DE102023204036A1 - Method and driver assistance device for executing at least one driver assistance function to support a driver when driving downhill - Google Patents

Abstract

Method for at least partially automatically carrying out at least one driver assistance function of a vehicle by means of at least one driver assistance device of the vehicle to assist a driver of the vehicle when driving downhill, comprising:- receiving environmental data, wherein the received environmental data is characteristic of an environment of the vehicle;- receiving vehicle data, in particular from at least one sensor device of the vehicle, wherein the received vehicle data is characteristic of at least one state of the vehicle;- determining a downhill driving variable based on the received environmental data and the received vehicle data, wherein the determined downhill driving variable is characteristic of a current and/or an upcoming section of the route;- determining a control variable for adapting at least one driver assistance function to be adapted as a function of the determined downhill driving variable;- at least partially automatically executing the at least one adapted driver assistance function by means of the at least one driver assistance device.

Description

The present invention relates to a method and a driver assistance device for carrying out at least one driver assistance function to assist a driver when driving downhill.

Numerous driver assistance systems for automatic longitudinal control (speed control) of vehicles are known from the state of the art. One example is adaptive cruise control (ACC). While such systems work very well when driving on flat terrain, they are less suitable for use when driving downhill, especially on steep and long downhill stretches such as on the Grossglockner.

For example, a vehicle with a heavy load and possibly a trailer is driving downhill on a mountain road. The vehicle is equipped with such an assistance system for automatic longitudinal guidance, for example with the ACC mentioned above. In the current state of the art, it is usual that when driving downhill and at a set target speed, this is constantly regulated (if the gradient is sufficiently steep) via the service brake.

As a result, the vehicle's service brake with fixed brake load distribution and the trailer's (overrun) brake drag continuously without being released and thus without reaching a cooling phase. There is also no downshifting to make maximum use of the engine brake (in the case of a combustion engine).

In extreme cases, this can lead to a high level of heat build-up and even smoke from the brakes. This places a great deal of strain on the brake components and pushes them to their design limits (high abrasion, glazing of the pads, possibly reduced braking performance). If a specified temperature of, for example, 700°C is exceeded, the automatic longitudinal guidance of the vehicle is automatically terminated or becomes passive and the driver of the vehicle is left alone in a borderline state.

From the CN 114 954 389 A A method for braking a semi-trailer is known in which an axle is selected from a plurality of axles whose braking device is to be used for braking.

From the DE 10 2021 125 205 A1 A method for controlling a hybrid vehicle drive train is known in which, in the event that no further energy can be obtained by braking the vehicle through recuperation (charge state of the energy storage device above a charge state threshold value), an internal combustion engine is started in order to enable active engine braking for at least part of the braking process.

From the US 7,630,817 B2 A method for controlling the speed of a vehicle is known which makes it possible to maintain a predetermined target speed even on downhill stretches. If the actual speed of the vehicle exceeds the predetermined target speed by more than a first predetermined speed difference, a service brake of the vehicle is activated.

From the DE 10 2008 043 777 A1 A method for braking a vehicle is known in which the gear ratio of the transmission is automatically changed during braking in order to increase the drag torque of the drive motor.

Therefore, no satisfactory solution is known from the state of the art which ensures automatic longitudinal guidance of the vehicle when driving downhill without placing unnecessary strain on the vehicle's braking systems and offering the driver the necessary comfort.

The present invention is therefore based on the object of overcoming the disadvantages known from the prior art and providing a method and a driver assistance device which enables the execution of a driver assistance function to support a driver when driving downhill.

The object is achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments and developments of the invention are the subject matter of the subclaims.

A method according to the invention for (preferably at least partially automatically and preferably fully automatically) executing at least one driver assistance function of a vehicle by means of at least one driver assistance device of the vehicle to assist a driver of the vehicle when driving downhill comprises, in one step, receiving environmental data preferably from at least one environmental detection device of the vehicle and/or particularly preferably from a source external to the vehicle, wherein the received environmental data are characteristic of an environment of the vehicle, in particular for a current and/or preferably for a section of the route ahead. In a further step Vehicle data is received from at least one sensor device of the vehicle, wherein the received vehicle data is characteristic of a state of the vehicle.

In a further step, a downhill driving variable is determined on the basis of the received environmental data and on the basis of the received vehicle data, the determined downhill driving variable being characteristic of a current and/or an upcoming section of road, particularly one that runs downhill. In a further step, a control variable for adapting at least one driver assistance function to be adapted is determined depending on the determined downhill driving variable. In a further step, the at least one adapted driver assistance function is carried out at least partially automatically and preferably fully automatically by means of the at least one driver assistance device.

In other words, it is proposed to adapt a driver assistance function in such a way that a detected vehicle environment and a state of the vehicle during downhill driving are taken into account. The proposed method offers the advantage that during downhill driving, the vehicle or the driver assistance function can be controlled in such a way that the vehicle's braking devices in particular can be protected during downhill driving.

In a preferred method, the received environmental data are characteristic of the environment of the vehicle, in particular in relation to a section of the route currently being traveled and preferably to a section of the route to be traveled in the future or ahead. A section of the route to be traveled in the future or ahead is preferably determined on the basis of navigation data. It is conceivable that such a section of the route is derived from a navigation route specified by the driver or is predicted; for example, a most likely route can be determined. For example, the vehicle is on a mountain pass with no alternative routes or branches. Alternatively or additionally, it would also be possible to determine a most likely route from historical driving data. It can preferably be assumed that the vehicle will travel on the same road at least temporarily, at least for the downhill section.

It is possible for the environmental data to be recorded by an environmental detection device in the vehicle and transmitted to the driver assistance system. Alternatively or additionally, it is also possible for the environmental data to be transmitted from a source external to the vehicle, for example from another vehicle, a remote server or part of the infrastructure (e.g. a variable message sign, a permanently installed rain sensor, etc.). This offers the advantage that the most current data can always be used.

Preferably, the environment detection device of the vehicle is a (front) camera, a radar sensor, a lidar sensor or the like. Preferably, the environment detection device is a sensor device for determining a current gradient of the road at the position of the vehicle. Preferably, a current position of the vehicle is detected, in particular by a position detection device of the vehicle, preferably via GPS. Preferably, the received environment data are characteristic of a current position of the vehicle.

In a preferred method, the received environmental data is characteristic of a gradient of the road at the detected position. In a preferred method, the received environmental data is characteristic of a section of the road ahead. It is conceivable that the environmental data is retrieved from a source external to the vehicle based on the detected position of the vehicle. The received environmental data preferably contains data relating to a gradient of the road for a section of the road to be traveled in the future or for a section of the road ahead. The environmental data is preferably provided by other vehicles or the environmental data is preferably swarm data. It would also be conceivable that the vehicle's navigation system already contains topographical maps and/or can retrieve them and that a gradient of the current section of the road and/or of a section of the road ahead is determined based on such a map.

It would also be possible to retrieve such data from a remote server, in particular a backend of the vehicle manufacturer, based on a recorded position of the vehicle and/or a predicted future position of the vehicle. It would also be conceivable for the environment detection device to record a gradient of the current section of the route and compare it with data from a topographical map of the navigation system or another source external to the vehicle. The received environment data are preferably characteristic of a gradient of the road, in particular of a gradient of a current section of the route or of a gradient of a section of the route to be traveled in the future or ahead.

In a preferred method, the environmental data are characteristic of the course of at least one section of the route. In other words, the environmental data contain data relating to a roadway width, curve radii, traffic signs, right-of-way regulations and the like. In a preferred method, the received environmental data are characteristic of at least one section of the route (current or ahead) and preferably for a large number of sections of the route. Preferably, the received environmental data are characteristic of a complete downhill ride. In other words, a downhill ride is made up of a large number of individual sections of the route and the received environmental data are characteristic of the individual sections, preferably for the entire downhill ride. It is conceivable that the environmental data for the individual sections of the route differ from one another, for example the entire downhill ride has different gradients, curve radii, traffic volumes or the like in sections. In a preferred method, at least one current and/or at least one ahead section of the route and preferably a large number of ahead sections of the route are determined and taken into account in the further method.

In a preferred method, the length of the entire downhill ride is taken into account, or the environmental data received is characteristic of the entire downhill ride. This offers the advantage that the driver assistance function (as explained in more detail below) can be adapted even better to the specific situation. For example, an adaptation for a short, very steep section could be different than for a longer, but less steep section.

In a preferred method, a threshold value for a gradient is specified or can be specified, in particular by the driver and/or by the manufacturer, and preferably each section of the route is evaluated on the basis of such a threshold value. In other words, each section of the route is evaluated as to whether it must be taken into account for the method described here, i.e. whether a gradient of the respective section of the route is above or below the threshold value. For example, for a journey on a road with a gradient below such a threshold value, the use of the engine brake or recuperation (in electric vehicles) is sufficient to regulate the speed of the vehicle to the set target speed and further actuation of a braking device of the vehicle is not necessary. Preferably, such a threshold value for the gradient is dependent on a particularly specified target speed of the vehicle and/or on a vehicle weight or the like.

If, however, a steeper stretch of road is traveled, it is necessary to activate at least one of the vehicle's braking devices in addition to using the engine brake or recuperation. Such a stretch of road must therefore be taken into account within the scope of the present invention.

Preferably, such a threshold value for the gradient of the route section is dependent on other influencing factors, in particular on the weight of the vehicle, the frictional resistance/rolling resistance of the tires of the vehicle or the road, wind conditions, weather conditions and the like. In a preferred method, a threshold value and in particular a basic setting of such a threshold value is specified by the manufacturer. For example, such a threshold value is specified for a vehicle with a standard weight, standard tires for a dry road and the like. In a preferred method, this threshold value is adaptable and in particular adaptable depending on the received environmental data and/or depending on the received vehicle data. It would also be possible for a large number of such threshold values to be specified for different scenarios, in particular by the manufacturer, and for a selection to be made from these. For example, threshold values can be specified for a journey with a fully loaded vehicle on a dry road, for a journey with a fully loaded vehicle with a trailer (with or without its own braking device on the trailer) on a wet road or the like. Preferably, such a predetermined threshold value is selected as the starting point for the further procedure.

In a preferred method, the received environmental data are characteristic of at least one environmental condition, the environmental condition being a coefficient of friction of the current or upcoming section of the route, a measure of the wetness of the current or upcoming section of the route, an outside temperature or the like. The received environmental data preferably contain meteorological data relating to a current and/or upcoming section of the route. In a preferred method, meteorological data is retrieved from a source external to the vehicle based on a detected position of the vehicle, in particular for the current and/or upcoming section of the route.

In an advantageous method, the received environmental data are characteristic of the current route section and in particular with respect to a gradient of the current route section and/or characteristic of the route section ahead, in particular with respect to a gradient of the route section ahead and/or characteristic of environmental conditions with respect to the current or ahead route section, in particular with respect to a coefficient of friction of the current or ahead route section, a wetness of the current or ahead route section and/or an ambient temperature.

In a preferred method, the vehicle data are recorded by at least one sensor device, preferably internal to the vehicle, and received by the driver assistance device. Preferably, the at least one sensor device is a mass estimator, in particular for determining/estimating a weight of the vehicle. Preferably, the at least one sensor device is a sensor device for detecting a trailer and in particular a device for estimating/detecting a weight of the trailer. Preferably, the received vehicle data are characteristic of a weight of the vehicle and in particular of a weight of a vehicle combination consisting of the vehicle and at least one trailer.

In a preferred embodiment, the at least one sensor device is a sensor device for detecting a temperature of the at least one braking device. The vehicle preferably has a plurality of braking devices and a plurality of sensor devices for detecting a temperature of the plurality of braking devices. The vehicle data is preferably data relating to a current temperature of the at least one braking device and preferably the current temperature of a plurality of braking devices. In this context, current is understood to mean the time of starting the driver assistance function or the start of the downhill journey.

In a preferred method, the received vehicle data are characteristic of a state of the vehicle, in particular of a state of at least one braking device of the vehicle. Preferably, the received vehicle data are characteristic of a state of an energy storage device of the vehicle, in particular of a state of charge or a temperature of the energy storage device.

In a preferred method, a loading state of the vehicle is detected in one step of the method. Such detection is preferably carried out by evaluating vehicle data received from a mass estimator and/or a trailer detection device.

In other words, on the one hand, data or influencing factors are recorded in relation to the environment of the vehicle, for example with regard to a gradient of the road, a condition of the road (wet, dry, coefficient of friction), a road course (curve radii, gradient, traffic control, permissible speed, etc.). On the other hand, data or influencing factors are recorded in relation to the vehicle itself, for example with regard to a weight of the vehicle, a weight of a trailer, a state of at least one braking device, in particular with regard to a temperature of the braking device, with regard to a state of charge and a temperature of the energy storage device of the vehicle and the like.

In an advantageous method, the at least one state of the vehicle is a loading state of the vehicle and/or a state of at least one braking device of the vehicle and/or a state of an energy storage device of the vehicle.

In a further step of a preferred method, an upcoming downhill stretch (ahead section of the route) is recorded and evaluated in particular with regard to its criticality. Preferably, such an evaluation is carried out on the basis of the received environmental data and/or received vehicle data and in particular on the basis of the previously mentioned data/influencing factors in relation to the vehicle and the vehicle's surroundings.

In a preferred method, a downhill driving variable is determined on the basis of the received environmental data and on the basis of the received vehicle data, the determined downhill driving variable being characteristic of a current and/or an upcoming section of the route and preferably of a plurality of upcoming sections of the route. In other words, the determined downhill driving variable is a measure of whether an adjustment of a driver assistance function, in this case an intervention in the automatic longitudinal guidance of the vehicle by intervening in at least one braking device, is required and to what extent.

For example, such a downhill driving parameter indicates that the gradient of a section of road ahead is below a threshold value as described above and below Taking into account other influencing factors such as vehicle weight, road surface conditions and the like, no deceleration of the vehicle by braking intervention is necessary, but the use of engine braking or recuperation is sufficient. In such a case, the process could be terminated. The driver of the vehicle could also be informed that automatic longitudinal guidance of the vehicle, for example by ACC, is being continued without any further measures being taken. It would also be conceivable that the driver would not be informed at all in such a case, e.g. so as not to distract or annoy him unnecessarily.

If, however, the hill start factor is such that additional intervention in the longitudinal guidance by actuating at least one braking device is/will be necessary in some form, the process can be continued, for example by activating a driver assistance system such as a hill descent assistant (driver assistance device). The terms driver assistant, driver assistance system and driver assistance device are used synonymously below.

In a preferred method, the driver assistance system is activated based on the hill start size determined. The driver assistance system is preferably activated automatically and the driver of the vehicle is particularly preferably prompted to activate the driver assistance system and/or informed of the activation. It is conceivable that the driver is informed via the HMI that a downhill stretch ahead has been detected which requires braking intervention in the longitudinal guidance of the vehicle and whether a corresponding downhill assistant should be activated to support the driver. The driver can preferably select whether he would like support when driving downhill or not.

In a preferred method, the activation of the driver assistance device (hill descent assistant) includes an adaptation of at least one driver assistance function to be adapted. This is explained using the example of the use of a driver assistance system (driver assistance device) for automatic longitudinal guidance of the vehicle, e.g. by ACC. The automatic longitudinal guidance of the vehicle by the ACC includes maintaining a target speed (specified by the driver) by means of appropriate engine and braking interventions while maintaining a specified distance from a vehicle in front. When driving downhill, the ACC in its classic mode of operation would permanently activate at least one braking device (service brake) of the vehicle if the road was on a corresponding gradient, which, as described at the beginning, would lead to a heavy load on the braking device.

In contrast, within the scope of the present invention, it is proposed to adapt a driver assistance function, in this case an intervention in the braking system of the vehicle, in order to prevent or significantly reduce such excessive loading of the braking devices. In an advantageous method, the at least one driver assistance function to be adapted is an at least partially and preferably fully automatic longitudinal guidance of the vehicle, in particular a deceleration of the vehicle by an automatic intervention in at least one braking device of the vehicle. In other words, the adaptation of the at least one driver assistance function includes an adaptation of the form and/or extent to which the at least one braking device is actuated.

In an advantageous method, the adapted driver assistance function is characteristic of a braking process in which the vehicle is decelerated by the at least one braking device, wherein at least one cooling phase is provided during the braking process, during which the at least one braking device provides a reduced braking force in order to cool the at least one braking device. The provision of a reduced braking force is understood here to mean that the at least one braking device only provides a small part of its maximum possible braking force, wherein it is also conceivable that the at least one braking device does not provide any braking force. In other words, in the at least one cooling phase, the braking device is operated in such a way that the temperature of this braking device can decrease in this phase, whether through slight actuation or through no actuation of the braking device.

In a preferred method, the temperature of the at least one braking device is reduced by 100°C, preferably by 50°C and particularly preferably by 20°C within the at least one cooling phase.

In a preferred method, the at least one driver assistance function is adapted by a control variable, wherein the control variable is determined on the basis of the determined downhill driving variable. In an advantageous embodiment, when determining the downhill driving variable, a target speed and/or a gradient of the current or upcoming section of the route and/or a state of the current or upcoming section of the route and/or a weight of the vehicle and/or a temperature ture of at least one braking device is taken into account.

Preferably, the target speed can be set and/or specified by the driver of the vehicle and particularly preferably can be specified automatically based on an applicable speed limit. It would also be conceivable that an applicable speed limit is detected by a front camera of the vehicle and the driver is informed whether a corresponding target speed should be set automatically. For example, the driver can confirm or reject such a request via the HMI (or via voice control).

In a preferred method, a temperature of at least one braking device is taken into account when determining the downhill driving variable and, particularly preferably, a temperature of a plurality of braking devices is taken into account.

In a preferred embodiment, the traffic environment of the vehicle and particularly preferably a distance to a vehicle driving ahead are taken into account when determining the downhill driving size.

In a preferred method, at least one current weather condition is taken into account when determining the downhill driving variable, in particular wetness of the current and/or upcoming section of the route.

In a preferred method, the downhill driving variable and/or the control variable for adapting the at least one driver assistance function is determined before the start of the downhill drive (start of the downhill stretch). The downhill driving variable and/or the control variable for adapting the at least one driver assistance function is advantageously adapted dynamically. In other words, the downhill driving variable or the control variable is repeatedly re-determined and adapted to a current situation, for example at a fixed time interval or depending on certain measurement parameters as explained below. In other words, the downhill driving variable/control variable is determined iteratively as soon as something changes in the relevant influencing factors, such as gradient, road surface condition, distance to the vehicle in front, permissible maximum speed and the like during the downhill drive.

In an advantageous method, the adaptation of the at least one driver assistance function includes an adaptation of at least one at least temporary intervention in the at least one braking device of the vehicle and preferably a repeated, particularly preferably interval-based or periodic intervention in the at least one braking device of the vehicle. In other words, it is proposed that the braking device of the vehicle is actuated at intervals in a pump-like manner, while the braking device is not actuated during the rest of the time, for example the brake is actuated for one second, not actuated for two seconds, then actuated again for one second, etc. This procedure causes the actual speed of the vehicle to oscillate around the predetermined target speed. In this way, a longitudinal guidance of the vehicle is achieved, which is generally known from manual downhill driving on steeper terrain. The proposed method offers the advantage that the braking device(s) is only loaded for a short time and there is enough time for the braking device(s) to ventilate or cool down. Such an embodiment could, for example, be called “commuting”.

In a preferred method, the adaptation of the at least one driver assistance function is carried out in such a way that an actual speed of the vehicle varies around a predetermined target speed during downhill driving, in particular in a preferably predetermined speed range in which the target speed lies, wherein the adaptation of the at least one driver assistance function preferably takes place as a function of at least one operating parameter or a limit value of such an operating parameter.

In a preferred method, the actual speed varies between an upper limit and a lower limit. Preferably, the upper limit is less than 150%, preferably less than 130% and particularly preferably less than 120% of the target speed. Preferably, the lower limit is higher than 80%, preferably higher than 85% and particularly preferably higher than 90% of the target speed.

In a preferred method, a first adjustment (basic adjustment) of the at least one driver assistance function is carried out at the beginning of the downhill journey and preferably at least one further adjustment of the at least one driver assistance function is carried out and particularly preferably a plurality of further adjustments of the at least one driver assistance function are carried out during the downhill journey. In other words, at the beginning of the downhill journey, a current situation is recorded (gradient of the road, weight of the vehicle/trailer combination, temperature of the brakes, road conditions, traffic environment, etc.) and a first (basic) adjustment is made. During the further journey, further adjustments are made continuously or in staggered time periods. Data is recorded and the driver assistance function is (iteratively) adjusted on the basis of this. For example, a reaction can be made to an unexpectedly high temperature of the brakes or it may have started to rain and a wet road surface can/must be taken into account. In other words, in an advantageous method, the adjustment of at least one driver assistance function takes place dynamically.

In a preferred method, the adaptation of the at least one driver assistance function, in particular the basic adaptation and/or the at least one further adaptation, includes an adaptation of a frequency of the intervention in the at least one braking device and/or an adaptation of an intensity of the intervention in the at least one braking device and/or an adaptation of a duration of the at least one intervention in the braking device. In other words, the adjustment is made as to how often, how strongly and how long the braking intervention is carried out.

In a preferred method, a change in the gradient of the road, a change in the volume of traffic, a change in the condition of the road, a change in the weather conditions and the like are taken into account when adapting the at least one driver assistance function. In other words, the at least one driver assistance function is continuously (iteratively) and/or dynamically adapted based on the current conditions.

In a preferred method, a (current) temperature of the at least one braking device is taken into account when adapting the at least one driver assistance function. This offers the advantage that the braking intervention can be adapted to a current state of the brakes. For example, if the measurement of the temperature of the brakes shows that they are still relatively cold and could be subjected to significantly greater load, an adjustment can be made in such a way that the vehicle is braked more often or is braked for a longer period of time in order to enable the driver to drive more comfortably (e.g. less oscillation around the target speed, less abrupt speed changes, etc.). On the other hand, it can also be recognized in this way that the current braking interventions are causing the temperature of the brakes to rise too much and therefore an adjustment is required so that braking should be carried out less frequently and/or for a shorter but more intensive period. In a preferred embodiment, the (current) temperature is displayed to the driver in particular via the HMI.

In a preferred method, the intensity of the intervention in the at least one braking device is adapted depending on the received environmental data and/or received vehicle data. In a preferred method, the duration of the intervention in the at least one braking device is adapted depending on the received environmental data and/or received vehicle data. In a preferred method, the frequency of the intervention in the at least one braking device is adapted depending on the received environmental data and/or received vehicle data.

Typically, when using a driver assistance system for automatic longitudinal guidance (e.g. ACC), a maximum deceleration of, for example, 3 m/s ² is specified by the manufacturer. In a preferred method, the adjustment of at least one driver assistance function includes an adjustment of a maximum permitted deceleration. Preferably, such an adjustment is carried out dynamically. In other words, a stronger deceleration (than 3 m/s ² ) can be carried out if necessary.

In a preferred method, a distance to a vehicle in front is taken into account when adapting the at least one driver assistance function. In particular, a permitted distance to a vehicle in front or a time gap to a vehicle in front is adapted dynamically. It is known from the prior art that when using an adaptive cruise control (ACC) a predetermined time gap must be maintained. In other words, a certain time distance to a vehicle in front must be maintained, which, knowing the vehicle speed, corresponds to a distance to be maintained. This is expressed, for example, in the fact that at high speeds a greater distance is maintained to the vehicle in front (to take braking distances and the like into account).

Within the scope of the present invention, it is proposed to dynamically adapt such a time gap, which is specified by the manufacturer, for example to increase it. This offers the advantage that a greater distance is maintained from the vehicle in front, which allows a larger range for the above-described oscillation of the actual speed of the vehicle, since when an upper maximum speed is reached, at which a braking intervention is carried out, the vehicle comes closer to the vehicle in front. This allows a greater deviation from the target speed without getting too close to the vehicle in front.

As described above, it is possible to periodically apply the brakes in predetermined and special adjustable time intervals. In a further preferred embodiment, such an intervention in the at least one braking device is initialized as a function of a speed of the engine and/or an actual speed of the vehicle and/or a distance to a vehicle in front.

In an advantageous method, the at least one driver assistance function is adapted in such a way that the vehicle is decelerated when a limit value of at least one operating parameter is exceeded or not reached.

In an advantageous method, the limit value of the at least one operating parameter is an upper limit value of a permissible rotational speed and/or an upper limit value of a permissible actual speed and/or a lower limit value of the distance to a vehicle driving ahead.

In other words, braking intervention always occurs when the engine speed exceeds a certain value. In a preferred method, an upper limit is specified, and if this upper limit is exceeded, intervention is carried out in the at least one braking device. The upper limit is preferably adjustable, in particular by the driver. In a preferred method, this upper limit depends on the type of engine in the vehicle. For example, such an upper limit for a gasoline combustion engine can be 6000 or 6500 rpm, and for a diesel combustion engine it can be 4000 or 4500 rpm.

In a preferred method, a lower limit is specified, and if this lower limit is undershot, the intervention in the at least one braking device is terminated. The lower limit is preferably adjustable, in particular by the driver. In a preferred method, this lower limit depends on the type of engine in the vehicle. For example, such a lower limit could be 2000 rpm for a gasoline combustion engine and 1500 rpm for a diesel combustion engine. In other words, it is proposed that the braking points, i.e. the points at which the automatic intervention in the braking device is carried out, are coupled to a speed of the engine, i.e. if an upper speed limit is exceeded, the vehicle is braked until a lower speed limit is reached and then the vehicle can be accelerated again (by the downhill force) until the upper speed limit is reached and during this time the brake can cool down/ventilate. The braking points are preferably selected depending on the upper and lower limit of the engine speed.

In an advantageous method, braking points are determined at which the intervention of the at least one braking device takes place, wherein a rotational speed of the engine, preferably an upper limit of the rotational speed of the engine, is taken into account when determining the braking points.

Preferably, the distance between the upper and lower limit for the engine speed depends on a selected gear and/or on a specified target speed and/or on a distance to a vehicle in front. If, for example, only a relatively small distance to a vehicle in front is available, the full speed range between the two limit values cannot be optimally utilized. In such a situation, it is advisable, for example, to raise the lower limit, since the engine braking effect is greater at higher speeds. Preferably, the engine speed and the current actual speed of the vehicle are directly related via a selected gear. In this case, it can be provided that a change of gear is necessary in order to be able to better utilize the engine braking effect.

In a preferred method, the adaptation of the at least one driver assistance function includes the selection of a gear. It is conceivable that a gear is selected automatically (with an automatic transmission) or the driver of the vehicle is prompted to engage a different, in particular lower gear (with a manual transmission). In the case of an electrically powered vehicle, a recuperation level of the vehicle can be selected or the driver can be prompted to do so.

Alternatively or in addition to the above-described selection of the braking points depending on the limit values of the engine speed, it is proposed to specify analog limit values for a speed of the vehicle. Such limit values can preferably be specified by the manufacturer or preferably adjusted by the driver. As described above, a target speed is selected in particular by the driver or is specified automatically. As described above, the actual speed of the vehicle oscillates around the target speed when the method is used according to the embodiment(s) described above. For example, a target speed of 60 km/h is specified and the actual speed oscillates between 70 and 55 km/h. In a preferred method, an upper limit is specified for the actual speed, and if this upper limit is exceeded, intervention in the at least one braking device is triggered. In a preferred method, a lower limit is specified for the actual speed, and if this lower limit is undershot, intervention in the at least one braking device is terminated. In an advantageous method, an upper limit of the actual speed (of the vehicle) is taken into account when determining the braking points.

It is also conceivable that the upper and/or lower limit of the actual speed can be adjusted by the driver of the vehicle. This offers the advantage that, for example, a nervous driver chooses a small distance between the two limits because he feels safer with a small fluctuation in speed. In another scenario, for example, the driver can set the upper limit of the actual speed to be above a permissible maximum speed and in particular how far above it, for example that a permissible maximum speed may only be exceeded by a maximum of 10 km/h or that the actual speed should always be below the permissible maximum speed.

In a preferred method, it is possible to link the individual procedures described above with one another. In a preferred method, when adapting the at least one driver assistance function, in particular when intervening in the at least one braking device, the limit values of the engine speed and/or the limit values of the actual speed and/or a limit value for a distance to a vehicle in front are taken into account, wherein in particular when determining the braking points, an upper limit value for the engine speed and/or the actual speed and/or a lower limit value for a permissible distance to a vehicle in front are taken into account.

In other words, it is possible that all of these factors or parts of them play a role together. It is conceivable that each of these limits triggers the activation and/or termination of braking intervention. For example, braking intervention always begins when the upper limit of the engine speed is exceeded, even if the upper limit of the actual speed has not yet been reached. Likewise, braking intervention always begins when the upper limit of the actual speed is exceeded, even if the upper speed limit has not yet been reached. Furthermore, braking intervention always begins when a permissible distance to a vehicle in front is undercut, regardless of whether the upper speed limit or the upper actual speed limit has been exceeded.

It would also be possible to offer the driver of the vehicle a choice between different driving modes, where these driving modes differ, for example, in pairs in at least one of the above-mentioned limit values or parameters. For example, at the start of a downhill journey, the driver of the vehicle can select a driving mode that best suits his needs (e.g. rather anxious). It would also be conceivable that a selection of such a driving mode is stored in a user profile of the driver and no manual selection is necessary. This offers the advantage that in such a situation the driver does not have to decide spontaneously which mode he wants to select, but can do so in a calm situation (e.g. when the vehicle is stationary).

In a further embodiment of the present invention, it is proposed to control more than one braking device of the vehicle, in particular independently of one another. In other words, it is proposed to control a braking device of the front axle and a braking device of the rear axle individually. Such an embodiment could be described as "blending". While in the embodiment described above the actual speed of the vehicle "oscillates" around a predetermined target speed, in the embodiment of the method according to the invention described below an actual speed can be adjusted closer to the target speed.

In a preferred method, the vehicle has at least two and preferably more than two braking devices, wherein the at least two braking devices can be controlled or operated independently of one another. This is preferably a braking device on the front axle and a braking device on the rear axle. In a preferred method, the at least two braking devices are operated together at least temporarily and preferably separately from one another at least temporarily. In other words, it is possible to operate both braking devices simultaneously, but it is also possible to operate only one of the two braking devices alone. This offers the advantage that the other braking device can ventilate/cool down during this time.

In an advantageous embodiment, the vehicle has at least two braking devices which operate independently of one another can be controlled and the adaptation of the at least one driver assistance function is carried out in such a way that at least temporarily only one of these two braking devices causes a deceleration of the vehicle.

In a preferred method, a required total braking force is determined to regulate the actual speed. Preferably, the environmental data and/or vehicle data described above are taken into account when determining the total braking force. Preferably, the total braking force is determined on the basis of the determined downhill driving size. In other words, a total braking force is determined on the basis of the road gradient, a road course, a road surface condition, a vehicle weight, a condition of the vehicle, a condition of the brakes, a condition of the engine, a condition of the energy storage device, etc., which is necessary to regulate the speed of the vehicle (as accurately as possible) to the specified target speed.

In other words, in comparison to the embodiment described above, in which the brake is only operated in a pumping/interval manner and therefore a significantly greater braking force is required during this time (braking intervention leads to a reduction of the actual speed below the target speed), it is proposed at this point to determine and apply a total braking force which is required to maintain the target speed.

In the current state of the art, this is done, for example, when using a conventional ACC system, but if the road gradient is high enough, the vehicle's braking system is permanently activated (dragging brakes), which leads to the problems mentioned above.

Therefore, within the scope of the present invention, it is proposed that the determined total braking force is not provided solely by the actuation of the service brake (braking devices as a whole), but rather that it is provided through various contributions or that the total braking force is divided between various components (braking devices of the vehicle) in such a way that, in total, the braking devices of the vehicle are protected and overloading/overheating can be effectively prevented, but sufficient braking force is still provided to regulate the vehicle to the specified target speed.

In an advantageous method, a variable braking force distribution is provided within the braking process, in which at least one braking phase and at least one cooling phase are distributed proportionately between at least two braking devices. In other words, it is proposed that each of the two braking devices can be operated with a variable strength and a braking force provided can be operated between 0 and 100% of the maximum possible braking force. For example, at one point in time, the braking force required to brake the vehicle is provided solely by the first braking device while the second braking device can cool down, while at another point in time the second braking device provides 100% of the required braking force and the first braking device can cool down. It would also be conceivable that any proportions are provided by the two braking devices as part of the braking force distribution.

In a preferred embodiment, the total braking force is provided by at least two braking devices of the vehicle, which can be operated independently of one another, and/or in particular additionally by a drive device of the vehicle. In other words, the braking force is provided by braking devices of the vehicle (braking devices of the front and rear axles) and the vehicle's engine (taking the vehicle data into account), the latter by an engine brake (combustion engine) or by recuperation (electric motor).

In a preferred method, the total braking force is provided at least temporarily by only one braking device of the vehicle. In other words, it is proposed that at least temporarily only the braking device of the front axle is actuated and at other times only the braking device of the rear axle is actuated. Furthermore, it would also be possible to operate both braking devices simultaneously, but with reduced intensity. In a preferred method, the total braking force is provided by the at least two braking devices of the vehicle.

In a preferred method, the total braking force is made up of the contributions of at least two braking devices of the vehicle. In a preferred method, when determining the total braking force, a braking force provided by the drive device of the vehicle, in particular by an engine brake (internal combustion engine) or by recuperation (electric motor), is taken into account. In a preferred embodiment, when determining the total braking force to be provided by the two braking devices, a braking force provided by the drive device is taken into account. In other words, the engine brake in the case of an internal combustion engine or the In the case of an electric motor, recuperation makes a certain contribution which does not have to be provided by the vehicle's at least two braking systems.

While the engine brake of a vehicle with a combustion engine makes a more or less fixed contribution to the braking force depending on the gear selected and is limited, especially when driving on a route with a steep gradient, in the case of an electrically powered vehicle the braking force provided by recuperation and thus the energy recovered can be changed. In other words, in the case of an electric vehicle the proportion through recuperation can be further increased, whereby the braking force to be provided by the braking devices can be (significantly) reduced. Due to this reduced requirement, it is now possible to distribute the required braking force by individually controlling the braking device on the front axle and the rear axle in such a way that the braking devices can be prevented from heating up too much.

In an advantageous method, a charge state of the energy storage device and/or an efficiency of the drive device and/or a load situation of the drive device and/or torque limits of the drive device are taken into account when determining the total braking force.

The present invention is further directed to a, preferably processor-based, driver assistance device for carrying out at least one driver assistance function of a vehicle by means of at least one driver assistance device of the vehicle to assist a driver of the vehicle when driving downhill, wherein the driver assistance device is suitable and intended to receive environmental field data from preferably at least one environmental detection device of the vehicle and/or preferably from a source external to the vehicle, wherein the received environmental data are characteristic of an environment of the vehicle, in particular for a current and/or preferably for a section of the route ahead.

Furthermore, the driver assistance device is suitable and intended to receive vehicle data, in particular from at least one sensor device of the vehicle, wherein the received vehicle data are characteristic of at least one state of the vehicle and furthermore the driver assistance device is suitable and intended to determine a downhill driving variable on the basis of the received environmental data and on the basis of the received vehicle data, wherein the determined downhill driving variable is characteristic of a current and/or an upcoming section of the route, in particular a downhill section.

According to the invention, the driver assistance device is suitable and intended to determine a control variable for adapting at least one driver assistance function to be adapted as a function of the determined downhill driving variable and to adapt the at least one driver assistance function. In a preferred embodiment, a data transmission device is provided for transmitting (sending/receiving) environmental data. The driver assistance device is preferably set up to receive environmental data from a source external to the vehicle (server, other vehicles, parts of the infrastructure) and/or to transmit it to a location external to the vehicle such as other vehicles or a remote server.

Furthermore, a display device is preferably provided in the vehicle, via which information can be output to the driver of the vehicle. In a preferred embodiment, the display device is an HMI.

Preferably, the driver assistance device is designed, suitable and/or intended to carry out the method described above for carrying out at least one driver assistance function as well as all method steps already described above in connection with the method individually or in combination with one another. Conversely, the method (in particular according to a preferred embodiment) can be equipped with or use all features described in the context of the driver assistance device individually or in combination with one another.

The present invention is further directed to a vehicle, in particular a motor vehicle, comprising a driver assistance device as described above in accordance with an embodiment. The driver assistance device is preferably a (fixed, in particular non-destructively removable) component of the vehicle.

The vehicle may in particular be a (motorised) road vehicle. In addition to a road vehicle, the vehicle may also be an air taxi, an aircraft and another means of transport or another type of vehicle, for example an aircraft, watercraft or rail vehicle.

A vehicle may be a motor vehicle, in particular a motor vehicle controlled by the driver himself (“Driver only”), a semi-autonomous, autonomous (for example, autonomy level 3 or 4 or 5 (of the SAE J3016 standard)) or self-driving motor vehicle. The autonomy level 5 refers to fully automated vehicles.

The present invention is further directed to a computer program or computer program product comprising program means, in particular a program code, which represents or encodes at least individual or multiple method steps of the method according to the invention individually or in combination with one another and preferably one of the described preferred embodiments and is designed to be executed by a processor device.

The present invention is further directed to a non-volatile memory, in particular a data memory, on which at least one embodiment of the computer program according to the invention or a preferred embodiment of the computer program is stored.

Further advantages and embodiments can be seen from the attached drawings.

• 1 ein Fahrzeug gemäß einer Ausführungsform der vorliegenden Erfindung;
• 2a-c Diagramme in Bezug auf eine automatische Geschwindigkeitsregelung gemäß dem Stand der Technik;
• 3a,b Diagramme in Bezug auf eine automatische Geschwindigkeitsregelung gemäß dem Stand der Technik;
• 4a,b Diagramme in Bezug auf eine automatische Geschwindigkeitsregelung gemäß einer Ausführungsform der vorliegenden Erfindung;
• 5a-c Diagramme in Bezug auf eine automatische Geschwindigkeitsregelung gemäß einer weiteren Ausführungsform der vorliegenden Erfindung.

In it show

• 1 a vehicle according to an embodiment of the present invention;
• 2a -c diagrams relating to automatic cruise control according to the state of the art;
• 3a ,b Diagrams relating to an automatic cruise control according to the state of the art;
• 4a ,b are diagrams relating to an automatic cruise control according to an embodiment of the present invention;
• 5a -c Diagrams relating to an automatic cruise control according to another embodiment of the present invention.

1 shows schematically a vehicle 1 according to an embodiment of the present invention. The vehicle 1 has a driver assistance device 10 according to an embodiment of the present invention. The vehicle 1 also has a position detection device 12 for determining a position of the vehicle 1, for example via GPS. The vehicle 1 has at least one environment detection device 16 for detecting environment data in relation to the environment of the vehicle. The environment detection device 16 is preferably a front camera, a radar sensor, a lidar sensor of the vehicle or the like. The vehicle also has a sensor device 18 for detecting vehicle data. For example, this sensor device 18 is a sensor for determining a load of the vehicle, for determining a trailer load, for determining a state of a braking device, for determining a temperature of a braking device or the like.

The vehicle has a data transmission device 14 which is set up to send and receive data, in particular to send or receive data to other vehicles or a remote server. It is possible that the environmental data used is recorded by the environmental detection device 16 of the vehicle 1 or is received from an external source via the data transmission device 14. It is conceivable that the environmental data is transmitted from other vehicles (car2car communication) or from parts of the infrastructure, for example from a traffic sign which indicates a dangerous gradient on a route ahead.

In the 2a -c are diagrams relating to automatic cruise control according to the state of the art, for example by means of an adaptive cruise control (ACC). In 2a a diagram 20 is shown which shows a curve of the engine speed 22 and a selected gear 24. In other words, the same gear (here gear 2) is kept at a constant speed over the period under consideration, which results in a constant speed curve (cf. 2c Graph 36).

While when driving on level ground, speed control is typically achieved by controlling the vehicle’s acceleration (engine intervention), when driving downhill, it is achieved by intervening in the brakes. 2b Diagram 26 shows that a constant braking force is applied here (graph 28). Continuous actuation of the braking system inevitably leads to a more or less significant increase in the temperature of the braking system, as is illustrated by graph 32. If a critical temperature 30 of, for example, 700°C is exceeded, the assistance system is deactivated (intersection 34) and further automatic speed control is not possible. Exceeding this temperature can, under certain circumstances, lead to a severe impairment of the braking force and to high material wear.

In the 3a ,b diagrams 40 and 42 show schematically a progression of the speed and the brake position according to the state of the art, for example by using the ACC described above. Here, a speed is constantly regulated, while the brake is continuously in a closed position (sliding position).

In the 4a ,b shows a first embodiment of the method according to the invention. In 4a a curve of a target speed 52 is shown, which can either be set by the driver of the vehicle 1 or can be set automatically, for example on the basis of a detected speed limit or a detected road gradient. In order to relieve the braking device of the vehicle 1, it is proposed in this embodiment to brake in a "pumping" manner, as is known from manual driving. This leads to an actual speed oscillating around the specified target speed (graph 54). This is done as in 4b shown by an intermittent actuation of the braking device. For example, in the time periods t ₁ , t ₃ and t ₅ the brake is automatically actuated, while the braking device can cool down in the time periods t ₂ , t ₄ and t ₆ .

It is conceivable that the times at which the braking device is activated and the duration and strength of the braking device activation depend on numerous parameters, for example the distance to a vehicle in front, the gradient of the road or the current temperature of the braking device or another section of road ahead. If the distance to a vehicle in front is sufficiently large, a further braking step can only be carried out later than if the vehicle in front is driving directly in front of the vehicle. It is also possible that a particularly steep road requires the braking device to be activated more frequently and/or for longer.

In the 5a -c shows the application of a further embodiment of the method according to the invention. While in the previously mentioned embodiment ( 4a ,b) the braking device is controlled as a whole, in the further embodiment it is proposed to control a braking device of the front axle and a braking device of the rear axle individually. In 5a The diagram 60 shows the course of the speed of the motor 62, a course of the speed 64 and a selected gear 66. This embodiment offers the advantage that a target speed can be regulated relatively precisely, while in the embodiment described above the predetermined target speed is oscillated around. 5a shows a constant curve of the engine speed, the speed and the selected gear.

In 5b In the diagram 70, a progression of the braking force distribution is shown, while the dotted lines 72 and 74 indicate the limits of the braking force distribution, namely the reference symbol 72 indicates the case in which the braking device of the rear axle is controlled at 100% and the reference symbol 74 indicates the case in which the braking device of the front axle is controlled at 100%. Such a change in the control of the braking device of the rear axle and the front axle offers the advantage that in the meantime the other braking device has time to cool down.

For example, in period t ₁ only the brake system on the front axle is activated so that the brake system on the rear axle can cool down. In period t ₂ the brake system on the rear axle is increasingly loaded, while the brake system on the front axle is increasingly relieved until only the brake system on the rear axle is used in period t _3. After a further transition phase t _4, for example, both brake systems can be loaded evenly in period t _5. After a further transition period t ₆ , only the brake system on the front axle is activated in period t _7. During this period the brake system on the rear axle can cool down again.

5c shows the application of a further embodiment of the method according to the invention, which in addition or alternatively to the method described in connection with the 5b described embodiment. A distribution of the braking force is shown, whereby this is divided into a hydraulic braking force (sum of the braking forces of the braking devices of the front and rear axles) and a braking force resulting from electrical recuperation. It is proposed that part of the braking effect is not achieved by the hydraulic braking devices of the front and rear axles, but by recuperation of an electric or at least partially electric vehicle. In the period t _1a , for example, the braking effect is achieved exclusively by the mechanical braking devices (hydraulic total braking force at 100%), while in the periods t _2a , t _3a , t _4a up to the period t _5a , the hydraulic total braking force is reduced and an increasingly larger proportion of the braking force is provided by recuperation of the electric motor. For example, if no further energy can be provided by recuperation are recovered, the braking effect can be quickly switched back to an actuation of the hydraulic braking force of the braking systems of the front and rear axles within a period t _6a by means of recuperation.

list of reference symbols

1

vehicle

10

driver assistance device

12

position detection device

14

data transmission device

16

environment detection device

18

sensor device

20

Course of engine speed and gear selection State of the art (SdT)

22

Course of gear selection SdT

24

Speed SdT curve

26

Brake force and temperature curve SdT

28

Brake force curve SdT

30

critical temperature

32

Temperature trend SdT

34

ejection assistance system, critical point

36

Course Speed SdT

40

Course Speed SdT

42

Course of brake position SdT

50

course speed

52

Course of target speed

54

actual speed curve

56

brake position progression

60

Course of rpm, speed

62

speed curve

64

course speed

66

course of gear selection

70

brake force distribution curve

72

Brake force curve rear axle 100%

74

Front axle braking force curve 100%

80

brake force distribution curve

82

hydraulic total braking force

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

• CN 114954389 A [0006]
• DE 102021125205 A1 [0007]
• US 7630817 B2 [0008]
• DE 102008043777 A1 [0009]

Claims (10)

Method for at least partially automatically executing at least one driver assistance function of a vehicle by means of at least one driver assistance device of the vehicle to assist a driver of the vehicle when driving downhill, comprising: - receiving environmental data, wherein the received environmental data is characteristic of an environment of the vehicle; - receiving vehicle data, in particular from at least one sensor device of the vehicle, wherein the received vehicle data is characteristic of at least one state of the vehicle; - determining a downhill driving variable based on the received environmental data and the received vehicle data, wherein the determined downhill driving variable is characteristic of a current and/or an upcoming section of the route; - determining a control variable for adapting at least one driver assistance function to be adapted depending on the determined downhill driving variable; - at least partially automatically executing the at least one adapted driver assistance function by means of the at least one driver assistance device. procedure according to claim 1 , characterized in that the at least one driver assistance function to be adapted is an at least partially and preferably fully automatic longitudinal guidance of the vehicle, in particular a deceleration of the vehicle by an automatic intervention in at least one braking device of the vehicle. Method according to the preceding claim, characterized in that the adapted driver assistance function is characteristic of a braking process in which the vehicle is decelerated by the at least one braking device, wherein at least one cooling phase is provided during the braking process, within which the at least one braking device provides a reduced braking force for cooling the at least one braking device. Method according to at least one of the preceding claims, characterized in that when determining the downhill driving variable, a target speed and/or a gradient of the current or preceding route section and/or a condition of the current or preceding route section and/or a weight of the vehicle and/or a temperature of at least one braking device and/or a distance to a preceding vehicle is taken into account. Method according to at least one of the preceding claims, characterized in that the adaptation of the at least one driver assistance function is carried out in such a way that a deceleration of the vehicle is carried out when a limit value of at least one operating parameter is exceeded or not reached. Method according to the preceding claim, characterized in that the limit value of the at least one operating parameter is an upper limit value of a permissible rotational speed and/or an upper limit value of a permissible actual speed and/or a lower limit value of the distance to a vehicle driving ahead. Method according to at least one of the preceding claims, characterized in that the vehicle has at least two braking devices which can be controlled independently of one another and the adaptation of the at least one driver assistance function takes place in such a way that at least temporarily only one of these two braking devices causes a deceleration of the vehicle. Method according to at least one of the preceding claims, characterized in that a variable braking force distribution is provided within the braking process, in which at least one braking phase and at least one cooling phase are distributed proportionally between the at least two braking devices. Driver assistance device for carrying out at least one driver assistance function of a vehicle by means of at least one driver assistance device of the vehicle to assist a driver of the vehicle when driving downhill, wherein the driver assistance device is suitable and intended to receive environmental field data, wherein the received environmental data are characteristic of an environment of the vehicle and is suitable and intended to receive vehicle data from at least one sensor device of the vehicle, wherein the received vehicle data are characteristic of at least one state of the vehicle, the driver assistance device is suitable and intended to determine a downhill driving variable on the basis of the received environmental data and on the basis of the received vehicle data, wherein the determined downhill driving variable is characteristic of a current and/or an upcoming section of the route, characterized in that the driver assistance device is suitable and is intended to determine a control variable for adapting at least one driver assistance function to be adapted as a function of the determined downhill driving variable and to adapt the at least one driver assistance function. Vehicle with a driver assistance device according to the preceding claim.

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