Trailer reversing assistance system with destination management

Abstract

Trailer reversing assistance system (10), comprising: a camera (46) for taking pictures of a trailer (12) connected to a vehicle (14); a display (82) which has a screen (29) for displaying recorded images (31) and for registering a touch event thereon in order to assign a target on the depicted pendant (12); and a control (28) for processing the recorded images and tracking the target in order to determine a coupling angle between the vehicle (14) and the trailer (12) when the vehicle (14) is automatically steered during a trailer reversing maneuver.

Description

AREA OF INVENTION

[0001] The present invention relates to trailer reversing assistance systems in general and in particular to systems that use image sensor-based target detection. BACKGROUND OF THE INVENTION

[0002] Reversing a vehicle while towing a trailer can be challenging for many drivers, especially those who tow trailers infrequently or with different types of trailers. Systems used to assist drivers when reversing with a trailer can determine the trailer's position relative to the vehicle using image-based target detection. The accuracy and reliability of this coupling angle determination can be critical for the operation of the reversing assistance system.

[0003] German patent application DE 10 2014 222 048 A1 describes how to determine a coupling angle using a camera and a marker. German patent application DE 10 2013 016 342 A1 describes a method for entering a target coupling angle via a touchscreen. BRIEF SUMMARY OF THE INVENTION

[0004] According to one aspect of the present invention, a trailer reversing assistance system is provided. A camera captures images of a trailer connected to a vehicle. A display has a screen for showing captured images and registering a touch event on it in order to assign a target on the depicted trailer. A controller processes the captured images and tracks the target to determine a coupling angle between the vehicle and the trailer when the vehicle is automatically steered during a trailer reversing maneuver.

[0005] According to a further aspect of the present invention, a trailer reversing assistance system is provided. A camera captures images of a trailer connected to a vehicle. A control unit processes the captured images and tracks a target on the depicted trailer in order to determine a coupling angle between the vehicle and the trailer during a trailer reversing maneuver. If the target is lost, the control unit calculates the time within which a maximum controllable coupling angle can be achieved at the current trailer yaw rate.

[0006] According to yet another aspect of the present invention, a coupling angle monitoring method is provided. The method comprises the following steps: capturing images of a trailer connected to a vehicle; displaying the captured images on a vehicle display screen; registering a touch event on the screen to assign a target on the depicted trailer; and processing the captured images to track the target in order to determine a coupling angle between the vehicle and the trailer when the trailer is automatically steered during a trailer reversing maneuver.

[0007] These and other features, advantages and objectives of the present invention will be better understood and appreciated by those skilled in the art by reference to the following description, the claims and the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the drawings: Fig. Figure 1 is a perspective top view of a vehicle attached to a trailer with an embodiment of a coupling angle sensor for operating a trailer reversing assistance system; Fig. 2 is a block diagram illustrating an embodiment of the trailer reversing assistance system with a steering input device, a curve path control and a trailer braking system; Fig. 3 and Fig. 4. Illustrating recorded images displayed on a vehicle display screen, showing various positions of a depicted trailer relative to a vehicle, together with points on the depicted trailer that are tracked to determine a coupling angle between the vehicle and the trailer; Fig. Figure 5 is a flowchart illustrating a method for monitoring a coupling angle between a vehicle and a trailer according to one embodiment; Fig. Figure 6 is an enlarged perspective view of the exterior mirror assembly, which includes a camera for capturing images of the vehicle's rear and side operating environment, as shown in Area VI of Fig. 1 is marked as VI; Fig. 7 is a schematic diagram that shows a Fig. 6 shows the horizontal field of view angle of the camera according to one embodiment; Fig. 8 is a schematic diagram that shows a Fig. 6 shows the horizontal field of view angle of the camera according to a further embodiment; Fig. Figure 9 is a schematic diagram illustrating the geometry of a vehicle and a trailer with a superimposed two-dimensional xy coordinate system that identifies variables used to determine a kinematic relationship between the vehicle and the trailer for the trailer reversing assistance system according to one embodiment; Fig. Figure 10 is a schematic diagram showing a relationship between a coupling angle and a steering angle of the vehicle, as it relates to the curve path of the trailer and an articulation angle; Fig. Figure 11 is a flowchart illustrating a procedure for managing a lost target according to one embodiment. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0009] For the purposes of the description contained herein, it is understood that the disclosed trailer reversing assistance system and the associated methods may assume various alternative embodiments and configurations, unless expressly stated otherwise. Furthermore, it is understood that the specific devices and methods illustrated in the attached drawings and described in the following description are simply exemplary embodiments of the concepts according to the invention, which are defined in the attached claims. Although various aspects of the trailer reversing assistance system and the associated methods are described with reference to a particular illustrated embodiment, the disclosed invention is not limited to such embodiments, and additional modifications, applications, and embodiments may be implemented without departing from the disclosed invention.Therefore, specific dimensions and other physical properties relating to the embodiments disclosed herein are not to be considered limiting unless expressly stated otherwise in the claims.

[0010] With reference to the Fig. 1 and Fig. Reference numeral 2 generally denotes a trailer reversing assistance system for controlling the reversing path of a trailer 12 attached to a vehicle 14 by allowing the driver of the vehicle 14 to specify a desired trajectory for the trailer's reversing path. In one embodiment, the trailer reversing assistance system 10 automatically steers the vehicle 14 to guide the trailer 12 along the desired trajectory or reversing path, while the driver uses the accelerator and brake pedals to control the reversing speed of the vehicle 14. To monitor the position of the trailer 12 relative to the vehicle 14, the trailer reversing assistance system 10 may include a sensor system 16 that detects or otherwise determines a coupling angle γ between the trailer 12 and the vehicle 14.In one embodiment, the sensor system 16 can comprise a sensor module 20 attached to the trailer 12, which monitors the dynamics of the trailer 12, such as its yaw rate, and communicates with a controller 28 of the trailer reversing assistance system 10 to determine the instantaneous coupling angle γ. Accordingly, one embodiment of a sensor module 20 is designed to be attached to the trailer 12 and to generate a trailer yaw rate ω2. The trailer reversing assistance system 10 according to such an embodiment can further comprise a vehicle sensor system 17, which generates a vehicle yaw rate ω1 and a vehicle speed v1. Based on the trailer yaw rate ω2, the vehicle yaw rate ω1, and the vehicle speed v1, the controller 28 of the trailer reversing assistance system 10 can thus estimate a coupling angle γ with respect to a kinematic relationship between the trailer 12 and the vehicle 14.In a further embodiment, the sensor system 16 may additionally or alternatively include a coupling angle sensor 44, such as a vision-based system which uses a camera 46 on the vehicle 14 to monitor a target, such as a sticker 52 or user-selected points (as described below), in order to determine the coupling angle γ.

[0011] Regarding the general operation of the trailer reversing assistance system 10, a steering input device 18, such as a rotary knob 30, can be provided so that a driver can specify the desired trajectory of the trailer 12. The steering input device 18 can be operated between several selections, such as successive rotation positions of a knob 30, each of which provides a stepwise change in the desired trajectory of the trailer 12. Upon input of the desired trajectory, the controller 28 can generate a steering command for the vehicle 14 to guide the trailer 12 along the desired trajectory, based on the estimated coupling angle γ and a kinematic relationship between the trailer 12 and the vehicle 14. Thus, the accuracy of the coupling angle estimation can be crucial for the operation of the trailer reversing assistance system 10.However, it is understood that such a system can be used for the direct estimation of the coupling angle in conjunction with additional or alternative vehicle features, such as trailer sway monitoring.

[0012] With reference to the in Fig. In the embodiment shown in Figure 1, the vehicle 14 is a pickup truck equipped with an embodiment of the trailer reversing assistance system 10 for controlling the reversing path of the trailer 12 attached to the vehicle 14. Specifically, the vehicle 14 is pivotally mounted to an embodiment of the trailer 12, which has a box frame 32 with an enclosed loading area 34, a single axle with a right-hand wheel arrangement and a left-hand wheel arrangement, and a drawbar 36 extending longitudinally forward from the enclosed loading area 34. The illustrated trailer 12 also has a trailer coupling connector in the form of a coupling assembly 38, which is connected to a vehicle coupling connector in the form of a coupling ball 40.The coupling arrangement 38 engages on the coupling ball 40 to provide a ball-joint swivel connection 42, taking into account the articulation of the coupling angle γ. It is understood that alternative embodiments of the trailer 12 can be coupled to the vehicle 14 to provide a swivel connection, for example, by connecting it with a fifth-wheel coupling. It is also considered that additional embodiments of the trailer may include more than one axle and may have different shapes and sizes designed for different loads and objects, such as a boat trailer or a low-loader trailer.

[0013] With further reference to Fig. In the illustrated embodiment, the sensor system 16 can include both a sensor module 20 and a vision-based coupling angle sensor 44 for estimating the coupling angle γ between the vehicle 14 and the trailer 12. The illustrated coupling angle sensor 44 employs a camera 46 (e.g., a video imaging camera) which, as shown, can be positioned near an upper area of ​​the vehicle's tailgate 48 at the rear of the vehicle 14, such that the camera 46 can be elevated relative to the drawbar 36 of the trailer 12. The illustrated camera 46 has a field of view 50 that is positioned and aligned to capture one or more images of the trailer 12, including an area encompassing one or more desired target placement zones for at least one sticker 52 to be secured.In the illustrated embodiment, the trailer reversing assistance system 10 includes a sticker 52 placed on the trailer 12 to enable the trailer reversing assistance system 10 to use information acquired through image capture and processing of the sticker 52. For example, the illustrated camera 46 may include a video imaging camera that repeatedly captures successive images of the trailer 12, which can be processed to identify the sticker 52 and its position on the trailer 12 in order to determine movement of the sticker 52 and the trailer 12 relative to the vehicle 14 and the corresponding coupling angle γ. It should also be noted that the camera 46 may include one or more video imaging cameras and may be positioned at other locations on the vehicle 14 to obtain images of the trailer 12 and the desired target placement zone, such as...at passenger compartment 54 of vehicle 14 for taking pictures of a gooseneck trailer.

[0014] Additionally or alternatively, the target can include a number of user-selected points on the trailer 12, and the camera 46 can be used to track the points on the trailer 12 in order to determine the coupling angle γ between the vehicle 14 and the trailer 12 based on the movement of the points within successive camera images. The points can be selected by a vehicle operator or another vehicle occupant via a human-machine interface 80 (HMI), which may include a vehicle display 82 located within a passenger compartment 54 of the vehicle 14. As exemplified in Fig. As shown in Figure 3, a captured image 31, taken by the camera 46, is displayed on a screen 29 of the vehicle display 82. The captured image 31 shows a view of the rear of the vehicle, including the drawbar 36 of the trailer 12 and a side 33 of the trailer 12 facing the vehicle 14. By modifying the field of view 50 of the camera 46, more or less of the trailer 12 can be visible in the captured image 31. For illustrative purposes, points 35a and 35b are selected by the vehicle operator or another vehicle occupant. In general, a selected point or points can correspond to a variety of objects or features located on the trailer 12. However, it is generally preferred to select objects or features that are easily distinguishable by the camera 46.

[0015] For example, the objects or features may have visual properties that make them easily imageable by the camera 46, including a recognizable color and / or shape.

[0016] As in Fig. As shown in Figure 3, point 35a corresponds to a dark inscription 37 located on the side 33 of the trailer 12, whereas point 35b corresponds to a wheel component 39 of a spare wheel 41 mounted on the trailer 12. Although two points 35a and 35b are shown, it is conceivable that in other embodiments more or fewer points can be selected. Points 35a and 35b can be selected by a touch event, whereby the vehicle operator or another vehicle occupant touches the screen 29 at the corresponding locations with their finger or a pointing device, such as a stylus. Thus, it is understood that the screen 29 of the vehicle display 82 can be designed as a touchscreen. The size of points 35a and 35b may be set by default or otherwise fine-tuned by a user.For example, the size of points 35a and 35b can be incrementally increased or decreased by turning knob 30 in a clockwise or counterclockwise direction. It is envisaged that the size of points 35a and 35b can be adjusted using other vehicle devices or via one or more additional touch events, including finger swiping, finger pulling, and other movements. It is further envisaged that points 35a and 35b are not limited to a circular shape and can include other shapes, such as a square or other geometric form.

[0017] In practice, points 35a and 35b should be selected when the vehicle 14 and the trailer 12 are essentially aligned, i.e., are on a straight line, as shown in the Fig. The captured image 31 shown in Figure 3 appears. Once the vehicle 14 and the trailer 12 are aligned and points 35a and 35b are selected, the image coordinates of points 35a and 35b are delivered to the controller 28. This allows the controller 28 to capture images of the label 37 and the wheel component 39, respectively, and associate these images with the corresponding points 35a and 35b. Later, if the trailer 12 moves relative to the vehicle 14, for example during a reversing maneuver, the controller 28 can analyze captured images to track the new position of points 35a and 35b within the captured images. For example, in Fig. Figure 4 shows a subsequently recorded image 43, taken by camera 46, which shows a new respective position of points 35a and 35b. The controller 28 can analyze the changes in pixels between the recorded images 31 and 43 and relate these changes to a corresponding change in the angular position of points 35a and 35b in degrees, with the position of points 35a and 35b in the recorded image 31 serving as the reference points. In this way, the change in the angular position of points 35a and 35b with respect to the position of points 35a and 35b in the recorded image 31 is equivalent to the coupling angle γ between the vehicle 14 and the trailer 12.

[0018] With reference to Fig. Figure 5 illustrates a method for monitoring a coupling angle γ between a vehicle 14 and a trailer 12 of the trailer reversing assistance system 10 and can correspond to an embodiment of a coupling angle estimation routine 130 ( Fig. 2) In step 134, the vehicle 14 and the trailer 12 are pulled into a straight alignment. Once the vehicle 14 and the trailer 12 are aligned, the vehicle operator can be notified by an audible warning, a visual warning, a tactile warning, or a combination thereof. In step 136, a captured image taken by the camera 46 is generated on the screen 29 of the vehicle display 82. In step 138, a number of points are assigned to objects or features of the trailer 12 that appear in the captured image shown on the screen 29. As described herein, the screen 29 can be a touchscreen, allowing a user to assign points via one or more touch events. Once the points have been assigned, in step 140, the vehicle operator initiates a trailer reversing maneuver.While the trailer reversing maneuver is being performed, the processor at step 150 analyzes further images taken by camera 46 to track changes in the pixels within the captured images. These changes ultimately relate to a change in the angular position of points 35a and 35b, in order to obtain the coupling angle γ between the vehicle 14 and the trailer at step 160, as previously described. Steps 150 and 160 can be repeated for the duration of the trailer reversing maneuver to provide immediate estimates of the coupling angle γ between the vehicle 14 and the trailer 12.

[0019] Referring back to Fig. 1 and Fig. 2 An additional camera 53 can be provided in an exterior mirror assembly 55 located on the passenger side of the vehicle 14. It is understood that the exterior mirror assembly on the driver's side of the vehicle 14 can be configured similarly. As shown, the camera 53 has a field of view 57 that is positioned and aligned to capture images encompassing an operating environment at the rear 59 of the vehicle and an operating environment at the side 61 of the vehicle. The camera 53 can include a video imaging camera that repeatedly captures successive images that can be processed to assist in various functions. For example, images captured by the camera 53 can be processed to determine trailer sway of the trailer 12. In another case, images captured by the camera 53 can be processed for object detection, blind spot detection, and the like.In yet another scenario, the images captured by camera 53 can be processed and displayed on a vehicle display 82 or another display to assist the vehicle operator during a trailer reversing maneuver. It is envisaged that the images captured by camera 53 will be processed together with images captured by any other cameras located on the vehicle 14 and / or the trailer 12 to produce composite images that will be displayed on the vehicle display 82 or another display. For example, points P1, P2, P3, and P4 illustrate other possible camera positions on the vehicle 14 and the trailer 12. Although not shown, cameras may also be located on the roof of the vehicle 14 and / or the trailer 12.It is intended that images captured by camera 53 can be combined with images from other cameras, which, as described here, are located at various locations on the vehicle 14 and / or the trailer 12, to generate a 360-degree view on the vehicle display 82 or another display. The 360-degree view can be generated using images captured only by cameras mounted on the vehicle 14, only by cameras mounted on the trailer 12, or a combination of cameras mounted on both the vehicle 14 and the trailer 12. Thus, it is understood that camera 53 can be operated independently of whether the vehicle 14 is attached to the trailer 12 or whether a feature related to trailer reversing is in operation.

[0020] According to one embodiment, the camera 53 can be mounted on a body part 65 of the exterior mirror assembly 55, as shown in Fig. Figure 6 shows a securing element 69 extending from the body part 65 and rigidly coupled to the vehicle 14. The body part 65 houses a side mirror 71 and includes a lower part 73 below the side mirror 71. The camera 53 can be located in a lower corner region 75 of the body part 65, which is defined by the lower part 73 and a side part 77 of the body part 65. The lower corner region 75 is designed such that it does not obstruct the field of view 57 of the camera 53. The camera 53 can be left partially exposed or otherwise covered by a substantially clear cover. However, thanks to its position on the body part 65, the camera 53 is generally well shielded from the operating environment of the vehicle 14 while the vehicle 14 is in an operating state.The camera 53 can be communicatively coupled to the control unit 28 of the trailer reversing assistance system 10 or another control unit by means of a wiring connection 85 extending from within the body panel 65 and through a side door frame 87 of the vehicle 14. The control unit 28 can be configured to process images captured by the camera 53 and can display the captured images on the vehicle display 82 and / or analyze the captured images while trailer reversing-related functions are being performed.

[0021] According to one embodiment, the camera 53 includes, as shown in Fig. Figure 7 shows a horizontal field of view angle (HFOV angle) θ HFOV, which is defined by the first horizontal area boundary 91 and the second horizontal area boundary 93. As shown, the horizontal area boundary 91 extends through the vehicle 14 and intersects a centerline longitudinal axis 95 of the vehicle 14, whereas the horizontal area boundary 93 extends forward and to the right from the vehicle 14 and is located (at an angle θ1) in front of a lateral axis 97 of the vehicle 14, which intersects the camera 53. In the illustrated embodiment, the HFOV angle θ HFOV Essentially obtuse, i.e., greater than 90 degrees. By increasing the angle θ1, a larger part of the operating environment can be mapped onto the vehicle side 61. Alternatively, as in Fig. As shown in Figure 8, the horizontal area boundary 93 is located behind the lateral axis 97 of the vehicle 14 (at an angle θ2), thereby reducing the portion of the operating environment on the side 61 of the vehicle that can be imaged by the camera 53. In this embodiment, the HFOV angle θ HFOV The angle may be essentially obtuse, normal (i.e., 90 degrees), or acute (i.e., less than 45 degrees). Although not shown, in other embodiments the horizontal area boundary 93 may coincide with the lateral axis 97 of the vehicle 14.

[0022] Referring back to Fig. In Figure 1, the embodiment of the sensor module 20 includes a sensor cluster 21 with a housing, which is mounted on the drawbar 36 of the trailer 12 near the enclosed loading area 34, and a left and a right wheel speed sensor 23 on laterally opposite wheels of the trailer 12. It is conceivable that the wheel speed sensors 23 could be bidirectional wheel speed sensors for monitoring both the forward and reverse speeds. Furthermore, it is considered that in additional embodiments, the sensor cluster 21 could be mounted on alternative parts of the trailer 12.

[0023] The sensor module 20 generates several signals indicating various dynamic characteristics of the trailer 12. These signals can include a yaw rate signal, a lateral acceleration signal, and wheel speed signals generated by a yaw rate sensor 25, an accelerometer 27, and the wheel speed sensors 23, respectively. Accordingly, in the illustrated embodiment, the yaw rate sensor 25 and the accelerometer 27 are contained within the sensor cluster 21 with housing, although other configurations are conceivable. It is conceivable that, in some embodiments, the accelerometer 27 could consist of two or more separate sensors arranged at an offset angle, such as two sensors positioned at plus and minus forty-five degrees from the longitudinal direction of the trailer or parallel to the longitudinal and lateral directions of the trailer, in order to generate a more robust acceleration signal.It is also considered that these sensor signals could be compensated and filtered to eliminate offsets or drifts and smooth out disturbances. Furthermore, the controller 28 can use processed signals received outside the sensor system 16, including standard signals from the brake control system 72 and the power steering system 62, such as vehicle yaw rate ω1, vehicle speed v1, and steering angle δ, to estimate the trailer coupling angle γ, the trailer speed, and related trailer parameters. As described in more detail below, the controller 28 can estimate the coupling angle γ based on the trailer yaw rate ω2, the vehicle yaw rate ω1, and the vehicle speed v1 with respect to a kinematic relationship between the trailer 12 and the vehicle 14.The control unit 28 of the trailer reversing assistance system 10 can also use the estimated trailer variables and trailer parameters to control the steering system 62, the brake control system 72 and the powertrain control system 74, for example to assist when reversing the vehicle-trailer combination or to mitigate a trailer sway condition.

[0024] With reference to the embodiment of the in Fig. In the trailer reversing assistance system 10 shown in Figure 2, the trailer reversing assistance system 10 can receive vehicle- and trailer-related information from additional sensors and devices. These additional sensors and devices can be used in place of the coupling angle sensor 44 or the sensor module 20 if one or more sensors used to determine the coupling angle γ (e.g., the coupling angle sensor 44) fail. This trailer-related information includes positioning information from a positioning device 56, which may include a Global Positioning System (GPS) on the vehicle 14 or a handheld device, to determine a coordinate position of the vehicle 14 and the trailer 12 based on the position of the positioning device 56 relative to the trailer 12 and / or the vehicle 14 and based on the estimated coupling angle γ.The positioning device 56 may additionally or alternatively include a dead reckoning navigation system for determining the coordinate position of the vehicle 14 and the trailer 12 in a localized coordinate system, based on at least the vehicle speed, the steering angle, and the coupling angle γ. Other vehicle information received by the trailer reversing assistance system 10 may include the vehicle 14's speed from a speed sensor 58 and the vehicle 14's yaw rate from a vehicle yaw rate sensor 60.It is considered that in additional embodiments the coupling angle sensor 44 and other vehicle sensors and devices may provide sensor signals or other information, such as proximity sensor signals or successive images of the trailer 12, which the control of the trailer reversing assistance system 10 can process with various routines to determine an indicator of the coupling angle γ, such as a range of coupling angles.

[0025] As further in Fig. Figure 2 shows an embodiment of the trailer reversing assistance system 10 connected to a power steering system 62 of the vehicle 14 to control the steered wheels 64 ( Fig. 1) to operate the vehicle 14 in such a way that the trailer 12 reacts in accordance with the desired trajectory of the trailer 12. In the illustrated embodiment, the power steering system 62 is an electric power-assisted steering system (EPAS) comprising an electric steering motor 66 for turning the steered wheels 64 to a steering angle based on a steering command, wherein the steering angle can be detected by a steering angle sensor 67 of the power steering system 62. The steering command can be provided by the trailer reversing assistance system 10 for autonomous steering during a reversing maneuver and can alternatively be given manually via a rotational position (for example, steering wheel angle) of a steering wheel 68 ( Fig. 1) be provided. In the illustrated embodiment, however, the steering wheel 68 of the vehicle 14 is mechanically coupled to the steered wheels 64 of the vehicle 14, so that the steering wheel 68 moves together with the steered wheels 64 via an internal torque, thereby preventing manual intervention via the steering wheel 68 during autonomous steering. In particular, a torque sensor 70 is provided on the power steering system 62, which detects torque (e.g., gripping and / or spinning) at the steering wheel 68 that is not expected from the autonomous control of the steering wheel 68 and thus indicates manual intervention by the driver. In some embodiments, the external torque applied to the steering wheel 68 can serve as a signal to the controller 28 that the driver has taken over manual control and for the vehicle 14 to abort steering maneuvers and / or warnings.

[0026] With renewed reference to the in Fig. In the illustrated embodiment 2, the power steering system 62 provides the control unit 28 of the trailer reversing assistance system 10 with information relating to the rotational position of the steered wheels 64 of the vehicle 14, including a steering angle. In the illustrated embodiment, the control unit 28 processes the current steering angle, in addition to other conditions relating to the vehicle 14 and the trailer 12, in such a way as to guide the trailer 12 along the desired curve. It is conceivable that in further embodiments the trailer reversing assistance system 10 could be an integrated component of the power steering system 62.For example, the power steering system 62 may include a trailer reversing assist algorithm for generating vehicle steering information and commands depending on all or part of the information received from the steering input device 18, the clutch angle sensor 44, the power steering system 62, a vehicle brake control system 72, a powertrain control system 74 and other vehicle sensors and devices.

[0027] As in Fig. As shown in Figure 2, the vehicle brake control system 72 can also communicate with the controller 28 to supply the trailer reversing assistance system 10 with braking information, such as vehicle wheel speeds, and to receive braking commands from the controller 28. For example, vehicle speed information can be determined from individual wheel speeds monitored by the brake control system 72. The vehicle speed can also be determined by the powertrain control system 74, the speed sensor 58, and the positioning device 56, among other conceivable means. In some embodiments, individual wheel speeds can also be used to determine a vehicle yaw rate, which is provided to the trailer reversing assistance system 10 as an alternative to, or in addition to, the vehicle yaw rate sensor 60.In certain embodiments, the trailer reversing assistance system 10 can supply vehicle braking information to the brake control system 72 to allow the trailer reversing assistance system 10 to control the braking of the vehicle 14 while the trailer 12 is reversing. For example, in some embodiments, the trailer reversing assistance system 10 can regulate the speed of the vehicle 14 while the trailer 12 is reversing, thereby reducing the possibility of unacceptable trailer reversing conditions occurring. Examples of unacceptable trailer reversing conditions include, but are not limited to, a condition of excessive vehicle speed, a high coupling angle rate, the inability to activate the sticker 52, or the user-selected points (e.g., points 35a, 35b). Fig. 3 and Fig. 4) to track dynamic instability of the trailer angle, a calculated theoretical buckling state of the trailer (defined by a maximum vehicle steering angle, a drawbar length, a wheelbase of the towing vehicle, and an effective trailer length), or a buckling limitation due to physical contact (defined by an angular displacement limit with respect to the vehicle 14 and the trailer 12), and the like. Unacceptable trailer reversing states can result from the failure of one or more sensors (e.g., the coupling angle sensor 44) and / or inputs (e.g., the steering input device 18) on the vehicle 14 and / or trailer 12 for providing information to the control unit 28 of the trailer reversing assistance system 10. In such cases, the driver may not be aware of the failure until the unacceptable trailer reversing state is imminent or already underway.Thus, it is revealed here that the trailer reversing assistance system 10 can generate a warning signal corresponding to a notification of an ongoing, imminent and / or anticipated unacceptable trailer reversing condition and can generate a countermeasure to prevent such an unacceptable trailer reversing condition before driver intervention, as is described in more detail below.

[0028] The one in the Fig. The powertrain control system 74 shown in the embodiment 2 can also cooperate with the trailer reversing assistance system 10 to regulate the speed and acceleration of the vehicle 14 during trailer reversing. As mentioned above, regulating the speed of the vehicle 14 may be necessary to limit the possibility of unacceptable trailer reversing conditions, such as buckling and dynamic instability of the trailer angle, or if the failure of a sensor and / or input device is detected. Similar to considerations of the relationship between high speed and unacceptable trailer reversing conditions, strong acceleration and highly dynamic cornering demands by the driver can also lead to such unacceptable trailer reversing conditions.

[0029] With further reference to Fig. 2 In the illustrated embodiment, the trailer reversing assistance system 10 can communicate with one or more devices, including a vehicle warning system 76, which can provide visual, audible, and tactile warnings. For example, vehicle brake lights 78 and the vehicle hazard warning lights can provide a visual warning, and a vehicle horn 79 and / or speaker 81 can provide an audible warning. In addition, the trailer reversing assistance system 10 and / or the vehicle warning system 76 can communicate with a human-machine interface (HMI) 80 for the vehicle 14. The HMI 80 can include the vehicle display 82, such as a navigation or entertainment display mounted in the center console ( Fig. 1) which is capable of displaying warning images. Such an embodiment may be desirable for notifying the driver of the vehicle 14 that a sensor and / or input device used by the reversing assistance system 10 has failed. Furthermore, the trailer reversing assistance system 10 can communicate wirelessly with another embodiment of the HMI 80, such as one or more handheld or portable devices, including one or more smartphones. The portable device may also include the display 82 for showing one or more images and other information to a user. For example, the portable device may display an image indicating a failure of the sensor and / or input device. In addition, the portable device may provide feedback information, such as visual, audible, and tactile warnings.

[0030] As further in Fig. As shown in Figure 2, the trailer reversing assistance system 10 comprises the steering input device 18, which is connected to the controller 28 to allow information transfer between them. It is disclosed here that the steering input device 18 can be coupled to the controller 28 in a wired or wireless manner. The steering input device 18 provides the trailer reversing assistance system 10 with information that defines the desired reversing path of the trailer 12 for the controller 28 to process and generate steering commands. In particular, the steering input device 18 can provide selection or position information that correlates with a desired trajectory of the desired reversing path of the trailer 12. The trailer steering commands provided by the steering input device 18 can include information regarding the commanded change in the path, such as...The information includes a stepwise change in the desired trajectory and information regarding a specification that the trailer 12 should move along a path defined by a longitudinal centerline axis of the trailer 12, such as a desired trajectory value of zero, which defines an essentially straight path for the trailer. Due to the importance of the steering input device 18 in controlling the vehicle 14 and the trailer 12 during movement, safety systems designed to mitigate a failure of the steering input device 18 by generating a countermeasure can be a desirable feature in the trailer reversing assistance system 10. Accordingly, the control unit 28 of the trailer reversing assistance system 10 can detect a failure of the steering input device 18 and initiate a countermeasure if the steering input device 18 fails, until the driver regains operational control of the vehicle 14.

[0031] With further reference to the in Fig. In the embodiment shown in Figure 2, the controller 28 is configured with a microprocessor 84 to process logic and routines stored in a memory 86, which receives information from the sensor system 16, including the trailer sensor module 20, the coupling angle sensor 44, the steering input device 18, the power steering system 62, the vehicle brake control system 72, the trailer brake system, the powertrain control system 74, and other vehicle sensors and devices. The controller 28 can generate vehicle steering information and commands as a function of all or part of the received information. The vehicle steering information and commands can then be supplied to the power steering system 62 to influence the steering of the vehicle 14 in order to execute a commanded path for the trailer 12.The controller 28 can include the microprocessor 84 and / or other analog and / or digital circuits for processing one or more routines. Furthermore, the controller 28 can include the memory 86 for storing one or more routines, including the clutch angle estimation routine 130, an operating routine 132, and a cam track routine 98. It is understood that the controller 28 can be a stand-alone, dedicated controller or a common controller integrated with other control functions, such as the sensor system 16, the power steering system 62, and other conceivable onboard or external vehicle control systems.

[0032] With reference to Fig. 9 We now consider a discussion of vehicle and trailer information and parameters for calculating a kinematic relationship between the trajectory of the trailer 12 and the steering angle of the vehicle 14 towing the trailer 12, which may be desirable for a trailer reversing assistance system 10 configured according to some embodiments, including an embodiment for use by a trajectory routine 98 of the controller 28. To achieve such a kinematic relationship, certain assumptions must be made regarding parameters associated with the vehicle / trailer system. Examples of such assumptions include, among others, that the trailer 12 is reversed by the vehicle 14 at a relatively low speed, that the wheels of the vehicle 14 and the trailer 12 have negligible (e.g., no) slip, and that the tires of the vehicle 14 have negligible (e.g.,exhibit no lateral compliance, the tires of the vehicle 14 and the trailer 12 exhibit negligible (e.g., no) deformation, the actuator dynamics of the vehicle 14 are negligible, and the vehicle 14 and the trailer 12 exhibit negligible (e.g., no) roll or pitch movements, in addition to other conceivable factors that have a potential effect on the steering of the trailer 12 with the vehicle 14.

[0033] As in Fig. As shown in Figure 9, the kinematic relationship for a system defined by a vehicle 14 and a trailer 12 is based on various parameters belonging to the vehicle 14 and the trailer 12. These parameters include: δ: Steering angle at the steerable front wheels of the vehicle; α: Yaw angle of the vehicle; β: Yaw angle of the trailer; γ: coupling angle (γ = β-α); W: Wheelbase of the vehicle; L: Drawbar length between the coupling point and the rear axle of the vehicle; D: Distance (trailer length) between the coupling point and the axle of the trailer or the effective axle in the case of a multi-axle trailer; and r2: Curve radius for the trailer.

[0034] One embodiment of a kinematic relationship between the radius of curvature r2 of the trailer path at the center point of an axis of the trailer 12, the steering angle δ of the steered wheels 64 of the vehicle 14, and the coupling angle γ can be expressed in the equation provided below. Thus, given the coupling angle γ, the curve of the trailer path κ2 can be determined. based on regulating the steering angle δ (where β̇ is the trailer yaw rate and η̇ is the trailer speed). κ2=1r2=β˙η˙=(W+KV2g)sin γ+L cos γ tan δD((W+KV2g)cos γ−L sin γ tan δ)

[0035] This relationship can be expressed to provide the steering angle δ as a function of the curve of the trailer path κ2 and the coupling angle γ. δ=tan−1((W+KV2g)[κ2D cos γ−sin γ]DLκ2 sin γ+L cos γ)=F(γ,κ2,K)

[0036] Accordingly, for a specific vehicle-trailer combination, certain parameters (e.g., D, W, and L) of the kinematic relationship are constant and assumed to be known. V is the vehicle's longitudinal speed, and g is the acceleration due to gravity. K is a speed-dependent parameter which, when set to zero, makes the calculation of the steering angle independent of the vehicle speed. For example, vehicle-specific parameters of the kinematic relationship can be predefined in an electronic control system of the vehicle 14, and trailer-specific parameters of the kinematic relationship can be entered by a driver of the vehicle 14, determined from the detected trailer behavior in response to vehicle steering commands, or otherwise determined from signals provided by the trailer 12.The curve path of the trailer κ2 can be determined from the driver input via the steering input device 18. By using the equation to provide the steering angle, a corresponding steering command for controlling the power steering system 62 of the vehicle 14 can be generated by the curve path routine 98.

[0037] In an additional embodiment, the cam track routine 98 can assume that the longitudinal distance L between the swivel linkage and the rear axle of the vehicle 14 is zero in order to operate the trailer reversing assistance system 10 when a gooseneck trailer or other similar trailer is connected to a coupling ball or a fifth wheel coupling positioned above a rear axle of the vehicle 14. This assumption essentially requires that the swivel linkage with the trailer 12 is oriented substantially vertically to the rear axle of the vehicle 14. When such an assumption is made, the controller 28 can generate the steering angle command for the vehicle 14 as a function that is independent of the longitudinal distance L between the swivel linkage and the rear axle of the vehicle 14.It is understood that the aforementioned gooseneck trailer generally refers to a drawbar configuration for attachment to the vehicle 14 at an elevated point above the rear axle, such as in a loading platform of a truck, wherein embodiments of the gooseneck trailer may include low-loaders, enclosed loading platforms, caravans, livestock trailers, horse trailers, low-loader trailers and other conceivable trailers with such a drawbar configuration.

[0038] Now, with reference to Fig. In the illustrated embodiments of the disclosed object, it is desirable to limit the possibility that the vehicle 14 and the trailer 12 reach an articulation angle (i.e., that the vehicle / trailer system reaches an articulation state). An articulation angle γ(j) refers to a coupling angle γ that cannot be overcome during reversing by the maximum steering input for a vehicle, such as when the steerable front wheels of the vehicle 14 are moved to a maximum steered angle δ with a maximum rate of change of steering angle. The articulation angle γ(j) is a function of a maximum wheel angle for the steered wheels of the vehicle 14, the wheelbase W of the vehicle 14, the distance L between the coupling point and the rear axle of the vehicle 14, and the trailer length D between the coupling point and the axle of the trailer 12, or the effective axle if the trailer 12 has multiple axles.If the coupling angle γ for the vehicle 14 and the trailer 12 reaches or exceeds the articulation angle γ(j), the vehicle 14 can be driven forward to reduce the coupling angle γ. Thus, to limit the possibility of a vehicle / trailer system reaching an articulation angle, it is preferred to control the yaw angle of the trailer 12 while keeping the coupling angle γ of the vehicle / trailer system relatively small.

[0039] A representation of a kinematic model of the vehicle 14 and the trailer 12 can also be used to determine an articulation angle for the vehicle-trailer combination. Accordingly, with reference to Fig. 9 and Fig. 10. A steering angle limitation for the steerable front wheels is imposed such that the coupling angle γ cannot exceed the articulation angle γ(j), which is also referred to as a critical coupling angle γ. With the restriction that the coupling angle γ cannot exceed the articulation angle γ(j), the articulation angle γ(j) is consequently the coupling angle γ that maintains circular motion for the vehicle / trailer system when the steered wheels 64 are at a maximum steering angle δ(max). The steering angle for circular motion with the coupling angle γ is defined by the following equation. tan δmax=w sin γmaxD+L cos γmax

[0040] Solving the above equation for the coupling angle γ allows the determination of the articulation angle γ(j). This solution, shown in the following equation, can be used in the implementation of the trailer reversing assistance functionality according to the disclosed subject matter to monitor the coupling angle γ with respect to the articulation angle. cos γ¯=−b±b2−4ac2a where the following applies: a = L 2 tan 2 δ(max) + W 2 ; b = 2 LD tan 2 δ(max); and c = D 2 tan 2 δ(max) - W 2 .

[0041] When reversing the trailer 12, in some cases, based on the current operating parameters of the vehicle 14 in combination with a corresponding coupling angle γ, a condition may arise that allows buckling. This condition can be indicated if one or more specified vehicle operating thresholds are reached at a specific coupling angle γ. For example, even if the specified coupling angle γ is not currently at the buckling angle for the vehicle 14 and the attached trailer 12, certain vehicle operating parameters may lead to a rapid (e.g., uncontrolled) transition of the coupling angle γ to the buckling angle for a currently commanded trailer curve and / or may reduce the steerability of the trailer 12 out of the buckling angle. One reason for a condition that allows buckling is that trailer curve control mechanisms (e.g.,(those according to the disclosed subject matter) generally calculate steering commands at an instantaneous point in time during the reversing of a trailer 12. However, these calculations will generally not take into account any delay in the steering control system of the vehicle 14 (e.g., delay in an EPAS steering control). Another reason for the condition that allows buckling is that trailer camber control mechanisms generally exhibit reduced steering sensitivity and / or effectiveness at relatively high speeds and / or relatively high acceleration of the vehicle 14.

[0042] According to one embodiment, buckling-determining information can be received by the control unit 28 in order to process and characterize a state that enables buckling of the vehicle-trailer combination at a specific time (e.g., at the time when the buckling-determining information was acquired).Examples of information that determines buckling include, but are not limited to, information characterizing an estimated coupling angle γ, information characterizing a transition state of the vehicle's accelerator pedal, information characterizing a vehicle's speed 14, information characterizing a vehicle's longitudinal acceleration 14, information characterizing a braking torque applied by a vehicle's braking system 14, information characterizing a drivetrain torque applied to the vehicle's driven wheels 14, and information characterizing the extent and rate of the trailer trajectory requested by the driver. This information would be continuously monitored, for example, by an electronic control unit (ECU) implementing the Trailer Backup Assist (TBA) function.After receiving the information that triggers buckling, a routine can process this information to determine whether the vehicle-trailer combination has reached a buckling-prone condition at a specific time. The goal of this buckling-prone process is to determine whether a buckling-prone condition, as defined by the information, has been reached at the specified time. If it is determined that a buckling-prone condition exists at the specified time, a routine can then determine an applicable countermeasure or countermeasures to be implemented.Accordingly, in some embodiments, an applicable countermeasure is selected depending on a parameter identified as a major influencing factor of the condition that enables buckling. In other embodiments, however, an applicable countermeasure is selected as the one most readily capable of eliminating the condition that enables buckling. In yet another embodiment, a predefined countermeasure or a predefined set of countermeasures may be the applicable countermeasure(s).

[0043] As previously disclosed with reference to the illustrated embodiments, a driver of the vehicle 14 may be restricted in the manner in which steering inputs are made using the steering wheel 68 of the vehicle 14 during the operation of the trailer reversing assistance system 10, since the power steering system 62 is directly coupled to the steering wheel 68. Accordingly, the steering input device 18 of the trailer reversing assistance system 10 can be used to input a desired curve path for the trailer 12, thereby preventing such commands from being made using the steering wheel 68 of the vehicle 14.Additional embodiments of the trailer reversing assistance system 10 may, however, have the ability to selectively decouple the steering wheel 68 from the movement of the steerable wheels of the vehicle 14, thereby allowing the steering wheel 68 to be used to command changes to the desired curve path of the trailer 12 or otherwise to select a desired reversing path during such trailer reversing assistance.

[0044] As described here, the trailer reversing assistance system 10 can use a camera 46 to detect targets such as a sticker 52 and / or user-selected points (e.g. points 35a, 35b; Fig. 3 and Fig. 4) to track the target(s) in order to determine the coupling angle γ between the vehicle 14 and the trailer 12. In some cases, however, the target(s) may be lost, i.e., not imaged by the camera 46. Examples of target(s) being lost include when the target(s) are no longer within the field of view 50 of the camera 46, when the target(s) are blocked by other objects or glare, and when the camera 46 malfunctions. If the target(s) are temporarily lost, the trailer reversing assistance system 10 may not be able to determine the coupling angle γ between the vehicle 14 and the trailer 12. In general, the longer the target(s) are lost, the greater the increase in the deviation of the coupling angle γ, depending on the speed at which the vehicle 14 and the trailer 12 are traveling.As a result, a potential collapse scenario may occur if no countermeasures are taken in response to the loss of the target(s).

[0045] With reference to Fig. 11 describes a method for managing a lost target of the trailer reversing assistance system 10 during a trailer reversing maneuver and can correspond to an embodiment of the operating routine 132 ( Fig. 2) As described here, the trailer reversing assistance system 10 can automatically steer the vehicle 14 as soon as the trailer reversing maneuver begins. In some embodiments, the trailer reversing assistance system 10 can also specify the speed of the vehicle 14 by actively controlling the vehicle brake control system 72 and / or the powertrain control system 74 of the vehicle 14. At step 170, the target(s) are imaged by the camera 46. If the target(s) are lost (decision block 180), the controller 28 calculates at step 190 the time it takes to achieve a maximum controllable coupling angle γ at a current trailer yaw rate. Otherwise, the coupling angle γ can be calculated at step 200, as long as the target(s) can be imaged, by any of the methods described here, such as the one with reference to Fig. The process described in section 5 is pursued. It is therefore understood that the method of the embodiment illustrated here can be regarded as an extension of any coupling angle detection methods described here that rely on the use of camera 46.

[0046] In step 190, the trailer yaw rate can be supplied to the control unit 28 via the yaw rate sensor 25 ( Fig. 2) If the time duration exceeds a predetermined threshold (decision block 210), the controller 28 can estimate the coupling angle γ at step 220 using non-camera-based means. For example, the controller 28 can estimate the coupling angle γ based on the trailer yaw rate ω2 supplied by the yaw rate sensor 25, the vehicle yaw rate ω1 supplied by the yaw rate sensor 60, and the vehicle speed v1 supplied by the speed sensor 58, with respect to the kinematic relationship between the trailer 12 and the vehicle 14 ( Fig. 9) As long as the time duration is above the predetermined threshold, the controller 28 can continue to estimate the coupling angle γ until the target is reacquired. If the time duration is below the predetermined threshold (decision block 210), the controller 28 initiates a preventive countermeasure against a potential buckling situation at step 230. The countermeasure may involve warning the vehicle operator to take control of the vehicle's steering wheel 68 14 and / or the vehicle's brake control system 72 (i.e., to apply the brakes). The warning may be visual, audible, and / or haptic and may be implemented using a variety of vehicle devices and systems.Additionally or alternatively, the countermeasure may involve controlling the power steering system 62, the vehicle brake control system 72, and / or the powertrain control system 74 of the vehicle 14 to reduce the clutch angle γ and the speed of the vehicle 14 to an acceptable threshold until the vehicle operator takes control of the steering wheel 68 of the vehicle 14. The controller 28 may be notified that the vehicle operator has taken control of the steering wheel 68 based on feedback from the torque sensor 70 of the power steering system 62. Fig. 2) or from (an) optional capacitive sensor(s) 250, which is / are arranged on the steering wheel 68 of the vehicle 14 ( Fig. 1) is received.

[0047] It is understood that variations and modifications of the above-mentioned structures and methods can be made without deviating from the concepts of the present invention, and it is further understood that such concepts are intended to be covered by the following claims, unless these claims expressly state otherwise.

Claims

[1] Trailer reversing assistance system (10), comprising: a camera (46) for taking pictures of a trailer (12) connected to a vehicle (14); a display (82) which has a screen (29) for displaying recorded images (31) and for registering a touch event thereon in order to assign a target on the depicted pendant (12); and a control (28) for processing the recorded images and tracking the target in order to determine a coupling angle between the vehicle (14) and the trailer (12) when the vehicle (14) is automatically steered during a trailer reversing maneuver. [2] Trailer reversing assistance system (10) according to claim 1, wherein the objective comprises a number of points on the illustrated trailer (12), wherein the points correspond to objects or features of the trailer (12). [3] Trailer reversing assistance system (10) according to claim 1 or 2, wherein the coupling angle is determined on the basis of changes in pixels of the recorded image (31) relating to a change in the angular position of the target. [4] Trailer reversing assistance system (10) according to claim 3, wherein, if the target is lost, the control unit (28) calculates a time in which a maximum controllable coupling angle can be achieved at a current trailer yaw rate. [5] Trailer reversing assistance system (10) according to claim 4, wherein, if the calculated time exceeds a predetermined threshold, the control unit (28) estimates the coupling angle based on a trailer yaw rate, a vehicle yaw rate and a vehicle speed. [6] Trailer reversing assistance system (10) according to claim 4 or 5, wherein, if the calculated time is below a predetermined threshold, the control system initiates a preventive countermeasure to reduce the coupling angle and the speed of the vehicle (14). [7] Trailer reversing assistance system (10), comprising: a camera (46) for taking pictures of a trailer (12) connected to a vehicle (14); and a control unit (28) for processing the recorded images and for tracking a target on the depicted trailer (12) in order to determine a coupling angle between the vehicle (14) and the trailer (12) during a trailer reversing maneuver, wherein, if the target is lost, the control unit (28) calculates a time in which a maximum controllable coupling angle can be achieved at a current trailer yaw rate. [8] Trailer reversing assistance system (10) according to claim 7, wherein the target is at least a sticker (52) attached to the trailer (12). [9] Trailer reversing assistance system (10) according to claim 7 or 8 with a number of points on the illustrated trailer (12), wherein the points correspond to objects or features of the trailer (12) and are assigned via one or more touch events on a screen (29) of a vehicle display (82). [10] Trailer reversing assistance system (10) according to claim 9, wherein the coupling angle is determined on the basis of changes in pixels of the recorded image (31) relating to a change in the angular position of the target. [11] Trailer reversing assistance system (10) according to one of claims 7-10, wherein, if the calculated time is above a predetermined threshold, the control unit (28) estimates the coupling angle based on a trailer yaw rate, a vehicle yaw rate and a vehicle speed. [12] Trailer reversing assistance system (10) according to one of claims 7-11, wherein, if the calculated time is below a predetermined threshold, the control unit (28) initiates a preventive countermeasure to reduce the coupling angle and the speed of the vehicle (14). [13] Coupling angle monitoring procedure comprising the following steps of: Taking pictures (31) of a trailer (12) connected to a vehicle (14); Displaying the recorded images (31) on a screen (29) of a vehicle display (82); Registering a touch event on the screen (29) to assign a target on the depicted pendant (12); and Processing the recorded images (31) to track the target in order to determine a coupling angle between the vehicle (14) and the trailer (12), when the trailer (12) is automatically steered during a trailer reversing maneuver. [14] Coupling angle monitoring method according to claim 13, further comprising the step of aligning the vehicle (14) and the trailer (12) prior to assigning the target on the illustrated trailer (12). [15] Coupling angle monitoring method according to claim 13 or 14, wherein the target comprises a number of points on the depicted trailer (12), wherein the points correspond to objects or features of the trailer (12) and wherein the coupling angle is determined on the basis of changes in pixels of the recorded images (31) relating to a change in the angular position of the target. [16] Coupling angle monitoring method according to one of claims 13-15, wherein, if the target is lost, the control (28) calculates a time in which a maximum controllable coupling angle can be achieved at a current trailer yaw rate. [17] Coupling angle monitoring method according to one of claims 14-16, wherein, if the calculated time is above a predetermined threshold, the control (28) estimates the coupling angle based on a trailer yaw rate, a vehicle yaw rate and a vehicle speed. [18] Clutch angle monitoring method according to one of claims 14-17, wherein, if the calculated time is below a predetermined threshold, the control (28) initiates a preventive countermeasure to reduce a potential buckling situation. [19] Clutch angle monitoring method according to claim 18, wherein the preventive countermeasure includes warning an operator of the vehicle (14) to take control of a steering device of the vehicle (14) and / or a vehicle brake control system of the vehicle (14). [20] Clutch angle monitoring method according to claim 18 or 19, wherein the preventive countermeasure includes actively controlling a power steering system (62) and / or a vehicle brake control system (72) and / or a powertrain control system (74) of the vehicle (14) to reduce the clutch angle and the speed of the vehicle (14).

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