DE102022125849A1 - Method for operating a braking system of a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a braking system (11) of a motor vehicle (1), comprising: providing (S1) movement information (18) which is stored in a map (15) and which describes a speed and/or acceleration that is usual for a section of the route (6) traveled by the motor vehicle (1), the movement information (18) having been determined from swarm data (19); providing (S2) self-movement information (20) of the motor vehicle (1); determining (S3) minimum distance information (22) which describes a minimum distance of the motor vehicle (1) from another motor vehicle (5) driving ahead, by applying a minimum distance determination criterion (21) to the movement information (18) and self-movement information (20); providing (S4) distance information (23) of the motor vehicle (1) from the other motor vehicle (5) driving ahead; checking (S5) whether the distance information (23) is smaller than the minimum distance information (22); if this is the case, determining (S6) a braking command (27) for the braking system (11) of the motor vehicle (1) to reduce the speed of the motor vehicle (1) at least until the distance to the other motor vehicle (1) corresponds to the minimum distance.

Description

The invention relates to a method for operating a braking system of a motor vehicle and to a motor vehicle for carrying out such a method.

A motor vehicle can have a vehicle function, such as a driver assistance system, which is designed to check a distance to another motor vehicle driving ahead and, by appropriately controlling a braking system of the motor vehicle, to ensure that the distance to the other motor vehicle driving ahead does not become smaller than a predetermined minimum distance. Such a vehicle function is typically based on detecting the speed of the other motor vehicle driving ahead.

In situations in which the motor vehicle driving ahead cannot be detected, at least temporarily, by means of a sensor device of the motor vehicle and/or in which it is not yet clear that the motor vehicle is to be regarded as a motor vehicle driving ahead, for example because it is driving in a lane that only merges into a lane of the motor vehicle in a further section of the road, it can be disadvantageous to base the control of the braking system to maintain the minimum distance on a detected or determined speed of the other motor vehicle. Depending on the situation, it may therefore not be sensible to control the braking system solely by taking into account the speed of the motor vehicle driving ahead.

The US 2021/0122373 A1 describes a procedure for influencing a trajectory of a vehicle based on an overlapping area with an object in the surroundings of the motor vehicle. It is determined whether the vehicle should follow an avoidance trajectory or an original trajectory due to the object.

The EN 10 2020 127 855 A1 describes a safety system from which vehicle position data is received that indicates a position of a vehicle. A relevant set of lane segments is also determined based on a safety area in front of a first lane segment and position data is determined that indicates a second lane segment in the lane coordinate system, wherein an obstacle is located in the second lane segment. The obstacle is assessed as either a relevant or non-relevant obstacle, depending on whether or not the second lane segment is included in the relevant set of lane segments.

The WO 2021/103510 A1 shows a method for controlling an acceleration for an automatically driving vehicle. Continuous information is determined for one lane of the vehicle and a driving trajectory is predicted for another vehicle in another lane, whereby it is predicted for the other vehicle when it will change into the lane of the autonomous vehicle. An acceleration of the autonomously driving vehicle is now calculated at which no collision with the other vehicle occurs.

It is the object of the invention to provide a solution by means of which a distance regulation to a motor vehicle driving ahead is made possible regardless of the situation by appropriately operating a braking system of a motor vehicle.

The object is solved by the subject matter of the independent patent claims. Possible embodiments of the invention are specified in the dependent claims, the following description and the figures.

A first aspect of the invention relates to a method for operating a braking system of a motor vehicle. The braking system is, for example, a brake-by-wire braking system. The braking system comprises, for example, several individual hydraulic and/or electric brakes, each of which is assigned to a wheel of the motor vehicle, for example. When the respective brake is activated in accordance with a braking command, a speed of the motor vehicle can at least be reduced.

The invention is based at least in part on the knowledge that it may be the case that in a curve situation and/or with another motor vehicle on an acceleration lane, it may be difficult to continuously record an actual speed and/or acceleration of another motor vehicle currently driving ahead of the motor vehicle or at the end of the acceleration lane. It may therefore be sensible to disregard the actual speed and/or acceleration of the other motor vehicle driving ahead and instead to assume a usual or average vehicle behavior for a stretch of road. It should therefore be assumed that the other motor vehicle driving ahead behaves like a typical vehicle on the stretch of road. It should therefore be assumed that its behavior corresponds to or at least resembles a likely expected behavior of the other motor vehicle driving ahead. The likely Expected behavior can be determined, for example, from swarm data collected during journeys on the route section.

The invention is also based, at least in part, on the realization that there is no internationally valid definition of a reasonable minimum distance to another motor vehicle driving ahead. It is therefore sensible to calculate an individual minimum distance to another motor vehicle driving ahead, which depends on the section of road and which should be maintained at least if the other motor vehicle driving ahead behaves normally on the section of road.

The method includes providing movement information. The movement information is stored in a map. It is stored in the map, for example. The movement information describes a speed and/or acceleration that is usual for a section of the route currently traveled by the motor vehicle. The movement information was determined by evaluating swarm data. The swarm data was recorded, for example, from other vehicles, in particular other motor vehicles, that traveled the section of the route before a current point in time. The swarm data can be in the form of travel trajectories of the other vehicles, for example. The trajectories include speed and/or acceleration information for at least individual points along the section of the route. The usual speed is, for example, a speed averaged over the individual speeds at a common point of the numerous trajectories or at least in a common part of the section of the route. The swarm data is evaluated to determine the usual speed. The usual speed can be specified depending on the time of day, day of the week and/or weather, in which case the movement information that is assigned to a current time of day, time of the week or weather is provided. The weather can be determined using a detection device in the motor vehicle, for example using a rain sensor, an external camera and/or an outside temperature sensor. Alternatively or additionally, information on the time of day, time of week and/or weather can be received from an external device, in particular a computing device and/or another motor vehicle. Analogously, the usual acceleration is, for example, an acceleration averaged over the respective accelerations according to the trajectories. The swarm data is evaluated to determine the usual acceleration. The usual acceleration can be specified depending on the time of day, day of the week and/or weather. For example, swarm data is recorded at a certain time interval and then an average speed and/or acceleration is determined that was recorded when driving along the trajectories according to the swarm data.

It may be specified that the usual speed and/or acceleration can only be provided if a minimum amount of swarm data is available, which was provided in particular during several trips and/or by means of several vehicles.

The route section includes, for example, a distance from a current position of the motor vehicle up to, for example, 100 meters, 200 meters, 250 meters, 500 meters, 750 meters, in particular 1 kilometer in the direction of travel in front of the motor vehicle. For this route section, values for the usual speed and/or acceleration and thus the movement information are typically available every 10 meters, 15 meters, 20 meters, 25 meters, 50 meters, 100 meters, in particular 200 meters.

The method includes providing self-motion information that describes a speed and/or acceleration of the motor vehicle. The self-motion information can be recorded, for example, using a recording device for recording the self-motion of the motor vehicle. The recording device can include a wheel speed sensor. Data from a drive device and/or the braking system of the motor vehicle can also be evaluated in order to at least be able to estimate the self-motion information.

A minimum distance information is determined that describes a minimum distance of the motor vehicle from a motor vehicle driving ahead. This is done by applying a minimum distance determination criterion to the provided movement information and self-movement information. The minimum distance determination criterion is an algorithm and/or a rule, when implemented or applied, the minimum distance information is determined, i.e. calculated. The minimum distance determination criterion can be designed as a computer code or computer program. The minimum distance determination criterion includes at least one formula by means of which the minimum distance information can be calculated from, for example, the movement information, the self-movement information and/or possibly other parameters. The minimum distance information does not relate to any actual current Distance to a specific other motor vehicle driving ahead, but is a value calculated here on the basis of the usual speed and/or acceleration of the vehicles that provided the swarm data on the section of road as well as the current speed and/or acceleration of the motor vehicle itself whose braking system is to be operated. The minimum distance can also be referred to as the minimum distance or minimum distance between the motor vehicle and another motor vehicle driving ahead.

The method includes providing distance information that describes a distance of the motor vehicle from the other motor vehicle driving ahead. The distance information can be calculated, for example, by evaluating sensor data that the motor vehicle itself records. The sensor data can, for example, have been recorded at a time when the other motor vehicle driving ahead was in a detection range of a sensor device of the motor vehicle that records the sensor data. It can then be provided that a current position of the other motor vehicle driving ahead is predicted based on its last recorded position and/or the last recorded distance from the motor vehicle. For the prediction, the movement information is assumed to be the speed and/or acceleration of the other motor vehicle and a time since the position and/or distance of the other motor vehicle driving ahead was last recorded is also taken into account. Preferably, the other motor vehicle is actually recorded so that the actual distance to the other motor vehicle driving ahead is provided as distance information at a current time. Furthermore, the other motor vehicle driving ahead can communicate its position via vehicle-to-vehicle communication. A position determination can be carried out based on data from a global navigation satellite system.

A check is then carried out to see whether the distance information provided is less than the minimum distance information determined. It is therefore checked whether the previously calculated minimum distance is currently met or not. If the distance information provided is less than the minimum distance information determined, i.e. if the detected or predicted distance is less than the previously determined minimum distance, a braking command is determined for the braking system of the motor vehicle. When the braking system is activated according to the determined braking command, the speed of the motor vehicle is at least reduced until the distance to the other motor vehicle corresponds to the minimum distance. The other motor vehicle is the other motor vehicle driving ahead. According to the braking command, the motor vehicle can therefore be braked until the distance of the braked motor vehicle to the other motor vehicle driving ahead is less than the minimum distance. It is not intended that the motor vehicle is braked to a standstill, but the distance should only be increased so that it is greater than or equal to the minimum distance. As soon as this is achieved, for example, the speed of the motor vehicle can be kept constant, at least temporarily.

The method further includes operating the braking system in accordance with the determined braking command. This means that there is an actual, at least partially automatic, in particular fully automatic, control of the longitudinal guidance of the motor vehicle by controlling the braking system in accordance with the determined braking command. However, this only occurs if the current distance is smaller than the determined minimum distance.

Based on the usual speed and/or acceleration for a section of road provided by the swarm data, an estimate is made as to whether the vehicle should be braked or not.

The method described makes it possible, for example, to dispense with the complex recording and/or evaluation of the current speed and/or acceleration of the other motor vehicle driving ahead, as this is not required, as the method only takes into account the movement information stored in the map. Since the swarm data underlying the movement information is route-specific, the optimal minimum distance for the route section is determined. Since the actual speed and/or acceleration of the other motor vehicle driving ahead is not taken into account, a situation-independent distance regulation to the other motor vehicle driving ahead is achieved by operating the braking system of the motor vehicle using the determined braking command.

The method steps of the method are preferably carried out by means of a control device of the motor vehicle. For this purpose, the control device is provided with the movement information and the self-movement information as well as the distance information. If necessary, at least one of these pieces of information can be determined in the control device itself. Determining the minimum distance information, checking and determining the braking command and controlling the braking system systems according to the determined braking command are preferably also carried out by means of the control device of the motor vehicle. Alternatively or additionally, it is possible for at least one of the method steps described to be carried out by means of an external computing device which is designed, for example, as a server device or backend. For this purpose, information or other data can be exchanged between the motor vehicle and the external computing device. This communication connection is preferably based on a cable-free, in particular wireless, communication connection. What is relevant is that the determined braking command is ultimately made available to the motor vehicle by the external computing device, i.e. is transmitted to it, so that the braking system in the motor vehicle itself can be controlled and consequently operated according to the determined braking command.

The invention includes embodiments which provide additional advantages.

One embodiment provides that the sensor data describing the other motor vehicle driving ahead are recorded by the sensor device of the motor vehicle and the distance information is determined by evaluating them. The sensor device is, for example, a camera device that has at least one camera, in particular a front camera, a rear camera and/or a side camera. Alternatively or additionally, the sensor device can be a radar device, a lidar device, an ultrasonic sensor, an infrared measuring device and/or a laser distance meter. Preferably, the sensor device detects a motor vehicle that is currently driving directly in front of the motor vehicle as the other motor vehicle driving ahead. Alternatively, the other motor vehicle driving ahead can currently be arranged transversely to a direction of travel and in front of, next to or behind the motor vehicle in the direction of travel. This can be the case, for example, if the motor vehicle is on the acceleration lane or another lane adjacent to a lane on which the motor vehicle is driving. This other motor vehicle will probably drive in front of the motor vehicle in the future at a location in front of the motor vehicle in the direction of travel and is therefore also referred to as another motor vehicle driving ahead. In other words, such another motor vehicle driving ahead is another motor vehicle driving ahead in the future. It is assumed that the acceleration lane or adjacent lanes merge into the lane of the vehicle at the location or vice versa. Ultimately, the situation can be clearly detected using the vehicle's own sensors that there is currently or is predicted to be another vehicle in front of the vehicle, so that the distance information can be determined reliably and precisely.

A further embodiment provides that the distance information is determined taking into account self-position information that describes a position of the motor vehicle and/or vehicle position information that describes a position of the other motor vehicle driving ahead. In addition to the sensor data, an actual position and thus a coordinate of the motor vehicle can therefore be determined, for example, using a position determination device of the motor vehicle, which is based on data from the global navigation satellite system, for example. The vehicle position information of the other motor vehicle driving ahead can be provided to the motor vehicle, for example, via vehicle-to-vehicle communication or via a computing device using vehicle-to-infrastructure communication. Alternatively or additionally, the vehicle position information can be determined, for example, as relative position information from the sensor data. If, for example, positions and thus position information that describe the respective position, in particular using position data, are determined using the position determination device of the motor vehicle and the position determination device of the other motor vehicle driving ahead, the distance information can be determined, for example, taking into account these two absolute position information items. Preferably, the distance information is determined by mutually supplementing sensor data, the self-position information and/or the vehicle position information. This makes it particularly clear which components must be present in the motor vehicle in principle in order to carry out the method, and these are typical components. The method can therefore be implemented in the motor vehicle with little effort.

A further embodiment provides that the minimum distance determination criterion takes into account a length of the motor vehicle. It is therefore assumed that, viewed from a center point of the motor vehicle, its edge in a front area is typically half the length of the motor vehicle away. If it is now assumed, for simplicity, that the other motor vehicle driving ahead has the same or at least a comparable length of the motor vehicle, it can be assumed that, viewed from a center point of the other motor vehicle driving ahead, its edge in a rear area is half the length of the motor vehicle away. The two distances to the respective center point result in adds the length of the motor vehicle. The length of the motor vehicle is typically known and can be stored, for example, in a control device of the motor vehicle. The length is taken into account when calculating the minimum distance information. The length is used, for example, as a variable in a formula included in the minimum distance determination criterion. This is because the minimum distance between the centers of the motor vehicles should be greater than the length so that the two motor vehicles do not collide with their edges. The length therefore offers a useful first approximation of the minimum distance actually required.

An additional embodiment provides that the minimum distance determination criterion takes into account a predetermined reaction time and/or a predetermined comfort distance. A fixed value of, for example, 0.1 second, 0.2 seconds, 0.3 seconds, 0.5 seconds, 1 second, 2 seconds, 3 seconds, in particular 5 seconds, can be assumed as the reaction time. It is assumed that the reaction time is a time that passes until a driver and/or the braking system can react to, for example, the braking command displayed to the driver or provided to the braking system and, for example, implements it. Alternatively or additionally, the reaction time can be a time that is required by the control device for the individual method steps it carries out.

The specified comfort distance can, for example, be a legally specified distance that must always be taken into account and that is taken into account, for example, as an additional value or offset by the minimum distance determination criterion. It can be included in the determined distance information. For example, the comfort distance can be added to an originally determined minimum distance according to an original minimum distance information. The final minimum distance information is then determined taking the comfort distance into account and is taken into account in the further process steps. The comfort distance can, for example, be a quarter, half a meter, 1 meter, 2 meters, or in particular 5 meters. This means that a sensible minimum distance is determined even more reliably.

An additional embodiment provides that route section information is provided for the route section currently traveled by the motor vehicle, which describes the route section. The route section information describes in particular a lane marking, a traffic sign and/or a usual driving trajectory determined from the swarm data, which can alternatively be referred to as a mean or average driving trajectory. The determined route section information is at least taken into account when providing the movement information. The route section information can alternatively be referred to as the electronic horizon of the motor vehicle. The route section information is preferably calculated based on the sensor data, wherein the sensor data is preferably static and/or moving image data and thus camera data. Furthermore, the route section information can be evaluated to define the route section in order to ultimately find out which map is needed to be able to provide the movement information. The route section information can alternatively or additionally be taken into account in order to locate the motor vehicle on the map. This makes it possible to define the route section, for example by means of edge or corner coordinates. The route information can make it possible to select and provide the movement information associated with the section of the route on which the motor vehicle is traveling from numerous pieces of movement information stored in the map. This makes the provision of the movement information more precise, since not only the map but also the section of the route information is used.

Furthermore, by taking the route section information into account, it can be taken into account that a road has, for example, several lanes. It can be relevant, for example, whether the motor vehicle is driving on a left, right or middle lane of the road. There can be different usual speeds and/or accelerations for the individual lanes, so that by taking the route information and the associated precise localization of the motor vehicle into account, the movement information for the actually relevant lane can be reliably selected and consequently provided.

In an advantageous embodiment, the method is always activated when the section of the road is curved. The method described can therefore be carried out automatically, for example, in the area of a curve and/or whenever the section of the road currently being driven by the motor vehicle has at least one curve. The reason for this may be that a situation may arise in the curved section of the road in which a motor vehicle driving ahead can no longer be detected by the motor vehicle's sensor device, at least temporarily, due to the curve, so that it may then be useful to maintain the described minimum distance. z assessment and, if necessary, braking of the motor vehicle. For example, it may be known from the swarm data that vehicles usually reduce speed in an area of the curve, so that such behavior is expected from the other motor vehicle driving ahead. In or behind the curve, however, the other motor vehicle driving ahead can no longer be optically detected because, due to the curves, no sensor data describing the other motor vehicle driving ahead can be detected by the motor vehicle. Furthermore, in a curve situation it can be particularly useful to choose a minimum distance that is greater than a legally prescribed minimum distance, for example, because in such a curve situation the usual speed and/or acceleration may be reduced according to the swarm data compared to, for example, a specified maximum speed for driving in the section of road. The swarm data make it possible to reliably estimate how fast the winding section of road is typically driven through, so that the method is particularly suitable for such sections of road.

An additional embodiment includes checking whether the section of road has an acceleration lane that, in a direction of travel of the motor vehicle, leads into a lane in which the motor vehicle is traveling. It is therefore determined whether an acceleration lane exists and whether this merges with the lane in which the motor vehicle is traveling. If this is the case, i.e. if there is an acceleration lane and this leads into the lane of the motor vehicle in the direction of travel in front of the motor vehicle, a point in time at which a motor vehicle traveling on the acceleration lane will drive into the lane is predicted, taking into account the movement information provided. It is therefore estimated, taking into account the usual speed and/or acceleration in the section of road, here on the acceleration lane, when the motor vehicle currently traveling there, which was detected to the side of the motor vehicle, for example, is likely to drive into the lane of the motor vehicle. It is assumed that the motor vehicle traveling on the acceleration lane is detected at a point in time, so that, for example, its initial position is known.

Taking into account the motor vehicle's own motion information, the distance information for the estimated point in time is predicted and provided. The distance between the motor vehicle and the other motor vehicle driving ahead of the motor vehicle from the estimated point in time is therefore determined. It is then checked whether the distance information is smaller than the minimum distance information, whereby the minimum distance information is again determined based on the motion information and the motor vehicle's own motion information. If this is the case, the braking command can be determined and the motor vehicle can ultimately be operated in accordance with the braking command. Ultimately, this supplements the method to include the use case in which the other motor vehicle does not drive in front of the motor vehicle from the start, but that this situation will only arise because the other motor vehicle initially drives on the acceleration lane. This procedure is particularly relevant for a highway or another road junction area where there is an acceleration lane.

Furthermore, one embodiment provides that the map is provided to the motor vehicle as a partial map by an external computing device. The partial map includes at least the route section. The partial map can, for example, be designed as a map tile of a certain size. The partial map can, for example, cover an area of 1 kilometer by 1 kilometer. Other sizes of the partial map are possible. The map is preferably continuously provided to the motor vehicle by the external computing device, so that at least information about the route section itself and about the movement information assigned to this route section is always available. This can ensure that the map is always based on current swarm data, since the partial map can be provided repeatedly updated by the external computing device. This makes the method particularly reliable with regard to movement information.

For use cases or application situations that may arise during the method and which are not explicitly described here, it may be provided that, in accordance with the method, an error message and/or a request to enter user feedback is issued and/or a default setting and/or a predetermined initial state is set.

A further aspect of the invention relates to a motor vehicle. The motor vehicle is designed to carry out the method described above. For this purpose, the motor vehicle can comprise the control device and the sensor device for recording the sensor data. The invention includes further developments of the motor vehicle according to the invention, which have features as have already been described in connection with the further developments of the method according to the invention. For this reason, the corresponding training courses are not described again here.

The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

The invention includes the control device for the motor vehicle. The control device can have a data processing device or a processor device that is set up to carry out an embodiment of the method according to the invention. For this purpose, the processor device can have at least one microprocessor and/or at least one microcontroller and/or at least one FPGA (Field Programmable Gate Array) and/or at least one DSP (Digital Signal Processor). Furthermore, the processor device can have program code that is set up to carry out the embodiment of the method according to the invention when executed by the processor device. The program code can be stored in a data memory of the processor device. The processor circuit of the processor device can, for example, have at least one circuit board and/or at least one SoC (System on Chip).

As a further solution, the invention comprises a computer-readable storage medium comprising program code which, when executed by a processor circuit of a computer or a computer network, causes it to carry out an embodiment of the method according to the invention. The storage medium can, for example, be provided at least partially as a non-volatile data memory (e.g. as a flash memory and/or as an SSD - solid state drive) and/or at least partially as a volatile data memory (e.g. as a RAM - random access memory). The storage medium can be arranged in the processor circuit in its data memory. The storage medium can also, for example, be operated as a so-called app store server on the Internet. The computer or computer network can provide a processor circuit with at least one microprocessor. The program code can be provided as binary code or assembler and/or as source code of a programming language (e.g. C) and/or as a program script (e.g. Python).

The invention also includes combinations of the features of the described embodiments. The invention therefore also includes implementations that each have a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

• 1 eine schematische Darstellung eines Kraftfahrzeugs auf einer geraden Strecke mit einem vorausfahrenden anderen Kraftfahrzeug;
• 2 eine schematische Darstellung eines Mindestabstandes zwischen zwei Kraftfahrzeugen,
• 3 in schematischer Darstellung einen Signalflussgraphen eines Verfahrens zum Betreiben eines Bremssystems eines Kraftfahrzeugs, und
• 4 eine schematische Darstellung des Verfahrens gemäß 3 im Bereich eines Beschleunigungsstreifens.

Exemplary embodiments of the invention are described below.

• 1 a schematic representation of a motor vehicle on a straight road with another motor vehicle driving ahead;
• 2 a schematic representation of a minimum distance between two motor vehicles,
• 3 in schematic representation a signal flow graph of a method for operating a braking system of a motor vehicle, and
• 4 a schematic representation of the process according to 3 in the area of an acceleration lane.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the components of the embodiments described each represent individual features of the invention that are to be considered independently of one another and which also develop the invention independently of one another. Therefore, the disclosure should also include combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by other features of the invention already described.

In the figures, identical reference symbols designate functionally identical elements.

In 1 a motor vehicle 1 is sketched that is driving on a road 2. It is driving there on a lane 3 in a direction of travel 4. In the direction of travel 4 in front of the motor vehicle 1 there is another motor vehicle 5, which is referred to as the other motor vehicle 5 driving ahead. A section of road 6 is also sketched in which a usual trajectory 7 with individual detection points, which are shown as crosses, is known. The trajectory 7 indicates how vehicles on average, i.e. usually, drive on the section of road 6. The data on which the usual trajectory 7 is based are recorded and made available, for example, during detection trips with vehicles, in particular swarm vehicles. A speed curve 8 is drawn for the section of road 6, which shows an example of a speed u of the motor vehicle 1 against time t. It is clear that along the drivable path in the section of road 6 according to the trajectory 7 the vehicle typically accelerates and then brakes again.

The motor vehicle 1 has a sensor device 9, which is designed here, for example, as a front camera. Alternatively or additionally, the sensor device 9 can be a radar device, a lidar device, an ultrasonic sensor and/or a laser distance meter.

The motor vehicle 1 also has a control device 10, which is a computing device of the motor vehicle 1.

The motor vehicle 1 has a braking system 11, by means of which a speed of the motor vehicle 1 can be reduced. The braking system 11 thus serves to guide the motor vehicle longitudinally. The braking system 11 can be controlled by the control device 10, for example by means of corresponding commands.

The motor vehicle 1 here also has a communication interface 12. An external computing device 13 can be provided, which also has the communication interface 12, so that a wireless, in particular cable-free, communication connection 14 can be established between the external computing device 13 and the motor vehicle 1. Via this, for example, a map 15 or at least a partial map of the map 15 can be transmitted from the external computing device 13 to the motor vehicle 1. The partial map can, for example, describe an area of 1 kilometer by 1 kilometer around the motor vehicle 1.

In 2 the motor vehicle 1 is sketched again with the other motor vehicle 5 driving ahead. The motor vehicle 1 is assigned a speed u ₁ and an acceleration a ₁ . Furthermore, the other motor vehicle 5 driving ahead is assigned a speed u ₂ and an acceleration a ₂ . The sizes u ₁ and u ₂ as well as a ₁ and a ₂ can each be different. A half length L of the motor vehicle 1 is also drawn in, which indicates the distance between a center point 16 of the motor vehicle 1 and an edge point 17 in a front area of the motor vehicle 1. Such a half length L is also drawn in for the other motor vehicle 5, here between the edge point 17 in a rear area of the motor vehicle 5 and the center point 16 of the other motor vehicle 5. A distance between the edge point 17 in the front area of the motor vehicle 1 and the edge point 17 in the rear area of the other motor vehicle 5 should have at least the distance d _min . It is part of the 3 outlined procedure to calculate the distance, which is called the minimum distance d _min .

3 shows a method for operating the braking system 11 of the motor vehicle 1. In a method step S1, movement information 18 is provided. This is stored in the map 15 and describes a speed and/or acceleration that is usual for a section of the route 6 currently traveled by the motor vehicle 1. The usual speed is the speed u ₂ and the usual acceleration is the acceleration a ₂ . The movement information 18 is determined by evaluating swarm data 19. This swarm data 19 therefore forms the basis of the map 15. The swarm data 19 are or were provided by the vehicles that traveled the trajectory 7.

In a method step S2, an item of self-motion information 20 is provided which describes the speed u ₁ and/or acceleration a ₁ of the motor vehicle 1. This is determined, for example, by means of a wheel speed sensor and/or another device of the motor vehicle 1 for determining the vehicle's own speed u ₁ and/or acceleration a _1. ^

In a method step S3, a minimum distance determination criterion 21 is applied to the provided movement information 18 and the provided self-movement information 20. Furthermore, the minimum distance determination criterion 21 can take into account the length L of the motor vehicle 1, a predetermined reaction time p and/or a predetermined comfort distance d _c . By applying the minimum distance determination criterion 21, a minimum distance information 22 is determined which describes the minimum distance d _min of the motor vehicle 1 to the other motor vehicle 5 driving ahead.

$$\frac{\partial x}{\partial t}=u+at$$

$$\frac{{\vartheta }^{2}x}{{\vartheta }^{2}t}=a$$

For the calculation of the minimum distance information 22, it is assumed that no lateral and thus transverse movements are relevant. As already described, the movement information 18 takes into account known typical and thus usual speed and/or acceleration information, i.e. the actual speed and/or acceleration of the other motor vehicle 5 is not determined for this purpose. A current position of the motor vehicle 1 is also assumed as location x _1. Taking into account the equation of motion for each motor vehicle 1, 5, the following equations result, whereby the number in brackets at the end of the respective equation serves to number the following equations: $$x\left(t\right)=x_0+ut+\frac{1}{2}a{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">t</figure-callout>}}^2$$

$$\frac{\partial x}{\partial t}=u+at$$

$$\frac{{\vartheta }^{2}x}{{\vartheta }^{2}t}=a$$

In the case of t = t _stop (4) the speed of the motor vehicle 1 is zero, i.e. u = 0 is assumed. Taking into account equations (2) and (4) we therefore obtain: $$u+a{t}_{stOp}=0\Rightarrow t_{stOp}=-\frac{u}{a}$$

Taking into account equations (5) and (1), this leads to the following equation: $$x_{stOp}=x_0+u{t}_{stOp}+\frac{1}{2}a{t}_{s\mathrm{<figure-callout\; id="2"\; label="t\; O\; p"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">t</figure-callout>}Op}^2\Rightarrow x_{stOp}=x_0-\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}^2}{2a}$$

$$x_{stop\mathrm{,2}}=x_{\mathrm{0,2}}-\frac{u_2^2}{2a_2}$$

$$\begin{array}{l}{x}_{stop\mathrm{,2}}-x_{stop\mathrm{,1}}=x_{\mathrm{0,2}}-\frac{u_2^2}{2a_2}-x_{\mathrm{0,1}}+\frac{u_1^2}{2a_1}=\\ \left(x_{\mathrm{0,2}}-x_{\mathrm{0,1}}\right)+\left(\frac{u_1^2}{2a_1}-\frac{u_2^2}{2a_2}\right)\end{array}$$

If equation (6) is assumed for both vehicles 1, 5, this leads to the following equation: $$x_{stOp\mathrm{,1}}=x_{0.1}-\frac{{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^2}{2a_1}$$

$$x_{stOp\mathrm{,2}}=x_{0.2}-\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_2^2}{2a_2}$$

$$\begin{array}{l}{x}_{stOp\mathrm{,2}}-x_{stOp\mathrm{,1}}=x_{0.2}-\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_2^2}{2a_2}-x_{0.1}+\frac{{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^2}{2a_1}=\\ \left(x_{0.2}-x_{0.1}\right)+\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^2}{2a_1}-\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_2^2}{2a_2}\right)\end{array}$$

The other motor vehicle 5 is assumed to be driving in front of motor vehicle 1. For this reason, the following relationship applies: $$x_{0.2}-x_{0.1}>0\exists x\in \left(\mathrm{...}\right)$$

Expressed in words, equation (8) means that the distance between a location of the other motor vehicle 5 driving ahead at the initial time 0 (x _0.2 ) and a location of the motor vehicle 1 at the initial time 0 (x _0.1 ) is greater than 0 for all locations x in the real number space.

From equations (7) and (8) we get: $$x_{stOp\mathrm{,2}}-x_{stOp\mathrm{,1}}=\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^2}{2a_1}-\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_2^2}{2a_2}\right)$$

Based on equation (9), it is determined that the motor vehicle 1 must adapt its speed u ₁ and acceleration a ₁ to the other motor vehicle 5 in order to maintain a sufficiently large distance, i.e. the minimum distance d _min . If the reaction time p is also taken into account and it is assumed that both motor vehicles 1, 5 can brake with a maximum braking acceleration, equation (9) gives: $$d_{min}=L+u_{1}p+\frac{1}{2}{a}_1{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">p</figure-callout>}}^2+\frac{{\left({\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_1+a_{1}p\right)}^2}{2a_{1max,brake}}-\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102022125849A1\_0012.png,DE102022125849A1\_0013.png"\; state="\{\{state\}\}">u</figure-callout>}}_2^2}{2a_{2max,brake}}+d_c$$

The comfort distance is abbreviated here as d _c . This describes an additional safety distance.

According to equation (10), the minimum distance information 22 is calculated in process step S3.

In a method step S4, after the minimum distance information 22 has been determined based on the own movement information 20 and the movement information 18, distance information 23 can be provided that describes the distance of the motor vehicle 1 from the other motor vehicle 5 driving ahead. For this purpose, sensor data 24 can be determined using the sensor device 17 of the motor vehicle 1, and the distance information 23 can be determined when evaluated. Furthermore, own position information 25 that describes a position of the motor vehicle 1 and/or vehicle position information 26 that describes the position of the other motor vehicle 5 driving ahead can be determined and taken into account. Ultimately, the distance information 23 is either calculated from actually recorded data and thus indicates the actual distance. Alternatively or additionally, it is possible for the distance information 23 to be predicted, i.e. that the distance information 23 provided, which indicates the distance of the motor vehicle 1 from the other motor vehicle 5 driving ahead, was only estimated. For this purpose, for example, appropriate models can be used, in particular whenever the other motor vehicle 5 can no longer be detected by the sensor device 9, for example due to a curve situation. The vehicle position information 26 can be transmitted from the other motor vehicle 5 to the motor vehicle 1, for example via vehicle-to-vehicle communication.

In a method step S5, a check is made as to whether the distance information 23 provided is smaller than the determined minimum distance information 22. If this is the case, a braking command 27 is determined for the braking system 11 of the motor vehicle 1 in a method step S6. When the braking system 11 is activated in accordance with the determined braking command 27, the speed of the motor vehicle 1 is at least reduced until the distance to the other motor vehicle 5 again corresponds to at least the minimum distance d _min . It can, for example, be undercut, i.e. the resulting distance can be greater than the minimum distance d _min . In this case, however, the motor vehicle 1 is not continuously braked, but only until, for example, an additional tolerance range in addition to the minimum distance d _min is met.

In a method step S7, the braking system 11 is operated according to the determined braking command 27. For this purpose, for example, a manual instruction can be given to a driver that he should brake the motor vehicle 1. Preferably, the braking system 11 is operated according to the determined braking command 27 partially automatically, in particular fully automatically.

The method steps described are carried out or at least initiated by the control device 10. The control device 10 can, for example, control the braking system 11 and/or the sensor device 9. If it is determined in method step S5 that the distance information 23 is greater than or equal to the minimum distance information 22, for example, no braking command 27 can be generated, but instead method steps S1 to S4 can be carried out again.

It is possible that route section information 28 is provided for the route section 6 currently traveled by the motor vehicle 1 and is taken into account when determining the movement information 18. The route section information 28 describes the route section 6, in particular a lane marking, a traffic sign and/or a usual trajectory 7 determined from the swarm data 19. This makes it particularly easy to locate the motor vehicle 1 on the route section 6, so that, for example, the partial map with the route section 6 can be reliably requested from the external computing device 13. Preferably, the method is activated at least whenever the route section 6 is curved.

In 4 a road 2 is outlined which comprises an acceleration lane 29 which, in the direction of travel 4, leads in front of the motor vehicle 1 into the lane 3 on which the motor vehicle 1 is travelling. In a method step S8, it can be checked whether the acceleration lane 29 is present and whether it leads in front of the motor vehicle 1 into its lane 3 in the direction of travel 4.

If this is the case, in a method step S9, taking into account the movement information 18 provided, a time 30 is predicted for the other motor vehicle 5 driving on the acceleration lane 29 at which it will drive into lane 3 and consequently become the other motor vehicle 5 driving ahead of the motor vehicle 1. Taking into account the self-motion information 20, the distance information 23 is predicted for the estimated time 30 and this is provided. The method steps S1 to S3 described above can be carried out before the method steps S8 to S10 described. Then, i.e. after the method step S10, the method steps S5, S6 and S7 preferably take place.

In 4 Furthermore, an eigentrajectory 31 is outlined, which is predicted for the motor vehicle 1. The individual stars in 4 indicate points along the usual trajectory 7 or the own trajectory 31. The meeting point at which the usual trajectory 7 of the other motor vehicle 5 coming from the acceleration lane 29 and the own trajectory 31 of the motor vehicle 1 are expected to intersect is sketched here with a symbol 32.

Overall, a method for predicting a braking situation to increase a safety distance to the minimum distance d _min is described. The map 15 can be used here, in which the motor vehicle 1 is located and from which a route ahead can be evaluated in the form of an electronic horizon. The map 15 includes information for future points on a drivable path (usual trajectory 7), such as a usual speed or generally the usual trajectory 7. A special case for sharp curves and sudden intersections is discussed here, in which a traffic situation could be confusing or potentially dangerous. In this, the usual speed at a specific future position for the other motor vehicle 5 is assumed in order to ultimately predict the most likely speed for the other motor vehicle 5 driving ahead. Taking into account this predicted speed of the other motor vehicle 5 and the speed of the own motor vehicle 1, the minimum distance d _min required to prevent a collision with the other motor vehicle 5 driving ahead is calculated. The usual speed can be specified in the form of a three-dimensional point (3D coordinate). This can be specified, for example, every 50 meters for a section of track ahead 6 of, for example, a total of 250 meters. The 3D coordinate specifies, for example, an expected speed for a specific location x, y in a z coordinate.

Furthermore, the minimum distance information 22 can be calculated based on the equation (10) described above. If this does not correspond to the actual distance information 23, the speed of the motor vehicle 1 is reduced, for which the determined braking command 27 is used. In connection with a coincident point between the motor vehicle 1 and the other motor vehicle 5 driving ahead on an acceleration lane 29, the position of the coincident point (symbol 32) is first determined, the usual speed for the drivable path is predicted in the electronic horizon for a certain number of meters in front of the motor vehicle 1, the own motion information 20 is taken into account and finally, if necessary, the speed of the other motor vehicle 5 is also determined, for example recorded. The minimum distance information 22 is calculated for the case in which a possible collision with the one motor vehicle is imminent, namely at time 30. The braking command 27 can then be determined, i.e. the speed of the motor vehicle 1 can be adjusted.

QUOTES INCLUDED IN THE DESCRIPTION

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

Cited patent literature

• US 20210122373 A1 [0004]
• DE 102020127855 A1 [0005]
• WO 2021103510 A1 [0006]

Claims (10)

Method for operating a braking system (11) of a motor vehicle (1), comprising: - providing (S1) movement information (18) which is stored in a map (15) and which describes a speed and/or acceleration that is usual for a section of the route (6) currently traveled by the motor vehicle (1), the movement information (18) having been determined by evaluating swarm data (19); - providing (S2) self-movement information (20) which describes a speed and/or acceleration of the motor vehicle (1); - determining (S3) minimum distance information (22) which describes a minimum distance of the motor vehicle (1) from another motor vehicle (5) driving ahead by applying a minimum distance determination criterion (21) to the provided movement information (18) and self-movement information (20); - providing (S4) distance information (23) which describes a distance of the motor vehicle (1) from another motor vehicle (5) driving ahead; - Checking (S5) whether the distance information (23) provided is smaller than the determined minimum distance information (22); - if the distance information (23) provided is smaller than the determined minimum distance information (22), determining (S6) a braking command (27) for the braking system (11) of the motor vehicle (1), wherein when the braking system (11) is activated according to the determined braking command (27), the speed of the motor vehicle (1) is at least reduced until the distance to the other motor vehicle (1) corresponds to the minimum distance; - Operating (S7) the braking system (11) according to the determined braking command (27). Procedure according to Claim 1 , wherein sensor data (24) describing the other motor vehicle (5) driving ahead are detected by means of a sensor device (9) of the motor vehicle (1) and the distance information (23) is determined by evaluating said data. Method according to one of the preceding claims, wherein the distance information (23) is determined taking into account self-position information (25) which describes a position of the motor vehicle (1) and/or vehicle position information (26) which describes a position of the other motor vehicle (5) driving ahead. Method according to one of the preceding claims, wherein the minimum distance determination criterion (21) takes into account a length of the motor vehicle (1). Method according to one of the preceding claims, wherein the minimum distance determination criterion (21) takes into account a predetermined reaction time and/or a predetermined comfort distance. Method according to one of the preceding claims, wherein route section information (28) is provided for the route section (6) currently traveled by the motor vehicle (1), which describes the route section (6), wherein the route section information (28) describes in particular a lane marking, a traffic sign and/or a usual trajectory (7) determined from the swarm data (19). Method according to one of the preceding claims, wherein the method is always activated when the route section (6) is curved. Method according to one of the preceding claims, wherein it is checked (S8) whether the route section (6) has an acceleration lane (29) which, in a direction of travel (4) of the motor vehicle (1), opens into a lane (3) in front of the motor vehicle (1) on which the motor vehicle (1) is traveling, wherein if this is the case, taking into account the provided movement information (18) for a motor vehicle (1) traveling on the acceleration lane (29) a time (30) is predicted (S9) at which the motor vehicle (1) will drive onto the lane (3), and taking into account the self-motion information (20), the distance information (23) for the estimated time (30) is predicted and provided (S10). Method according to one of the preceding claims, wherein the map (15) is provided as a partial map, which comprises at least the route section (6), by an external computing device (13) for the motor vehicle (1). Motor vehicle (1) designed to carry out a method according to one of the preceding claims.

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