Driver assistance system for combinations

Abstract

A driver assistance system for combinations of a towing vehicle and a trailer, comprising an environmental sensor system (10, 12) and an electronic evaluation and control device (14) in which driver assistance functions are implemented, characterized in that one of the driver assistance functions is an articulation-angle warning function (38) which outputs a signal (S) if the articulation angle (α) between the towing vehicle and the trailer exceeds a threshold value (T).

Description

[0001] Description

[0002] title

[0003] Driver assistance system for trailers

[0004] Description

[0005] The invention relates to a driver assistance system for combinations consisting of a towing vehicle and a trailer, with an environmental sensor system and an electronic evaluation and control device in which driver assistance functions are implemented.

[0006] State of the art

[0007] Motor vehicles are often equipped with a driver assistance system that provides various driver assistance functions, such as cruise control, distance control, blind spot monitoring, and / or lane change assistance. If the vehicle is a towing vehicle that can be towed, this requires certain adaptations to the functionality of the driver assistance system.

[0008] US 2015325126 A1 discloses a driver assistance system in which the presence of a trailer is detected using a radar system on the towing vehicle. To distinguish between a trailer and another vehicle following closely behind, the system exploits the fact that the trailer always maintains the same distance from the towing vehicle when driving straight ahead, and that the distance measured by the radar system only changes within very narrow limits when cornering. US 9 211 889 B1 discloses a similar system in which, if a trailer is present, the length of the vehicle combination is also measured. For this purpose, the distance between reflection centers located in the rear end area of ​​the trailer is measured when cornering.

[0009] From DE 11 2020 000325 T5 a driver assistance system is known in which the environmental sensors (e.g. a radar system) are used to measure important properties of a trailer such as the length, the number of axles and the height of the trailer.

[0010] Disclosure of the invention

[0011] The object of the invention is to improve the functionality of a driver assistance system for trailers.

[0012] This object is achieved according to the invention in that one of the driver assistance functions is a bend angle warning function which emits a signal when the bend angle between the towing vehicle and the trailer exceeds a threshold value.

[0013] Towing vehicles generally have a trailer coupling which – at least within certain limits – permits the trailer to pivot around a vertical axis. The articulation angle is defined as the angle between the longitudinal axis of the towing vehicle and the longitudinal axis of the trailer. When the towing vehicle reverses with a trailer attached and the steering turned, the articulation angle tends to increase. If the driver of the towing vehicle is inexperienced or inattentive, the articulation angle may exceed a critical value above which there is a risk of damage to the towing vehicle or trailer, for example because the pivoting range permitted by the coupling is exceeded or because parts of the trailer or its drawbar come into contact with parts of the towing vehicle. According to the invention, the environmental sensor system is used to measure the current articulation angle and to issue a warning signal when the articulation angle approaches the critical value.If the length of the trailer's drawbar is known and the trailer, as is usually the case, has a substantially flat front end oriented at a right angle to the longitudinal axis, the articulation angle can be determined, for example, by using a radar sensor to measure the minimum distance between the radar sensor and the front of the trailer, which is directly dependent on the articulation angle. Alternatively, the directional angle of a prominent reflection point on the front of the trailer can be measured using an angle-resolving radar sensor. For example, a radar sensor that is already present on the vehicle can be used for the measurements. This sensor is used to monitor the rear area on one side of the vehicle and to issue blind spot warnings, for example. It is not necessary for parts of the trailer to be constantly in the field of view of the radar sensor.It is sufficient if parts of the trailer come into the field of view of the radar sensor before the maximum permissible articulation angle is reached.

[0014] It is understood that other types of sensors can be used to measure the articulation angle instead of radar sensors, for example cameras with electronic image analysis, ultrasonic or lidar sensors or the like.

[0015] Advantageous embodiments and further developments of the invention emerge from the subclaims.

[0016] The signal emitted by the articulation angle warning function does not have to consist solely of a warning signal. In an advantageous embodiment, a visual or acoustic warning signal is emitted when the articulation angle exceeds a first threshold value. If the driver does not intervene subsequently, a brief active braking intervention is triggered in further cascaded steps, followed by a gradually more severe braking intervention up to an emergency maneuvering stop, in order to avoid damage to the towing vehicle or trailer. In addition to avoiding damage and increasing driving safety, the invention also offers increased comfort for the driver, as it allows them to concentrate more on the obstacles (e.g. people) in the vicinity of the driving maneuver. When determining the threshold value orWhen setting the threshold values ​​for the articulation angle warning function, the respective coupling type should generally be taken into account. For example, a distinction should be made between:

[0017] 1) for cars: ball head coupling at the rear of the vehicle

[0018] 2) for cars: gooseneck or fifth wheel coupling on the loading area of ​​a pick-up

[0019] 3) for tractor units: fifth wheel coupling

[0020] 4) for trucks: jaw coupling at the rear of the vehicle (standard coupling)

[0021] 5) for trucks: jaw coupling below the loading area between the last rear axle and the rear of the vehicle (low coupling)

[0022] 6) for cars / trucks: Hook coupling (e.g. NATO coupling). For coupling types 1), 4) and 5), a maximum articulation angle of approximately + / - 90° typically results, depending on the respective vehicle geometry. For coupling types 2) and 3), however, maximum articulation angles of approximately + / - 100° are also possible. Since the coupling usually remains permanently attached to the towing vehicle, the parameters that determine the coupling type only need to be entered once in the driver assistance system of the towing vehicle. Other parameters that relate, for example, to the geometry of the

[0023] trailer, however, may need to be updated if another trailer is attached.

[0024] As the aforementioned publications on the state of the art demonstrate, it is in principle also possible to measure trailer parameters directly using the environment sensors. Likewise, the fact that a trailer is attached at all can be determined using the environment sensors. This makes it possible to exploit the fact that the kinematics and dynamics of a trailer differ in characteristic ways from those of a self-driving vehicle.

[0025] The following example is explained in more detail using the drawing. It shows:

[0026] Fig. 1 is a block diagram of a driver assistance system according to the invention; and

[0027] Fig. 2 a sketch of a towing vehicle and a trailer in a situation where the articulation angle approaches the permissible limit.

[0028] The driver assistance system shown in Fig. 1 comprises an environmental sensor system formed by two radar sensors 10, 12 and an electronic evaluation and control unit 14. The radar sensors 10, 12 are installed at the left and right rear corners of a motor vehicle and each monitor an area behind and to the left and right of the vehicle, respectively. If necessary, the detection ranges of the two radar sensors can overlap, so that the area immediately behind the vehicle can also be detected.

[0029] The evaluation and control device 14 contains a radar module 16, which further evaluates the digitized signals received by the radar sensors 10, 12 and calculates distances, relative velocities, azimuth angles, and preferably also elevation angles of various reflection points on one or more located objects. This yields location data 18, which are further analyzed in an assignment module 20. In particular, the assignment module 20 searches for groups of radar reflections that, based on largely identical relative velocities, can be assumed to belong to the same object.If the vehicle equipped with the radar system is a towing vehicle towing a trailer, the radar sensors 10, 12 will also receive radar reflections from the trailer, at least when cornering, and the assignment module 20 will assign these reflections to a common object, although it is not yet clear whether this is actually a trailer or another vehicle. The average relative speed measured for these reflection points provides an initial indication. Since the trailer is moving at the same speed as the towing vehicle, the measured relative speeds for a trailer will be close to zero. For objects whose relative speed deviates from zero by more than a certain threshold value, it can be ruled out from the outset that they are a trailer.

[0030] Even with objects whose relative speed is almost zero, there is the possibility that it is not a trailer, but another vehicle that happens to be traveling at the same absolute speed as your own vehicle.

[0031] To resolve this uncertainty, the evaluation and control device 14 has a model module 22 in which various trailer types can be modeled. Each trailer model is characterized by a set of parameters, which include, for example, the distance between the coupling position and the (frontmost) axle of the trailer and, in the case of multi-axle trailers, the number of axles and the wheelbase. Other parameters can specify the width, height, length, and track width of the trailer.

[0032] The model module 22 receives data from the vehicle's own sensor system 24. This data includes, in particular, the vehicle's absolute speed v and yaw rate co.

[0033] In model module 22, the dynamic behavior of the trailer is modeled based on the dynamic data of the towing vehicle and the model parameters. In particular, it is predicted how the location data of individual reflection points located in various positions on the supposed trailer will change depending on the current speed v and the current change in the yaw rate co. If the yaw rate is zero, i.e. when driving straight ahead, neither the distances nor the relative speeds nor the azimuth angles of the reflection points change. The same applies if the yaw rate is different from zero (cornering) but has remained constant over a longer period of time. In this case, the towing vehicle and the trailer move in a circular path, and the spatial relationships between the radar sensors and the various reflection points remain unchanged.Predicted values ​​26 for the location data of the reflex points are passed from the model module 22 to the assignment module 20 and compared there with the measured location data 18.

[0034] At the start of a journey, when no location data is yet available, the model parameters in model module 22 are set to default values ​​that, for example, indicate the most common trailer type. If a trailer is attached, the model defined by the preset parameters will not accurately describe the trailer, so the location data predicted using this model will deviate significantly from the measured location data. Based on these deviations, new parameter values ​​are estimated in an estimation module 28, minimizing the deviation between the predicted values ​​and the measured values.

[0035] A classification module 30 tracks the history of deviations and model parameters. If the model parameters converge towards stable values ​​where the deviations between the predicted location data and the measured location data are below suitable thresholds, the classification module decides that the located object is indeed a trailer. A flag can then be set in the driver assistance system, which sets the functionality to trailer operation. As long as the deviations remain greater than the thresholds, no trailer message is issued. Likewise, the classification module 30 decides that no trailer is attached if the deviations are temporarily below the threshold but the model parameters fluctuate over time, because the deviations can only be minimized by continuously adjusting the model parameters that describe the trailer.The threshold values ​​for the deviations and for the range of fluctuation of the model parameters can be determined by training the classification module 30 by machine learning, for example during test drives with different trailer types and with following vehicles that could be confused with trailers.

[0036] An input module 32 is used to enter parameters that identify the coupling type of the towing vehicle. Optionally, parameters of the currently attached trailer can also be entered via this input module. This allows for faster convergence and greater precision of the trailer model.

[0037] Fig. 2 shows a plan view of a towing vehicle 34 and a trailer 36. The positions of the radar sensors 10, 12 can also be seen in Fig. 2. A longitudinal axis f of the towing vehicle 34 and a longitudinal axis t of the trailer 36 intersect at the location of a coupling K and form an angle a with each other, which is referred to as the articulation angle. If the towing vehicle 34 continues to reverse in the situation shown in Fig. 2, the articulation angle a increases, and there is a risk that the trailer's drawbar will strike a part of the towing vehicle.

[0038] One of the model parameters calculated and continuously updated in the classification module 30 is the articulation angle α. The current value of the articulation angle α is forwarded to a warning module 38 (Fig. 1). In addition, the classification module 30 calculates a set of threshold values ​​T for an articulation angle warning based on the coupling parameters entered via the input module 32 and the calculated or entered parameters of the trailer model. The warning module 38 compares the current articulation angle α with the threshold values ​​T. As soon as the articulation angle α exceeds one of these threshold values, a signal S is output. If α exceeds the smallest threshold value, the signal S is a warning signal that triggers an acoustic and / or visual warning for the driver.If the next higher threshold value a exceeds, the signal S is an intervention signal that triggers a brief braking intervention in a braking system 40 of the vehicle. If further threshold values ​​are exceeded, successively stronger and longer braking interventions are triggered, up to and including an emergency maneuvering braking. The intervals between the threshold values ​​T and the maximum permissible articulation angle a can depend on dynamic parameters such as the driving speed v or the yaw rate c0, in such a way that the signal S is output earlier the faster the current articulation angle a approaches the limit value.

Claims

Claims 1. Driver assistance system for combinations consisting of a towing vehicle (34) and a trailer (36), with an environmental sensor system (10, 12) and an electronic evaluation and control device (14) in which driver assistance functions are implemented, characterized in that one of the driver assistance functions is an articulation angle warning function (38) which outputs a signal (S) when the articulation angle (α) between the towing vehicle and the trailer exceeds a threshold value (T).

2. Driver assistance system according to claim 1, wherein the environmental sensor system comprises at least one radar sensor (10, 12).

3. Driver assistance system according to claim 1 or 2, wherein the signal (S) output by the articulation angle warning function (38) is one of several signals which are output at successively higher threshold values ​​(T) and which, when the lowest threshold value is exceeded, trigger a visual or acoustic warning to the driver and, when higher threshold values ​​are exceeded, trigger interventions in the braking system (40) with increasing intensity and / or duration.

4. Driver assistance system according to one of the preceding claims, wherein the The threshold value or the threshold values ​​(T) are variable, the distance between each threshold value (T) and a maximum permissible articulation angle (a) being greater the faster the articulation angle approaches the maximum permissible value.

5. Driver assistance system according to one of the preceding claims, with a Input module (32) for entering parameters that characterize a trailer coupling (K) of the towing vehicle (34).

6. Driver assistance system according to claim 5, wherein the input module (32) is also designed for the input of parameters that characterize the trailer (36).

7. Driver assistance system according to one of the preceding claims, with a classification module (30) which is designed to determine the presence of a trailer (36) on the basis of the data detected by the environmental sensors (10, 12) and to classify the trailer in more detail.

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