Method for operating a driver assistance system

Abstract

The invention relates to a method for operating a driver assistance system (4) for the longitudinal guidance of a motor vehicle (2), wherein the actual vehicle speed (I) is regulated to a target vehicle speed (S) while the vehicle is traveling. The driver assistance system (4) comprises a pushbutton unit (14) and a foot pedal (15) for manually setting the target vehicle speed (S), a detection device (6) for detecting a speed specification (8), a display unit (18) for displaying the actual vehicle speed (I), and an input device (16) for detecting a user input, wherein a speed specification (8) is detected by the detection device (6), the detected speed specification (8) is compared with a stored target vehicle speed (S), an optical indication (H) for a speed adoption (8) is displayed on the display unit (18) if the detected speed specification (8) deviates from the current target vehicle speed (S) and if the target vehicle speed (S) has not been manually adjusted by means of the pushbutton unit (14) since the last change in the target vehicle speed (S), and the detected speed specification (8) is adopted as the new target vehicle speed (S) if the detected speed specification (8) deviates from the current target vehicle speed (S) and if a user input is detected by the input device (16).

Description

[0001] Description

[0002] Method for operating a driver assistance system

[0003] The invention relates to a method for operating a driver assistance system for longitudinal control of a motor vehicle. The invention further relates to a driver assistance system and software for carrying out the method.

[0004] Modern motor vehicles are regularly equipped with various driver assistance systems that support the driver. These systems primarily monitor and analyze the vehicle's surroundings to detect dangerous situations, especially collision risks, early on and to assist the driver with their maneuvers or prevent them altogether.

[0005] In this and the following, an Advanced Driver Assistance System (ADAS) refers specifically to a device in a motor vehicle that assists the driver while driving the vehicle. Such ADAS systems can be either purely informational systems that display supporting information to the driver (e.g., directional arrows on a screen / display) or driving systems that automatically influence the vehicle's movement (e.g., steering and / or acceleration).

[0006] Driver assistance systems for longitudinal guidance of the vehicle, such as adaptive distance or speed control (also called adaptive cruise control, ACC) or a speed limiter (Speed ​​Limit Assist, SLA), control and / or regulate an actual vehicle speed to a target vehicle speed during a journey of the vehicle.

[0007] In particular, speed limiters or cruise control systems detect speed limits during operation using traffic sign recognition systems, such as camera sensors, and / or by utilizing map data. The determined speed limits are displayed to the driver and can optionally be adopted for vehicle control, for example, by adjusting the target vehicle speed (setpoint, set speed) for a longitudinal guidance assistance system. Here and in the following, a "speed limit" refers specifically to a speed restriction (speed limit), i.e., a predetermined maximum speed that a vehicle may not exceed on a specific section of road. This limit can be established by traffic signs, electronic displays, or legal regulations.

[0008] The driver can manually adopt the speed setting, for example, by operating an input device, such as a button on the steering wheel. Operating the input device to directly adopt the currently permitted maximum speed as the target vehicle speed for the active longitudinal control driver assistance system offers the driver a convenient way to adjust the target vehicle speed to the permitted speed limit.

[0009] User interfaces in motor vehicles, such as a driver information display (DID) or input / function buttons on the steering wheel, are preferably designed to be as simple and clear as possible to reduce the complexity of operation and make interaction more intuitive. However, this simplification can result in the driver receiving less information about how the driver assistance function works, making it more difficult to understand the functional logic and use it correctly. In particular, a lack of feedback or insufficient guidance can lead to the driver inadequately learning how the driver assistance function works or misinterpreting it.

[0010] To improve the learning curve for the manual override function of a speed limiter or cruise control, a visual cue for operating the input device can be used in the driver information display. Typically, however, this visual cue is always displayed simultaneously with the operating option, thus increasing the visual complexity of the driver information display, even if the driver is already familiar with the function.

[0011] US Patent 2005 / 0006165 A1 describes a driver assistance system for longitudinal control of a motor vehicle. This system has a standard mode in which the actual vehicle speed is regulated to a target vehicle speed set by the driver, and at least one exception mode in which the actual vehicle speed is regulated to a target vehicle speed that may differ from the set target vehicle speed. The system also includes a display for showing the target vehicle speed and an auxiliary display. The auxiliary display is active when the exception mode is active.

[0012] US Patent 2018 / 0273050 A1 describes a method for operating a driver information display. In this method, the driver is shown a first piece of information on a head-up display and a second piece of information, which differs from the first, on a digital cluster display. The method can further include receiving input control signals from a touch-sensitive steering wheel to interact with the information displayed on the head-up display and / or the digital cluster display.

[0013] The German patent IN 202341014740 A describes a driver assistance system for longitudinal control of a motor vehicle, comprising a multifunction button and an anti-lock braking system (ABS). The ABS is configured to activate one or more cruise control states, which can be switched between using the multifunction button.

[0014] The invention is based on the objective of providing a particularly suitable method for operating a driver assistance system. The invention is further based on the objective of providing a particularly suitable driver assistance system and particularly suitable software for carrying out the method.

[0015] The problem is solved according to the invention with respect to the method by the features of claim 1, with respect to the driver assistance system by the features of claim 6, and with respect to the software by the features of claim 8. Advantageous embodiments and further developments are the subject of the dependent claims.

[0016] The advantages and features mentioned with regard to the process are analogously transferable to the driver assistance system and / or the software, and vice versa. Where process steps are described below, advantageous configurations for the driver assistance system and / or the software arise particularly from their ability to execute one or more of these process steps. The conjunction "and / or" here and in the following is to be understood as meaning that the features linked by this conjunction can be configured both together and as alternatives to each other.

[0017] The method according to the invention is designed and configured for operating a driver assistance system. The driver assistance system is suitable and configured for longitudinal control of a motor vehicle. In its active state, the driver assistance system regulates the actual vehicle speed to a target vehicle speed during a journey. The driver assistance system is preferably designed as a speed limiter or a speed controller, which adjusts the target vehicle speed to a specified speed.

[0018] The driver assistance system includes at least one detection device for recording a speed setting and an interface for the (vehicle) driver of the motor vehicle, through which the driver can interact with the vehicle assistance system. The interface is specifically designed as a human-machine interface (HMI), which has input and output devices through which the driver can transmit information to or receive information from the driver assistance system.

[0019] The interface, or HMI, comprises an operating device and an input device as input devices. As an output device, the interface includes, in particular, a display unit.

[0020] The detection device is designed and configured to detect a speed limit or a change in a current speed limit. For this purpose, the detection device includes, for example, optical sensors (e.g., a camera), radar systems, or a navigation device to detect a speed limit or its change on a current road segment or (driving) route segment. The detection device also includes, for example, a traffic sign recognition system for evaluating the sensor data.

[0021] The operating device is designed, suitable, and configured for manually setting the target vehicle speed. The operating device has at least two controls for the driver. The first control is a keypad (control or function keypad), for example, on the steering wheel of the vehicle, via which the target vehicle speed can be manually increased or decreased, for example, in increments. The keypad has, for example, a number of buttons, at least two: one for increasing the target vehicle speed (plus button) and one for decreasing it (minus button).Additionally or alternatively, the keypad may have a further (Set) button which is designed and configured to adopt a current actual vehicle speed value as the target vehicle speed value for the longitudinal guidance of the motor vehicle.

[0022] Additionally, the control device features a foot pedal as a second control element. This foot pedal is typically an accelerator or brake pedal, which allows the user to set a target vehicle speed that is above or below a current speed setting. If the target vehicle speed set by the driver assistance system is exceeded (or fallen below) by the current actual vehicle speed due to manual operation of the accelerator pedal, the target vehicle speed is automatically updated to reflect the current actual vehicle speed. The target vehicle speed used before the deviation is then replaced by the current actual vehicle speed as the new target vehicle speed; in other words, the target vehicle speed used before the deviation is updated.

[0023] The display unit is designed specifically as a driver information display (DID). It is intended and configured to provide the driver with vehicle-specific information visually. The display unit is positioned within the driver's field of vision and may be, for example, a digital instrument cluster, a screen, a control and display device (e.g., a touchscreen), or a head-up display. The display unit shows information such as driver assistance system data or driving parameters. It is designed and configured to display the current vehicle speed. Optionally, the display unit can also show, for example, a current speed limit and / or the target vehicle speed.The input device is designed, suitable, and configured to detect user input, i.e., an action taken by the driver. The input device includes a control element, in particular a button, whereby the user input is the actuation of the control element or the pressing of a button. The detection of user input by the input device triggers, in particular, the adoption of a speed setting detected by the device as the target vehicle speed.

[0024] The term "adopting the speed setting as the target vehicle speed" here and in the following refers specifically to the process of storing the speed setting value in memory and using it as the new target vehicle speed. In other words, the current target vehicle speed is overwritten with the speed setting value. It is irrelevant whether the current target vehicle speed is above or below the detected speed setting. The change occurs when the detected speed setting does not match the currently set target vehicle speed.

[0025] The input device thus implements a comfort driver assistance system, or a comfort function of the driver assistance system, which allows the driver to set the current target vehicle speed to the currently detected speed setting with a single user input. The control element or button of the input device is, for example, located on the steering wheel of the vehicle. The input device or its control element is, for example, a separate element for triggering this comfort function. Alternatively, the input device or its control element can also be implemented as a multi-function device with other functionalities on another input device of the interface, where the user input is, for example, a predefined operating action (e.g., a long push).

[0026] The method according to the invention is carried out in the active state of the driver assistance system, i.e., when the function of the speed limiter or cruise control is active. According to the method, an optical cue is displayed in the display unit to enable the system to learn its behavior. Here and in the following, an "optical cue" refers in particular to a visual or optical HMI cue from the interface, which indicates to the driver the possibility of adopting the detected speed setting by user input via the input device.

[0027] According to the invention, to use the display unit more efficiently and to reduce its optical complexity, a logic is provided which displays the visual indicator situationally and intelligently, so that the visual indicator is not permanently displayed. For this purpose, the previous operating steps for setting the current target vehicle speed are evaluated according to the method, so that the visual indicator is displayed depending on how the current target vehicle speed was set.

[0028] The visual indicator is displayed, for example, when the driver assistance system is activated. Furthermore, the visual indicator for speed takeover is displayed when the detection device registers a speed setting and a comparison of the registered speed setting with the stored target vehicle speed reveals a deviation or difference.

[0029] According to the inventive method, the visual indication for speed acceptance is displayed only if, in addition, no manual adjustment of the target vehicle speed has been made using the keypad since the last change to the target vehicle speed. In other words, the visual indication is displayed when the current target vehicle speed has not been set using the keypad since the last change to the speed setting. Preferably, the visual indication is always displayed when the current target vehicle speed has been set using the accelerator pedal.

[0030] Regardless of whether the visual indicator is displayed, the speed setting is adopted as the new target vehicle speed if the detected speed setting deviates from the current target vehicle speed and user input is registered by the input device. Preferably, the display of the visual indicator is terminated upon registration of user input.

[0031] According to the invention, when the target vehicle speed is changed, not only the value of the new target vehicle speed is stored, but also how the target vehicle speed was changed, i.e., whether the target vehicle speed was changed by the keypad, the foot pedal, or the input device. This information is then used to evaluate the previous operating procedure.

[0032] This results in a particularly suitable method for operating a longitudinal control driver assistance system. In particular, it advantageously reduces the optical complexity of the display unit and its use. Furthermore, the method enables better understanding and easier learning of the speed takeover functionality, since the operating path-dependent display of the visual cue explicitly alerts the driver to the use of the input device only when they have not already adjusted the target vehicle speed manually using the button unit.

[0033] In an advantageous further development of the method, the visual indication for speed adoption is displayed on the display unit if, in addition, a difference, in particular a specific amount of the difference, between the target vehicle speed and the speed setpoint is greater than or equal to a stored threshold value. In other words, the visual indication is displayed under the additional condition that a minimum speed difference exists between the current target vehicle speed and the detected speed setpoint. The threshold value is thus a minimum value or a de minimis limit below which the visual indication is not displayed.

[0034] This means the visual warning is only displayed to the driver if there is a sufficient difference between the speed limit and the actual vehicle speed. This further reduces the need for the visual warning. The threshold is predefined or stored in memory. In a possible alternative training method, the threshold could be set or changed by the driver.

[0035] The threshold is, for example, implemented as an absolute speed value for the difference. Preferably, the threshold is set in a range between 2 km / h (kilometers per hour) and 12 km / h, for example, to approximately 6 km / h. Alternatively, the threshold is implemented, for example, as a relative or percentage deviation, i.e., as a normalized difference. The normalized difference is, for example, the quotient of the (absolute) difference between the target vehicle speed and the speed setpoint (dividend) and the current target vehicle speed (divisor). In such a configuration, the threshold is, for example, set between 2% and 15%, particularly to approximately 6%.

[0036] In an advantageous embodiment, the visual cue is displayed for a predetermined or stored duration. Once this duration has elapsed, the display of the visual cue ceases. In other words, the display has a timeout function that sets a maximum display time for the visual cue. The timeout function also improves the clarity of the speed takeover function, as the time-limited display of the visual cue explicitly alerts the driver to the possibility of using the input device. The duration is, for example, between 5 and 15 seconds, particularly around 10 seconds. This duration is predefined or stored in memory. In a conceivable alternative embodiment, the duration can be set or changed by the driver.

[0037] An additional aspect of the invention provides that a representation of the input device is displayed as a visual cue. In other words, for example, a schematic or symbolic image (icon) of the input device or its control element is displayed as a visual cue on the display unit. This clearly communicates to the driver how to activate the speed takeover function in order to adopt the detected speed setting as the new target vehicle speed for longitudinal control.

[0038] In a suitable training environment, the indicator on the display unit is shown as close as possible to the input device. "As close as possible" here and in the following refers specifically to the fact that the input device and the visual indicator are within the driver's shared field of vision. This ensures that the driver has the input device in view when the visual indicator appears. In other words, this allows the driver to perceive the visual indicator and the input device essentially simultaneously, thus further supporting the learning of the speed takeover function.

[0039] The driver assistance system according to the invention is designed, suitable, and configured for longitudinal guidance of a motor vehicle. During operation, the driver assistance system regulates the actual vehicle speed to a target vehicle speed. The driver assistance system is specifically designed as a speed limiter or speed controller.

[0040] The driver assistance system includes a control device for manually setting a target vehicle speed and an input device for recording user input. The driver assistance system also includes a detection device for recording a speed setting and a display unit for showing the current vehicle speed.

[0041] The driver assistance system also includes a controller (i.e., a control unit) which is linked via signals to the operating device, the input device, the detection device, and the display unit. The controller is also connected, for example, to a speed sensor to measure the vehicle's current speed.

[0042] The controller is generally configured – programmatically and / or circuit-wise – to carry out the method described above according to the invention. Specifically, the controller is configured to change the target vehicle speed for the longitudinal guidance system and preferably to regulate the actual vehicle speed to the target vehicle speed. In particular, the controller is configured to change the target vehicle speed based on information (speed setpoint) acquired by the detection device.

[0043] The controller is designed and configured to receive user input from the keypad and foot pedal, evaluate this input with regard to an operating path for setting the current target vehicle speed, and, depending on this evaluation and a comparison of a detected speed setting and the current target vehicle speed, initiate the display of a visual indicator on the display unit. According to the invention, the controller initiates the display of the visual indicator when the detection device detects a speed setting that deviates from the current target vehicle speed, and when no manual adjustment of the target vehicle speed has been made via the keypad since the last change to the target vehicle speed.If the controller detects a user input via the input device, and the detected speed setting differs from the current target vehicle speed, the speed setting is adopted as the new target vehicle speed, and the actual vehicle speed is adjusted to the new target vehicle speed.

[0044] In a preferred embodiment, the controller is formed, at least in its core, by a microcontroller comprising a processor and a data memory. The functionality for carrying out the method according to the invention is implemented programmatically in the form of operating software (firmware), so that the method—possibly in interaction with a driver—is carried out automatically when the operating software is executed in the microcontroller. Alternatively, within the scope of the invention, the controller can also be formed by a non-programmable electronic component, such as an application-specific integrated circuit (ASIC) or an FPGA (field-programmable gate array), in which the functionality for carrying out the method according to the invention is implemented by circuitry.

[0045] In a preferred embodiment, the keypad and the input device share a common control element. In other words, a single control element with multiple functions is provided for both the keypad and the input device. This advantageously reduces the number of controls required for an HMI.

[0046] The control element is implemented, for example, as a (set) button on the control unit, particularly on a steering wheel. In one operation, this button adopts the current vehicle speed as the new target vehicle speed (functionality of the control device). In another operation (e.g., long push), it adopts a detected speed setting as the new target vehicle speed. Alternatively, the operation can be triggered situationally, so that the adoption of the speed setting is only possible while the visual indicator is displayed, and otherwise, the current vehicle speed is adopted as the target vehicle speed upon activation.

[0047] An additional aspect of the invention provides for software on a medium or data carrier for carrying out the method described above. This means that the software is stored on a data carrier and is designed and configured for carrying out the method described above. The software comprises commands which, when executed by a computer (in particular by the controller of the driver assistance system), cause the computer to execute the method according to the invention. This results in particularly suitable software for operating a driver assistance system for the longitudinal guidance of a motor vehicle, with which the functionality for carrying out the method according to the invention is implemented programmatically. The software is thus, in particular, operating software (firmware), with the data carrier being, for example, a data storage device of the controller.

[0048] The invention is explained in more detail below with reference to a drawing, which shows simplified and schematic representations of:

[0049] Fig. 1 shows a motor vehicle with a driver assistance system for longitudinal guidance,

[0050] Fig. 2 shows an operating device and an input device of the driver assistance system, Fig. 3 shows a display unit of the driver assistance system with an optical indicator, Fig. 4 shows a flowchart for a method for operating the driver assistance system.

[0051] Corresponding parts and sizes are always marked with the same reference symbols in all figures.

[0052] Fig. 1 shows a top view of a motor vehicle 2 with a driver assistance system 4 for longitudinal guidance of the motor vehicle 2. The driver assistance system 4 is designed in particular as a speed limiter or speed controller.

[0053] The driver assistance system 4 comprises at least one detection device 6 for detecting a speed setpoint 8, an interface 10 for the (vehicle) driver of the motor vehicle 2, and a controller 12. During operation of the driver assistance system 4, the controller 12 regulates the actual vehicle speed I (Fig. 3) to a target vehicle speed S (Fig. 3). The controller 12 is interconnected by signal transmission with the detection device and the interface 10. The controller 12 has a memory in which the value of the target vehicle speed S is stored. The controller 12 is also connected to a speed sensor (not shown) for detecting the current actual vehicle speed I. Additionally, the controller 12 is connected to a longitudinal control unit of the motor vehicle 2 to regulate the detected actual vehicle speed I to the target vehicle speed S.

[0054] The detection device 6 is designed and configured to detect a speed limit 8 or a change in a current speed limit 8 on a current road segment or (driving) route segment. In Fig. 1, the speed limit 8 is, for example, implemented as a traffic sign with a speed limit. The detection device 6 is implemented here, in particular, as an optical sensor, especially as a camera.

[0055] The interface 10 is designed in particular as an HMI, which includes a keypad 14, a foot pedal 15, an input device 16 and a display unit 18. The keypad 14 and the input device 16 are, for example, function keys of a keypad (control panel) 20 arranged on the steering wheel and shown in Fig. 2.

[0056] The foot pedal 15, also shown in Fig. 2, is specifically designed as an accelerator pedal. The foot pedal 15 is designed to influence the actual vehicle speed. The foot pedal 15 is additionally designed and configured to allow manual setting of a target vehicle speed.

[0057] The keypad 20 has a button 22 for activating the driver assistance system 4 and a button 24 for deactivating the driver assistance system 4. The keypad 20 also has three buttons 26, 28, 30, which are assigned to the button unit 14 and / or the input device 16. The buttons 22 to 30 are arranged, for example, in a plus or cross shape, with button 22 in the center, button 24 on the right, button 28 at the bottom, button 30 on the left, and button 26 at the top.

[0058] The keypad unit 14 is designed and configured for manually setting the target vehicle speed S. The keypad unit 14 shown in Fig. 2 has three keys 26, 28, 30 for manually setting or changing the target vehicle speed S. Key 26 is designed and configured to increase the currently set value of the target vehicle speed S, particularly incrementally, when pressed. Key 28 is designed and configured to decrease the currently set value of the target vehicle speed S, particularly incrementally, when pressed. Key 30 is designed and configured to adopt the current value of the actual vehicle speed I as the value for the target vehicle speed S when pressed.

[0059] The control element 30 has multiple functions and, in addition to the functionality of the keypad unit 14, also features the functionality of the input device 16. The input device 16 is designed, suitable, and configured for capturing user input. In particular, the capture of user input by the input device 16 triggers the adoption of the speed setting 8 detected by the capture device 6 as the target vehicle speed.

[0060] The multiple assignment of the button or control element 30 is implemented, for example, such that a long push activates the functionality of the button unit 14, i.e., the adoption of the currently recorded actual vehicle speed I as the new target vehicle speed S, and a short push activates the functionality of the input device 16, i.e., the adoption of the recorded speed specification 8 as the new target vehicle speed S.

[0061] The display unit 18 is designed, in particular, as a driver information display. The display unit 18 is arranged, in particular, within the driver's field of vision and is, for example, designed as a digital instrument cluster. In the embodiment shown, the display unit has a digital display window 32 for the driver assistance system 4.

[0062] Display window 32 contains a display element 34, which shows the activity status (on / off) of the driver assistance system 4. Display window 32 also includes a display element 36 for showing the detected actual vehicle speed I, a display element 38 for showing the currently set target vehicle speed S, and a display element 40 for showing a currently detected speed target 8.

[0063] Display elements 34 to 40 are preferably shown when the driver assistance system 4 is switched on or activated, for example by pressing button 22 or by means of the foot pedal 15, and the display of display elements 34 to 40 is ended by pressing button 24 when the driver assistance system 4 is switched off or deactivated.

[0064] The display window 32 further includes a display element in the form of an optical indicator H. The optical indicator H is configured as a representation of the input device 16 or as a representation of the control element 30. The display window 32, and in particular the optical indicator H, are arranged such that they are as close as possible to the input device 16 or the control element 30. In particular, the control element 30 on the steering wheel and the optical indicator H of the display unit 18 are arranged in a common field of vision of the driver. Preferably, the control element 30 on the steering wheel and the optical indicator H of the display unit 18 are arranged substantially in alignment along a line of sight of the driver.

[0065] The following section describes in more detail a method for operating the driver assistance system 4 with reference to Fig. 4. This method is implemented, for example, by software implemented on the controller 12.

[0066] The procedure is started in a process step 42 by actuating the control element 22 with the activation of the driver assistance system 4.

[0067] In process step 44, the longitudinal guidance of the motor vehicle 2 takes place, i.e., the control and / or regulation of the currently detected actual vehicle speed I to the target vehicle speed S. For this purpose, for example, a value for the target vehicle speed stored in the memory of the controller 12 is used, which was last set during a previous operation of the driver assistance system 4 (resume function).

[0068] In process step 46, the detection device 6 records a speed specification 8.

[0069] Subsequently, in process step 48, a deviation, in particular an absolute or relative difference, between the currently stored target vehicle speed S and the detected speed specification 8 is determined. If there is no deviation, i.e., if the speed specification corresponds to the currently set target vehicle speed S, the longitudinal guidance of the motor vehicle 2 is regulated to the target vehicle speed S in process step 44.

[0070] In the event of a deviation, a threshold comparison with a stored threshold is performed in process step 48. Furthermore, in process step 49 (independent of the threshold), it is checked whether a user input from the input device 16 is detected. If such a user input is detected, in process step 50 the speed value of the detected speed specification 8 is stored as the new target vehicle speed S, thus overwriting or deleting the previous target vehicle speed S, and the longitudinal guidance of the vehicle 2 is adjusted to the new target vehicle speed S in process step 44. If the difference is less than the stored threshold, the optical indicator H is not displayed.

[0071] If the difference is greater than or equal to the stored threshold value, a process step 51 checks whether the currently stored target vehicle speed S was set manually via the keypad 14 or the accelerator pedal 15, or whether it was adopted from a previous speed setting 8. This information is stored in the memory of the controller 12 whenever the target vehicle speed S is changed.

[0072] If the currently set or stored value of the target vehicle speed S has been manually set by the driver since the last change of the speed setting 8 by the key unit 14, in particular by means of keys 26 or 28, the visual indication H will not be displayed.

[0073] If the currently set or stored value of the target vehicle speed S has not been manually set by the key unit 14 since the last change of the speed setting 8, i.e. if the value of the target vehicle speed S has been adopted, for example, by the foot pedal 15 or by the resume function, then in a procedure step 52 the optical indication H is displayed in the display window 32 of the display unit 18.

[0074] Following process step 52, a timer is started in process step 54, checking whether the time duration recorded by the timer is less than a predefined time duration (minimum display time). After the predefined minimum display time has elapsed, i.e., when the recorded time duration is greater than or equal to the predefined time duration, the display of the optical indicator H in display window 32 is terminated in process step 56 (timeout).

[0075] The procedure thus incorporates a logic through steps 48, 51, 52, 54, and 56 that runs in parallel to the adoption of the speed limit 8 as the new target vehicle speed S (steps 49 and 50), and which displays the visual indicator H situationally and intelligently. The visual indicator H is only displayed if the following conditions are cumulatively met: 1) the driver assistance system 4 is active (step 42), 2) the difference between the current target vehicle speed S and the detected speed limit 8 is greater than or equal to the stored threshold value (step 48), 3) the target vehicle speed S has not been manually adjusted by the keypad 14 since the last change to the detected speed limit 8 (step 51), and 4) the display duration of the visual indicator H is less than the stored timeout duration (steps 54 and 56).

[0076] The claimed invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in connection with the various embodiments can also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention. List of reference numerals

[0077] 2 motor vehicles

[0078] 4 Driver assistance system 6 Detection device 8 Speed ​​limiter 10 Interface

[0079] 12 controllers

[0080] 14 key unit

[0081] 15 Foot pedal

[0082] 16 Input device

[0083] 18 Display unit

[0084] 20 Keypad

[0085] 22, 24, 26, 28, 30 Control element, Button 32 Display window

[0086] 34, 36, 38, 40 Display element

[0087] 42, 44, 46, 48, 50, 51, 52, 54, 56 Procedure step

[0088] I Actual vehicle speed S Target vehicle speed H Note

Claims

Patent claims 1. Method for operating a driver assistance system (4) for longitudinal guidance of a motor vehicle (2), in which, during a vehicle journey, an actual vehicle speed (I) is regulated to a target vehicle speed (S), wherein the driver assistance system (4) comprises a button unit (14) and a foot pedal (15) for manually setting the target vehicle speed (S), a detection device (6) for detecting a speed setting (8), a display unit (18) for displaying the actual vehicle speed (I), and an input device (16) for detecting a user input, - in which a speed specification (8) is detected by the detection device (6), - in which the recorded speed specification (8) is compared with a stored target vehicle speed (S), - in which an optical indication (H) for speed takeover (8) is displayed on the display unit (18) if the detected speed setpoint (8) deviates from the current target vehicle speed (S) and no manual setting of the target vehicle speed (S) has been made by the keypad unit (14) since a last change of the target vehicle speed (S), and - in which the detected speed input (8) is adopted as the new target vehicle speed (S) if the detected speed input (8) differs from the current target vehicle speed (S), and if a user input is detected by the input device (16).

2. Method according to claim 1 , characterized by that the optical indication (H) for speed takeover is displayed on the display unit (18) if, in addition, there is a difference between the target vehicle speed (S) and the speed setpoint (8) greater than or equal to a stored threshold value.

3. Method according to claim 1 or 2, characterized by that the visual indicator (H) is displayed for a predetermined duration.

4. Method according to one of claims 1 to 3, characterized by that a representation of the input device (14) is displayed as an optical indication (H).

5. Method according to any one of claims 1 to 4, characterized by that the optical indicator (H) is displayed on the display unit (18) at the smallest possible spatial distance to the input device (16).

6. Driver assistance system (4) for longitudinal guidance of a motor vehicle (2), which regulates an actual vehicle speed (I) to a target vehicle speed (S) during a vehicle journey. - a keypad (14) and a foot pedal (15) for manually setting a target vehicle speed (S), - a detection device (6) for detecting a speed setting (8), - a display unit (18) for displaying the actual vehicle speed (I), - an input device (16) for capturing user input, and - a controller (12) for carrying out a method according to any one of claims 1 to 5.

7. Driver assistance system (4) according to claim 6, characterized by that the key unit (14) and the input device (16) have a common control element (30).

8. Software on a data carrier for carrying out a method according to any one of claims 1 to 5, if the software runs on a computer.

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