METHOD AND SYSTEM FOR STEERING CONTROL DURING VEHICLE REVERSING OPERATION FOR MANEUVERING A TRAILER

Abstract

A trailer assistance system for assisting in the reversing maneuvering of a trailer attached to a vehicle, the trailer assistance system comprising: a rear video camera to provide a rear image of the trailer and the surrounding area; an interior vehicle display and an input device for selectively displaying a rear image from the rear video camera, and wherein the input device is configured to receive inputs from a driver; a yaw angle determining device for determining a yaw angle of the vehicle; a steering angle sensor for detecting a vehicle steering angle of the front wheels of the vehicle; a vehicle speed determining device for determining a vehicle speed of the vehicle; and an electronic processor and a memory, wherein the electronic processor is configured to, when a trajectory mode and a Angle setpoint can be received from a driver: determine a trailer angle for the trailer relative to the vehicle based on video data received from the rear video camera; determine a trailer trajectory based on the turn angle setpoint, the trailer angle, the vehicle yaw angle and physical characteristics of the vehicle and the trailer; to display the trailer trajectory on the vehicle interior display with the rear image of the trailer and the surrounding area; and wherein the electronic processor is configured to, when an automatic steering maneuvering mode is selected by a driver: provide an output vehicle steering angle signal for a vehicle steering wheel positioning controller for positioning the vehicle steering angle of the vehicle to perform the trailer maneuvering operation according to the turning angle command value; When the vehicle is moving backward, update the vehicle steering angle signal based on the turn angle setpoint, the trailer angle, the vehicle speed, the vehicle yaw angle and the physical characteristics of the vehicle and the trailer, and provide the updated vehicle steering angle signal to the vehicle steering wheel positioning controller for controlling the vehicle steering angle to achieve the desired turning angle, with the vehicle and trailer aligned after maneuvering; and wherein the electronic processor operates as a PID cascade structure, wherein a trailer angle error is determined in an inner loop and a vehicle yaw angle error is determined in an outer loop, wherein the trailer angle error is determined more often than the vehicle yaw angle error.

Description

BACKGROUND

[0001] This arrangement relates to a system and method for providing steering control during vehicle reversing operation when maneuvering a trailer in a reverse direction with turns or the like, and occasionally maximizing the sharpness of the maneuvering turn. In an end position, the vehicle and trailer are aligned with each other.

[0002] For an inexperienced driver, maneuvering a trailer can be a difficult task. In addition to requiring active stabilization when reversing, the steering is counterintuitive. To correct a trailer drifting to one side, the driver must steer in that direction to maneuver it back to center. The embodiments herein assist a driver in maneuvering a trailer.

[0003] DE 10 2017 113 469 A1 relates to a method for operating a parking assistance device of a motor vehicle with a combined view of a transparent trailer and surroundings.

[0004] DE 10 2018 004 108 A1 relates to a method for reversing a vehicle combination consisting of a vehicle and a trailer.

[0005] DE 10 2014 108 482 A1 relates to a method for assisting a driver when maneuvering a motor vehicle. SUMMARY

[0006] The present invention is directed to a trailer assist system for assisting in the reversing maneuvering of a trailer attached to a vehicle. The trailer assist system includes a rear video camera for providing a rear image of the trailer and the surrounding area; a vehicle interior display and an input device for selectively displaying a rear image from the rear video camera, and wherein the input device is configured to receive inputs from a driver; a yaw determining device for detecting a yaw angle of the vehicle; a steering angle sensor for detecting a vehicle steering angle of the front wheels of the vehicle; a vehicle speed determining device for determining a vehicle speed of the vehicle;and an electronic processor and memory. The electronic processor is configured, when a trajectory mode and a turn angle command are received from a driver: receive a yaw angle for the vehicle; determine a trailer angle for the trailer relative to the vehicle based on video data received from the rear video camera; determine a trailer trajectory based on the turn angle command, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle and the trailer;and display the trailer trajectory on the vehicle interior display with the rear image of the trailer and the surrounding area. The electronic processor is configured, when an automatic steering maneuvering mode is selected by a driver: to provide an output vehicle steering angle signal to a vehicle steering wheel positioning controller for positioning the vehicle's steering angle to perform the trailer maneuvering operation according to the turn angle command;when the vehicle is moving backward, updating the vehicle steering angle signal based on the turn angle command, the trailer angle, the vehicle speed, the vehicle yaw angle, and the physical characteristics of the vehicle and the trailer, and providing the updated vehicle steering angle signal to the vehicle steering wheel positioning controller for controlling the vehicle steering angle to achieve the turn angle command, wherein the vehicle and the trailer are aligned with each other after maneuvering; and wherein the electronic processor operates as a PID cascade structure, wherein a trailer angle error is determined in an inner loop and a vehicle yaw angle error is determined in an outer loop, wherein the trailer angle error is determined more often than the vehicle yaw angle error.

[0007] The present invention features a method for assisting in the reverse maneuvering of a trailer attached to a vehicle with a trailer assist system including an electronic processor. The method is performed by determining a trailer angle for the trailer relative to the vehicle based on video data received from a rear video camera; and receiving a yaw angle for the vehicle. In response to inputs from a driver for selecting a trajectory mode and for selecting a turn angle setpoint for reverse maneuvering the trailer, the method is performed by determining, with the electronic processor, a trailer trajectory based on the turn angle setpoint, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle and the trailer, and wherein the electronic processor operates as a PID cascade structure, determining a trailer angle error in an inner loop and determining a vehicle yaw angle error in an outer loop, wherein the trailer angle error is determined more frequently than the vehicle yaw angle error; and displaying the trailer trajectory on the vehicle interior display with a rearward image of the trailer and surroundings. A driver can then position the vehicle at an appropriate position for maneuvering the trailer in a reverse direction to a desired location by moving the vehicle and trailer to align the trailer trajectory provided on the vehicle interior display with a desired location.

[0008] The present invention is directed to a non-transitory computer-readable medium comprising program instructions executed by an electronic processor for assisting in the reverse maneuvering of a trailer attached to a vehicle along a trailer trajectory. The electronic processor is configured to: determine a trailer angle for the trailer relative to the vehicle based on video data received from a rear video camera; receive a yaw angle for the vehicle; receive a steering angle of the front wheels of the vehicle; andand a vehicle speed of the vehicle. The electronic processor performs a trailer steering maneuver along the trailer trajectory according to a turn angle command by: determining an output vehicle steering angle signal based on the turn angle command, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle and the trailer; providing an output vehicle steering angle signal to a vehicle steering wheel positioning controller for positioning the steering angle of the vehicle to perform the trailer maneuvering operation according to the turn angle command;when the vehicle is moving backward, updating the vehicle steering angle signal based on the turn angle command, the trailer angle, the vehicle speed, the vehicle yaw angle, and the physical characteristics of the vehicle and the trailer, and providing the updated vehicle steering angle signal to the vehicle steering wheel positioning controller for automatically controlling the vehicle steering angle to maneuver the trailer along the trailer trajectory to achieve the turn angle command, wherein the vehicle and the trailer are aligned with each other after maneuvering, and wherein a PID cascade structure operates to determine a trailer angle error in an inner loop and a vehicle yaw angle error in an outer loop, wherein the trailer angle error is determined more often than the vehicle yaw angle error;

[0009] Further aspects, features and embodiments will become apparent upon consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a plan view of a vehicle and a trailer on a road and in a rearward target position. Fig. 2 illustrates a block diagram of one embodiment of a trailer assist system for assisting in the reversing maneuvering of a trailer. Fig. 3 illustrates a flowchart for an embodiment of a trajectory mode of the trailer assistance system. Fig. 4 illustrates a flowchart for an embodiment of an automatic steering maneuver mode of the trailer assistance system. Fig. 5 illustrates an example image for display showing a trailer trajectory and a trailer with surroundings. Fig. Figure 6 shows a geometric diagram of a vehicle with a connected trailer. Fig. Figure 7 is a block diagram illustrating the operation of an electronic processor (or processors). Fig. 8A-8D show diagrams of vehicle data for a target rotation angle of 90 degrees. DETAILED DESCRIPTION

[0010] Before any embodiments are explained in detail, it is to be understood that this disclosure is not intended to be limited in its application to the details of construction and arrangement of components set forth in the following description or illustrated in the following drawings. Embodiments may have other configurations and may be variously practiced or carried out.

[0011] Multiple hardware- and software-based devices, as well as a variety of structural components, may be used to implement various embodiments. Furthermore, embodiments may include hardware, software, and electronic components or modules, which, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented only in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, will appreciate that, in at least one embodiment, the electronics-based aspects of the invention may be implemented in software (e.g., stored on non-transitory computer-readable media) executable by one or more electronic controllers.For example, “units,” “control units,” and “controllers” described in the patent specification may include one or more electronic controllers, one or more memories, including non-transitory computer-readable media, one or more input / output interfaces, one or more ASICs and other circuits, and various connections or connectors (e.g., cables, traces, and buses) connecting the various components.

[0012] Fig. 1 shows a vehicle 30 and a trailer 32 disposed on a road 34. From a starting position on the road 34, the vehicle 30 moves in a reverse direction path 36 to maneuver the trailer 32 into a driveway 38 with the assistance of a trailer assist system and a driver applying an accelerator pedal and a brake pedal, or the like. In this embodiment, the trailer assist system controls the vehicle steering to move the vehicle 30 / trailer 32 combination through a reverse turn angle of 90° along a trailer trajectory, which is the sharpest rearward path with the shortest distance. Other turn angle setpoints are contemplated, including a first range between about 10 degrees and about 90 degrees and / or a second range between about -10 degrees and -90 degrees in some embodiments.In one embodiment, trailer 32 is a conventional non-steering single-axle trailer. In some embodiments, trailer 32 has a length of about 1 to about 20 meters. In some embodiments, the sharpest path to achieve the desired turning angle is not desired. In most embodiments, trailer 32 and vehicle 30 are longitudinally aligned in a final position. Thus, trailer 32 and vehicle 30 are oriented in the same direction of travel.

[0013] Fig. 2 shows a block diagram view of a trailer assist system 40 for controlling vehicle steering to maneuver a trailer 32. In one embodiment, the trailer assist system 40 includes an electronic trailer assist unit 44. The electronic trailer assist unit 44 includes an electronic processor 50 and memory. The memory includes one or more memory modules, such as random access memory (RAM) 54 and / or electronically erasable programmable read-only memory (EEPROM) 56. An input / output interface 58 sends and receives information over a communications bus 60. The electronic processor 50 processes the information by executing one or more applications or modules. The applications or modules may be stored as instructions or commands in the memory 54, 56. The electronic processor 50 also stores information generated by applications in the memory 54.

[0014] The Fig. The communication bus 60 shown in Figure 2 is a FlexRay automotive communication bus, a CAN bus, or other type of communication link between multiple controllers, sensors, and other devices. In some embodiments, the communication bus 60 connects the electronic trailer assist unit 44 to an electronic steering wheel positioning controller 62, such as a power steering control motor, controlled by the electronic trailer assist unit 44 in a trailer assist mode of operation.

[0015] Fig. 2 also shows a vehicle speed limiter 66 that limits the speed of a vehicle in an automatic steering maneuver mode. In one embodiment, the vehicle speed limiter 66 is an electronic traction control system of a vehicle that receives a vehicle speed limit signal input from the electronic processor 50 from the trailer assist system that limits the reverse direction speed for a vehicle to prevent a driver from exceeding the vehicle speed limit for an automatic steering maneuver mode.

[0016] Fig. 2 shows a rear video camera 70 for providing images from the rear of a vehicle. The images may include a trailer attached to the vehicle. In one embodiment, the images are a panoramic view. In another embodiment, multiple video cameras are provided. The rear video camera 70 transmits video data to the electronic processor 50 via the communication bus 60.

[0017] Fig. Figure 2 shows a vehicle yaw angle determination device 74 provided on a vehicle. In one embodiment, the vehicle yaw angle determination device 74 includes a gyro sensor that transmits the yaw rate to units via the communication bus 60. The yaw rate is integrated to determine a yaw. In a further embodiment, the vehicle yaw angle is calculated based on vehicle speed and vehicle steering angle. Thus, in one embodiment, the vehicle yaw angle determination device is provided by the electronic processor 50. The vehicle yaw angle is determined with respect to a starting position for a vehicle maneuver.

[0018] A steering angle sensor 80 is connected to the communication bus 60 to transmit a steering wheel position to the electronic processor 50 via the input / output interface 58. In one embodiment, the steering angle sensor 80 is disposed on a steering column of the steering device. In another embodiment, the steering angle sensor 80 is configured to detect rotation of a pinion gear secured to a steering shaft of the vehicle. In another embodiment, the steering angle sensor 80 determines a steering angle based on motor rotation of the power steering control motor and a ratio related to the rack and pinion gear.

[0019] In one embodiment, a Fig. 2, the vehicle speed determining device 84 determines a vehicle speed and communicates the vehicle speed to other units via the communication bus 60. In another embodiment, the vehicle speed determining device 84 is a vehicle speed sensor. In another embodiment, calculations of other information provide the vehicle speed.

[0020] Fig. 2 shows a vehicle interior display 90 and an input device 94. In one embodiment, the vehicle interior display 90 is a display panel for displaying images and instructions to a driver. The input device 94 is a keyboard, joystick, keypad, or other data entry mechanism, such as a microphone and speech analysis for receiving voice commands. In one embodiment, the assembly is a touchscreen 98 that integrates the vehicle interior display 90 and the input device 94 into a single element that displays information and images and receives touch input. In one embodiment, the touchscreen 98 is disposed on a console within the vehicle interior. OPERATION

[0021] In operation, the electronic trailer assistance unit 44 includes a trajectory mode and an automatic steering maneuver mode. The trajectory mode is selected and executed before the automatic steering maneuver mode as follows. TRAJECTORY MODE

[0022] Fig. 3 shows a flowchart 100 of the trajectory mode for the Fig. 2 shown electronic trailer assistance unit 44. While in Fig. 2 a single electronic trailer assistance unit 44 is shown, several control units and / or electronic processors 50 may be used in Fig. 3. The functions shown in Fig. 3 may be performed substantially simultaneously or in parallel with multiple electronic processors of the electronic trailer assistance unit 44.

[0023] At step 104, in one embodiment, a trajectory mode selection is received from the electronic processor 50 via the communication bus 60 from the input device 94. Thereafter, at step 108, the electronic processor 50 also receives a turn angle command from the input device 94. In another embodiment, the driver may input the turn angle command prior to selecting the trajectory mode. The turn angle command may range from 10 degrees to 90 degrees and from -10 degrees to -90 degrees, depending on the direction of the desired reverse turning maneuver of the trailer 32.

[0024] The electronic processor 50 is configured to, at step 112, which is shown in Fig. As shown in Fig. 3, the trailer angle is determined based on video data received by the rear video camera 70 via the communication bus 60. The trailer angle is defined by the relative orientation of the trailer 32 with respect to the vehicle 30. When the vehicle 30 and the trailer 32 are aligned along the same axis, for example, when the vehicle 30 is driven straight forward, the trailer angle is zero degrees. After step 112, the electronic processor proceeds to step 116.

[0025] At step 116, the electronic processor 50 receives a yaw angle from the vehicle yaw angle determination device 74 on the vehicle 30. In one embodiment, the vehicle yaw angle is determined by integrating the yaw rate signal. The electronic processor 50 proceeds to step 120.

[0026] At step 120, the electronic processor 50 determines a trailer trajectory for the turn angle command based on the turn angle command, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle and trailer. The determination is made when the vehicle 30 is stationary or driven by a driver. Thereafter, the electronic processor 50 proceeds to step 124. Physical characteristics or parameters of the vehicle and trailer may include the vehicle wheelbase, vehicle overhang, trailer length, maximum wheel angle, and maximum wheel angle rate of change.

[0027] At step 124, the electronic processor 50 displays a trailer trajectory on the vehicle interior display 90 with the rear image of the trailer 32 and the surrounding area. The trailer trajectory is copied or overlaid onto the video image. The electronic processor 50 proceeds to step 128.

[0028] At decision step 128, the electronic processor 50 determines whether a driver input has been received at the input device 94 to select an automatic steering maneuver mode, and the vehicle is in reverse gear and stationary due to brake application. As long as the inputs are not received, decision step 128 returns to step 112 and again determines the trailer angle, the vehicle yaw angle, and a trailer trajectory, as discussed above. Thus, if the vehicle 30 and trailer 32 are moving, the trailer trajectory is updated to display the new relative position thereof shown in the rearward image of the trailer 32 on the vehicle interior display 90.During operation in the trajectory mode, a driver views the trailer trajectory on the vehicle interior display 90 and manually moves the vehicle 30 and trailer 32 to a location such that the trailer trajectory for each of the trailer wheels leads to a desired area onto which the driver intends to maneuver the trailer.

[0029] At decision step 128, the electronic processor 50 proceeds to step 132 if the electronic processor 50 receives input that the vehicle is not moving and that a driver has selected the automatic steer maneuver mode. This selection occurs when the driver sees that the trailer trajectory is directed toward a desired location for the trailer and performs a manual operation to select the mode with the input device 94. In some embodiments, the vehicle 30 must also be in reverse gear to enter the automatic steer maneuver mode. AUTOMATIC STEERING MANEUVER MODE

[0030] Fig. 4 shows a flowchart 200 of switching to the automatic steering maneuver mode corresponding to step 132, which in Fig. 3. The automatic steering maneuver mode provides automatic vehicle steering to achieve reverse maneuvering of the vehicle along the trailer trajectory as follows.

[0031] The electronic processor 50 is configured to determine the trailer angle based on video data received from the rear video camera 70 via the communication bus 60 at step 212. The trailer angle is defined by the relative position of the trailer 32 with respect to the vehicle 30. After step 212, the electronic processor proceeds to step 216.

[0032] At step 216, the electronic processor 50 receives a vehicle yaw rate from the vehicle yaw rate determining device 74 on the vehicle 30. The vehicle yaw rate is determined, in one embodiment, by integrating the yaw rate signal. The electronic processor 50 proceeds to step 220.

[0033] At step 220, the electronic processor 50 receives a steering angle for the front wheels of the vehicle 30, which is sensed by the steering angle sensor 80 and provided via the communication bus 60. The electronic processor 50 proceeds to decision step 230.

[0034] At decision step 230, the electronic processor 50 determines whether the automated steering maneuver mode has already begun. If no, the electronic processor 50 proceeds to step 234. At step 234, the electronic processor 50 transmits an output vehicle steering angle signal to the electronic steering wheel positioning controller in preparation for reverse operation of the vehicle 30. The output vehicle steering angle signal is determined to follow a trailer trajectory based on the turn angle command, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle 30 and the trailer 32. Thereafter, the electronic processor 50 returns to step 212 and repeats steps 212, 216, 220, and 224.

[0035] At decision step 230, the electronic processor proceeds to decision step 240 if initial vehicle steering is already provided. At step 240, the vehicle steering angle signal is updated based on the turn angle command, the trailer angle, the vehicle speed, the vehicle yaw angle, and the physical characteristics of the vehicle 30 and the trailer 32. The electronic processor 50 returns to and repeats steps 212, 216, 220, 224, 230, and 240 until the vehicle 30 is taken out of reverse or otherwise deactivated by input from a driver. In one embodiment, the vehicle trailer assist system 40, or at least its automatic steering maneuver mode, is automatically deactivated or terminated when the vehicle 30 is taken out of reverse.

[0036] The above steps, which are used in the embodiments of Fig. 3 and Fig. The steps shown in Figure 4 are provided for illustrative purposes. The steps may be performed in a completely different order. ADDITIONAL EMBODIMENT(S)

[0037] In one embodiment, the Fig. 3, the trajectory mode continues with the operation and display of the trailer trajectory on the vehicle interior display 90 with the rear image of the trailer and the surroundings during the automatic steering maneuver mode. Fig. Figure 5 shows a picture of the trailer 32 and the surrounding area. Fig. 5 also shows that the trailer trajectory has paths 250 corresponding to each of the spaced trailer wheels. Fig. 5 is continuously updated and presented on the vehicle interior display 90. Including continuing to perform the trajectory mode, including displaying the trailer trajectory 250 on the vehicle interior display 90 with the rearward image of the trailer 32 and the surrounding area, while the electronic processor 50 automatically controls the steering angle of the vehicle 30. In another embodiment, the trailer trajectory is a single path corresponding to a center point of the trailer 32. GEOMETRIC EQUATIONS

[0038] Fig. Figure 6 shows a geometric diagram of the vehicle 30 in combination with the trailer 32. Furthermore, Fig. 6 an embodiment of the angles for determining the different values ​​for algorithms executed in the operating modes with respect to an XY axis.

[0039] A first equation for the trailer angle rate is as follows: γ˙=−(vl1+vl12l1l2cos(γ))tan(δ)−vl2sin(γ)

[0040] The above equation is based on the vehicle speed v, the trailer angle γ, the steering angle δ, the vehicle overhang l 12 (distance from the rear axle of the vehicle to the trailer ball), the vehicle wheelbase l 1 and a trailer length l 2 (Distance from the trailer coupling to the trailer axle). The vehicle yaw rate ψ̇ 1 is based on the following equation: ψ˙=vl1tan(δ)

[0041] The above vehicle yaw rate equation is based on the steering angle δ, the vehicle wheelbase l 1 and the vehicle speed v. Integration of the yaw rate leads to a value for the yaw ψ 1 . PID CASCADE STRUCTURE

[0042] Fig. 7 shows a block diagram 300 of an embodiment of an electronic processor 50 of the trailer assist system 40 operating as a proportional-integral-derivative (PID) cascade structure. In this embodiment, a fixed yaw value corresponding to the rotation angle command is provided as a fixed yaw, with a trailer angle error being determined in an inner loop and a vehicle yaw angle error being determined in an outer loop, and with one embodiment, the trailer angle error being determined more frequently than the vehicle yaw angle error. In another embodiment, the trailer angle error and the vehicle yaw angle error are determined at the same rate.

[0043] The yaw angle value is part of the trailer angle equation. A change in the vehicle yaw angle therefore affects the trailer angle value. Fig. The inner loop shown in Figure 7 operates faster than the outer loop. For a given speed and wheel angle, the rate of change of the trailer angle is higher than that of the vehicle yaw angle.

[0044] The Fig. The PID cascade structure approach shown in Figure 7 is chosen as a control concept in one embodiment. The trailer angle is processed in the inner loop and the vehicle yaw in the outer loop. By constructing a cascade control, the inner loop must be stable without the outer loop control, so that the Fig. 7 can be operated independently. Thus, the first step is to develop and configure the inner loop as a separate control system. After that, the system and the inner loop are considered together as the control system for the outer loop.

[0045] More precisely, Fig. 7 a yaw P control 304, which provides an adjustable parameter for control. The yaw output = Kyaw_P * (set yaw - measured yaw) is adjustable and determines the sharpness of the turn and must be adjusted for different trailer lengths.

[0046] The electronic processor 50 goes to Fig. 7 shown breakout saturation 308. Breakout angles vary with different trailer lengths l 2 The breakaway angle provides a maximum value for the permissible yaw angle output to prevent the trailer 32 from breaking away.

[0047] The electronic processor 50 proceeds to P-Control Trailer Angle 312 where a trailer angle error is calculated based on the breakaway output angle minus the measured trailer angle as shown in Fig. 7. The P-control trailer angle is an adjustable parameter that is stable for a desired operating range. Adjustable factors include vehicle speed, etc. In one embodiment, gain scheduling is performed.

[0048] Fig. Figure 7 shows a feedforward controller 320. The latter part is responsible for good setpoint tracking, while the measured feedback from the systems leads to stabilization and error compensation. The feedforward controller 320 calculates the appropriate steady-state vehicle steering angle for a given trailer angle based on a steady-state equation. This wheel angle is added as an offset to the turning angle output from the P-control trailer angle 312 to achieve faster setpoint tracking.

[0049] The electronic processor 50 then goes to maximum wheel angle saturation 330 as shown in Fig. 7. The combined turning angle is compared to a maximum wheel angle so that the steering angle communicated to the electronic steering wheel positioning controller 62 in a vehicle-trailer system 334 does not exceed a maximum wheel angle of the vehicle 30. The maximum wheel angle depends on characteristics of the vehicle 30 and the trailer 32, as discussed above.

[0050] In general, a PID controller processes the error of the measured variable compared to the setpoint and consists of three terms: the P term is proportional to the error, the I term is proportional to the integral of the error, and the D term is proportional to the derivative of the error. However, not all terms need to be included to achieve good control quality. EXAMPLE 1 - TARGET ROTATION ANGLE OF 90 DEGREES

[0051] Fig. 8A-8D show diagrams of vehicle data for a target turning angle of 90 degrees, which corresponds to the Fig. 1 shown reverse direction path 36. Fig. 8A shows a specified or desired trailer angle (specified TA) of approximately 40 degrees. At time 0 seconds, the trailer angle is 0 degrees because the trailer 32 has approximately the same axis direction as the vehicle 30. Fig. Figure 8B shows a desired vehicle steering angle (desired WA) of approximately 10 degrees. At start or time 0, the vehicle steering angle is 0 degrees. At approximately 3 seconds, the actual steering wheel is automatically adjusted to approximately 10 degrees by the electronic steering wheel positioning control 62 in response to the vehicle steering angle signal from the electronic processor 50. This adjustment is stored in Fig. 8B shown.

[0052] At a time point of approximately seven seconds, a driver operates the vehicle in reverse at a negative speed, as in Fig. is shown in 8D. At this time, the trailer angle begins to increase, as shown in Fig. 8A, the vehicle steering angle is adjusted, as shown in Fig. 8B, and the vehicle yaw angle and the trailer yaw angle change, as shown in Fig. 8C. After the increase in the trailer angle according to the illustration in Fig. 8A, the steering angle is set to a negative value between 10 and 15 seconds to bring the rotation angle back to approximately 0 degrees, with the vehicle 30 and the trailer 32 in the position that is at an angle of 90 degrees to the starting position, as shown in Fig. 1. At a time of approximately 45 seconds, the vehicle speed returns to zero because the maneuver along the steering path is completed.

[0053] Although the electronic trailer assistance unit 44 in Fig.2 as a separate unit, in some embodiments the electronic trailer assist unit is provided as an algorithm executed by a vehicle assist unit that performs other functions such as collision avoidance warnings and lane change warnings.

[0054] Although the system depicts components as logically separate, such depiction is for illustrative purposes only. In some embodiments, the depicted components may be combined or separated into separate software, firmware, and / or hardware. Regardless of how they are combined or separated, these components may execute on the same computing device or may be distributed among different computing devices or electronic processors 50 connected by one or more networks or other suitable communication means.

[0055] Various features, advantages and further developments are listed in the following claims.

Claims

[1] Trailer assistance system for assisting in the reversing maneuvering of a trailer attached to a vehicle, the trailer assistance system comprising: a rear video camera to provide a rear image of the trailer and the surrounding area; an interior vehicle display and an input device for selectively displaying a rear image from the rear video camera, and wherein the input device is configured to receive inputs from a driver; a yaw angle determining device for determining a yaw angle of the vehicle; a steering angle sensor for detecting a vehicle steering angle of the front wheels of the vehicle; a vehicle speed determining device for determining a vehicle speed of the vehicle; and an electronic processor and a memory, wherein the electronic processor is configured to, when a trajectory mode and a Angle setpoint can be received from a driver: determine a trailer angle for the trailer relative to the vehicle based on video data received from the rear video camera; determine a trailer trajectory based on the turn angle setpoint, the trailer angle, the vehicle yaw angle and physical characteristics of the vehicle and the trailer; to display the trailer trajectory on the vehicle interior display with the rear image of the trailer and the surrounding area; and wherein the electronic processor is configured to, when an automatic steering maneuvering mode is selected by a driver: provide an output vehicle steering angle signal for a vehicle steering wheel positioning controller for positioning the vehicle steering angle of the vehicle to perform the trailer maneuvering operation according to the turning angle command value; When the vehicle is moving backward, update the vehicle steering angle signal based on the turn angle setpoint, the trailer angle, the vehicle speed, the vehicle yaw angle and the physical characteristics of the vehicle and the trailer, and provide the updated vehicle steering angle signal to the vehicle steering wheel positioning controller for controlling the vehicle steering angle to achieve the desired turning angle, with the vehicle and trailer aligned after maneuvering; and wherein the electronic processor operates as a PID cascade structure, wherein a trailer angle error is determined in an inner loop and a vehicle yaw angle error is determined in an outer loop, wherein the trailer angle error is determined more often than the vehicle yaw angle error. [2] The trailer assistance system of claim 1, wherein displaying the trailer trajectory path on the vehicle interior display with a rearward image of the trailer and the surrounding area is provided by an overlay corresponding to the trailer trajectory for each of the wheels on the rearward image on the vehicle interior display, and wherein, during operation, a driver views the trailer trajectory on the vehicle interior display and manually moves the vehicle and trailer to a location such that the trailer trajectory for each of the wheels leads to a desired area onto which the driver intends to maneuver the trailer, the vehicle and trailer being aligned with each other,and thereafter, upon manual operation of the trailer assistance system in an automatic steering maneuver mode, the electronic processor performs an automatic steering maneuver by updating the vehicle steering angle signal for the vehicle steering wheel positioning control for the rotation angle setpoint. [3] The trailer assist system of claim 2, wherein the trailer assist system provides a vehicle speed limit signal that prevents a driver operating the vehicle in the reverse direction from exceeding the vehicle speed limit. [4] A trailer assist system according to claim 2, wherein the trailer assist system is automatically deactivated when the vehicle is taken out of reverse gear. [5] The trailer assist system of claim 1, wherein the trailer trajectory is the sharpest rearward path with the shortest distance and provides the turning angle setpoint. [6] The trailer assist system of claim 1, wherein the yaw angle determining device comprises a gyro sensor and a vehicle yaw rate is integrated over time to determine the vehicle yaw angle. [7] Trailer assistance system according to claim 1, wherein the rotation angle setpoint is provided by a driver and wherein the rotation angle setpoint is in a first range between about 10 degrees and about 90 degrees or in a second range between about -10 degrees and -90 degrees. [8] Trailer assistance system according to claim 1, wherein the vehicle interior display and the input device are provided as a touchscreen arranged on a console in the vehicle interior. [9] The trailer assist system of claim 1, wherein the physical characteristics of the vehicle and the trailer include: vehicle wheelbase, vehicle overhang, maximum wheel angle, maximum wheel angle change rate, and trailer length. [10] A method of assisting in the reversing maneuvering of a trailer attached to a vehicle with a trailer assistance system comprising an electronic processor, comprising: Determining a trailer angle for the trailer relative to the vehicle based on video data received from a rear video camera; Receiving a vehicle yaw angle for the vehicle; in response to inputs received from an input device from a driver for selecting a trajectory mode and for selecting a turn angle setpoint for reversing the trailer: Determining with the electronic processor a trailer trajectory based on the turn angle setpoint, the trailer angle, the vehicle yaw angle and physical characteristics of the vehicle and the trailer, and wherein the electronic processor operates as a PID cascade structure, wherein a trailer angle error is determined in an inner loop and a vehicle yaw angle error is determined in an outer loop, wherein the trailer angle error is determined more often than the vehicle yaw angle error; Displaying the trailer trajectory on the vehicle interior display with a rear image of the trailer and the surrounding area, wherein a driver can position the vehicle at an appropriate position for maneuvering the trailer in a reverse direction to a desired location by moving the vehicle and the trailer to align the trailer trajectory provided on the vehicle interior display with a desired location. [11] A method according to claim 10, comprising: in response to inputs received from an input device from a driver to select an automatic steering maneuver mode, the vehicle being in reverse gear, the trailer assist system operates in the automatic steering maneuver mode, comprising: Determining the trailer angle for the trailer relative to the vehicle based on video data received from the rear video camera; Determining a yaw angle for the vehicle; Detecting a steering angle of the vehicle’s front wheels; and Determining a vehicle speed of the vehicle; and Perform a trailer steering maneuver for the desired turning angle by: Providing an output vehicle steering angle signal to a vehicle steering wheel positioning controller for positioning the steering angle of the vehicle to perform the trailer steering maneuver according to the rotation angle setpoint; when the vehicle is moving backward, updating the vehicle steering angle signal based on the turn angle command, the trailer angle, the vehicle speed, the vehicle yaw angle and the physical characteristics of the vehicle and the trailer and providing the updated vehicle steering angle signal to the vehicle steering wheel positioning controller for automatically controlling the vehicle steering angle to achieve the turn angle command, wherein the vehicle and the trailer are aligned with each other after maneuvering. [12] The method of claim 11, wherein the electronic processor determines the output vehicle steering angle signal from the turn angle command, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle and the trailer. [13] The method of claim 11, wherein the method comprises continuing to perform the trajectory mode, including displaying an updated trailer trajectory on the vehicle interior display with the rear image of the trailer and the surrounding area while the electronic processor automatically controls the steering angle of the vehicle. [14] The method of claim 11, wherein the method comprises automatically terminating the automatic steering maneuver mode when the vehicle is taken out of reverse gear. [15] The method of claim 11, wherein the trailer trajectory is the sharpest rearward path with the shortest distance to achieve the desired turning angle. [16] The method of claim 11, wherein the physical characteristics of the vehicle and trailer include vehicle wheelbase, vehicle overhang, maximum wheel angle, maximum wheel angle change rate, and trailer length. [17] A non-transitory computer-readable medium comprising program instructions executed by an electronic processor for assisting in the reversing maneuvering of a trailer attached to a vehicle along a trailer trajectory by: Determining a trailer angle for the trailer relative to the vehicle based on video data received from a rear video camera; Receiving a vehicle yaw angle for the vehicle from a yaw angle determining device; Receiving a steering angle of the vehicle's front wheels; Receiving a vehicle speed of the vehicle; and Performing a trailer steering maneuver along the trailer trajectory according to a setpoint angle of rotation by: Determining an output vehicle steering angle signal based on the turn angle command, the trailer angle, the vehicle yaw angle, and physical characteristics of the vehicle and the trailer; providing the output vehicle steering angle signal to a vehicle steering wheel positioning controller for positioning the steering angle of the vehicle to perform the trailer maneuvering operation according to the turn angle command; when the vehicle is moving backward, updating the vehicle steering angle signal based on the desired turning angle, the trailer angle, the vehicle speed, the yaw, and the physical characteristics of the vehicle and the trailer, and providing the updated vehicle steering angle signal to the vehicle steering wheel positioning controller for automatically controlling the vehicle steering angle to maneuver the trailer along the trailer trajectory to achieve the desired turning angle, the vehicle and the trailer being aligned with each other after maneuvering; and wherein the electronic processor operates as a PID cascade structure, wherein a trailer angle error is determined in an inner loop and a vehicle yaw angle error is determined in an outer loop, wherein the trailer angle error is determined more often than the vehicle yaw angle error.

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