Method for predicting lateral dynamic stability behavior of current vehicle configuration of vehicle

Abstract

The invention relates to a method (1) for predicting a lateral dynamic stability behavior of a current vehicle configuration (3) of a vehicle (300), comprising: ascertaining (11) two or more geometric features (5) of the current vehicle configuration (3); ascertaining (13) two or more load characteristics (7) of the current vehicle configuration (3); generating (19) a uniquely processed vehicle model (21) of the current vehicle configuration (3) from a vehicle base model (22) of the vehicle (300) using the geometric features (5) and the load features (7); predicting (33) a dynamic characteristic of the current vehicle configuration (3) using the uniquely processed vehicle model (21); and defining (37) at least one driving dynamic limit value (35) for the vehicle (300) on the basis of a dynamic characteristic of the current vehicle configuration (3). The invention also relates to a driver assistance system (200), a vehicle (300) and a computer program product.

Description

Technical Field

[0001] The invention relates to a method for predicting the lateral dynamic stability behavior of a vehicle in its current vehicle configuration. The invention also relates to a driver assistance system for a vehicle, a vehicle and a computer program product. Background Art

[0002] An experienced professional driver can already tell based on his experience whether the vehicle is displaying behavior that threatens stability. The driving style selected by a skilled driver is adapted to the existing boundary conditions and enables safe control of the vehicle. However, the experience required to correctly judge the current situation usually only comes after years of practice.

[0003] In contrast, an inexperienced driver is unable or only partially able to make a correct judgment of the vehicle behavior to be expected. Even so-called virtual drivers who control an automatically driven vehicle or who take on subtasks when controlling an automatically driven vehicle have not been able to ensure a correct judgment of the stability behavior so far. This brings the risk of a driving style that is not suitable for the current vehicle configuration and therefore also an increased risk of accidents. Known stability systems only stabilize the vehicle passively, that is, only when there is a significant deviation between the target behavior and the actual behavior of the vehicle. Therefore, traditional stability systems only intervene within the boundary range, so that compared with stable driving, significantly more space is required for adjusting to leave the unstable state. Therefore, there is a need to reliably predict the lateral dynamic instability of the vehicle and avoid it by adapting the driving style when necessary.

[0004] DE 10 2007 008 486 A1 discloses a method for regulating the driving stability of a commercial vehicle during a lane change maneuver, wherein the pressure for each brake of the commercial vehicle is determined as a function of a plurality of input conditions, so that the driving stability is improved by wheel-specific brake interventions, the method comprising the steps of predicting an unstable driving behavior when changing from a first turning path to a second turning path, and applying brake pressure to the wheel on the inside of the curve when the unstable driving behavior is predicted. In the disclosed method, the unstable driving behavior is detected taking into account a first condition, which comprises the steps of determining a friction value required for stabilizing the commercial vehicle, determining an estimated friction value that is fully utilized, comparing the estimated friction value with the friction value required for stabilizing the commercial vehicle, and confirming that the first condition is met when the estimated friction value is lower than the friction value required for stabilizing the commercial vehicle. However, in the method according to DE 10 2007 008 486 A1, the prediction of unstable driving behavior takes place only at the transition from the first curve path to the second curve path, and thus a response to an inappropriate driving style or a dangerous situation occurs. Summary of the invention

[0005] The object of the present invention is to reliably predict the transverse dynamic stability behavior of a vehicle's current vehicle configuration and thus to enable adapted vehicle guidance.

[0006] In a first aspect, the task is solved by a method for predicting the lateral dynamic stability behavior of a current vehicle configuration of a vehicle, the method comprising the following steps: obtaining two or more geometric characteristics of the current vehicle configuration; obtaining two or more load characteristics of the current vehicle configuration; generating a uniquely processed vehicle model of the current vehicle configuration based on a vehicle basic model of the vehicle using the geometric characteristics and the load characteristics; predicting the dynamic characteristics of the current vehicle configuration using the uniquely processed vehicle model; and limiting at least one driving dynamics boundary value for the vehicle based on the dynamic characteristics of the current vehicle configuration.

[0007] Particularly preferably, the vehicle is a commercial vehicle. A commercial vehicle (Nfz), i.e. a commercial motor vehicle (Nkw), is a motor vehicle which, according to its type of construction and equipment, is intended for transporting people or goods, or for towing a trailer, but is not a passenger car or a motorcycle, but is, for example, a bus, a truck, a tractor or a crane truck. Within the scope of the present disclosure, a commercial vehicle can be a single commercial vehicle, which is also usually referred to in English as a rigid vehicle, or a towing vehicle group consisting of a towing vehicle and one or more trailer vehicles. Typical examples of towing vehicle groups include saddle tractors and semitrailers.

[0008] The method according to the invention makes it possible to prevent instabilities that could have been predicted in the case of an accurate analysis of the current vehicle configuration and could therefore be forwarded to the driver in a limited form. The invention makes use of the knowledge that the lateral dynamic stability behavior of the vehicle is greatly influenced by the current vehicle configuration. By taking into account the geometrical and load characteristics, the method according to the invention makes it possible to reliably predict the dynamic behavior of the vehicle in its current configuration. If the geometrical and load characteristics of the current vehicle configuration are known, the driving dynamics boundary values ​​of the current vehicle configuration can be inferred therefrom. Compliance with the driving dynamics boundary values ​​ensures safe and stable driving of the vehicle during normal operation. The intervention of conventional stability systems, which are usually referred to as electronic stability control systems (ESC) or electronic stability programs (ESP®), is minimized because the vehicle no longer reaches the intervention threshold of these systems during operation. However, it should be understood that in exceptional cases, such as when the tires of the vehicle are damaged, the vehicle may still become unstable despite compliance with the driving dynamics boundary values.

[0009] The current vehicle configuration relates to both vehicle-specific aspects and load-specific aspects. In addition, the current vehicle configuration may also include the friction coefficient between the vehicle and the road surface on which the vehicle is traveling. The geometrical features represent the geometrical dimensions of the vehicle. In addition to or instead of the geometrical dimensions, the geometrical features preferably also contain a quantitative description (e.g. the number of axles of the vehicle). The geometrical features are in particular geometrical parameters that define the driving dynamics of the vehicle, such as the wheelbase of the vehicle, the axle distance between the axles of the vehicle, the track width of the vehicle, the distance between the coupling point of the rear axle of the vehicle and the trailer, and / or the design of the trailer vehicle (e.g. a full trailer or a center axle trailer). Compared to a vehicle with a center axle trailer or semitrailer, a vehicle with a full trailer has additional folding points, so that the vehicle configuration with a full trailer is often more critical in terms of dynamic characteristics than a vehicle with a center axle trailer or semitrailer. The design of the trailer can be taken into account with the help of the geometrical features.

[0010] In addition to the geometric characteristics of the vehicle, the current vehicle configuration also includes a load characteristic. The load characteristic represents the loads acting on the vehicle, which may come from the vehicle's own weight and may come from the vehicle's load. Therefore, the current vehicle configuration of an unloaded vehicle is different from the current vehicle configuration of the same vehicle in a loaded state. The load characteristic may preferably be or include wheel loads, axle loads, total vehicle mass, mass of a vehicle part and / or the position of the center of gravity of the vehicle or of a vehicle part. Furthermore, preferably, the load characteristic may also include data representing wheel loads, axle loads, total vehicle mass and / or mass of a vehicle part.

[0011] The prediction of the dynamic characteristics of the current vehicle configuration is based on the model and is therefore forward-looking. The behavior of the vehicle can therefore be predicted. In a preferred design, the vehicle model is a single wheel track model of the vehicle. Preferably, the vehicle base model of the vehicle is a parameterized model. The model can be personalized by setting the characteristics of the current vehicle configuration as parameter values. The vehicle base model can also preferably be personalized in the following way, that is, the towing vehicle model is supplemented by a trailer vehicle model corresponding to the current vehicle configuration. The vehicle base model can preferably be pre-stored in the vehicle or stored remotely from the vehicle. Alternatively, however, the vehicle base model can also be generated during the method, preferably by the control unit.

[0012] The dynamic characteristics may preferably include the yaw behavior of the towing vehicle, the tuck behavior of the trailer vehicle or the trailer vehicles, the natural angular frequencies of the vehicles and / or the damping of the vehicle or of a dynamic system formed by the vehicle.

[0013] Another recognition on which the present invention is based is that in modern vehicles, a large number of geometrical and load characteristics are known, because these geometrical and load characteristics are processed in a variety of ways in different vehicle systems (such as electronic brake systems). Therefore, the method can be carried out particularly economically, especially because separate sensor devices can often be omitted. The steps of the method are preferably implemented by a control unit. The control unit is preferably a brake control unit of the brake system of the vehicle. Many of these geometrical and / or load characteristics (for other purposes) are already provided and / or processed on the brake control unit of a modern brake system, so that these characteristics may already exist at the brake control unit. In addition, a large amount of sensor data from the sensors of the vehicle is often present on the brake control unit. By configuring the brake control unit to implement the method, the functions corresponding to the method can be particularly easily integrated into the vehicle.

[0014] In a first preferred embodiment of the method, generating a unique vehicle model of the current vehicle configuration includes: using geometric features and load features, approximately calculating the mass distribution of the current vehicle configuration in at least one vehicle longitudinal direction; and using the geometric features and the approximately calculated mass distribution, generating a unique vehicle model of the current vehicle configuration based on a vehicle base model of the vehicle. The mass distribution of the vehicle can be inferred from the load features and the geometric features. This mass distribution allows conclusions to be drawn about the position of the center of gravity of the vehicle in the longitudinal direction of the vehicle or includes conclusions about the position of the center of gravity of the vehicle in the longitudinal direction of the vehicle. A known center of gravity position enables a particularly accurate prediction of the dynamic characteristics. The quality of the approximate calculation depends on the quality and / or number of the features provided. In the case of a large number and quality of features, the approximately calculated mass distribution of the current vehicle configuration can be very close to the real existing mass distribution of the current vehicle configuration or correspond to the real existing mass distribution. If only limited information is available, the mass distribution can be approximately determined using the lever law. It should be understood that, for example, if axle load information is only provided for the axles of the vehicle, the mass distribution of the current vehicle configuration can also be inferred using the load features.

[0015] Preferably, the driving dynamics boundary value is the maximum permissible vehicle speed, the maximum permissible lateral acceleration, the maximum permissible vehicle acceleration, the maximum permissible vehicle deceleration, the maximum permissible steering angle gradient, the maximum permissible steering frequency or the minimum permissible turning radius of the vehicle. With the method according to the invention, a plurality of driving dynamics boundary values ​​can also be defined for the vehicle, so that, for example, the maximum permissible vehicle speed is defined as the first driving dynamics boundary value and the maximum permissible lateral acceleration is defined as the second driving dynamics boundary value. The maximum permissible vehicle speed is not necessarily the speed at which the vehicle immediately becomes unstable once it is exceeded by the vehicle. On the contrary, instability will only occur if there is a corresponding stimulus, for example, when an evasive action is required. Preferably, the maximum permissible vehicle speed is selected in such a way that it is ensured that the vehicle still drives stably at this vehicle speed even when an evasive action is suddenly performed and / or when driving in a bend.

[0016] Preferably, the geometrical features include at least the number of axles of the vehicle and the axle distances between the axles of the vehicle. Particularly preferably, the geometrical features include all axle distances between the axles of the vehicle. However, the method can also be performed if only some of the axle distances are known or if the axle distances are unknown. Thus, preferably the axle distances of the vehicle can also be approximately calculated if the vehicle length is known. The wheels of the axles of the vehicle represent the contact points of the vehicle with the road surface. The axle distances influence the dynamic behavior of the vehicle and are particularly suitable as geometrical features of the current vehicle configuration. If the geometrical features known include at least the number of axles of the vehicle and the axle distances, the dynamic behavior of the vehicle can be predicted with high accuracy and relatively low computational effort. In addition or alternative preferred geometrical features are or include, for example, the position of the coupling point relative to the rear axle of the towing vehicle, the position of the center point of the axle group formed by a plurality of axles of the trailer vehicle, the wheelbase of the vehicle and / or the wheelbase of the vehicle or of a sub-vehicle of the vehicle.

[0017] In a preferred development, the method further comprises: during vehicle activation of the vehicle, the following steps are performed: determining two or more geometric features, determining two or more load features, generating a uniquely processed vehicle model, predicting the dynamic behavior of the current vehicle configuration and defining at least one driving dynamics boundary value; and if a change is detected in at least one feature on which the prediction of the dynamic behavior is based, at least the following steps are performed again: predicting the dynamic behavior of the current vehicle configuration and defining at least one driving dynamics boundary value. Vehicle activation is the setting of a vehicle to a state in which it is ready for driving. Vehicle activation is often also referred to as commissioning, wherein this should not only include the first commissioning of a vehicle after manufacture. In conventional vehicles, vehicle activation is usually achieved by operating the ignition of the vehicle. Performing the above steps during vehicle activation ensures that the current vehicle configuration is reliably detected and used as a basis for the prediction. For example, if the vehicle is loaded in an inactive state, this is also taken into account. If a change is detected in the feature on which the prediction of the dynamic behavior is based, the prediction of the dynamic behavior and the definition of at least one driving dynamics boundary value are performed again to ensure that the driving dynamics boundary value always matches the current vehicle configuration. For example, if the vehicle is loaded in an active state (with the motor running), the dynamic behavior of the vehicle may change significantly. However, due to the loading, the load characteristics on which the prediction is based also change, so that the prediction needs to be re-performed, the prediction needs to be re-performed and the driving dynamics limit values ​​need to be redefined or adapted to the changed conditions. In this way, the safety gains provided by the method are further increased. The above steps are performed during vehicle activation, wherein the steps do not necessarily need to be completed when the vehicle is activated. Preferably, the above steps can also be triggered by the vehicle activation.

[0018] Preferably, after the vehicle starts to travel, one or more of the learned features are subjected to a credibility check. In addition, if one or more of the features are not credible, the method is preferably re-executed. In this case, the result of the credibility check is preferably taken into account when the method is re-executed. The credibility check improves safety because features that are not correctly provided by the vehicle system can be learned and excluded. For example, shortly after the vehicle starts to travel refers to a time period of five minutes, preferably three minutes, and especially one minute after the vehicle starts to travel. The start of travel refers to the moment when the vehicle leaves a stationary state or starts to move. Shortly after the start of travel can also preferably refer to the time period from the first acceleration of the vehicle after the initial stationary state to a predetermined speed. The predetermined speed is preferably 30 km / h, more preferably 25 km / h, more preferably 20 km / h, more preferably 15 km / h, and particularly preferably 10 km / h. Since the drive power that can be provided by the vehicle drive device is always limited, a minimum time period is required for the vehicle to reach a predetermined speed from a stationary state. This minimum time period can preferably be used to perform a credibility check on one or more features because the vehicle speed is low in this case and the risk of instability is negligible. Preferably, the load characteristic representing the total mass of the vehicle is subjected to a plausibility check while the vehicle is accelerating up to a predetermined speed. Thus, in the case of a level road surface, the total mass of the vehicle can be inferred from the known drive torque of the vehicle's drive and from the time period required for the vehicle to accelerate to a predetermined speed and thus subjected to a plausibility check. Furthermore, the known geometrical characteristics of the coupled trailer vehicle representing the vehicle can be subjected to a plausibility check by inferring the total mass of the vehicle from the drive power required to achieve the corresponding acceleration. Thus, for example, in order to accelerate a towing vehicle and trailer vehicle, a significantly greater drive power is required than in the case of an empty towing vehicle in order to achieve a speed of 1 m / s 2 The geometrical characteristics representative of the coupled trailer vehicle are preferably determined by evaluating a signal provided on a trailer network, particularly preferably an ISO 11992 CAN.

[0019] In a preferred design, the method further comprises: providing a driving dynamics boundary value at an interface. The interface is preferably or includes a human-machine interface, and the human-machine interface particularly preferably includes a warning light, a head-up display, a digital display and / or a speaker. Providing the driving dynamics boundary value on the human-machine interface can make it easy for the human driver to perceive the boundary value, so that the human driver can take the driving dynamics boundary value into account when controlling the vehicle. For example, the maximum permissible vehicle speed can be displayed on the speedometer of the vehicle. More preferably, the interface can be constructed as a network interface, particularly preferably a CAN interface. Via such a network interface, the boundary value can preferably be provided to a driver assistance system of the vehicle or a positioning regulator of the vehicle. Preferably, the driving dynamics boundary value is only provided at the interface when the driving dynamics boundary value is violated. Therefore, the maximum permissible vehicle speed can only be displayed by the head-up display when the vehicle is traveling at a speed greater than the maximum permissible vehicle speed. Preferably, the method further comprises: when using the driving dynamics boundary value provided at the interface, limiting the driving dynamics parameter that can be provided by the vehicle actuator. Preferably, the vehicle dynamics parameter is the vehicle speed of the vehicle. Preferably, the control unit of the vehicle can limit the vehicle speed of the vehicle based on the maximum permissible vehicle speed defined as a driving dynamics limit value. Thus, for example, the driver can be prevented from (unintentionally) exceeding the maximum permissible vehicle speed, since the maximum motor torque of the drive motor of the vehicle is limited by the control unit. Preferably, when turning into a bend, the vehicle can automatically decelerate to a vehicle speed corresponding to the maximum permissible lateral acceleration.

[0020] Preferably, the method further comprises: when planning the trajectory of the vehicle, the virtual driver takes into account the driving dynamics boundary value provided at the interface. The virtual driver is a unit that at least undertakes the subtask of autonomous control of the vehicle. At least one subtask of autonomous control of the vehicle includes trajectory planning. The virtual driver performs trajectory planning and obtains a trajectory of an autonomous journey, for example, from point A to point B, which is set to perform the driving task. The trajectory includes at least one planned driving path (target driving path), which is driven by the vehicle to perform the driving task. In addition, the trajectory also includes at least one driving dynamics predetermined parameter. The driving dynamics predetermined parameter is preferably or includes a predetermined speed or a predetermined speed change curve for driving along the driving path. The virtual driver plans the trajectory based on environmental information, which is preferably provided by different environmental sensors of the vehicle. Therefore, the vehicle can, for example, have a camera that detects the environment in front of the vehicle along the driving direction. Then, the virtual driver plans the trajectory to be driven based on the environmental information provided by the camera. According to a preferred improvement of the method, the virtual driver also takes into account the driving dynamics boundary value when planning the trajectory. Thus, although the permissible speed on the road to be traveled according to traffic law is 80 km / h, the speed set along the driving path can be limited to 60 km / h (the driving dynamics limit value is then the maximum permissible vehicle speed of 60 km / h). The virtual driver can preferably perform trajectory planning using map data. It can be preferred to perform trajectory planning even when there is no environmental information when using map data. Therefore, the virtual driver can preferably plan a slower but shorter suburban road route instead of a highway route. It is preferred if the maximum permissible vehicle speed is defined as a driving dynamics limit value that is lower than the permissible speed on the highway belonging to the highway route. In this case, for example, the destination can be reached faster on a shorter suburban road than on a longer highway, because a speed advantage cannot be achieved on the highway route due to the predetermined maximum permissible vehicle speed.

[0021] In a preferred improvement, the method further comprises: obtaining the current friction coefficient for the vehicle, wherein the current friction coefficient for the vehicle is taken into account when predicting the dynamic characteristics. The obtaining of the current friction coefficient for the vehicle should be understood in the sense of an approximate calculation in this article, and the approximate calculation will have a certain approximation error. The quality of the prediction of the dynamic characteristics of the current vehicle configuration is further improved by obtaining the current friction coefficient for the vehicle, because the current friction coefficient is subject to large fluctuations in reality. Therefore, in wet or icy conditions, the friction coefficient between the vehicle and the road surface is significantly reduced relative to dry conditions. This causes a considerable impact on the dynamic characteristics of the vehicle. If the current friction coefficient is taken into account when predicting the dynamic characteristics, this will have an impact on the defined driving dynamic boundary value and improve the safety of the vehicle during operation. In the absence of a step of obtaining the current friction coefficient, the method can preferably be carried out based on a predefined or pre-stored friction coefficient.

[0022] Preferably, historical control interventions of a stability control system for similar vehicle configurations are taken into account when predicting the dynamic behavior of the current vehicle configuration. Such a stability control system is preferably an anti-lock braking system (ABS), a traction control system (ASR) and / or an electronic stability control system (ESC). The selection of a drive torque acting on the wheels of the vehicle that is too large will lead to severe tire slip (wheel spin), especially in the case of wet or slippery roads. The traction control system will prevent or minimize such tire slip by correspondingly intervening in the engine torque and braking the wheels that are slipping. In particular, in unladen or light vehicles, the above-mentioned drive slip occurs due to the low wheel load. If an ASR intervention (historical control intervention) has already been carried out for a similar loading state (similar vehicle configuration), it can also be advantageously taken into account when predicting the dynamic behavior of the current vehicle configuration. As a result, the maximum drive torque that can be applied to the road surface by the drive wheels of the vehicle for the current vehicle configuration can follow the historical control intervention. Preferably, the method includes: determining the intervention of the stability control system and determining the exceeding of the driving dynamics variable that triggered the intervention.

[0023] Preferably, similar vehicle configurations are vehicle configurations having identical geometrical features and a maximum displacement of the center of gravity of the similar vehicle configuration in one or more spatial directions relative to the center of gravity of the current vehicle configuration within a range of at most 1 m, in particular at most 0.5 m, more in particular at most 0.3 m. Preferably, similar vehicle configurations may also be characterized by having the same number of axles of the towing vehicle and / or trailer vehicle. Furthermore, preferably, the vehicle configurations are similar if the trailer vehicle is identical to the trailer vehicle of the current vehicle configuration or if the trailers are of the same model. Preferably, the vehicles of the current vehicle configuration are identical to the vehicles of the similar vehicle configuration. Preferably, the vehicle configurations may differ due to different loading of the vehicles and / or due to different lifting and lowering of lifting axles.

[0024] Preferably, the method also includes: monitoring the actual vehicle behavior of the vehicle during operation; comparing the actual vehicle behavior with a target vehicle behavior known when using a personalized vehicle model; and detecting instability if the actual vehicle behavior deviates from the target vehicle behavior. It should be understood that preferably only some aspects of the actual vehicle behavior can be monitored and / or only some aspects of the actual vehicle behavior can be compared with the target vehicle behavior. Preferably, instability can only be detected when the actual vehicle behavior deviates from the target vehicle behavior by a permissible value. Thus, for example, when driving through a bend, if the actual yaw rate (rotation rate about the height axis) of the vehicle does not correspond to the expected yaw rate that can be inferred from the steering angle or the provided trajectory (in the case of a virtual driver), then instability of the towing vehicle can be detected. By comparing these yaw rates with each other, it is possible to determine whether an oversteering situation or an understeering situation is taking into account the required turning direction.

[0025] Preferably, the actual vehicle behavior is monitored by monitoring the folding angle between the towing vehicle and the trailer vehicle, the folding angle being known from a folding angle signal emitted by a folding angle sensor. Furthermore, preferably, the target vehicle behavior is a target folding angle known when using a vehicle model. Monitoring the folding angle allows the overall traction stability of the towing vehicle-trailer combination to be monitored. In this way, if a folding angle deviating from the target folding angle occurs in the driving condition of the vehicle, it can be known that the trailer is unstable (folding or tail-spinning occurs).

[0026] In a preferred embodiment, the method further comprises: if the vehicle exceeds one or more driving dynamics limit values ​​provided at the interface during operation, a safety operation is performed. The safety operation is a method step performed if the vehicle is in danger of becoming unstable due to exceeding the driving dynamics limit values.

[0027] Preferably, the safety operation is to load an additional yaw moment when the vehicle is turning and / or to set the stability control system of the vehicle to a preventive control mode. By loading an additional yaw moment, understeering of the vehicle when turning can be preferably compensated. By setting the stability control system to the preventive control mode, early intervention of the stability control system (preferably ESC) is achieved, so that possible vehicle instability is identified in advance and balanced. In this case, the steering angle is smaller than the steering angle when no preventive measures are taken. The steering work or the integral of the steering angle required to drive through the curve is reduced. Preferably, in the preventive control mode, the intervention threshold of the vehicle stability control system is reduced compared to the conventional control mode. With the help of this preferred improvement, the existing stability control system of the vehicle can therefore be used to compensate for instability in advance.

[0028] Preferably, the vehicle is a commercial vehicle, which is a towed vehicle group consisting of a tractor vehicle and at least one trailer vehicle, wherein the uniquely processed vehicle model is a uniquely processed whole vehicle model of the towed vehicle group. The uniquely processed whole vehicle model enables a particularly accurate prediction of the dynamic characteristics of the current vehicle configuration, because the mutual influence between the tractor vehicle and the trailer vehicle is taken into account during the prediction. Preferably, the geometric characteristics of the current vehicle configuration include the geometric characteristics of the trailer vehicle. Preferably, the load characteristics of the current vehicle configuration include the load characteristics of the trailer vehicle. Preferably, the geometric characteristics and / or the load characteristics of the trailer vehicle are obtained based on signals provided on the trailer bus (preferably a CAN bus, more preferably a SAEJ11992 CAN bus).

[0029] In a preferred development, the individualized complete vehicle model of the towed vehicle group is a reduced individualized vehicle model if no geometrical or load characteristics are known for a certain vehicle part of the towed vehicle group. The vehicle parts are the tractor vehicle and the trailer vehicle of the towed vehicle group. The reduced individualized vehicle model is preferably a vehicle model that represents only that component of the towed vehicle group for which known characteristics, axle loads, etc. are known. For example, if only the characteristics of the tractor vehicle of the towed vehicle group are known, the reduced individualized vehicle model is a unique vehicle model of the tractor vehicle without the trailer vehicle. The reduced individualized vehicle model is reduced relative to the individualized complete vehicle model in that the quality of its representation of the current vehicle configuration is lower than that of the individualized complete vehicle model. The reduced individualized vehicle model ensures that a prediction is performed even when the known characteristics are not sufficient to achieve a nearly realistic representation of the entire current vehicle configuration. Preferably, in the reduced individualized vehicle model, the vehicle parts for which no geometrical or load characteristics are known are represented by a non-individualized basic model. Preferably, if only the geometry and the load characteristics of the towing vehicle of the towing vehicle combination are known, the reference trailer model is taken into account in the reduced individualized vehicle model for the trailer vehicle. Vehicle parts for which the geometry or the load characteristics are not known are preferably not taken into account in the prediction or are represented by a simplified basic model in the prediction. It should be understood that for vehicle parts for which the load characteristics are not known but the geometry is known, at least the geometry can be taken into account in the reduced individualized vehicle model, and vice versa.

[0030] Preferably, the individualized complete vehicle model of the towed vehicle combination is a reduced individualized vehicle model if the load characteristic represents an unloaded state of the trailer vehicle. The inventors have recognized that an unloaded trailer vehicle leads to vehicle instability only in rare cases. This means that for a towed vehicle combination with an unloaded trailer vehicle, the instability usually originates from the tractor vehicle or another loaded trailer vehicle. In the case of an unloaded towed vehicle, a reliable prediction of the dynamic behavior of the current vehicle configuration can also be achieved using a reduced individualized vehicle model that only takes into account the tractor vehicle. This allows the method to be carried out in a particularly resource-saving manner.

[0031] In a second aspect, the present invention achieves the object described at the outset by a driver assistance system for a vehicle, in particular a commercial vehicle. Preferably, the driver assistance system is configured to implement a method according to one of the preferred embodiments of the first aspect of the present invention described above. Preferably, the driver assistance system for a vehicle has a control unit, which is configured to determine two or more geometric characteristics of a current vehicle configuration of the vehicle, to determine two or more load characteristics of the current vehicle configuration, to generate a uniquely processed vehicle model of the current vehicle configuration based on a vehicle basic model of the vehicle using the geometric characteristics and load characteristics of the current vehicle configuration, to predict the dynamic characteristics of the current vehicle configuration using the uniquely processed vehicle model, to define at least one driving dynamics boundary value for the vehicle based on the dynamic characteristics of the current vehicle configuration, and to provide the driving dynamics boundary value at an interface of the control unit.

[0032] According to a third aspect of the invention, the object mentioned at the outset is achieved by a vehicle having at least two axles, which has a driver assistance system according to the second aspect of the invention. It is understood that the driver assistance system according to the second aspect of the invention and the vehicle according to the third aspect of the invention have identical and similar sub-aspects, which are particularly noted in the dependent claims.

[0033] In a fourth aspect, the invention achieves the object stated at the outset by a computer program product having program code means stored on a computer-readable data carrier so that, when the computer program product is executed on a computing unit, the method according to one of the above-described preferred embodiments of the first aspect of the invention is implemented. Preferably, the computing unit is a computing unit of a driver assistance system according to the second aspect of the invention.

[0034] The following describes the embodiments of the present invention with the aid of the drawings. These drawings do not necessarily show the embodiments with exact dimensions, but rather the drawings used for explanation are implemented in a schematic and / or slightly distorted form. For additional information on the teachings that can be directly derived from the drawings, reference is made to the relevant prior art. It should be taken into account that various modifications and changes can be made to the manner and details of the embodiments without departing from the general idea of ​​the present invention. The features of the present invention disclosed in the specification, drawings and claims are of great significance to the improvement scheme of the present invention, whether individually or in any combination. In addition, all combinations of at least two features disclosed in the specification, drawings and / or claims fall within the scope of the present invention. The general idea of ​​the present invention is not limited to the exact form or details of the preferred embodiments shown and described below, or to the subject matter that is limited compared to the subject matter claimed in the claims. With regard to the set measuring range, the values ​​within the mentioned boundary range should also be disclosed as boundary values ​​and can be used arbitrarily and protected by rights. For the sake of clarity, the same figure marks are used below for the same or detailed parts or parts with the same or similar functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Further advantages, features and details of the present invention can be derived from the following description of preferred embodiments and based on the accompanying drawings, in which:

[0036] Figure 1 shows a current vehicle configuration of a commercial vehicle according to a first embodiment;

[0037] Figure 2 shows a current vehicle configuration of a commercial vehicle according to a second embodiment;

[0038] Figure 3 A schematic flow chart of a preferred embodiment of the method is shown;

[0039] Figure 4 shows a uniquely processed vehicle model according to one embodiment;

[0040] Figure 5 a graph showing the trend of minimum damping exhibited for different vehicle configurations as a function of vehicle speed;

[0041] Figure 6 A schematic diagram of a commercial vehicle during cornering is shown;

[0042] Figure 7 A schematic diagram showing a commercial vehicle during cornering at an extremely high speed;

[0043] Figure 8A schematic flowchart diagram of a preferred design scheme for generating a unique vehicle model is shown;

[0044] Figure 9a A vehicle base model is shown; and

[0045] Figure 9b A reduced uniqued vehicle model is shown. DETAILED DESCRIPTION

[0046] Figure 1 A vehicle 300 is shown, which is configured as a tow vehicle-trailer combination 302 having a tractor vehicle 304 and a trailer vehicle 306. The tractor vehicle 304 is a truck having a first loading surface 308, while the trailer vehicle 306 is a full trailer connected to the tractor vehicle 304 and having a second loading surface 310. A first load 312 is arranged on the first loading surface 308, while a second load 314 is mounted on the second loading surface 310. Figure 1 It should be noted that the weight of the second load 314 on the second loading surface 310 of the trailer vehicle 306 is approximately twice the weight of the first load 312 on the first loading surface 308 of the tractor vehicle 304 .

[0047] Figure 1 The commercial vehicle 300 shown in FIG. 1 is characterized by a current vehicle configuration 3 . The current vehicle configuration 3 comprises geometric characteristics 5 and load characteristics 7 . Figure 1 For a better overview, only some geometric features 5 and load features 7 of the current vehicle configuration 3 of the commercial vehicle 300 are described in conjunction with the following. By way of example, the axle distance L between the two axles 316 of the tractor vehicle 304 is 11 , the coupling distance L between the rear axle 318 of the towing vehicle 304 and the coupling point 320 13 and the lifting axle distance L between the rear axle 318 of the tractor vehicle 304 and the lifting axle 322 12 The geometrical features 5 of the current vehicle configuration 3 also include the raised and lowered state 324 of the lift axle 322. When the lift axle 322 is lowered, the wheelbase of the tractor 304 that is effective for driving dynamics changes, more precisely from Figure 1 The axle distance L shown in 11 becomes the axle distance L 11 Distance from lift bridge L 12 The dynamic behavior of the commercial vehicle 3 is influenced by the wheelbase, wherein the lifting condition 324 of the lifting axle 322 is a geometric feature 5 that directly characterizes this influence. Further geometric features 5 of the commercial vehicle 300 shown are, for example, the towbar length of the towbar of the trailer vehicle 306 or the wheelbase of the trailer vehicle 306, but these are not Figure 1 Not clearly marked.

[0048] The load characteristic 7 characterizes the loads acting on the commercial vehicle 300 in the current vehicle configuration 3, which loads are caused by the own weight of the commercial vehicle 300, the first load 312 and the second load 314. Figure 1 , the load characteristic 7 is simplified to the loads acting on the rear axle 318 of the tractor vehicle 304 and the front axle 326 of the trailer vehicle 306. As already mentioned, the trailer vehicle 306 has a larger load than the tractor vehicle 304, so that the load acting on the rear axle 318 of the tractor vehicle 304 is smaller than the load acting on the front axle 326 of the trailer vehicle 306. This is illustrated by the length of the arrow representing the load characteristic 7.

[0049] Here, the load characteristic 7 acting on the rear axle 318 of the tractor vehicle 304 is the axle load of the rear axle 318, which is detected by the electronically controllable air suspension 327 of the commercial vehicle 300. The electronically controllable air suspension 327 detects the axle load acting on the front axle 326 of the trailer vehicle 306 as another load characteristic 7. In the present embodiment, in addition to the detected axle load on the rear axle 318 of the tractor vehicle 304, the total mass of the tractor vehicle 304 and the lifting condition 324 of the lifting axle 322 are also known, so that the axle load on the front axle 330 of the tractor vehicle 304 can be determined by calculation. In addition, based on the axle load of the front axle 326 of the trailer vehicle 306 and the known total mass of the trailer vehicle 306, the axle load on the rear axle of the trailer vehicle 306 can also be determined. Therefore, in the present embodiment, the load characteristic 7 can be directly detected by measurement on the one hand, and can also be indirectly determined by calculation on the other hand.

[0050] For the same commercial vehicle 300, the vehicle configuration 3 can vary depending on the geometrical characteristics 5 and the load characteristics 7. Thus, when the lifting axle 322 of the commercial vehicle 300 is lowered (i.e. the lifting condition is different from the lifting condition), the vehicle configuration 3 can vary depending on the geometrical characteristics 5 and the load characteristics 7. Figure 1 324) or when the first load 312 and the second load 314 are exchanged, the vehicle configuration of the commercial vehicle 300 will be different from Figure 1 The current vehicle configuration is shown in 3. Figure 1 It should be noted that current vehicle configuration 3 is situation-dependent and represents the current state of commercial vehicle 5 .

[0051] Additional factors that may be included in the current vehicle configuration 3 are the commercial vehicle 300 and Figure 19 between the road surface 328 illustrated by the dash-dotted line in FIG. 3 . Even with identical geometric configurations of the commercial vehicle 3 and identical loading conditions, the current vehicle configuration 3 of the commercial vehicle 300 changes due to different road surface conditions or different friction coefficients 9. In particular, it is directly understood in conjunction with the friction coefficient 9 that the current vehicle configuration 3 of the commercial vehicle 300 also changes during the operation of the commercial vehicle 300. Thus, for example, when rain begins to fall while the commercial vehicle 300 is traveling, the friction coefficient 9 may decrease.

[0052] Figure 2 A commercial vehicle 300 is shown which is designed as a towing vehicle-trailer combination 302. The towing vehicle-trailer combination 302 has a towing vehicle 304 which is designed as a saddle tractor and a trailer vehicle 306 which is designed as a semitrailer. Figure 1 and Figure 2 Identical or similar components of commercial vehicle 300 are labeled with the same reference numerals. Figure 2 The commercial vehicle 300 shown in FIG. 3 is typically widely used in Europe. The tractor vehicle 304 has two axles 316, wherein the front axle 330 of the tractor vehicle 304 is steerable. The tractor vehicle 304 pulls a three-axle semitrailer.

[0053] The following will mainly refer to Figure 2 and Figure 3 Explain the preferred design of the method 1 according to the present invention. If necessary, you can also refer to Figure 1 The explanation relates in particular to various aspects of the commercial vehicle 300 .

[0054] exist Figure 3 In the first step of the method 1 schematically shown in FIG. 1 , two or more geometrical characteristics 5 are determined 11 . In this case, the first geometrical characteristic 5 determined is the axle distance L between the axles 316 of the tractor vehicle 300 11 , which here also corresponds to the wheelbase of the tractor vehicle 304. 22 As a further geometric feature 5, the trailer coupling distance L is known. 22 It is defined as the distance between the coupling point 320 and the axle group center 332 of the axle group 334 of the trailer vehicle 306. Based on other geometric features 5 known in advance, it is also possible to Figure 2 The vehicle 300 is calculated for each geometric feature 5. Therefore, in the present embodiment, the positioning of the coupling point 320 within the wheelbase of the tractor vehicle 304 is based on the previously known total towing length according to EU Directive 96 / 53 / EC, the length of a typical trailer vehicle 306 that complies with the directive, and the wheelbase L of the tractor vehicle 304. 11 Come to know.

[0055] While the geometrical characteristic 5 is being known 11 , two or more load characteristics 7 are also known 13 , for reasons of overview, Figure 2 In this embodiment, load characteristic 7 includes axle loads acting on the front axle 330 and the rear axle 318 of the towing vehicle 304. Figure 2 The load characteristics of the commercial vehicle 300 also include an axle load acting on the axle group center 332 , which is representative of the axle loads acting on each axle 316 of the axle group 334 .

[0056] When the commercial vehicle 300 is activated 15, the geometrical characteristics 5 and the load characteristics 7 are determined 11, 13 for the first time. The vehicle type of the commercial vehicle 300 and the geometrical characteristics 5 (number of axles 316, axle distance L 11 ) is known when the ignition of the commercial vehicle 300 is activated. In addition, other characteristics of the axle 316, such as the lifting condition 324 of the lifting axle 322, can also be used. These other characteristics are stored as geometric characteristics 5 in the ESC controller 336 of the commercial vehicle 300, because these other characteristics are also necessary for the conventional stability control system 360. In the present case, the trailer vehicle 306 has an electronic brake system (EBS). The trailer vehicle 306 is connected to the tractor 304 via a trailer interface 328, which is configured as an ISO11992 interface. The trailer vehicle 306 provides a signal to the tractor 304 at the trailer interface 328, which is used to determine the geometric characteristics 5 of the trailer vehicle 306. The geometric characteristics 5 of the trailer vehicle 306 include the model type of the trailer vehicle 306, the number of axles of the trailer vehicle 306 and their distance from the coupling point 320. These geometric features 5 of the trailer vehicle 306 are directly provided to the ISO11992 interface, so that the features of the trailer vehicle 306 are obtained by receiving corresponding signals. In addition, the EBS trailer vehicle 306 also has sensors ( Figure 3 306 as load characteristic 7. The determination 13 of the load characteristic 7 also includes the calculation of the axle load on the front axle 330 of the tractor vehicle 304.

[0057] After the geometrical feature 5 is known 11 and the load feature 7 is known 13 ( Figure 3 11 and 13 in the method 1), then, in the next step, according to the vehicle basic model 22 of the commercial vehicle 300 (see Figure 9a ) generates a unique vehicle model 21 of the current vehicle configuration 3 ( Figure 3in Generation 19). Figure 4 The uniquely processed vehicle model 21 is shown, which is here a single wheel track model 23 of the commercial vehicle 300. The single wheel track model 23 is a simplified model of the commercial vehicle 300, which is Figure 2 The tractor vehicle 304 and trailer vehicle 306 are depicted in their minimum coordinates, wherein the vehicle width approaches zero and the lifting, rolling or pitching movements of the commercial vehicle 300 are neglected. In the single wheel track model 23, for the sake of simplicity, the axle group 334 is replaced by an axle that is combined at the axle group center 332. Figure 4 , the uniquely processed vehicle model 21 is a uniquely processed complete vehicle model 24, which represents all vehicle parts of a commercial vehicle 300 configured as a towing vehicle-trailer combination 302. Therefore, the uniquely processed vehicle model 21 includes a (sub) model of a tractor vehicle 304 and a (sub) model of a trailer vehicle 306.

[0058] The generation 19 of the uniquely processed vehicle model 21 takes place using the geometrical features 5 and the load features 7. For this purpose, in a first step, the mass distribution 25 ( Figure 3 27). Based on the known axle loads acting on the front axle 330 and the rear axle 318 of the tractor vehicle 304, the position of the first center of gravity 342 of the tractor vehicle 304 in the vehicle longitudinal direction R1 is known. 11 is one of the geometric features 5 known in advance, so that the position of the first center of gravity 342 in the longitudinal direction R1 of the vehicle can be inferred using the simple lever law. In a similar manner, the position of the second center of gravity 344 of the trailer vehicle 306 in the longitudinal direction R1 of the vehicle is also known when the mass distribution 25 is approximated 27. The mass distribution 25 includes the distance L between the front axle 330 of the towing vehicle 304 and the first center of gravity 342 14 , a distance L between the first center of gravity 342 of the tractor vehicle 304 and the rear axle 318 of the tractor vehicle 304 15 , the distance L between the coupling point 320 and the first center of gravity 342 16 , the distance L between the connection point 320 and the second center of gravity 344 of the trailer vehicle 306 21 , the distance L between the coupling point 320 and the axle group center 332 of the axle group 334 of the trailer vehicle 306 23 , a first mass m1 of the tractor vehicle 304 acts on a first center of gravity 342 , and a second mass m2 of the trailer vehicle 306 acts on a second center of gravity 344 .

[0059] Generating 19 a unique vehicle model 21 includes generating 29 a unique vehicle model 21 of the commercial vehicle 300 using the geometrical features 5 and the mass distribution 25 after an approximate calculation 27 of the mass distribution 25. For this purpose, a parameterized vehicle base model 22 of the commercial vehicle 300 is uniquely processed using the geometrical features 5 and the load features 7. The acquired features 5, 7 are therefore used here as parameter values ​​in the vehicle base model.

[0060] In addition to features 5 and 7, the uniquely processed vehicle model 21 also includes degrees of freedom of movement 31 of the commercial vehicle 300 in the vehicle longitudinal direction R1, the vehicle transverse direction R2 perpendicular to the vehicle longitudinal direction R1, and the vehicle height direction R3. Figure 4 , these degrees of freedom are the first yaw rate of the towing vehicle 304 about the first center of gravity 342 , the vehicle speed V in the vehicle longitudinal direction R1, the lateral speed V of the towing vehicle 304 in the vehicle lateral direction R2 y , the folding angle between the tractor vehicle 304 and the trailer vehicle 306 And folding speed The degree of freedom of movement 31 describes the possible directions of movement of the positively coupled towed vehicle combination 302 and can be expressed as a state vector x as follows:

[0061]

[0062] Steering angle δ of commercial vehicle 300 and friction torque M in coupling point 320 of commercial vehicle 300 D It is considered as an input quantity in the unique vehicle model 21. The input quantity vector u representing the input quantity can be expressed as follows:

[0063]

[0064] The input variables or input variable vectors u and the system behavior of the individualized vehicle model 21 result in values ​​of the degrees of freedom of movement 31 of the commercial vehicle 300 that are specific to the current vehicle configuration 3. For example, when the commercial vehicle 300 is characterized by straight driving with a steering angle δ of 0°, the yaw rate The value of may also have a value of 0. The commercial vehicle 300 will then travel stably straight and will not exhibit any rotational movement about the height axis.

[0065] After the unique vehicle model 21 is generated 19 , the dynamic behavior of the current vehicle configuration 3 is predicted using the unique vehicle model 21 . Figure 3For this purpose, the equations of motion for the commercial vehicle 300, which represent the individualized vehicle model 21 in this case, are solved with the aid of suitable mathematical measures. In the present exemplary embodiment, these equations of motion are linearized for an operating point representing a stable straight-ahead motion of the commercial vehicle 300, whereby the state vector x formed by the degrees of freedom of the commercial vehicle 300 is simplified as follows:

[0066]

[0067] When the commercial vehicle 300 is moving straight ahead in a steady state, the steering angle δ and the folding angle are small, so that at this operating point the equations of motion can be linearized and represented in matrix form.

[0068] The tire restoring forces acting on the tires of the axle 316 are represented in the individualized vehicle model 21 by the tire cornering stiffnesses. In the present exemplary embodiment, these tire cornering stiffnesses are modeled linearly and adapted via empirically based relationships as a function of the respective axle loads and the friction coefficient 32 between the road surface 328 and the commercial vehicle 300. In a similar manner, the friction torque M in the coupling point 320 is determined for the determined mass distribution 25. D , where the load on the coupling point 320 and the friction torque M are used D However, in other embodiments, the friction torque can also be considered as a nonlinear relationship.

[0069] The friction coefficient 32 can in principle be a predetermined value. However, in the preferred embodiment, the method comprises determining 34 the current friction coefficient 32. To this end, the weather conditions ( Figure 3 ). Subsequently, the current friction coefficient 32 is obtained by selecting the friction coefficient 32 corresponding to the known weather conditions and the known load characteristics 7 from a pre-stored database. However, preferably, the friction coefficient 32 can also be measured or obtained in other ways.

[0070] In the prediction 33 of the dynamic behavior, the damping D and the natural angular frequency are then calculated for the eigenvalues ​​of the individualized vehicle model 21 of the commercial vehicle 300 for the “steady straight ahead” operating point and for different vehicle speeds V (10, 20, 30, . . . , 120 km / h). This makes it known which vehicle part of the commercial vehicle 300 has the least damping and from which vehicle speed V the damping D falls below a predefined minimum. Furthermore, the natural angular frequency itself also represents the dynamic behavior of the commercial vehicle 300.

[0071] Figure 5 For variants 1 to 4 (in Figure 5Four different current vehicle configurations 3 (abbreviated as Var 1 to Var 4 in FIG. 1 ) show the curve of the minimum damping D of the commercial vehicle 300 as a function of the vehicle speed V. The damping amount D for all vehicle configurations 3 decreases as the vehicle speed V of the commercial vehicle 300 increases. In addition, the comparison of variant 3 and variant 4 also shows the influence of the current vehicle configuration 3 on the dynamic characteristics of the commercial vehicle 300. Variant 4 represents the following example. Figure 1 The vehicle configuration 3 is shown with a heavily loaded trailer vehicle 306 at the rear. Due to the heavily loaded state at the rear, the vehicle configuration 3 according to variant 4 has a lower damping quantity D, so that steering excitations quickly cause the commercial vehicle 300 to sway. In contrast, the vehicle configuration 3 according to variant 3, which represents a loaded tractor vehicle 304 and an empty trailer vehicle 306, has a much higher damping quantity D at the same vehicle speed V, so that the excitations can be damped and destabilization can be prevented. Excitations that would have already destabilized the commercial vehicle 300 in variant 4 can still be sufficiently damped in the commercial vehicle according to variant 3, so that stable driving can be achieved despite the excitations.

[0072] In the present exemplary embodiment, the prediction 31 of the dynamic behavior is accomplished by knowing the minimum damping D and the natural angular frequency of the commercial vehicle 300. As a next step of the method 1, a driving dynamics limit value 35 is defined 37 for the commercial vehicle 300 based on the dynamic behavior of the current vehicle configuration 3. In the present exemplary embodiment, a maximum permissible steering frequency 39 is defined as a first driving dynamics limit value 35, which is less than the minimum natural angular frequency of the commercial vehicle 300. The driving dynamics limit value 35 defined in this way prevents the commercial vehicle 300 from entering a resonance state, which would cause the commercial vehicle 300 to sway uncontrollably due to a small deflection. Based on the described method 1 according to the invention, the critical natural angular frequency is already known when the vehicle is activated 15 or shortly thereafter, and can be taken into account in the form of the driving dynamics limit value 35 when the commercial vehicle 300 is controlled.

[0073] The further driving dynamics limit value 35 is determined from the determined minimum damping value D of the commercial vehicle configuration 5. The ideal damping for the commercial vehicle configuration 5 corresponds to a damping value of D=1 for the determined eigenvalue. This damping value represents the aperiodic boundary case in which the excited vibrations are damped again without overvibration. In reality, this ideal damping value cannot be achieved or can only be achieved with an excessively high adjustment effort. In practice, however, significantly lower damping values ​​D are also sufficient for stable operation of the commercial vehicle 300. As described above with reference to Figure 5As explained, the damping amount D decreases as the driving speed V of the commercial vehicle 300 increases. This means that the risk of the commercial vehicle 300 becoming unstable increases as the driving speed V increases. Therefore, it is possible to calculate the minimum damping amount D that still just ensures the required 最小 The maximum permissible vehicle speed V that cannot be exceeded is the driving speed 最大 , and it is defined as the driving dynamic boundary value 35. In this embodiment, the minimum damping amount D 最小 Designed for D 最小 = 0.4. Therefore, according to Figure 5 , the commercial vehicle 300 according to variant 1 can only be safely moved at a driving speed V of up to 40 km / h, while the commercial vehicle 300 according to variant 3 is still able to operate safely up to a driving speed of 60 km / h.

[0074] Based on the minimum damping amount D, the maximum permissible steering angle gradient is also defined. As further driving dynamics limit values ​​35, the individualized vehicle model 21 preferably also includes the position of the center of gravity 342, 344 in the vehicle height direction R3. 最小 Just can be defined as driving dynamics limit value 35, meet these driving dynamics limit values ​​just prevent commercial vehicle 300 from rolling over when turning.In addition, maximum permissible vehicle acceleration 43 and maximum permissible vehicle deceleration 45 are also defined as driving dynamics limit value 35.

[0075] In the present embodiment, the steps of the above method 1 are executed by a driver assistance system 200 of a commercial vehicle 300. The driver assistance system 200 has a control unit 202 and an interface 204. The control unit 202 is a brake control unit 345 of a brake system 347 of the commercial vehicle 300, but may also be or include a control unit 202 of another vehicle subsystem, a main control unit of the commercial vehicle 300, or a separately arranged control unit 202.

[0076] Shortly after the commercial vehicle 300 starts driving, the driver assistance system 200 performs a plausibility check on some of the geometric features 3 known in advance ( Figure 3 In the present case, the driver assistance system 200 performs a plausibility check on the lifting condition 324 of the lifting axle 322 of the commercial vehicle 300, which is preferably provided on the SAE J1939 CAN bus of the commercial vehicle 300. For this purpose, the control unit 202 of the driver assistance system 200 receives the reference speed n of the wheels of the front axle 330 of the towing vehicle. 参考 and the wheel speed n of the wheels of the lifting axle 322 of the tractor vehicle 304 升降, and compare them. Figure 2 In the vehicle configuration 3 shown in FIG. 3 , the lifting axle 322 of the tractor vehicle 304 is lowered. The wheels of the lifting axle 322 and the wheels of the front axle 330 roll on the road surface 328 , so that the wheel speed n of the lifting axle 322 升降 With reference speed n 参考 The control unit 202 obtains the consistent speed n 升降 、n 参考 , and it is known that the lifting condition 324 representing the lowered lifting axle 322 is credible.

[0077] The plausibility check 47 is performed shortly after the commercial vehicle 300 starts to move, so that errors in the determined characteristics 5, 7 are detected early and within a range of vehicle speed V that does not endanger stability. In the present exemplary embodiment, the plausibility check speed V is detected as soon as the vehicle speed V reaches the plausibility check speed V for the first time after the vehicle is activated 15. P (preferably a value of 5 km / h), a plausibility check 47 is performed. Plausibility check speed V P is the minimum speed that triggers the plausibility check 47. This minimum speed ensures that a sufficiently large difference occurs between the learned characteristics and the true characteristics. 参考 and the wheel speed n of the lifting axle 322 升降 Implausible features can also be reliably detected when detected only with lower accuracy5,7.

[0078] During operation of the commercial vehicle 300, one or more of the geometrical characteristics 5 or the load characteristics 7 may change. Figure 1 If the second load 314 of the trailer vehicle 306 is removed from the commercial vehicle 300 or the tractor vehicle 304 is refueled, the load characteristic 7 and therefore also the dynamic behavior of the commercial vehicle 300 changes. In order to ensure stable driving of the commercial vehicle 300, feedback is provided in method 1. The feedback includes monitoring 49 of the known geometric characteristics 5 and the known load characteristics 7 and detecting 51 a change in at least one characteristic 5, 7. Due to the detection of the change in the characteristics 5, 7, the uniquely processed vehicle model 21 is updated or regenerated, the prediction 33 of the dynamic behavior of the current vehicle configuration 3 is repeated, and one or more driving dynamics boundary values ​​35 are redefined. The driving dynamics boundary values ​​35 defined here may differ from the driving dynamics boundary values ​​35 defined when the method 1 is initially performed, both in terms of the boundary value type (speed variable, acceleration) and in terms of the magnitude of the boundary value. For example, when the trailer 300 is unloaded, the maximum permissible vehicle speed V 最大 Can be improved. Figure 5In the diagram of , this unloading situation corresponds to a change in vehicle configuration 3 from variant 4 to variant 3.

[0079] Immediately after the definition 37 of the driving dynamics limit value 35, the driving dynamics limit value 35 is provided 53 to an interface 204 of the driver assistance system 200. The interface 204 is here a network interface 206, which is connected to a virtual driver 346 of the commercial vehicle 300. The driver assistance system 200 provides the previously defined driving dynamics limit value 35 to the virtual driver 346 via the interface 204. The virtual driver 346 performs a trajectory planning 55 in order to obtain a trajectory T for the commercial vehicle 300 and, for this purpose, calls up environmental information 350 provided by environmental sensors 348 of the commercial vehicle 300. In accordance with Figure 2 In the embodiment of the present invention, the environment sensor 348 is a camera 352, which detects the environment in front of the commercial vehicle 300. In other embodiments, the commercial vehicle 300 may also preferably have a plurality of environment sensors 348, preferably radar sensors, lidar sensors and / or cameras.

[0080] The top view of the commercial vehicle 300 is shown when it is driving through the curve 354. Figure 6 It is shown how driving dynamics limit value 35 can be taken into account in trajectory planning 55. Virtual driver 346 plans a trajectory T for commercial vehicle 300 for driving around curve 354. For this purpose, camera 352 detects the course of road surface 328 in front of commercial vehicle 300 as environmental information 350. As further environmental information 350, camera 352 checks speed limit 358 predefined on road signs 356. In the illustrated route, the permissible speed corresponds to predefined speed limit 358 of 80 km / h. If driving dynamics limit value 35 was not predefined, virtual driver 346 would have made vehicle speed V follow predefined speed limit 358 and planned a vehicle speed V of 80 km / h for trajectory T.

[0081] However, in the current vehicle configuration 3, the load at the rear causes the commercial vehicle 300 to become unstable already at 80 km / h. Without the intervention of the stability control system 360, the commercial vehicle 300 would become unstable when driving through the bend 354 at a vehicle speed V of 80 km / h. For example, this instability may include an oversteering or understeering of the tractor vehicle 304 and / or a folding or tail-spinning of the trailer vehicle 306 due to the steering impulse. Based on the prediction of the dynamic characteristics of the commercial vehicle 300, this upcoming vehicle behavior is known in advance, so that when defining 37 the driving dynamics limit value 35, the maximum permissible vehicle speed V is set. 最大 Confirmed to be 60 km / h.

[0082] In order to prevent the commercial vehicle 300 from becoming unstable, the driver assistance system 200 provides the driving dynamics limit value 35 to the virtual driver 346 at the interface 204. The virtual driver 346 takes the driving dynamics limit value 35 provided at the interface 204 into account within the scope of the trajectory planning 55 and limits the vehicle speed V of the commercial vehicle 300 covered by the trajectory T to the maximum permissible vehicle speed V. 最大 Therefore, the commercial vehicle 300 can travel through the curve 354 in a stable driving state without the commercial vehicle 300 becoming unstable. Figure 3 The consideration 57 of the driving dynamics limit value 35 is shown in a schematic flow chart of method 1 .

[0083] The preferred method 1 also includes monitoring 59 the actual vehicle behavior 60 of the commercial vehicle 300, which in the present exemplary embodiment is performed by a control unit 202 of the driver assistance system 200. The control unit 202 continuously monitors the vehicle speed V and then compares it with the maximum permissible vehicle speed V. 最大 If the vehicle speed V of the commercial vehicle 300 is greater than the maximum permissible vehicle speed V provided at the interface 204 最大 , then perform safety operation 61 ( Figure 3 63 in the execution). In this case, the control unit 202 of the driver assistance system 200 sets the ESC controller 336 of the commercial vehicle 300 to the preventive control mode ( Figure 3 65), so that the stability control system 360 including the ESC controller 336 can perform early corrective control intervention on the commercial vehicle 300 when the commercial vehicle 300 becomes unstable.

[0084] Figure 7 It is shown that the commercial vehicle 300 is moving at a speed greater than the maximum permissible vehicle speed V 最大 354. A steering angle δ has been predefined at the front wheels 362 of the commercial vehicle 300 for turning. Without driving dynamics intervention, the commercial vehicle 300 would be pulled out of the curve due to the excessively high vehicle speed V. In addition to setting 65 the ESC controller 336 to the preventive control mode, the control unit 202 of the driver assistance system 200 also provides a brake actuation variable 67 at the interface 204 as an additional safety operation 61 when the commercial vehicle 300 turns. The provision 69 of the brake actuation variable 67 causes a brake force F to be controlled from a brake actuator 362 of a brake system 347 connected directly or indirectly to the interface 204 to a wheel 364 of the commercial vehicle 300 on the inside of the curve. B This braking force results in an additional yaw moment M about the vertical axis of the commercial vehicle 300 G Yaw moment M GThe commercial vehicle 300 is caused to turn and thus the commercial vehicle 300 can be driven along the curve 354. The safety operation 61 performed by the control unit 202 of the driver assistance system 200 thus prevents the commercial vehicle 300 from understeering and ensures stable driving.

[0085] In addition to defining 37 the driving dynamics limit value 35 and carrying out 63 the safety maneuver 61, the method in the illustrated exemplary embodiment also includes detecting 71 a loss of stability of the commercial vehicle 300. As a first step of the detection 71, after monitoring 59 the actual vehicle behavior 60, the actual vehicle behavior 60 of the commercial vehicle 300 is first compared 75 with a target vehicle behavior 73. The target vehicle behavior 73 is determined by the control unit 202 of the driver assistance system 200 using the individualized vehicle model 21 and using the trajectory T provided by the virtual driver 346 at the interface 204 of the driver assistance system 200. If a deviation is detected when comparing 75 the actual vehicle behavior 60 with the target vehicle behavior 73, then in the next step, a loss of stability of the commercial vehicle 300 is detected 71. The detection 71 can preferably be carried out before, at the same time or after defining 37 the driving dynamics limit value 35. In this case, the monitoring 59 of the actual vehicle behavior 60 can also be carried out independently of the remaining steps of the method 1. Thus, the actual vehicle behavior 60 can be monitored 59 even when a prediction 33 of the commercial vehicle 300 has not yet been made or the prediction 300 has not yet been completed. Preferably, a signal corresponding to a detected instability of the commercial vehicle 300 is provided at the interface 204 so that it can be received by the virtual driver 346. The virtual driver 346 can then take the detected instability of the commercial vehicle 300 into account and preferably compensate for it.

[0086] Figure 8 A preferred design for generating 19, 29 a uniquely processed vehicle model 21 is shown when neither the geometrical features 5 nor the load features 7 are known for the trailer vehicle 306 of the tow vehicle group 302. Therefore, in a second embodiment of the method 1, when the geometrical features 5 are known 11, only the commercial vehicle 200 is identified as including the trailer vehicle 306. In order to be able to predict 33 the dynamic characteristics of the current vehicle configuration 3, despite the lack of the features 5, 7 of the trailer vehicle 306, generating 19, 29 a uniquely processed vehicle model 21 still includes simplifying 77 the uniquely processed full vehicle model 24 to a reduced uniquely processed vehicle model 79. To this end, the uniquely processed vehicle model 24 is first reduced. Figure 9a The vehicle base model 22 of the trailer vehicle group 302 shown in FIG. Figure 381). In this case, the model part representing the trailer vehicle 306 is removed from the vehicle base model 22. Subsequently, the vehicle base model 22 is uniquely processed 83 using the geometric characteristics 5 and the load characteristics 7 of the towing vehicle 304 in order to obtain Figure 9b , which now represents only the tractor vehicle 304. In addition, simplification 77 can also be performed when the load characteristic 7 determined for the trailer vehicle 306 indicates that the trailer vehicle 306 is in an unloaded state. In this case, the instability of the commercial vehicle 300 originates from the tractor vehicle 304 in most cases, so that the calculation load of the control unit 202 can be minimized by reducing the vehicle basic model 22. The remaining steps of the method 1 following the generation 19, 29 can be performed as described above.

[0087] List of reference numerals (part of the description)

[0088] 1 Methods

[0089] 3 Current vehicle configuration

[0090] 5 Geometric features

[0091] 7 Load characteristics

[0092] 9 Current friction coefficient

[0093] 11. Get the geometric features

[0094] 13 Obtaining Load Characteristics

[0095] 15 Vehicle Activation

[0096] 19 Generate a unique vehicle model

[0097] 21 unique vehicle models

[0098] 22 Vehicle Basic Model

[0099] 23 Single wheel track model

[0100] 24 Uniquely processed vehicle models

[0101] 25 Mass distribution

[0102] 27 Approximate calculation of mass distribution

[0103] 29 Generate a unique vehicle model using geometric features and mass distribution

[0104] 31 Freedom of movement for commercial vehicles

[0105] 32 Friction coefficient

[0106] 33 Predict the dynamic characteristics of the current vehicle configuration

[0107] 34 Get the current friction coefficient

[0108] 35 Driving dynamics limit value

[0109] 37 Limiting driving dynamics limits

[0110] 39 Maximum permissible turning frequency

[0111] 41 Maximum permissible lateral acceleration

[0112] 43 Maximum permissible vehicle acceleration

[0113] 45 Maximum permissible vehicle deceleration

[0114] 47 Perform credibility check on features

[0115] 49 Monitoring the learned features

[0116] 51 Detect changes in at least one feature

[0117] 53 Providing driving dynamics limit values ​​at the interface

[0118] 55 Trajectory Planning

[0119] 57 Considering driving dynamics limits in trajectory planning

[0120] 59 Monitoring actual vehicle behavior

[0121] 60 Actual Vehicle Behavior

[0122] 61 Safe Operation

[0123] 63 Performing safe operations

[0124] 65 Set the stability control system to control mode

[0125] 67 Braking Amount

[0126] 69 Provides brake control amount

[0127] 71 Detecting instability

[0128] 73 Target Vehicle Behavior

[0129] 75 Comparing actual vehicle behavior with target vehicle behavior

[0130] 77 Simplify the unique vehicle model

[0131] 79 Reduced unique vehicle models

[0132] 200 Driver assistance systems

[0133] 202 Control unit

[0134] 204 Interface

[0135] 206 Network Interface

[0136] 300 Vehicles; Commercial vehicles

[0137] 302 trailer group

[0138] 304 Towing vehicle

[0139] 306 Trailer Vehicles

[0140] 308 First loading surface

[0141] 310 Second loading surface

[0142] 312 First Load

[0143] 314 Second Load

[0144] 316 Axle

[0145] 318 Rear axle of towing vehicle

[0146] 320 Coupling point

[0147] 322 Lifting Axle

[0148] 324 Lifting Condition

[0149] 326 Front axle of trailer vehicle

[0150] 327 Electronically controlled air suspension

[0151] 328 Road surface

[0152] 330 Front axle of towing vehicle

[0153] 332 Axle Center

[0154] 334 Axle Group

[0155] 336 ESC Controller

[0156] 338 trailer interface

[0157] 340 Sensored Axles

[0158] 342 First Center of Gravity

[0159] 344 Second Center of Gravity

[0160] 345 Brake control unit

[0161] 346 Virtual Driver

[0162] 347 Braking System

[0163] 348 Environmental Sensors

[0164] 350 Environmental Information

[0165] 352 Cameras

[0166] 354 Bend

[0167] 356 Road Sign

[0168] 358 Speed ​​Limit

[0169] 360 degree stability adjustment system

[0170] 362 Front Wheel

[0171] 364 Brakes

[0172] 366 Wheel on the inside of the curve

[0173] D Damping amount

[0174] D 最小 Minimum damping

[0175] F B Braking force

[0176] L 11 Bridge distance

[0177] L 12 Lifting axle distance

[0178] L 13 Coupling distance

[0179] L 14 Distance between the front axle of the towing vehicle and the first center of gravity

[0180] L 15 Distance between the rear axle of the towing vehicle and the first center of gravity

[0181] L 16 Distance between coupling point and first center of gravity

[0182] L 21 Distance between coupling point and second center of gravity

[0183] L 22 Trailer coupling distance

[0184] L 23 Distance between coupling point and axle group center

[0185] M D Friction torque in the coupling point

[0186] M G Yaw moment

[0187] m1 Mass of the towing vehicle

[0188] m2 The mass of the trailer vehicle

[0189] n 升降 Wheel speed of the wheels of the lift axle

[0190] n 参考 Reference speed

[0191] R 最小 Minimum allowable turning radius

[0192] R1 Vehicle longitudinal direction

[0193] R2 Vehicle lateral direction

[0194] R3 Vehicle height direction

[0195] T track

[0196] V is the vehicle's speed in the longitudinal direction of the vehicle

[0197] V 最大 Maximum permitted vehicle speed

[0198] V P Credibility check speed

[0199] V y Vehicle speed in the lateral direction of the vehicle

[0200] Var 1 to Var 4 Vehicle configuration variants

[0201] δ Steering angle

[0202] Maximum permissible steering angle gradient

[0203] Folding angle

[0204] Folding speed

[0205] First yaw rate

Claims

1. A method (1) for predicting the lateral dynamic stability behavior of a current vehicle configuration (3) of a vehicle (300), the method comprising: - knowing (11) two or more geometrical characteristics (5) of the current vehicle configuration (3), - obtaining (13) two or more load characteristics (7) of the current vehicle configuration (3); - generating (19) a personalized vehicle model (21) of the current vehicle configuration (3) based on a basic vehicle model (22) of the vehicle (300) using the geometrical features (5) and the load features (7); - predicting (33) the dynamic characteristics of the current vehicle configuration (3) using the uniquely processed vehicle model (21); and - defining (37) at least one driving dynamics limit value (35) for the vehicle (300) based on the dynamic characteristics of the current vehicle configuration (3).

2. The method according to claim 1, wherein: Generating (19) a uniquely processed vehicle model (21) of a current vehicle configuration (3) includes: - using the geometrical characteristic (5) and the load characteristic (7), approximately calculating (27) the mass distribution (25) of the current vehicle configuration (3) in at least one vehicle longitudinal direction (R1); and - generating (29) a personalized vehicle model (21) of the current vehicle configuration (3) from a basic vehicle model (22) of the vehicle (3) using the geometric features (5) and the approximately calculated mass distribution (25).

3. The method (1) according to claim 1 or 2, wherein: The driving dynamics limit value (35) is the maximum permissible vehicle speed (V 最大 )、maximum permissible lateral acceleration(41)、maximum permissible vehicle acceleration(43)、maximum permissible vehicle deceleration(45)、maximum permissible steering angle gradient( ), the maximum permissible turning frequency (39) or the minimum permissible turning radius (R 最小 ).

4. The method (1) according to any one of claims 1 to 3, wherein: The geometrical characteristics (5) include at least the number of axles (316) of the vehicle (300) and the axle distance (L) between the axles (33, 63) of the vehicle (3). 11 , L 12 ).

5. The method (1) according to any one of claims 1 to 4, comprising: - during vehicle activation (15) of the vehicle (3), performing: determining (11) two or more geometrical characteristics (5), determining (13) two or more load characteristics (7), generating (19) the uniquely processed vehicle model (21), predicting (33) the dynamic characteristics of the current vehicle configuration (3) and defining (37) at least one driving dynamics boundary value (35), and - If a change is detected in at least one characteristic (5, 7) on which the dynamic behavior is based, at least the following steps are repeated: predicting (33) the dynamic behavior of the current vehicle configuration (3) and defining (37) at least one driving dynamics limit value (35).

6. The method (1) according to any one of claims 1 to 5, wherein: After the vehicle (300) starts driving, a plausibility check is performed on one or more of the acquired characteristics (5, 7).

7. The method (1) according to any one of claims 1 to 6, further comprising: - providing the driving dynamics limit value (35) at an interface (204).

8. The method (1) according to claim 7, further comprising: - taking into account (57) the driving dynamics limit value (35) provided at the interface (204) by a virtual driver (346) during trajectory planning (55) for the vehicle (300).

9. The method (1) according to any one of claims 1 to 8, further comprising: - determining (34) a current friction coefficient (32) for the vehicle (300), wherein: The current friction coefficient (32) for the vehicle is taken into account when predicting (33) the dynamic behavior.

10. The method (1) according to any one of claims 1 to 9, wherein: When predicting (33) the dynamic behavior of the current vehicle configuration (3), historical control interventions of the stability control system (360) for similar vehicle configurations are taken into account.

11. The method (1) according to any one of claims 1 to 10, further comprising: - monitoring (59) actual vehicle behavior of the vehicle (300) during operation; - comparing (75) the actual vehicle behavior with a target vehicle behavior (73) known using the uniquely processed vehicle model (21); and If the actual vehicle behavior deviates from the target vehicle behavior (55), an instability is detected (71).

12. The method (1) according to any one of claims 1 to 11, further comprising: - executing (63) a safety operation (61) if the vehicle (300) exceeds one or more of the driving dynamics limit values ​​(35) provided at the interface (204) during operation.

13. The method (1) according to claim 12, wherein: The safety operation (61) includes applying an additional yaw moment (M) when the vehicle (300) turns. G ) and / or setting the stability control system (360) of the vehicle (300) to a preventive control mode.

14. The method (1) according to any one of claims 1 to 13, wherein: The vehicle (300) is a trailer vehicle group (302) consisting of a tractor vehicle (304) and at least one trailer vehicle (306), and wherein the uniquely processed vehicle model (21) is a uniquely processed whole vehicle model (24) of the trailer vehicle group (302).

15. The method (1) according to claim 14, wherein: If the geometrical characteristics (5) or the load characteristics (7) are not known at a certain vehicle part (304, 306) of the trailer group (302), the uniquely processed whole vehicle model (24) of the trailer group (302) is a reduced uniquely processed vehicle model (79).

16. The method according to claim 14 or 15, wherein: If the load characteristic (7) represents that the trailer vehicle (306) is in an unloaded state, the uniquely processed full vehicle model (24) of the tow vehicle group (302) is a reduced uniquely processed vehicle model (79).

17. A driver assistance system (200) for a vehicle (300), the driver assistance system being designed to carry out the method (1) according to any one of the preceding claims 1 to 16.

18. A vehicle (300) having at least two axles (316), the vehicle having a driver assistance system (200) according to claim 17.

19. Computer program product having program code means stored on a computer-readable data carrier in order to carry out the method according to claim 1 when the computer program product is executed on a computing unit.

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