Trailer reversing aid system with device for standardized steering input for various trailers

Abstract

Trailer reversing aid system for a vehicle (14) reversing a trailer (12), comprising: a knob (30) rotatable into a plurality of positions, each defining a desired curvature (26); and a controller that generates a steering command for the vehicle (14) based on a kinematic relationship between the vehicle (14) and the trailer (12), to guide the trailer (12) on the desired curvature (26), wherein the desired curvature (26) is defined for each of the plurality of positions on the basis of standardized trailer dimensions, characterized in that the standardized trailer dimensions include dimensions of additional trailers (12) suitable for being towed by the vehicle (14) and / or that the standardized trailer dimensions include lengths of additional trailers (12) that have previously been attached to the vehicle (14) and have been reversed with guidance by the trailer reversing assistance system (10).

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application is a continuation-in-part of U.S. Patent Application No. 13 / 336,042, filed December 23, 2011, entitled "ROTATABLE DRIVER INTERFACE FOR TRAILER BACKUP ASSIST," which claims the benefit of U.S. Provisional Patent Application No. 61 / 477,136, filed April 19, 2011, entitled "INTUITIVE DRIVER INTERFACE FOR TRAILER REVERSE ASSIST," which are incorporated herein by reference in their entirety. FIELD OF THE INVENTION

[0002] The present disclosure relates generally to driver assistance and active safety technologies in vehicles, and more particularly to a trailer backup assist system configured with a normalized steering input device for guiding various trailers. BACKGROUND OF THE INVENTION

[0003] Reversing a vehicle while towing a trailer can be challenging for many drivers, particularly those who drive with a trailer on an infrequent basis or with different types of trailers. One reason for this difficulty may be that reversing a vehicle with a trailer attached requires steering inputs that are opposite to the steering inputs required when reversing the vehicle without a trailer attached. Another reason for this difficulty may be that small errors in steering are amplified while reversing a vehicle with a trailer attached, which can cause the trailer to quickly deviate from a command path.Yet another reason why reversing a trailer can prove difficult is the need to control the vehicle in a manner that limits the possibility of jackknifing. These difficulties may also be experienced, and in some cases exacerbated, when attempting to quickly achieve a tight turning radius or when switching between different trailers that exhibit wide variation in how they respond to similar steering inputs, such as how a relatively short trailer may respond more quickly than a long trailer to a steering change. DE 10 2012 205 416 A1 discloses a trailer path curvature control for a trailer reversing aid. DE 10 2010 021 052 A1 discloses a reversing aid device for controlling reversing of a vehicle combination. SUMMARY OF THE INVENTION

[0004] The features of the independent claims represent an improvement on the prior art. Preferred embodiments thereof are specified in the further claims. According to one aspect of the present invention, a trailer backup assist system for a vehicle backing up a trailer includes a knob rotatable to a plurality of positions, each defining a desired curvature. The trailer backup assist system also includes a controller that generates a steering command for the vehicle to guide the trailer along the desired curvature based on a kinematic relationship between the vehicle and the trailer. The desired curvature for each of the plurality of positions is defined based on standardized trailer dimensions.

[0005] According to another aspect of the present invention, a trailer backup assist system for a vehicle backing up a trailer includes a trailer hitch sensor that senses a hitch angle between the vehicle and the trailer. The trailer backup assist system also includes a steering input device operable between a plurality of selections, each providing an incremental change in a desired curvature of the trailer. The trailer backup assist system further includes a controller that generates a steering command to the vehicle based on the sensed hitch angle and a kinematic relationship with the trailer to guide the trailer on the desired curvature. To normalize the control of the desired curvature, the incremental change is substantially the same for a population of trailers.

[0006] According to another aspect of the present invention, a method for steering a vehicle backing a trailer provides dimensions for a set of trailers that can be backed by the vehicle. The method further provides a rotary knob. The method further determines a target curvature for the trailer based on a position of the rotary knob, wherein a change in the target curvature based on the degree of change in the position of the rotary knob and the dimensions of the set of trailers is a function of a normalized ratio.

[0007] These and other aspects, objects and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following description, the following claims and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the drawings: Fig. 1 is a top perspective view of a vehicle coupled to a trailer, including one embodiment of a trailer hitch angle sensor for operating a trailer backup assist system; Fig. 2 is a block diagram illustrating an embodiment of the trailer backup assist system with a steering input device, a curvature controller, and a trailer braking system; Fig. 3 is a schematic diagram illustrating the geometry of a vehicle and a trailer with an overlaid two-dimensional xy coordinate system identifying variables used to determine a kinematic relationship of the vehicle and the trailer for the trailer backup assist system, according to one embodiment; Fig. 4 is a schematic block diagram illustrating portions of a curvature controller according to an additional embodiment and other components of the trailer backup assist system according to such embodiment; Fig. 5 a schematic block diagram of the curvature controller from Fig. 4, which shows the feedback architecture and signal flow of the curvature controller according to such an embodiment; Fig. 6 is a schematic diagram showing a relationship between a trailer coupling angle and a steering angle of the vehicle with respect to the curvature of the trailer and a cornering angle; Fig. 7 is a plan view of a steering input device with a rotary knob for operating the trailer backup assist system according to one embodiment; Fig. 8 is a plan view of another embodiment of a rotary knob for selecting a desired curvature of a trailer and a corresponding schematic diagram illustrating a vehicle and trailer with various trailer curvature paths correlating with desired curvatures that can be selected; Fig. 9 is a schematic diagram illustrating a vehicle and trailer reversing sequence implementing various curvature selections with the trailer reversing assist system, according to one embodiment; Fig. 10 is a flowchart illustrating a method of operating a trailer backup assist system using an operating routine for steering a vehicle backing up a trailer with normalized target curvature control according to one embodiment; and Fig. 11 is a flowchart illustrating a method of operating a trailer backup assist system using a trailer aggregate routine according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Unless expressly stated to the contrary, it is to be understood that the disclosed trailer backup assist system and related methods are capable of assuming various alternative embodiments and orientations for the purposes of this description. Furthermore, it is to be understood that the specific devices and processes set forth in the accompanying drawings and described in the following description are simply exemplary embodiments of the inventive concepts defined in the appended claims. Although various aspects of the trailer backup assist system and related methods are described with reference to a particular illustrative embodiment, the disclosed invention is not limited to these embodiments, and additional modifications, applications, and embodiments may be implemented without departing from the disclosed invention.Unless the claims expressly state the contrary, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are therefore not to be considered limiting.

[0010] Based on Fig. 1-11, reference numeral 10 generally designates a trailer backup assist system for controlling a backup path of a trailer 12 coupled to a vehicle 14 by allowing a driver of the vehicle 14 to specify a desired curvature 26 of the backup path of the trailer 12. In one embodiment, the trailer backup assist system 10 automatically steers the vehicle 14 to guide the trailer 12 along the desired curvature 26 while a driver uses the accelerator pedal and the brake pedal to control the backup speed of the vehicle 14.In some embodiments, trailer 12 may be one of a number of trailers that may be coupled to vehicle 14, such that a set of additional trailers may be defined by trailers that may be towed by vehicle 14 or by trailers that have previously been coupled to vehicle 14 and reversed under guidance of trailer backup assist system 10, among other alternatively defined sets of additional trailers. To monitor the position of coupled trailer 12 relative to vehicle 14, trailer backup assist system 10 may include a sensor system 16 that senses a hitch angle γ between trailer 12 and vehicle 14, which may be referred to as a hitch angle sensor 44.Additionally, the trailer backup assist system 10 may include a steering input device 18, such as a rotary knob 30, for a driver to provide the desired curvature 26 of the trailer 12. Thus, the steering input device 18 may be operable between multiple selections, such as successively rotated positions of the knob 30, each providing an incremental change in the desired curvature 26 of the trailer 12. Upon inputting the desired curvature 26, a controller may then generate a steering command for the vehicle 14 to guide the trailer 12 along the desired curvature 26 based on the sensed trailer hitch angle γ and a kinematic relationship between the trailer 12 and the vehicle 14. The incremental change in the desired curvature 26 of the trailer 12 may then be configured to be substantially the same for all of the trailers, thereby normalizing control of the desired curvature 26, according to one embodiment.

[0011] Further on the basis of Fig. 1, the vehicle 14 is a flatbed van embodiment equipped with an embodiment of the trailer backup assist system 10 to control the backup path of the trailer 12 coupled to the vehicle 14. More specifically, the vehicle 14 is pivotally coupled to an embodiment of the trailer 12 having a box frame 32 with an enclosed cargo area 34, a single axle with a right wheel assembly and a left wheel assembly, and a tongue 36 extending longitudinally forward from the enclosed cargo area 34. The illustrated trailer 12 also includes a trailer hitch connector in the form of a coupler assembly 38 connected to a vehicle trailer hitch connector in the form of a hitch ball 40.The coupling assembly 38 locks to the hitch ball 40 to provide a pivoting ball joint connection 42 that enables the articulation of the hitch angle γ. It should be appreciated that additional embodiments of the trailer 12 may alternatively couple to the vehicle 14 to provide a pivoting connection, such as by connecting to a fifth wheel connector. It is also contemplated that additional embodiments of the trailer may include more than one axle and may have various shapes and sizes configured for various loads and items, such as a boat trailer or a flatbed trailer.

[0012] Further based on Fig. 1, the sensor system 16, in the illustrated embodiment, includes an image recognition-based hitch angle sensor 44 for sensing the hitch angle γ between the vehicle 14 and the trailer 12. The illustrated hitch angle sensor 44 utilizes a camera 46 (e.g., a video imaging camera), which, as shown, may be located near an upper region of the vehicle tailgate 48 at the rear of the vehicle 14 such that the camera 46 may be elevated relative to the tongue 36 of the trailer 12. The illustrated camera 46 has an imaging field of view 50 located and oriented to capture one or more images of the trailer 12, including an area containing one or more desired placement zones for at least one target 52 to be attached.Although it is contemplated that camera 46 may capture images of trailer 12 without a target 52 to determine the hitch angle γ, in the illustrated embodiment, trailer backup assist system 10 includes a target 52 disposed on trailer 12 to enable trailer backup assist system 10 to utilize information acquired via image capture and image processing of target 52. For example, illustrated camera 46 may include a video imaging camera that repeatedly captures successive images of trailer 12, which may be processed to identify target 52 and its location on trailer 12 to determine the movement of target 52 and trailer 12 relative to vehicle 14 and the corresponding hitch angle γ.Additionally, it should be appreciated that the camera 46 may include one or more video imaging cameras and may be located at other locations on the vehicle 14 to capture images of the trailer 12 and the desired target placement zone, such as may be located on a cab 54 of the vehicle 14 to capture images of a gooseneck trailer.Furthermore, it is contemplated that additional embodiments of the hitch angle sensor 44 and the sensor system 16 for providing the hitch angle γ may include one or a combination of a potentiometer, a magnetic-based sensor, an optical sensor, a proximity sensor, a rotation sensor, a capacitive sensor, an inductive sensor, or a mechanically based sensor such as a mechanical sensor assembly mounted on the pivot ball joint 42, a yaw rate sensor on the trailer 12 and on the vehicle 14, energy converters of a backup assist system, a blind spot system, and / or a cross traffic alert system, and other conceivable sensors or indicators of the hitch angle γ to supplement or be used in place of the image recognition-based hitch angle 44.

[0013] Based on the Fig. In the embodiment of the trailer backup assist system 10 shown in FIG. 2, the trailer hitch angle sensor 44 provides the sensed trailer hitch angle γ to the trailer backup assist system 10. Similarly, the illustrated embodiment of the trailer backup assist system 10 receives vehicle status-related information from additional sensors and devices. This information includes positioning information from a positioning device 56, which may include a global positioning system (GPS) on the vehicle 14 or on a related device, to determine a coordinate location of the vehicle 14 and the trailer 12 based on the location of the positioning device 56 relative to the trailer 12 and / or relative to the vehicle 14 and the sensed trailer hitch angle γ.Additionally or alternatively, the positioning device 56 may include a dead reckoning system to determine the coordinate location of the vehicle 14 and the trailer 12 within a localized coordinate system based on the vehicle speed and / or the steering angle and / or the trailer hitch angle γ. Other vehicle information received by the trailer backup assist system 10 may include a speed of the vehicle 14 from a speed sensor 58 and a yaw rate of the vehicle 14 from a yaw sensor 60.It is contemplated that in additional embodiments, the trailer hitch angle sensor 44 and other vehicle sensors and vehicle devices may provide sensor signals or other information, such as proximity sensor signals or sequential images of the trailer 12, which a controller of the trailer backup assist system 10 may process using various routines to determine an indicator of the trailer hitch angle γ, such as a range of trailer hitch angles.

[0014] How to continue in Fig. 2, one embodiment of the trailer backup assist system 10 is in communication with a power steering system 62 of the vehicle 14 to control the steered wheels 64 ( Fig. 1) of the vehicle 14 in such a way as to move the vehicle 14 such that the trailer 12 responds according to the desired curvature 26 of the trailer 12. In the illustrated embodiment, the power steering system 62 is an electric power assisted steering (EPAS) system that includes an electric steering motor 66 to turn the steered wheels 64 based on a steering command to a steering angle, which steering angle may be sensed by a steering angle sensor 67 of the power steering system 62. The steering command may be provided by the trailer backup assist system 10 for autonomous steering during a reversing maneuver and may alternatively be manually provided via a rotational position (e.g., the steering wheel angle) of a steering wheel 68 ( Fig. 1). However, in the illustrated embodiment, the steering wheel 68 of the vehicle 14 is mechanically coupled to the steered wheels 64 of the vehicle 14 such that the steering wheel 68 moves along with the steered wheels 64, preventing manual intervention with the steering wheel 68 during autonomous steering. More specifically, a torque sensor 70 is provided on the power steering system 62 that detects torque on the steering wheel 68 that is not expected by the autonomous control of the steering wheel 68 and thus indicates manual intervention, whereby the trailer backup assist system 10 can alert the driver to interrupt manual intervention with the steering wheel 68 and / or to interrupt autonomous steering.

[0015] In alternative embodiments, some vehicles include a power steering system 62 that allows a steering wheel 68 to be partially decoupled from the movement of the steered wheels 64 of such a vehicle. Accordingly, the steering wheel 68 can be rotated independently of the manner in which the vehicle's power steering system 62 controls the steered wheels 64 (e.g., autonomous steering as commanded by the trailer backup assist system 10). Thus, as disclosed in more detail below, in those types of vehicles in which the steering wheel 68 can be selectively decoupled from the steered wheels 64 to enable its independent operation, the steering wheel 68 can be used as a steering input device 18 for the trailer backup assist system 10.

[0016] Again based on the Fig. In the embodiment illustrated in Figure 2, the power steering system 62 provides information related to a rotational position of the steered wheels 64 of the vehicle 14, including a steering angle, to the curvature controller 28 of the trailer backup assist system 10. In the illustrated embodiment, the curvature controller 28 processes the current steering angle, in addition to other conditions of the vehicle 14 and the trailer 12, to guide the trailer 12 along the desired curvature 26. In additional embodiments, it is contemplated that the trailer backup assist system 10 may be an integrated component of the power steering system 62.For example, the power steering system 62 may include a trailer backup assist algorithm for generating vehicle steering information and vehicle steering commands as a function of all or a portion of the information received from the steering input device 18, the trailer hitch angle sensor 44, the power steering system 62, the vehicle brake control system 72, a powertrain control system 74, and other vehicle sensors and vehicle devices.

[0017] As also in Fig. 2, the vehicle brake control system 72 may also communicate with the curvature controller 28 to provide braking information, such as wheel speed, to the trailer backup assist system 10 and to receive braking commands from the curvature controller 28. For example, the vehicle speed information may be determined from individual wheel speeds as monitored by the brake control system 72. Among other conceivable means, the vehicle speed may also be determined by the powertrain control system 74, the speed sensor 58, and the position determining device 56. In some embodiments, the individual wheel speeds may also be used to determine a vehicle yaw rate, which may be provided to the trailer backup assist system 10 for use in determining vehicle steering commands, alternatively or in addition to the yaw sensor 60.In certain embodiments, the trailer backup assist system 10 may provide vehicle braking information to the brake control system 72 to enable the trailer backup assist system 10 to control the braking of the vehicle 14 while the trailer 12 is backing up. For example, in some embodiments, the trailer backup assist system 10 may regulate the speed of the vehicle 14 while the trailer 12 is backing up, which may reduce the possibility of unacceptable trailer backing conditions.Examples of unacceptable trailer backing conditions include, but are not limited to, an overspeed condition of the vehicle 14, a high hitch angle rate, dynamic trailer angle instability, a calculated theoretical trailer jackknife condition (defined by a maximum vehicle steering angle, by the tongue length, by the tractor wheelbase, and by an effective trailer length), or a physical contact jackknife limitation (defined by an angular displacement limit relative to the vehicle 14 and to the trailer 12), and the like. It is disclosed herein that the trailer backing assist system 10 may output a warning signal corresponding to a notification of an actual, impending, and / or expected unacceptable trailer backing condition.

[0018] The powertrain control system 74, as shown in Fig. 2, may also cooperate with the trailer backup assist system 10 to control the speed and acceleration of the vehicle 14 during backing of the trailer 12. As mentioned above, controlling the speed of the vehicle 14 may be necessary to limit the possibility of unacceptable trailer backup conditions, such as, for example, jackknifing and dynamic trailer angle instability. Similar to high-speed considerations relating to unacceptable trailer backup conditions, high acceleration and highly dynamic driver curvature requirements may also result in such unacceptable trailer backup conditions.

[0019] Further based on Fig. 2, the trailer backup assist system 10 in the illustrated embodiment may communicate with one or more devices including a vehicle warning system 76, which may provide visible, audible, and tactile warnings. For example, the vehicle brake lights 78 and the vehicle hazard warning lights may provide a visible warning, and a vehicle horn 79 and / or speaker 81 may provide an audible warning. In addition, the trailer backup assist system 10 and / or the vehicle warning system 76 may communicate with a human-machine interface (HMI) 80 for the vehicle 14. The HMI 80 may include a vehicle display 82, such as a center console-mounted navigation or entertainment display ( Fig. 1). Further, the trailer backup assist system 10 may communicate via wireless communication 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 displaying one or more images and other information to a user. For example, the portable device may display one or more images of the trailer 12 and the target location within a desired target placement zone on the display. Additionally, the portable device may provide feedback information, such as visual, audible, and tactile warnings.

[0020] As in Fig. 2, the trailer backup assist system 10 includes a steering input device 18 connected to the curvature controller 28 to enable the communication of information therebetween. It is disclosed herein that the steering input device 18 may be coupled to the curvature controller 28 in a wired or wireless manner. The steering input device 18 provides the trailer backup assist system 10 with information defining the desired reverse path of travel of the trailer 12 for the curvature controller 28 to process and generate steering commands. More specifically, the steering input device 18 may provide selection or position information correlating with a desired curvature 26 of the desired reverse path of the trailer 12.Additionally, the trailer steering commands provided by the steering input device 18 may include information related to a commanded change in the travel path, such as an incremental change in the target curvature 26, and information related to an indication that the trailer 12 should travel along a path defined by a longitudinal centerline axis of the trailer 12, such as a target curvature value of zero, which substantially defines a straight travel path for the trailer. As discussed in more detail below, according to one embodiment, the steering input device 18 may include a movable control input device to enable a driver of the vehicle 14 to command target trailer steering actions or otherwise select and change a target curvature. The movable control input device may, for example,a rotary knob 30 that may be rotatable about a rotation axis passing through a top surface or top of the knob 30. In other embodiments, the rotary knob 30 may be rotatable about a rotation axis that is substantially parallel to a top surface or top of the rotary knob 30. As will be generally understood by those of ordinary skill in the art, according to additional embodiments, the steering input device 18 may further include alternative devices for providing a desired curvature 26 or other information defining a desired return path, such as a joystick, a keypad, a series of pushbuttons or switches, a slide input device, various user interfaces on a touchscreen display, an image recognition-based system for receiving gestures, a control interface on a portable device, and other conceivable input devices.It is contemplated that the steering input device 18 may also function as an input device for other features, such as providing inputs to other vehicle features or vehicle systems.

[0021] Further on the basis of Fig. In the embodiment shown in Figure 2, the curvature controller 28 is configured with a microprocessor 84 for processing logic and routines stored in memory 86 that receive information from the steering input device 18, the trailer hitch angle sensor 44, 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 curvature sensor 28 can generate vehicle steering information and vehicle steering commands as a function of all or a portion of the received information. The vehicle steering information and vehicle steering commands can then be provided to the power steering system 62 to effect steering of the vehicle 14 to achieve a commanded travel path for the trailer 12.The curvature controller 28 may include the microprocessor 84 and / or other analog and / or digital circuitry for processing one or more routines. The curvature controller 28 may also include the memory 86 for storing one or more routines, including an operating routine 132, a trailer aggregate routine 130, and a curvature routine 98. It should be appreciated that the curvature controller 28 may be a single dedicated controller or a shared controller integrated with other control functions, such as one integrated with the sensor system 16, the power steering system 62, and other conceivable on-board or off-board vehicle control systems.

[0022] Based on Fig. 3, we now turn to a discussion of the vehicle and trailer information and vehicle and trailer parameters used to calculate a kinematic relationship between a curvature of a travel path of the trailer 12 and the steering angle of the vehicle 14 pulling the trailer 12, which may be desired for a trailer backup assist system 10 configured according to some embodiments, in one embodiment including for use by a curvature routine 98 of the curvature controller 28. To achieve such a kinematic relationship, certain assumptions may be made regarding the parameters associated with a vehicle / trailer system.Among other conceivable factors that may have an effect on the control of the trailer 12 with the vehicle 14, examples of such assumptions may include, but are not limited to, that the trailer 12 is being 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) slippage, that the tires of the vehicle 14 have negligible (e.g., no) lateral compliance, that the tires of the vehicle 14 and the trailer 12 have negligible (e.g., no) deformation, that the actuator dynamics of the vehicle 14 are negligible, and that the vehicle 14 and the trailer 12 have negligible (e.g., no) roll or pitch motions.

[0023] As in Fig. As shown in Figure 3, the kinematic relationship for a system defined by a vehicle 14 and a trailer 12 is based on various parameters associated with the vehicle 14 and the trailer 12. These parameters include: δ: steering angle when the vehicle’s front wheels are steered; α: yaw angle of the vehicle; β: yaw angle of the trailer; γ: trailer coupling angle (γ = β - α); W: wheelbase of the vehicle; L: length between the towbar point and the rear axle of the vehicle; D: distance between the towbar coupling point and the axle of the trailer or the effective axle for a multi-axle trailer (axle length may be an equivalent); and r2: radius of curvature for the trailer.

[0024] One embodiment of a kinematic relationship between the trailer path radius with curvature r2 at the center of an axle of the trailer 12, the steering angle δ of the steered wheels 64 of the vehicle 14, and the trailer hitch angle γ can be expressed in the equation given below. Thus, the trailer path curvature ĸ2 can be controlled based on the control of the steering angle δ if the trailer hitch angle γ is given (where β̇ is the trailer yaw rate and ή is the trailer speed). κ2=1r2=β˙η˙=(W+KV2g)sin γ+Lcos γ tan δD((W+KV2g)cos γ−L sin γ tan δ).

[0025] This relationship can be expressed as providing the steering angle δ as a function of the trailer path curvature ĸ2 and the trailer coupling angle γ. δ=tan−1((W+KV2g)[κ2D cos γ−sin γ]DLκ2sin+L cos γ)=F(γ,κ2,K).

[0026] Accordingly, for a particular vehicle and 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 vehicle speed. For example, vehicle-specific parameters of the kinematic relationship may be predefined in an electronic control system of the vehicle 14, and trailer-specific parameters of the kinematic relationship may be entered by a driver of the vehicle 14, determined from sensed trailer behavior in response to vehicle steering commands, or otherwise determined from signals provided by the trailer 12. The trailer path curvature ĸ2 may be determined from the driver input via the steering input device 18.By using the equation to provide the steering angle, the curvature routine 98 can generate a corresponding steering command to control the power steering system 62 of the vehicle 14.

[0027] In an additional embodiment, when a gooseneck or similar trailer is connected to a hitch ball or fifth wheel that connects over a rear axle of the vehicle 14, an assumption may be made by the curvature routine 98 that a longitudinal distance L between the pivot connection and the rear axle of the vehicle 14 is zero for operation of the trailer backup assist system 10. Essentially, the assumption assumes that the pivot connection to the trailer 12 is substantially vertically aligned with the rear axle of the vehicle 14. When such an assumption is made, the curvature controller 28 may generate the steering angle command for the vehicle 14 as a function independent of the longitudinal distance L between the pivot connection and the rear axle of the vehicle 14.It will be appreciated that the referenced gooseneck trailer generally refers to the tongue configuration that is raised for attachment to the vehicle 14 at an elevated location above the rear axle, such as within a truck bed, and embodiments of the gooseneck trailer may include flatbed truck beds, enclosed truck beds, camper vans, livestock trailers, horse trailers, low-bed trailers, and other conceivable trailers having such a tongue configuration.

[0028] In Fig. 4, which shows a general architectural layout, yet another embodiment of the curvature routine 98 of the trailer backup assist system 10 is illustrated, wherein a measuring module 88, a trailer hitch angle controller 90, and a curvature controller 92 are routines that may be stored in the memory 86 of the curvature controller 28. In the illustrated layout, the steering input device 18 provides the curvature controller 92 of the curvature controller 28 with a value of the desired curvature ĸ2, which may be determined from the desired reversing path 26 input with the steering input device 18. The curvature controller 92 calculates a desired trailer hitch angle y(d) based on a current desired curvature ĸ2 together with the steering angle δ, which in this embodiment of the curvature controller 28 is provided by a measuring module 88.The measurement module 88 may be a storage device separate from or integrated with the curvature controller 28 that stores data from sensors of the trailer backup assist system 10, such as the hitch angle sensor 44, the vehicle speed sensor 58, and the steering angle sensor. Alternatively, the measurement module 88 may otherwise directly send data from the sensors without acting as a storage device. When the desired hitch angle γ(d) is calculated by the curvature controller 92, the hitch angle controller 90 generates a steering angle command based on the calculated desired hitch angle γ(d), a measured hitch angle γ(m), and a current speed of the vehicle 14.The steering angle command is provided to the power steering system 62 of the vehicle 14 and then fed back to the measurement module 88 to re-evaluate the effects of other vehicle characteristics affected by the implementation of the steering angle command or other changes to the system. Accordingly, the curvature controller 92 and the trailer hitch angle controller 90 continuously process information from the measurement module 88 to provide accurate steering angle commands that position the trailer 12 on the target curvature κ2 and on the target return path 26 without significant overshoot or continuous oscillation of the travel path around the target curvature κ2.

[0029] As also in Fig. 5 is the embodiment of the device shown in Fig. 4 is depicted in a control system block diagram. More specifically, an input κ2 representing the desired curvature 26 of the trailer 12 is input to the control system, which is provided to the curvature controller 92. The curvature controller 92 may be expressed as a static map p(κ2, δ), which in one embodiment is the following equation: p(κ2,δ)=tan−1(κ2D+L tan(δ)κ2DL tan(δ)−W), where κ2 is the nominal curvature of the trailer 12 or 1 / r2 as in Fig. 3 shown represents; δ represents the steering angle; L represents the distance from the rear axle of the vehicle 14 to the trailer coupling pivot point; D represents the distance from the trailer coupling pivot point to the axle of the trailer 12; and W represents the distance from the rear axle to the front axle of the vehicle 14.

[0030] Further based on Fig. 5 the output trailer coupling angle p(κ2, δ) is used as the reference signal γ ref provided for the rest of the control system, although the value of the steering angle δ used by the curvature controller 92 is fed back from the nonlinear function of the trailer hitch angle controller 90. It is shown that the trailer hitch angle controller 90 uses feedback linearization to define a feedback control law as follows: g(u,γ,v)=δ=tan−1(Wv(1+LDcos(γ))(u−vDsin(γ))).

[0031] As also in Fig. 5, the feedback control law g(u, γ, v) is implemented with a proportional-integral (PI) controller, where the integral portion essentially eliminates a steady-state tracking error. More precisely, the Fig. 5 can be expressed as the following algebraic differential equations: γ˙(t)=v(t)Dsin(γ(t))+(1+LDcos(γ(t)))v(t)Wδ¯, tan(δ)=δ¯=Wv(t)(1+LDcos(γ(t)))(KP(p(κ2,δ)−γ(t)−v(t)Dsin(γ(t))).

[0032] It is contemplated that the PI controller may include gain terms based on trailer length D, as shorter trailers generally have fast dynamics. As disclosed in more detail below, the hitch angle controller 90 may also be configured to prevent the desired hitch angle γ(d) from reaching or exceeding a break-in angle y(j) as calculated by the controller or otherwise determined by the trailer backup assist system 10.

[0033] Now based on Fig. 6, in the illustrated embodiments of the disclosed subject matter, it is desirable to limit the possibility of the vehicle 14 and trailer 12 reaching a jackknife angle (i.e., the vehicle / trailer system reaching a jackknife condition). A jackknife angle γ(j) refers to a trailer hitch angle γ that cannot be overcome during reverse travel by the maximum steering input for a vehicle, such as, for example, when the steered front wheels of the vehicle 14 are moved at a maximum rate of steering angle change to a maximum steered angle δ.The jackknife angle y(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 hitch point and the rear axle of the vehicle 14, and the length D between the hitch point and the axle of the trailer 12 or the effective axle if the trailer 12 has multiple axles. When the jackknife angle γ for the vehicle 14 and for the trailer 12 meets or exceeds the jackknife angle y(j), the vehicle 14 can be pulled forward to reduce the jackknife angle γ. Thus, to limit the possibility of a vehicle / trailer system reaching jackknife angle, it is preferable to control the yaw angle of the trailer 12 while keeping the jackknife angle γ of the vehicle / trailer system relatively small.

[0034] To determine a steering angle for the vehicle-trailer combination, a representation of the vehicle 14 and the trailer 12 in a kinematic model can be used. Accordingly, a steering angle limit for the steered front wheels according to Fig. 3 and Fig. 6, that the hitch angle γ cannot exceed the articulation angle γ(j), which is also referred to as a critical hitch angle γ. Subject to the constraint that the hitch angle γ cannot exceed the articulation angle γ(j), the articulation angle γ(j) is thus the hitch angle γ that maintains a 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 hitch angle γ is defined by the following equation. tan δmax=w sin γmaxD+L cos γmax.

[0035] Solving the above equation for the trailer hitch angle γ allows the articulation angle γ(j) to be determined. This solution, shown in the following equation, can be used when implementing a trailer backup assist functionality according to the disclosed subject matter for monitoring the trailer hitch angle γ with respect to an articulation angle. cos γ¯=−b±b2−4ac2a, where a=L2 tan2 δ(max)+W2; b=2LD tan2 δ(max); and c=D2 tan2 δ(max)−W2.

[0036] In certain cases of reversing the trailer 12, a jackknife-enabling condition may occur based on current operating parameters of the vehicle 14 along with a corresponding hitch angle γ. This condition may be indicated when one or more specified vehicle operating thresholds are met while a particular hitch angle γ is present. For example, certain vehicle operating parameters may result in a rapid (e.g., uncontrolled) transition of the hitch angle γ to the jackknife angle for a currently commanded trailer turn and / or may reduce an ability to steer the trailer 12 away from the jackknife angle even though the particular hitch angle γ is not currently at the jackknife angle for the vehicle 14 and the attached trailer 12. One reason for a jackknife-enabling condition is that the trailer turn control mechanisms (e.g.,Steering control mechanisms (e.g., those according to the disclosed subject matter) generally calculate steering commands at a current time during the backing of a trailer 12. However, these calculations typically do not account for any delay in the steering control system of the vehicle 14 (e.g., delay in a steering EPAS controller). Another reason for the jackknife-enabling condition is that the trailer jackknife control mechanism generally exhibits reduced steering sensitivity and / or effectiveness when the vehicle 14 is at relatively high speeds and / or when experiencing relatively high acceleration.

[0037] According to one embodiment, the jackknife-determining information may be received by the curvature controller 28 to process and characterize a jackknife-enabled condition of the vehicle-trailer combination at a particular time (e.g., at the time the jackknife-determining information was sampled).Examples of jackknife-determining information include, but are not limited to, information characterizing a trailer hitch angle γ, information characterizing a vehicle accelerator pedal transient state, information characterizing a speed of the vehicle 14, information characterizing a longitudinal acceleration of the vehicle 14, information characterizing a braking torque applied by a braking system of the vehicle 14, information characterizing a driveline torque applied to the driven wheels of the vehicle 14, and information characterizing the amount and rate of driver-requested trailer camber. In this regard, the jackknife-determining information would be continuously monitored, such as by an electronic control unit (ECU) executing trailer backup assist (TBA) functionality.Upon receiving the jackknife-determining information, a routine may process the jackknife-determining information to determine whether the vehicle-trailer configuration has reached the jackknife-enabling condition at the particular time. The task of the jackknife-determining information evaluation operation is to determine whether a jackknife-enabling condition has been reached at the time defined by the jackknife-determining information. If it is determined that a jackknife-enabling condition exists at the particular time, a routine may further determine one or more applicable countermeasures to be implemented. Accordingly, in some embodiments, an applicable countermeasure is selected depending on a parameter identified as a primary influencing factor of the jackknife-enabling condition.In other embodiments, however, an applicable countermeasure is selected as the one best able to mitigate the buckling-enabling condition. In yet another embodiment, the one or more applicable countermeasures may be a predetermined countermeasure or a predetermined set of countermeasures.

[0038] As previously disclosed with respect to the illustrated embodiments, during operation of the trailer backup assist system 10, a driver of the vehicle 14 may be limited in the manner in which steering inputs may be provided to the steering wheel 68 of the vehicle 14 because the power steering system 62 is directly coupled to the steering wheel 68. Accordingly, the steering input device 18 of the trailer backup assist system 10 may be used to input a desired curvature 26 of the trailer 12, thereby decoupling these commands from being input to the steering wheel 68 of the vehicle 14.However, additional embodiments of the trailer backup assist system 10 may include the capability to selectively decouple the steering wheel 68 from the movement of the steerable wheels of the vehicle 14 during this trailer backup assist, thereby allowing the steering wheel 68 to be used to command changes in the desired curvature 26 of a trailer 12 or otherwise to select a desired backup path.

[0039] Now based on Fig. 7 illustrates an embodiment of the steering input device 18 disposed proximate a shift lever 110 on a center console 108 of the vehicle 14. In this embodiment, the steering input device 18 includes a rotary knob 30 for providing the desired return path of the trailer 12 to the curvature controller 28. As described in more detail below, the angular position of the rotary knob 30 may more accurately correlate with a desired curvature, such that rotation of the knob to a different angular position with an incremental change based on the amount of rotation, and in some embodiments, at a normalized rate, provides a different desired curvature.

[0040] The one like in Fig. The rotary knob 30 illustrated in Figures 7-8 may be biased (e.g., by a spring return) between opposite rotational ranges of motion R(R), R(L) to a center or rest position P(AR). In the illustrated embodiment, a first of the opposite rotational ranges of motion R(R) is substantially equal to a second of the opposite rotational ranges R(L), R(R). To provide a tactile indication of an amount of rotation of the rotary knob 30, a force biasing the knob toward the rest positions P(AR) may increase (e.g., nonlinearly) as a function of the amount of rotation of the rotary knob 30 relative to the rest position P(AR). In addition, the rotary knob 30 may be configured with position indication detents so that the driver can definitely feel the rest position P(AR) and the ends of the approaching opposite rotational movement ranges R(L), R(R) (e.g., soft end stops).

[0041] Further based on Fig. 7-8, the rotary knob 30 may generate a desired curvature value as a function of an amount of rotation of the rotary knob 30 relative to the rest position P(AR) and a direction of movement of the rotary knob 30 relative to the rest position P(AR). In addition, it is contemplated that the rate of rotation of the rotary knob 30 may also be used to determine the desired curvature output for the curvature controller 28. As discussed in more detail below, the rest position P(AR) of the knob corresponds to a signal indicating that the vehicle 14 should be steered such that the trailer 12 will reverse along a substantially straight return path (zero trailer curvature request from the driver) as defined by the longitudinal direction 22 of the trailer 12 when the knob has been returned to the rest position P(AR). A maximum clockwise position and a counterclockwise position of the knob (i.e.The limit values of the opposite rotational movement ranges R(R), R(L) may each correspond to a respective signal indicating a tightest radius of curvature (i.e., a sharpest trajectory or a smallest radius of curvature) of a travel path of the trailer 12 that is possible without the corresponding vehicle steering information causing a jackknife condition. In this regard, the rest position P(AR) with respect to the opposite rotational movement ranges R(R), R(L) is a curvature command position of zero. Accordingly, a ratio of a commanded curvature of a path of a trailer 12 (e.g., a radius of a desired return path) and a corresponding rotation amount of the knob 30 may vary across each of the opposite rotational movement ranges R(L), R(R) of the knob.Thus, it is further contemplated that the ratio may also be normalized based on the degree of change in the position of the knob 30 and the dimensions of a trailer assembly, such that the knob 30 may provide substantially the same target curvature output for different trailers and by the driver. It is further contemplated that the ratio may additionally or alternatively be a function of vehicle speed, trailer geometry, vehicle geometry, trailer hitch geometry, and / or trailer load.

[0042] Fig. Figure 8 shows an example of a graphical representation of a trailer path curvature function for a steering input device 18, wherein a degree of rotation of the rotary knob 30 correlates with the desired curvature of the trailer path. According to one embodiment, a relationship between the desired curvature relative to the user input (e.g., the amount of rotation) to the rotary knob may be defined as a cubic function. However, it will be appreciated that embodiments of the disclosed subject matter, as described in more detail below, are not limited to any particular function between an amount and / or rate of input to a steering input device 18 (e.g., a knob rotation) and a resulting desired curvature value, including the implementation of a normalized relationship.The desired curvature of the trailer 12, as commanded by the steering input device 18 and by the trailer backup assist system 10, is also described in more detail below.

[0043] Based on Fig. 8-9, a driver can turn the knob 30 to provide a desired curvature 26 while the driver of the vehicle 14 is reversing the trailer 12. According to the Fig. 8, the steering input device 18 is embodied as a rotary knob 30 to enable the driver of the vehicle 14 to command a desired return path by specifying a desired curvature 26. In the illustrated embodiment, the rotary knob 30 rotates about a central axis between a central or mid-position 114 corresponding to a substantially straight return path 26 as defined by the longitudinal direction 22 of the trailer 12, and various rotated positions 116, 118, 120, 122 on opposite sides of the mid-position 114 that command a desired curvature 26 corresponding to a radius of the desired return path for the trailer 12 at the commanded rotated position. It is contemplated that the rotary knob 30 may be configured in accordance with embodiments of the disclosed subject matter and a means for biasing it to a rest position P(AR) between the opposite rotational ranges of motion may be omitted.The absence of such a preload may allow a current rotational position of the rotary knob 30 to be maintained until the rotary control input device is manually moved to a different position. Additionally, it is contemplated that the steering input device 18 may include a non-rotary control device that may be configured to selectively provide a desired curvature 26 and to override or supplement an existing curvature value. Examples of such a non-rotary control input device include, but are not limited to, multiple pushbuttons (e.g., left turn, right turn, and straight ahead), a touchscreen on which a driver tracks or otherwise inputs curvature for travel path commands, a knob that is slidable along an axis to allow a driver to input reverse path commands, or a joystick-type input device, and the like.

[0044] According to some embodiments, the rotary knob 30 or other steering input device 18 may be configured to provide a tactile feedback signal (e.g., a vibration via the knob) as a warning if any of a variety of conditions occur. Conditions for causing a tactile feedback signal may include, for example, the trailer 12 approaching a jackknife angle, the vehicle or trailer approaching an object, the trailer backup assist system 10 experiencing a fault, the trailer backup assist system 10 detecting a fault, the trailer backup assist system 10 or another system of the vehicle 14 predicting a collision on the current path of travel of the trailer 12, the trailer backup assist system limiting a commanded curvature, or the available backup paths (e.g.,due to excessive speed of the vehicle 14 or due to the approach of an object in the perimeter area), and the like. Still further, it is contemplated that the steering input device 18 may utilize illumination and / or an audible signal output (e.g., the speaker) to provide certain feedback information or warnings.

[0045] Now again based on Fig. 9 shows an example of using the steering input device 18 to prescribe a curvature of a target reverse path (POT) of the trailer 12 during backing of the trailer 12 with the vehicle 14. In preparation for backing of the trailer 12, the driver of the vehicle 14 may drive the vehicle 14 forward along a merging path (PTP) to position the vehicle 14 and trailer 12 at a first reverse position B1. In the first reverse position B1, the vehicle 14 and trailer 12 are longitudinally aligned such that a longitudinal centerline axis L1 of the vehicle 14 is aligned with (e.g., parallel to or coincident with) a longitudinal centerline axis L2 of the trailer 12.It is disclosed here that such functionality of aligning the longitudinal axes L1, L2 at the beginning of an example of trailer reversing is not a requirement for the functionality of a trailer reversing aid system 10, but may be performed for calibration purposes.

[0046] After activating the trailer backup assist system 10 (e.g., before, after, or during the merging sequence), the driver begins backing the trailer 12 by backing the vehicle 14 from the first backing position B1. As long as the rotary knob 30 of the trailer backup steering input device 18 remains in the rest position P(AR) and no other steering input devices 18 are activated, the trailer backup assist system 10 steers the vehicle 14 as needed to cause the trailer 12 to be backed up along a substantially straight path of travel as defined by the longitudinal direction 22 of the trailer 12, more specifically, by the centerline L2 of the trailer 12 at the time the trailer 12 began backing up. When the trailer 12 reaches the second reversing position B2, the driver turns the rotary knob 30 to instruct the trailer 12 to steer to the right (iea clockwise rotated knob position R(R)). Accordingly, the trailer backup assist system 10 steers the vehicle 14 to cause the trailer 12 to steer right as a function of an amount of rotation of the knob 30 relative to the rest position P(AR), a rate of movement of the knob, and / or a direction of movement of the knob relative to the rest position P(AR). Similarly, by rotating the knob 30 to the left, the trailer 12 can be commanded to steer left.When the trailer 12 reaches the reverse position B3, the driver allows the rotary knob 30 to return to the rest position P(AR), thereby causing the trailer backup assist system 10 to steer the vehicle 14 as needed to cause the trailer 12 to reverse along a substantially straight path of travel, as defined by the longitudinal centerline L2 of the trailer 12 at the time the rotary knob 30 was returned to the rest position P(AR). Thereafter, the trailer backup assist system 10 steers the vehicle 14 as needed to cause the trailer 12 to reverse along this substantially straight path to the fourth reverse position B4.In this regard, curved sections of a travel path POT of the trailer 12 are prescribed by the rotation of the rotary knob 30 and straight sections of the travel path POT are prescribed by an orientation of the centerline longitudinal axis L2 of the trailer 12 when the knob is in / is returned to the rest position P(AR).

[0047] To operate the trailer reversing aid system 10 in the Fig. 9, the driver interacts with and automatically steers the trailer backup assist system 10 while the driver reverses the vehicle 14. As discussed above, the driver may command the trailer backup path using a steering input device 18, and the curvature controller 28 may determine the vehicle steering angle to achieve the desired curvature 26, whereby the driver controls the throttle and brake while the trailer backup assist system 10 controls the steering.

[0048] In Fig. 10, a method of operating an embodiment of the trailer backup assist system 10 is illustrated, which may be used as an embodiment of the operating routine 132 ( Fig. 2). In step 134, the method is initiated by activating the trailer backup assist system 10. It is contemplated that this may be done in a variety of ways, such as by making a selection on the display 82 of the vehicle HMI 80. The next step 136 then determines the kinematic relationship between the attached trailer 12 and the vehicle 14. To determine the kinematic relationship, various parameters of the vehicle 14 and the trailer 12 must be sensed, entered by the driver, or otherwise determined for the trailer backup assist system 10 to generate steering commands for the power steering system 62 according to the desired curvature or the desired reversing path 26 of the trailer 12. As will be appreciated from Fig. 3-6, the kinematic parameters for defining the kinematic relationship include, among other variables and parameters as previously described, a length of the trailer 12, a wheelbase of the vehicle 14, a distance from a hitch connection to a rear axle of the vehicle 14, and a hitch angle γ between the vehicle 14 and the trailer 12. Accordingly, the trailer backup assist system 10 may proceed to step 138 to process the trailer aggregate routine 130 after the kinematic relationship has been determined.

[0049] In Fig. 11, one embodiment of the trailer aggregate routine 130 is illustrated. The first determination of the illustrated trailer aggregate routine 130 is at step 140, where it is determined whether a common trailer feature is desired. The common trailer feature may enable the curvature controller 28 to generate steering commands and trailer brake application commands that cause the attached trailer 12 to behave in substantially the same manner as a common trailer as defined by the trailer aggregate routine 130 in response to inputs from the steering input device 18. If the common trailer feature is not desired, the trailer aggregate routine 130 ends and the operation routine 132 continues. Otherwise, the attached trailer 12 is added to a stored database of trailers at step 142.The stored trailer database may be a database of trailers previously attached to the vehicle 14, trailers previously attached to the vehicle 14 that have been reversed using the trailer backup assist system 10, trailers that can be attached to the vehicle 14, or other conceivable trailer groupings. For example, the vehicle manufacturer may provide the database with a grouping of the most common trailers attached to the particular vehicle type equipped with the trailer backup assist system 10.

[0050] In step 144 of the Fig. In the trailer aggregate routine 130 illustrated in FIG. 11, the driver is prompted, such as on the display 82 of the vehicle HMI 80, to select a common trailer mode. The illustrated trailer aggregate routine 130 presents an average trailer mode and a specific trailer mode for potential selection, although it should be understood that more or fewer common trailer modes may be selected. If it is determined in step 146 that the average trailer mode is selected, the routine 130 calculates the average trailer dimensions from the database of trailers in step 148.With the average trailer dimensions, in step 150, the typical trailer is defined with the average or otherwise normalized trailer dimensions for use in generating speed commands and steering commands for the vehicle such that inputs or changes to the target curvature 26 with the steering input device 18 are substantially the same across the entire population of trailers stored in the database. More specifically, the typical trailer dimensions can be used to define a normalized ratio based on selections or movements of the steering input device 18 to provide an incremental change to the target curvature 26 that is the same or substantially the same across the entire population of trailers.Otherwise, if it is determined in step 152 that the specific trailer mode is selected, routine 130 prompts the driver in step 154 to select from the database a trailer that the driver wishes to become the usual trailer. It is also contemplated that the driver may alternatively enter dimensions to be used as the usual trailer. In step 156, the dimensions of the selected trailer are re-stored to define the usual trailer to be used in determining which incremental change in the target curvature 26 corresponds to the change in selection or movement of the steering input device 18, such as the change in degrees of rotation of the rotary knob 30. After storing the dimensions of the usual trailer variable, routine 132 resumes in step 158.

[0051] Again based on Fig.10, the hitch angle γ between the vehicle 14 and the trailer 12 is detected in step 160, although this may occur continuously during operation of the trailer backup assist system 10. It is contemplated that in additional embodiments of the trailer backup assist system 10, the steps of determining the kinematic relationship and detecting the hitch angle γ may occur prior to activation of the trailer backup assist system 10 or at any other time before steering commands are generated. Accordingly, in step 162, the position and rate of change, such as the angular position and rotation rate, of the rotary knob 30 are received from the steering input device 18 to determine the target curvature 26 according to the conventional trailer, if selected.If a conventional trailer is selected, steering commands may be generated in step 164 based on the desired curvature as determined from the normalized values and the rate correlated with the position and rate of change of the steering input device 18. As previously discussed, the generated steering commands and actuation commands may be generated in conjunction with the processing of the curvature routine 98. In step 166, the steering commands and actuation commands have been executed to guide the trailer 12 on the desired curvature provided by the steering input device 18, as desired normalized by the operating routine 132.

[0052] In parallel with performing the operations for receiving the trailer backup assist requests, determining the target curvature 26 of the trailer 12, and generating the vehicle steering commands, the trailer backup assist system 10 may perform an operation for monitoring whether there is an unacceptable trailer backup condition. Examples of such monitoring include, but are not limited to, accessing a trailer hitch angle γ to determine whether a threshold hitch angle γ is exceeded, assessing a backup speed to determine whether a backup speed threshold is exceeded, assessing the vehicle steering angle to determine whether a vehicle steering angle threshold is exceeded, assessing other operating parameters (e.g.,the vehicle's longitudinal acceleration, the accelerator pedal demand rate, and the trailer hitch angle rate) to determine whether a respective threshold is exceeded, and the like. The reverse travel speed may be determined from wheel speed information obtained from one or more wheel speed sensors 58 of the vehicle 14. If it is determined that an unacceptable trailer reverse condition exists, an operation to cause the current travel path of the trailer 12 to be disabled (e.g., to stop the movement of the vehicle 14) may be performed, followed by the operation to terminate the current trailer reverse assist. It is disclosed herein that prior to and / or concurrently with causing the current trailer path to be disabled, one or more actions (e.g., operations) may be implemented to provide feedback (e.g.,a warning) that such an unacceptable hitch angle condition is imminent or approaching. In one example, if such feedback results in the unacceptable hitch angle condition being resolved before a critical condition is reached, the method may continue to provide the trailer backup assist functionality according to operations. Otherwise, the method may proceed to the operation for terminating the current instance of the trailer backup assist. Along with performing the operation for terminating the current trailer backup assist instance, an operation for controlling the movement of the vehicle 14 to correct or limit a jackknife condition (e.g.,Steering the vehicle 14, decelerating the vehicle 14, limiting the amount and / or rate of the driver-requested trailer curvature input, limiting the amount and / or rate of the steering command, and / or the like to preclude exceeding the trailer hitch angle).

[0053] Those of ordinary skill in the art will understand that the construction of the described invention and other components is not limited to any specific material. Unless otherwise described herein, other exemplary embodiments of the invention disclosed herein may be formed from a wide variety of materials.

[0054] For purposes of this disclosure, the term "coupled" (in all its forms, coupled, coupling, coupled, etc.) generally means the direct or indirect connection of two components (electrical or mechanical) together. Such a connection may be fixed in nature or movable in nature. Such a connection may be achieved with two components (electrical or mechanical) and any additional intermediate elements formed as a single unitary body with each other or integral with the two components. Unless otherwise specified, such a connection may be permanent in nature or removable or detachable in nature.

[0055] It is also important to note that the structure and arrangement of the elements of the invention as shown in the exemplary embodiments are exemplary only. Although only a few embodiments of the present innovations have been described in detail in this disclosure, those skilled in the art will readily appreciate, upon reviewing this disclosure, that many modifications (e.g., changes in sizes, dimensions, structures, shapes, and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) are possible without materially departing from the novel teachings and advantages of the presented subject matter.For example, elements shown as being formed in one piece may be constructed of multiple parts, or elements shown as multiple parts may be formed in one piece, the operation of the interfaces may be reversed or otherwise altered, the length or width of the structures and / or members or connectors or other elements of the system may be altered, or the nature or number of adjustment positions provided between the elements may be altered. It is noted that the elements and / or assemblies of the system may be constructed of any of a variety of materials that provide sufficient strength or durability, in any of a variety of colors, textures, and combinations. Accordingly, all such changes are intended to be within the scope of the present invention.Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the desired and other exemplary embodiments without departing from the spirit of the present invention.

[0056] Of course, any described processes or steps within described processes may be combined with other disclosed processes or steps to form structures within the scope of the present invention. The exemplary structures and processes disclosed herein are for illustrative purposes and are not to be considered limiting.

[0057] Furthermore, it is to be understood that changes and modifications may be made to the above-mentioned structures and methods without departing from the concepts of the present invention, and further that these concepts are intended to be encompassed by the following claims unless these claims expressly state the contrary.

Claims

[1] Trailer reversing aid system for a vehicle (14) reversing a trailer (12), comprising: a knob (30) which can be rotated into a plurality of positions, each of which defines a desired curvature (26); and a controller that generates a steering command for the vehicle (14) based on a kinematic relationship between the vehicle (14) and the trailer (12), to guide the trailer (12) on the desired curvature (26), wherein the desired curvature (26) is defined for each of the plurality of positions on the basis of standardized trailer dimensions, characterized by that the standardized trailer dimensions include dimensions of additional trailers (12) which are suitable for being towed by the vehicle (14), and / or that the standardized trailer dimensions include lengths of additional trailers (12) which have previously been attached to the vehicle (14) and have been reversed with guidance by the trailer reversing aid system (10). [2] Trailer backup assist system according to claim 1, further comprising: a trailer coupling angle sensor (44) for detecting a trailer coupling angle (γ) between the trailer (12) and the vehicle, wherein the steering command is generated on the basis of the detected trailer coupling angle (γ). [3] A trailer reversing assist system according to claim 1 or 2, wherein the kinematic relationship is determined based on a length of the trailer (12), a wheelbase of the vehicle (14) and a distance between a trailer coupling point and a rear axle of the vehicle (14). [4] Trailer reversing aid system according to one of claims 1 to 3, wherein the knob (30) is rotatable from a central position (114) to opposite rotational end positions in opposite directions, the central position (114) defining the desired curvature (26) as zero. [5] Trailer reversing aid system according to claim 4, wherein the opposite rotational end positions are defined by the smallest radius of curvature controllable over an entirety of additional trailers (12). [6] Trailer reversing aid system for a vehicle (14) reversing a trailer (12), comprising: a trailer coupling sensor that detects a trailer coupling angle (γ) between the vehicle (14) and the trailer (12); a steering input device (18) operable between a plurality of selections each providing an incremental change to a desired curvature (26) of the trailer (12); and a controller that generates a steering command for the vehicle (14) to guide the trailer (12) on the target curvature (26) based on the detected trailer coupling angle (y) and a kinematic relationship with the trailer (12), wherein the incremental change is substantially the same for a set of trailers (12) to normalize the control of the target curvature (26), characterized by that the set of trailers (12) includes a set of additional trailers (12) suitable for being towed by the vehicle (14), and / or that the set of trailers (12) includes trailers (12) that have previously been coupled to the vehicle (14) and have been reversed under the guidance of the trailer reversing assistance system (10). [7] Trailer backup assist system according to claim 6, wherein the incremental change in the desired curvature (26) is determined based on an average length of the entirety of trailers (12). [8] A trailer backup assist system according to claim 6 or 7, wherein the steering input device (18) includes a knob (30) rotatable between a first position and a second position such that the incremental change to the desired curvature (26) is defined as a function of the degrees of rotation of the knob (30) between the first and second positions. [9] Trailer reversing assist system according to one of claims 6 to 8, wherein the steering input device (18) is movable between a plurality of successive positions each providing the incremental change in the desired curvature (26). [10] A trailer backup assist system according to any one of claims 6 to 9, wherein the steering input device (18) includes a knob (30) rotatable from a center position (114) in opposite directions to opposite end positions of rotation, the center position (114) defining the desired curvature (26) as zero. [11] Trailer reversing aid system according to claim 10, wherein the opposite rotational end positions are defined by the smallest radius of curvature controllable over the entirety of trailers (12). [12] A method for steering a vehicle (14) reversing a trailer (12), comprising: Providing dimensions for a set of trailers (12) that can be reversed by the vehicle (14); Providing a rotary knob (30); and Determining a target curvature (26) for the trailer (12) based on a position of the rotary knob (30), wherein the change in the target curvature (26) is a function of a normalized ratio based on the degrees of change in the position and the dimensions of the entire trailer (12), Detecting a trailer coupling angle between the vehicle (14) and the trailer (12) attached to the vehicle (14); and Generating a steering command for the vehicle (14) based on the trailer coupling angle to guide the trailer (12) on the desired curvature (26), characterized by that the set of trailers (12) includes a set of trailers (12) which have previously been attached to the vehicle (14) and have been driven backwards with guidance through the predetermined curve (26), and / or that the set of trailers (12) includes a set of additional trailers (12) suitable for being towed by the vehicle (14). [13] The method of claim 12, wherein the rotary knob (30) is rotatable from a center position (114) to opposite end rotation positions in opposite directions, the center position (114) defining the desired curvature (26) as zero and the opposite end rotation positions being defined by the smallest radius of curvature controllable over the entirety of trailers (12). [14] Method according to one of claims 12 to 13, wherein the target curvature (26) is determined on the basis of a kinematic relationship between the vehicle (14) and the trailer (12) and wherein the normalized ratio for changes in the target curvature (26) is determined on the basis of an average length of the entirety of trailers (12).

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