DE102023109973A1 - System for automated longitudinal guidance of a vehicle and computer-implemented method for setting a stopping distance for automated longitudinal guidance of a vehicle - Google Patents

Abstract

A system (1) for the automated longitudinal guidance of a vehicle (3) is designed to detect a target object (4) located in the direction of travel, to determine a road gradient (α1, α2), and to bring the vehicle (3) to a stop at a defined stopping distance (d1, d2) from the target object (4), wherein the stopping distance (d1, d2) depends on the road gradient (α1, α2).

Description

The invention relates to a system for automated longitudinal guidance of a vehicle and a computer-implemented method for setting a stopping distance for automated longitudinal guidance of a vehicle. Furthermore, the invention relates to a computer program for carrying out such a method and a computer-readable storage medium on which such a computer program is stored.

Modern motor vehicles are often equipped with driver assistance functions that can enable automated longitudinal guidance of the vehicle. One widely used driver assistance function is adaptive cruise control (ACC). The system usually regulates the speed of the vehicle while driving at a certain distance of a few seconds from the vehicle in front of you in the direction of travel. If the vehicle in front stops, your vehicle is also braked and brought to a stop at a predefined stopping distance from the vehicle in front. With ACC systems with a so-called stop-and-go function, your vehicle can also automatically start moving again if the vehicle in front continues to drive.

In conventional ACC systems, the stopping distance is fixed or lies within a fixed range that cannot be changed depending on the situation. In certain situations, however, the stopping distance is not perceived as appropriate by the driver or vehicle occupants. Particularly on steep road sections, the normal stopping distance of an ACC system can often be too small for the well-being of the driver or vehicle occupants.

Proceeding from this, it is an object of the present invention to provide a system for automated longitudinal guidance of a vehicle and a method for setting a stopping distance for automated longitudinal guidance of a vehicle, which at least partially overcome the aforementioned disadvantages of solutions known in the prior art.

The object is achieved by the subject matter of the independent patent claims. Advantageous embodiments are specified in the dependent patent claims.

A first aspect of the invention relates to a system for automated longitudinal guidance of a vehicle.

The system is set up to provide at least partially automated longitudinal guidance during vehicle operation as part of an automated driving function. This can be done, for example, as part of a dedicated longitudinal guidance driver assistance function, such as ACC stop-and-go. However, it is also possible for the automated longitudinal guidance to be provided as part of a more comprehensive automated driving function, which can also include, for example, at least partially automated lateral guidance.

In general, the term "automated driving function" in this document refers to a vehicle function that enables automated driving. The term "automated driving" is understood to mean driving with automated longitudinal and/or lateral guidance. This can, for example, be driving on the highway for a longer period of time or driving for a limited period of time when parking. The term "automated driving" includes automated driving with any degree of automation. Example levels of automation are assisted, partially automated, conditionally automated, highly automated and fully automated driving (with increasing levels of automation in each case). The five levels of automation mentioned above correspond to SAE levels 1 to 5 of the SAE J3016 standard (SAE - Society of Automotive Engineering) as of April 30, 2021. In assisted driving (SAE level 1), the system performs longitudinal or lateral guidance in certain driving situations, with the expectation that the driver will take over all remaining aspects of the dynamic driving tasks. In partially automated driving (SAE level 2), the system takes over longitudinal and lateral guidance in certain driving situations, whereby the driver must constantly monitor the system, as in assisted driving. In conditionally automated driving (SAE level 3), the system takes over longitudinal and lateral guidance in certain driving situations without the driver having to constantly monitor the system; however, the driver must be able to take over vehicle control within a certain time when requested by the system. In highly automated driving (SAE level 4), the system takes over vehicle control in certain driving situations, even if the driver does not respond to a request to intervene, so that the driver is no longer needed as a fallback. In fully automated driving (SAE level 5), the system can carry out all aspects of the dynamic driving task under any road and environmental conditions that can also be mastered by a human driver.

The system is set up in a manner known per se to detect a target object in the direction of travel while the vehicle is moving. The target object can in particular be a vehicle in front. However, the target object can also be an immobile object, such as a traffic light, a traffic sign or a stop line at an intersection. To detect such a target object, the vehicle is equipped with suitable environmental sensors, which can include, for example, a camera, a radar sensor, a lidar sensor and/or an ultrasonic sensor.

The system is also designed to bring the vehicle to a stop at a defined stopping distance from the target object. For example, the system can carry out the automated longitudinal guidance in such a way that the vehicle stops at the stopping distance behind a vehicle in front when it is driving forward and the vehicle in front also comes to a stop or has previously come to a stop. However, it is also possible for the vehicle to be brought to a stop at the defined stopping distance from a target object behind the vehicle when it is driving backwards.

According to the invention, the system is designed to determine a road gradient and to set the stopping distance at which the vehicle is brought to a stop in relation to the target object depending on the determined road gradient. In other words, the stopping distance is selected depending on the road gradient from the location of the vehicle. The road gradient can in particular be a road gradient in the current longitudinal direction of the vehicle.

To determine the road gradient, the system or the vehicle equipped with the system can have a gradient sensor. The gradient sensor can provide one or more measured values from which the road gradient can be derived, for example in the form of a mathematical gradient (i.e. a quotient of the lengths of a vertical and a horizontal leg of a gradient triangle) or in the form of a gradient angle. Gradient sensors are known to those skilled in the art and are therefore not explained further here.

A second aspect of the invention relates to a vehicle with a system according to the first aspect of the invention.

The vehicle can in particular be a motor vehicle. The term motor vehicle is to be understood in particular as a land vehicle that is moved by mechanical power without being tied to railway tracks. A motor vehicle in this sense can, for example, be designed as a passenger car, motorcycle or tractor.

A third aspect of the invention is a computer-implemented method for setting a stopping distance for automated longitudinal guidance of a vehicle, comprising the steps of: determining a road gradient; determining a stopping distance depending on the road gradient; and generating control signals for stopping the vehicle at the stopping distance from a target object.

For example, the determined stopping distance can be set as the target stopping distance as part of a longitudinal guidance control. During the stopping process, a distance control can therefore be carried out with the determined stopping distance as the target stopping distance, in contrast to a control based on a target time gap (for example with a certain second interval as the control target), which is usually carried out during (following) travel in longitudinal driver assistance systems such as ACC. In other words, the control target during the stopping process can be specified in the form of an absolute length specification, for example in meters or centimeters, for the stopping distance.

The method according to the third aspect of the invention can be carried out by means of a system according to the first aspect of the invention. Accordingly, the above and following explanations of the system according to the invention and of its possible embodiments can apply analogously to the method according to the invention and vice versa.

The system according to the invention can, for example, comprise a (data) processing device which has at least one processor and is set up to carry out the method according to the third aspect of the invention by means of the at least one processor. According to some embodiments, this can also be a spatially distributed processing device (for example, distributed over several processors or microcontrollers spaced apart from one another).

For example, the processing device can be a control unit or part of a control unit of the vehicle. In particular, it can be a control unit for controlling an automated driving function, which enables the at least partially automated longitudinal guidance of the vehicle.

The method step of determining the road gradient can include or consist of receiving one or more measured values from a gradient sensor by the processing device or by a software module running on the processing device. According to some embodiments, determining the road gradient can also include further processing of one or more received measured values from a gradient sensor by the processing device. For example, the road gradient can be calculated from one or more received measured values from a gradient sensor.

In one possible embodiment of the method according to the invention, the stopping distance is determined in such a way that the stopping distance is continuously increased as the road gradient increases (in terms of magnitude). The continuous increase in the stopping distance as the road gradient increases in terms of magnitude can apply at least for a certain road gradient range and/or at least for a certain distance range.

In general, the term road gradient as used in this document can refer to both a positive gradient and a negative gradient, i.e. a decline in the direction of travel of the vehicle.

According to one embodiment, the stopping distance is determined in such a way that the stopping distance is increased as the positive road gradient increases in magnitude. The stopping distance can be increased continuously depending on the (positive) road gradient, at least in a certain area. However, it is also possible that the stopping distance is not increased continuously depending on the road gradient, i.e. it is increased abruptly at least in one or more places.

The same applies to another design variant in which the stopping distance is increased with increasing negative road gradient.

For example, it can be provided that the stopping distance is increased from a certain threshold value of the (positive or negative) road gradient. For example, a continuous increase in the stopping distance can begin as soon as the amount of the road gradient exceeds the threshold value. It is conceivable, for example, that as soon as the amount of the road gradient exceeds the threshold value, a predefined factor is multiplied by the normal stopping distance. The higher the amount of the road gradient, the greater the factor and, accordingly, the stopping distance. The factor can, for example, increase continuously, such as linearly, with the amount of the road gradient.

It can also be provided that the stopping distance is increased to a predetermined maximum stopping distance. In other words, the stopping distance can be capped at a certain maximum value.

The method according to the invention can be used to counteract the problem that, on a very steep road, stopping too close behind a vehicle in front is often perceived as unpleasant by the driver or other vehicle occupants. This may be due to the driver's experience that manually driven vehicles can often easily roll back on a hill. Therefore, some drivers do not like to stop close behind another vehicle, especially a large and heavy vehicle such as a truck, on a hill (i.e. on a positive road gradient in the direction of travel). But even on a slope (i.e. on a negative road gradient) in the direction of travel, it can feel safer for the driver of a vehicle if a larger stopping distance is maintained from an object, for example with a view to the possible slight rolling forward (or rolling back in the case of reversing into a parking maneuver) of the driver's own vehicle, which can be better controlled with a larger stopping distance and can be caught if necessary.

A fourth aspect of the invention is a computer program which comprises instructions which, when the computer program is executed by a processing device, such as a processing device of a system according to the first aspect of the invention, cause the processing device to carry out a method according to the third aspect of the invention. The computer program can also be divided into several separate subprograms, each of which can be executed by different processing devices (such as several separate processors) which may be spatially separated from one another.

A processing device of a system according to the first aspect of the invention can be configured (in particular programmed) to execute a computer program according to the fourth aspect of the invention.

A fifth aspect of the invention is a computer-readable storage medium comprising instructions which, when executed by a (possibly distributed) processing device, cause it to carry out a method according to the third invention. aspect of the invention. In other words, a computer program according to the fourth aspect of the invention can be stored on the computer-readable storage medium.

• 1A-1B veranschaulichen beispielhaft und schematisch zwei verschiedene Anhaltesituationen mit einem Fahrzeug, das mit einem System zur automatisierten Längsführung ausgestattet ist.
• 2 veranschaulicht beispielhaft und schematisch Schritte eines Verfahrens zum Einstellen eines Anhalteabstands für eine automatisierte Längsführung eines Fahrzeugs.

The invention will now be explained in more detail using embodiments and with reference to the accompanying drawings.

• 1A-1B illustrate, by way of example and schematically, two different stopping situations with a vehicle equipped with a system for automated longitudinal guidance.
• 2 illustrates exemplary and schematic steps of a method for setting a stopping distance for automated longitudinal guidance of a vehicle.

The 1A and 1B The motor vehicle 3 shown comprises a system 1 for automated longitudinal guidance of the vehicle 3. The system 1 comprises a (data) processing device 10 and a gradient sensor 11, which is connected to the processing device 10 by means of signals. The processing device 10 can be, for example, a control unit of a driver assistance system of the vehicle 3, which enables at least partially automated longitudinal guidance of the vehicle 3. The processing device 10 can be connected by means of signals to an environmental sensor system of the vehicle 3, which is integrated in the 1A and 1B is not shown separately. Such environmental sensors can, for example, comprise one or more radar sensors, one or more ultrasonic sensors and/or one or more cameras.

The system 1 is set up to use the environmental sensors to detect a target object 4 located in the direction of travel of the vehicle 3. In the embodiment shown, the vehicle 3 initially drives forward in a following journey with another vehicle 4 as the target object. During the following journey, for example, a certain distance of seconds can be set to the target object 4. The target object 4 then stops in front of the vehicle 3, so that the vehicle 3 has to stop behind the target object 4 in order to avoid a rear-end collision.

The system 1 is set up to bring the vehicle 3 to a stop at a defined stopping distance d1, d2 from the target object 4. The stopping distance d1, d2 is set by the processing device 10 depending on a respective road gradient α1, α2, which is determined by means of the gradient sensor 11. For example, the processing device 10 can receive a respective gradient angle α1, α2 from the gradient sensor 11, which indicates the respective road gradient in the longitudinal direction of the vehicle 3. The processing device 10 then determines a respective stopping distance d1, d2, which depends on the road gradient α1, α2 in such a way that the stopping distance is increased as the road gradient increases.

In the in the 1A and 1B In each of the situations shown, the road gradient is positive, with the road gradient α2 in 1B is greater than the road gradient α1 in 1A Accordingly, vehicle 3 in the situation according to 1B brought to a stop at a greater distance d2 behind the target object 4 than in the situation according to 1B , in which a stopping distance d1<d2 is selected. For the driver of the vehicle 3's sense of safety, this can result in the advantage that the larger stopping distance d2 allows more scope for a reaction to a possible rolling back of the vehicle 4 in front, for example when the vehicle 4 in front starts moving again.

As a result, System 1 can help to increase driver comfort and driving safety when using an automated longitudinal guidance function, such as ACC Stop-and-go.

In accordance with the above, the system 1 is configured to carry out the following method steps 21 to 23 by means of the processing device 10 in accordance with 2 to execute.

In a method step 21, the road gradient α1, α2 is determined at the location of the vehicle 3, for example by receiving a respective corresponding measured value α1, α2 from the gradient sensor 11.

In a further method step 22, a (target) stopping distance d1, d2 is determined depending on the respective road gradient α1, α2. The stopping distance can be determined in such a way that the stopping distance is increased with an increasing (here positive) road gradient. For example, a continuous increase in the stopping distance depending on the road gradient can be provided from a certain threshold value of the road gradient and up to a defined maximum stopping distance.

In a further method step 23, the processing device 10 generates control signals for stopping the vehicle 3 with the respectively determined stopping distance d1, d2 to the vehicle 4 in front. The control signals can, for example, be output to a longitudinal guide actuator of the vehicle 3 and converted by this into a corresponding Longitudinal movement of the vehicle 3 can be implemented. In this case, a distance control with respect to the vehicle 4 in front can be carried out with the respectively determined stopping distance d1, d2 as the target value.

Claims (10)

System (1) for automated longitudinal guidance of a vehicle (3), wherein the system (1) is set up to - detect a target object (4) located in the direction of travel, - determine a road gradient (α1, α2), and - bring the vehicle (3) to a stop at a defined stopping distance (d1, d2) from the target object (4), wherein the stopping distance (d1, d2) depends on the road gradient (α1, α2). Vehicle (3) with a system (1) according to one of the preceding claims. Computer-implemented method (2) for setting a stopping distance (d1, d2) for automated longitudinal guidance of a vehicle (3), comprising the steps: - determining (21) a road gradient (α1, α2); - determining (22) a stopping distance (d1, d2) depending on the road gradient (α1, α2); and - generating (23) control signals for stopping the vehicle (3) at the stopping distance (d1, d2) from a target object (4). Procedure (2) according to claim 3 , wherein the determination (23) of the stopping distance (d1, d2) is carried out in such a way that the stopping distance (d1, d2) is increased continuously, in particular linearly, with increasing road gradient (α1, α2). Method (2) according to one of the Claims 4 , wherein the continuous increase of the stopping distance (d1, d2) begins from a threshold value of the road gradient (α1, α2). Method (2) according to one of the Claims 3 until 5 , wherein the determination (23) of the stopping distance (d1, d2) is carried out in such a way that the stopping distance (d1, d2) is increased with increasing positive road gradient (α1, α2). Method (2) according to one of the Claims 3 until 6 , wherein the determination (23) of the stopping distance (d1, d2) is carried out in such a way that the stopping distance (d1, d2) is increased with increasing negative road gradient (α1, α2). Method (2) according to one of the Claims 3 until 7 , wherein the stopping distance (d1, d2) is increased to a maximum of a predetermined maximum stopping distance. Computer program comprising instructions which, when the computer program is executed by a processing device (10), cause the processing device (10) to carry out a method (2) according to one of the Claims 3 until 8 to execute. Computer-readable storage medium comprising instructions which, when executed by a processing device (10), cause the processing device (10) to carry out a method (2) according to one of the Claims 3 until 8 to execute.

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