overwritten. This has the advantage of reducing the technical requirements for the DMS.It does not have to be equipped with a large number of sensors.

[0029] The invention further relates to a driver assistance system for a motor vehicle, wherein the driver assistance system is designed to carry out the described method. The driver assistance system comprises a sensor device or a sensor system with a plurality of sensors and a control unit for carrying out the method according to the invention. The driver assistance system can comprise or control environmental sensors or an environmental sensor system, in particular the plurality of sensors of the sensor system, for detecting environmental data of the motor vehicle. An environmental sensor system can be understood, for example, as a sensor system capable of generating sensor data or sensor signals that map, represent, or reproduce an environment of the environmental sensor system. In particular, the ability to detect electromagnetic or other signals from the environment is not sufficient for a sensor system to be considered an environmental sensor system.For example, cameras, radar systems, lidar systems or ultrasonic sensor systems can be considered environmental sensor systems.

[0030] The sensor system may, for example, include sensors that can detect an impending collision and / or the time until such a collision. These sensors may, in particular, be cameras, radar systems, lidar systems, or ultrasonic sensor systems.

[0031] In addition, the sensor system can have sensors with which a movement of the motor vehicle can be detected or sensors that can detect variables relating to a movement of the motor vehicle. These sensors can include, for example, an IMU (Inertial Measurement Unit), which measures accelerations of the motor vehicle in one or more directions and / or rotation rates, for example a yaw rate. These sensors can also include wheel sensors that measure the revolutions of the motor vehicle's wheels, based on which the speed of the motor vehicle can be calculated. Furthermore, these sensors can also include a steering wheel / steering column sensor, which measures the angle and / or angular velocity of the steering wheel or a steering wheel revolution or partial revolution.

[0032] Furthermore, the driver assistance system can include an electronic control unit, which can record or capture the triggering events and / or the corresponding reactions or reaction speeds of the motor vehicle driver to the triggering events. The control unit can also control a steering system, a drive motor, and / or a braking system of the motor vehicle.

[0033] The invention also relates to a computer program comprising instructions which, when executed by the driver assistance system according to the invention, cause the driver assistance system according to the invention to carry out the method steps of the method according to the invention.

[0034] The invention also relates to a computer-readable storage medium on which the computer program is stored.

[0035] The invention also relates to a motor vehicle with a driver assistance system according to the invention. The motor vehicle is preferably designed as a passenger car, a truck, a bus, a motorcycle, or a moped.

[0036] The preferred embodiments presented with reference to the method according to the invention and their advantages apply accordingly to the driver assistance system according to the invention and to the motor vehicle according to the invention and vice versa.

[0037] Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures are not only usable in the respective combination specified, but also in other combinations without departing from the scope of the invention. Thus, embodiments are to be regarded as encompassed and disclosed by the invention that are not explicitly shown and explained in the figures, but which emerge and can be produced by separate combinations of features from the explained embodiments. Embodiments and combinations of features are also to be regarded as disclosed that therefore do not have all the features of an originally formulated independent claim.Furthermore, embodiments and combinations of features are to be regarded as disclosed, in particular by the embodiments set out above, which go beyond or deviate from the combinations of features set out in the reliances of the claims.

[0038] Exemplary embodiments of the invention are described below. Shown are:

[0039] Fig. 1 shows a motor vehicle with a driver assistance system;

[0040] Fig. 2 is a schematic representation of a method according to an embodiment of the invention.

[0041] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0042] In the figures, the same reference symbols designate elements with the same function.

[0043] Fig. 1 shows a schematic representation of a motor vehicle 10, having a driver assistance system 12. In the illustrated embodiment, the motor vehicle 10 is designed as a passenger car. The motor vehicle 10 has a plurality of sensors 14 of a sensor device not described in more detail. According to the exemplary embodiment described here, these sensors 14 include, for example, camera sensors and / or distance sensors, which can be arranged in different areas of the motor vehicle 10. In addition, the sensor device comprises one or more sensors 16, which can be designed, for example, to detect a movement of the motor vehicle 10 or to detect variables that relate to or influence a movement of the motor vehicle 10. The sensor 16 can be used, for example, to determine a steering angle and / or a rotation of at least one wheel of the motor vehicle 10.Sensor 16 can be configured to detect a current speed and / or one or more accelerations and / or yaw rates of motor vehicle 10. This can also include detecting a braking operation, in particular an autonomously performed braking operation. Motor vehicle 10 can also have additional sensors 14, for example, a brake pedal sensor and / or camera sensors for driver monitoring in the vehicle interior.

[0044] The sensors 14, 16 can be connected to a control unit 18 of the driver assistance system 12 for data transmission.

[0045] Fig. 2 shows, with reference to the components designated and described in connection with Fig. 1, a schematic representation of a method for operating a driver assistance system 12 for a motor vehicle 10. In the method, a predetermined safety measure for the motor vehicle 10 is triggered by the driver assistance system 12 when a predetermined warning threshold is reached during a journey of the motor vehicle 10.

[0046] In a step S1, a first triggering event is detected, wherein the first triggering event comprises a first triggering of the predetermined safety measure within a first section of the journey. In a step S2, a reaction and / or reaction speed of a driver of the motor vehicle 10 to the first triggering event is observed. In a step S3, an attention level of the driver is adjusted or updated depending on the observed reaction and / or the observed reaction speed. Finally, in a step S4, the warning threshold is adjusted or updated depending on the adjusted attention level.

[0047] A preferred embodiment of the present invention provides for dynamically adjusting warning thresholds during a journey of the motor vehicle 10. The adjustment can be made depending on the extent and / or frequency of observed trigger events during the journey or during a predetermined journey section.

[0048] For example, the driver assistance system 12 stores the described triggering events during a previous period of time or a previous journey segment and evaluates the driver's attention based on the triggering events. A triggering event can be described by a timestamp, by the type of safety measure triggered, and / or by the driver's reaction.

[0049] At the start of a journey, for example when starting a vehicle engine, the driver's attention value can be 100 percent. The warning thresholds for various safety measures can be preset at the start of the journey. The presetting can be determined, for example, by a factory setting or by a driver selection. If an initial safety measure is triggered, such as issuing a warning of an impending collision, and at the same time a braking and / or steering action by the driver is detected so that no automatic braking action is triggered, a small proportion is deducted from the driver's current attention value. If the driver's braking or steering action is insufficient to prevent the automatic braking function from intervening, a larger proportion is deducted from the current attention value.If the driver brakes and / or steers while the automatic braking function has intervened, an even greater proportion is deducted from the current attention value. If the driver does not react or only reacts after the vehicle has stopped autonomously, an even greater proportion is deducted from the attention value. If the attention value falls below a predefined limit, for example below 50 percent of the initial value, the warning thresholds for the various safety measures can be increased. There can be different limit values. For example, a further limit could be 25 percent of the initial value of 100 percent. The lower the respective limit is, the more the warning thresholds are increased.

[0050] If one of the recorded trigger events occurred more than a predetermined time ago, the contribution of this trigger event can be discarded or dropped when adjusting the attention score. This means that the portion deducted from the attention score based on this trigger event can be added back in. The trigger events can be deleted or overwritten by newly recorded trigger events. This mechanism can prevent deductions from the attention score from accumulating over an indefinite period of time. This can prevent the driver's attention score from constantly decreasing, which could lead to unnecessarily increased warning thresholds and / or unnecessarily early triggered safety measures.The described solution can function standalone if the motor vehicle 10 is not equipped with an additional driver monitoring system or similar for assessing driver attention. Alternatively, the proposed solution can also be used in conjunction with an existing driver observation system or similar.

[0051] Mechanisms work. For example, if a DMS reports increased driver attention, the attention value described here can also be increased. If one or more trigger events are detected, the DMS can also lower its driver attention value.

[0052] The invention provides a simple, reliable, and effective solution for adjusting warning thresholds as needed. This can be done using driver assistance functions already existing in the vehicle or functions of an ADAS (Automated Driver Assistance System).

Claims

Patent claims Method for operating a driver assistance system (12) for a motor vehicle (10), wherein the driver assistance system (12) comprises a sensor system with a plurality of sensors (14, 16) and a control unit (18), wherein a predetermined safety measure for the motor vehicle (10) is triggered by the driver assistance system (12) when a predetermined warning threshold is reached during a journey of the motor vehicle (10), the method comprising the steps - detecting (S1) a first triggering event by means of at least one sensor (14, 16) of the sensor system, wherein the first triggering event comprises a first triggering of the predetermined safety measure within a first section of the journey, - observing (S2) a reaction and / or a reaction speed of a driver of the motor vehicle (10) by means of at least one further sensor (14, 16) of the sensor system to the first triggering event, - adjusting (S3) a driver's attention value as a function of the observed reaction and / or the observed reaction speed by the control unit (18), - adjusting (S4) the warning threshold value as a function of the adjusted attention value by the control unit (18). Method according to claim 1, wherein, if at least one further triggering event is detected in a further course of the journey during further subsequent journey sections, the reaction and / or the reaction speed of the driver to the at least one further triggering event is observed and the adjusted attention value of the driver is updated based on the observed reaction and / or the observed reaction speed to the at least one further triggering event, and wherein the adjusted warning threshold value is adjusted as a function of the updated attention value is adjusted again. Method according to claim 2, wherein the time interval between successive triggering events during the course of the journey and / or the frequency of the triggering events during the course of the journey is taken into account when adjusting the attention value and / or the warning threshold. Method according to one of the preceding claims, wherein at a predetermined point in time after the expiration of a predetermined driving time, the driver's attention value is updated by discarding the triggering event that occurred furthest back at that point in time and the driver's reaction and / or reaction speed observed therein, wherein the warning threshold is adjusted at that point in time, in particular again, as a function of the updated attention value.Method according to one of the preceding claims, wherein the predetermined safety measure comprises successive individual measures, wherein the individual measures are classified based on predefined measure classes, and wherein the adjustment of the attention value and / or the warning threshold value takes place depending on which of the successive individual measures the driver's reaction occurs during. Method according to one of the preceding claims, wherein the predetermined safety measure comprises issuing a warning, in particular a collision warning about an impending collision of the motor vehicle (10) with an object external to the motor vehicle, to the driver of the motor vehicle (10) and / or intervening by at least one autonomous safety system of the motor vehicle (10) in a current operation of the motor vehicle (10).The method according to claim 6, wherein the intervention of the at least one autonomous safety system of the motor vehicle comprises autonomously performing a braking operation. The method according to one of the preceding claims, wherein the driver's reaction comprises a steering intervention and / or a braking operation. Method according to one of the preceding claims, wherein data from a driver monitoring system is acquired, and wherein the data is additionally taken into account for adjusting the driver's attention level and / or for adjusting the warning threshold. Driver assistance system (12), comprising a sensor system with a plurality of sensors (14, 16) and a control unit (18), wherein the driver assistance system (12) is designed to trigger a predetermined safety measure for the motor vehicle (10) upon reaching a predetermined warning threshold during a journey of the motor vehicle (10), wherein - at least one sensor (14, 16) of the sensor system is designed to detect a first triggering event, wherein the first triggering event comprises a first triggering of the predetermined safety measure within a first section of the journey, - at least one further sensor (14, 16) of the sensor system is designed to observe a reaction and / or a reaction speed of a driver of the motor vehicle (10) to the first triggering event, - the control unit (18) is designed to adapt an attention value of the driver as a function of the observed reaction and / or the observed reaction speed, and wherein - the control unit (18) is configured to adjust the warning threshold value depending on the adjusted attention level. A motor vehicle (10) having a driver assistance system (12) according to claim 10. A computer program comprising commands which, when executed by a driver assistance system (12) according to claim 10, cause the driver assistance system (12) of claim 10 to execute the method steps according to any one of claims 1 to 9. A computer-readable storage medium on which the computer program according to claim 12 is stored.

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