Towing assistance device

Abstract

A towing assistance device (30, 130) assists in the reversing of a towing vehicle (10) towing a towed vehicle (20). The towing assistance device includes: a target path calculation unit (301) configured to calculate a target path on which the towed vehicle is to be moved; an acquisition unit (302) configured to acquire coordinates of the towed vehicle in a plane coordinate system and a coupling angle between the towed vehicle and the towing vehicle; a calculation unit (303) configured to calculate a first target curvature (κ 2FF ) which is a target curvature of the towed vehicle used for forward control based on the target path; a first conversion unit (304, 314) configured to convert the first target curvature into a second target curvature (κ 1FF) which is the target curvature of the towing vehicle; and a second conversion unit (306) adapted to convert the second target curvature into a target steering angle (δ* SW , δ** SW ) of the towing vehicle.

Description

TECHNICAL FIELD

[0001] The present invention relates to a towing assistance device. BACKGROUND OF THE INVENTION

[0002] A device for performing towing assistance in a towing vehicle, such as a tractor, for towing a towed vehicle, such as a trailer, is known. For example, during towing assistance, when the towed vehicle is towed backward, a towing assistance device calculates a target path for the towed vehicle in advance and controls the towing vehicle such that the towed vehicle moves along the calculated target path.

[0003] For example, according to a technique in JP 2022-107175A (Reference 1), a data series of an attitude angle and a steering angle of a towing vehicle and a towed vehicle is calculated in advance by simulation and used for feedforward control and feedback control in a case where the towing vehicle and the towed vehicle are moved backward.

[0004] However, since the technique described in Reference 1 is a method in which the data series is calculated and stored in advance through simulation, the computation cost is high and the memory consumption is large. In addition, feedback control is performed for three state variables—lateral deviation, yaw angle deviation, and trailer hitch angle deviation. The steering control logic is complex, and gain adjustment is difficult.

[0005] Therefore, there is a need for a towing assistance device that can assist in reversing towing with a simple steering control logic. SUMMARY OF THE INVENTION

[0006] A towing assistance device according to an embodiment is a towing assistance device that assists in reversing a towing vehicle that is towing a towed vehicle, the towing assistance device including: a target path calculation unit configured to calculate a target path on which the towed vehicle is to be moved; an acquisition unit configured to acquire coordinates of the towed vehicle in a plane coordinate system and a coupling angle between the towed vehicle and the towing vehicle; a calculation unit configured to calculate a first target curvature, which is a target curvature of the towed vehicle used for forward control, based on the target path;a first conversion unit configured to convert the first target curvature into a second target curvature, which is the target curvature of the towing vehicle; and a second conversion unit configured to convert the second target curvature into a target steering angle of the towing vehicle.

[0007] The towing assistance device according to the embodiment can assist in reversing towing with a simple steering control logic. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing and additional features and characteristics of this invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 shows a side view showing a tractor and a trailer according to an embodiment; Fig. Figure 2 is a plan view showing the tractor and trailer according to the embodiment; Fig. 3 shows an example of a configuration of a towing assistance system according to the embodiment provided in the tractor; Fig. 4 is a block diagram showing an example of a functional configuration of a towing assist device according to the embodiment; Fig. 5 shows a trailer position acquired by the towing assistance device according to the embodiment; Fig. 6 shows a nearest point calculated by the towing assist device according to the embodiment; Fig. 7 shows a distance used by the towing assist device according to the embodiment; and Fig. 8 is a block diagram showing an example of a functional configuration of a towing assist device according to a modification of the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0009] An embodiment of a towing assistance device disclosed herein will be described in detail below with reference to the accompanying drawings. Configuration examples for tractor and trailer

[0010] Fig. 1 shows a side view showing a tractor 10 and a trailer 20 according to the embodiment. Fig. Figure 2 shows a plan view showing the tractor 10 and the trailer 20 according to the embodiment. Fig. 1 and Fig. 2, the tractor 10 serves as a reference, where a direction to the left on the side is defined as the front (forward travel direction) and a direction to the right on the side is defined as the rear (reverse travel direction). The tractor 10 is an example of a towing vehicle, and the trailer 20 is an example of a towed vehicle towed by the towing vehicle, such as the tractor 10.

[0011] The tractor 10 may, for example, be a vehicle such as an internal combustion engine car that uses an internal combustion engine as a power source, a vehicle such as an electric car or a fuel cell car that uses an electric motor (engine) as a power source, or a vehicle such as a hybrid car that uses both an internal combustion engine and an electric motor as a power source. Therefore, the tractor 10 may be equipped with various transmission devices and may also be equipped with various devices, systems, and components required to drive the internal combustion engine or the electric motor.

[0012] The tractor 10 may also be a Sport Utility Vehicle (SUV) as in Fig. 1 may be a so-called “pick-up truck” with a loading area provided on a rear side of the vehicle, or a general passenger vehicle.

[0013] The tractor 10 includes, for example, four wheels 14, including a pair of front wheels 14F and a pair of rear wheels 14R. The tractor 10 in the embodiment is, for example, a rear-wheel drive vehicle driven by the rear wheels 14R. A method, number, layout, and the like related to driving the wheels 14 of the tractor 10 can be set in various ways.

[0014] An imaging unit 12 is provided on a rear lower wall portion of the tractor 10. The imaging unit 12 is, for example, a digital camera including an imaging element such as a charge-coupled device (CCD) or a CMOS image sensor (CIS), and is a rear view camera that captures an image in the reverse direction (rear) of the tractor 10.

[0015] The imaging unit 12 successively takes images of an area including a rear end of the tractor 10, a coupling element 22 coupling the tractor 10 and the trailer 20, and at least a front end of the trailer 20, which is an area indicated, for example, by dashed double-dot lines in Fig. 1. An image captured by the imaging unit 12 can be used to detect a coupling angle representing an inclination of the trailer 20 in a left-right direction relative to the tractor 10. The coupling angle is also referred to as a trailer hitch angle, which is described below.

[0016] The tractor 10 may include a plurality of imaging units that capture images of a lateral side or a front side of the tractor 10 to check a situation around the tractor 10. An imaging unit may also be provided on a lateral side or a rear side of the trailer 20. Calculation processing and image processing may be performed based on the captured image data obtained with the plurality of imaging units to generate an image with a wider viewing angle or to generate a virtual overhead image of the tractor 10 viewed from above.

[0017] A trailer coupling 18, which is a towing device for towing the trailer 20, protrudes from a lower portion of a center portion of a rear bumper 16 of the tractor 10, for example, in a vehicle width direction. The trailer coupling 18 is attached to a frame of the tractor 10, for example. The trailer coupling 18 includes, for example, a trailer coupling ball 19 having a spherical tip portion erected in a vertical direction (vehicle up-down direction), and a coupling device provided at a tip end of the coupling member 22 attached to the trailer 20 covers the trailer coupling ball 19. Thereby, the tractor 10 and the trailer 20 are connected to each other, and the trailer 20 is rotatable in the vehicle width direction relative to the tractor 10.This means that the trailer coupling ball 19 transmits movements in the front-rear and left-right directions to the trailer 20 via the trailer coupling 18 and receives energy for acceleration or braking.

[0018] The trailer 20 can, for example, as in Fig. 1, may be a box trailer having at least one passenger compartment, a living area or a storage space, or it may be a flatbed trailer on which a load such as a container or a boat is placed. Fig. For example, the trailer 20 shown in Figure 1 includes a pair of wheels 24. The trailer 20 in the exemplary embodiment is assumed to be a powered vehicle with powered wheels that include neither a drive wheel nor a steered wheel. Configuration example for a towing assistance system

[0019] The tractor 10 in the exemplary embodiment is equipped, for example, with a towing assistance system 100. The towing assistance system 100 assists the driving of the tractor 10, which tows the trailer 20.

[0020] Fig. 3 shows an example of a configuration of the towing assistance system 100 provided in the tractor 10 according to the embodiment. As shown in Fig. 3, the towing assistance system 100 includes a towing assistance device 30, a monitoring device 40, a steering system 51, an actuator 52, a torque sensor 53, a steering angle sensor 61, a shift sensor 62, a wheel speed sensor 63, and the imaging unit 12.

[0021] In the towing assistance system 100, the towing assistance device 30, the monitoring device 40, the steering system 51, the steering angle sensor 61, the shift sensor 62, and the wheel speed sensor 63 are electrically connected via an in-vehicle network 80, such as an electrical communication line. The in-vehicle network 80 is implemented, for example, as a Controller Area Network (CAN).

[0022] The towing assistance device 30 is, for example, an electronic control unit (ECU) and is implemented as a computer having a central processing unit (CPU) 31, a read-only memory (ROM) 32, a random access memory (RAM) 33, and a solid state drive (SSD) 34.

[0023] The CPU 31 can read a program installed and stored in a non-volatile storage device such as the ROM 32 and perform calculation processing according to the program. The RAM 33 temporarily stores various types of data used in the calculation of the CPU 31. The SSD 34 is a rewritable non-volatile storage unit and can store data even when the towing assist device 30 is turned off.

[0024] The CPU 31, the ROM 32, the RAM 33, and the like may be integrated into the same housing. The towing assist device 30 may be implemented using another logical operation processor, such as a digital signal processor (DSP) or a logic circuit, instead of the CPU 31. Additionally, a hard disk drive (HDD) may be provided instead of the SSD 34, and the SSD 34 or the HDD may be provided separately from the towing assist device 30.

[0025] The towing assist device 30 can control the steering system 51 and the like by transmitting a control signal via the in-vehicle network 80. The towing assist device 30 can receive detection results from the torque sensor 53, the steering angle sensor 61, the shift sensor 62, the wheel speed sensor 63, and the like via the in-vehicle network 80. The CPU 31 provided in the towing assist device 30 can receive an operation signal or the like from an operation input unit 42 or the like provided in the monitoring device 40, and can output a control signal or the like to a display device 41, an audio output device 43, or the like. The CPU 31 also receives the image captured by the imaging unit 12.

[0026] The monitoring device 40 includes the display device 41, the operation input unit 42 and the audio output device 43 and is arranged in a central portion of an instrument panel in the vehicle width direction (left-right direction).

[0027] The display device 41 is, for example, a liquid crystal display (LCD) or an organic electroluminescent display (OELD). The display device 41 can display the image captured by the imaging unit 12, for example, when the trailer 20 is pushed back by the tractor 10, which is reversing, and is towed backward under the control of the towing assistance device 30.

[0028] The display device 41 is covered with the operation input unit 42, such as a transparent touch panel. A driver of the tractor 10 can visually recognize an image displayed on a screen of the display device 41 via the operation input unit 42. The driver can give various instructions to the towing assist device 30 by touching, pressing, or moving the operation input unit 42 with a finger or the like at a position corresponding to the image displayed on the screen of the display device 41.

[0029] For example, the driver can instruct the towing assist device 30 to start the towing assist by operating the operation input unit 42. At this time, the driver can select at least one of a backward movement assist mode, a forward movement assist mode, and a parking assist mode, for example.

[0030] The reverse movement assist mode is selected when the trailer 20 is towed backward by the tractor 10. The forward movement assist mode is selected when the trailer 20 is towed forward by the tractor 10. The parking assist mode is selected when the tractor 10, which is towing the trailer 20, is parked. The towing assist device 30 performs the towing assistance according to the selected mode.

[0031] The audio output device 43 is, for example, a loudspeaker.

[0032] The monitoring device 40 may also be used as a navigation system, audio system or the like, or may be provided separately from such systems.

[0033] The steering system 51 is, for example, an electric power steering system or a steer-by-wire (SBW) system and includes the actuator 52 and the torque sensor 53.

[0034] The steering system 51 causes the actuator 52 to add torque, ie, an assist torque, to a steering unit, such as a steering wheel, to supplement a steering force, or causes the actuator 52 to steer the wheels 14. In the tractor 10 in the exemplary embodiment, the front wheels 14F are steerable wheels. The actuator 52 can steer one wheel 14 or a plurality of wheels 14.

[0035] The steering system 51 is electrically controlled by the towing assist device 30 or the like, or actuates the actuator 52 according to an operation performed by the driver on the steering unit, such as the steering wheel. The torque sensor 53 detects, for example, the torque applied by the driver to the steering unit.

[0036] The steering angle sensor 61 is, for example, an angle sensor that detects the steering angle of the steering unit, such as the steering wheel. The steering angle of the steering unit is a steering angle of the tractor 10. The steering angle sensor 61 is implemented using, for example, a Hall element and detects a rotation angle of a rotating portion provided in the steering unit. The towing assist device 30 acquires a steering amount of the steering unit by the driver, a steering amount of the wheels 14 during automatic steering, and the like from the steering angle sensor 61 and performs various types of control.

[0037] The shift sensor 62 is, for example, a sensor that detects the position of a movable portion of a shift operating unit, such as a shift lever. The shift sensor 62 may detect the position of a lever, an arm, a knob, or the like as the movable portion. The shift sensor 62 may include a distance sensor or be embodied as a switch.

[0038] The wheel speed sensor 63 is a sensor that detects the rotation amount of the wheels 14 and the rotation speed per unit time. The wheel speed sensor 63 is arranged at each wheel 14 and outputs the number of wheel speed pulses indicating the rotation speed detected at each wheel 14 as a sensor value. The wheel speed sensor 63 may include, for example, a Hall element. The towing assist device 30 calculates the amount of movement of the tractor 10 based on the sensor value obtained from the wheel speed sensor 63 and performs various types of control.

[0039] Configurations, arrangements, electrical connection forms and the like of the various sensors and actuators described above are merely examples and can be set in various ways. Configuration example for a towing assistance device

[0040] Next, an example of a functional configuration of the towing assist device 30 in the embodiment will be described with reference to Fig. 4 to 7.

[0041] Fig. 4 is a block diagram showing the example of the functional configuration of the towing assist device 30 according to the embodiment. As shown in Fig. 4, the towing assist device 30 includes, as functional units, a target path calculation unit 301, a trailer position acquisition unit 302, a nearest point calculation unit 303, a tractor curvature conversion unit 304, a feedback control unit 305, and a steering angle conversion unit 306.

[0042] These functional units of the towing assist device 30 are implemented by the CPU 31 by loading a program stored in the ROM 32 or the like into the RAM and executing the program. The program executed by the CPU 31 can be provided by recording it on a computer-readable storage medium such as a CD-ROM, a flexible disk (FD), a CD-R, a digital versatile disc (DVD), or a universal serial bus (USB) as a file in an installable or executable format, or it can be provided or distributed via a network such as the Internet. Various programs can be provided by embedding them in advance in a non-volatile storage medium such as ROM.

[0043] However, what is disclosed here is not limited to the embodiment described above, and at least part of the functional units described above can be implemented using a dedicated hardware circuit.

[0044] An example is described below where the driver selects the reversing assist mode or the like, and the towing assist device 30 assists the tractor 10 towing the trailer 20 in reversing. When assisting the tractor 10 in reversing, the towing assist device 30 calculates a target path serving as a moving path for the trailer 20 and, for example, controls the steering of the tractor 10 so that the trailer 20 moves along the target path.

[0045] The target path calculation unit 301 calculates the target path for the trailer 20 when the towing assist device 30 starts the reversing assistance.

[0046] The trailer position obtaining unit 302 sequentially obtains an X-direction position X2, a Y-direction position Y2 and a yaw angle ψ2 of the trailer 20 as shown in Fig. 5, during the backward movement assistance by the towing assistance device 30.

[0047] Fig. 5 shows a trailer position P2 obtained by the towing assistance device 30 according to the embodiment. As in Fig. 5, for example, by placing the tractor 10 and the trailer 20 on absolute coordinates of an X coordinate and a Y coordinate, the trailer position P2 and a tractor position P1 can be represented. That is, the tractor position P1 is represented, for example, by an X-direction position X1 and a Y-direction position Y1 of the tractor 10 and a yaw angle ψ1, which is an inclination of the tractor 10 from an X-axis of the absolute coordinates. The trailer position P2 is represented, for example, by the X-direction position X2 and the Y-direction position Y2 of the trailer 20 and the yaw angle ψ2, which is an inclination of the trailer 20 from the X-axis of the absolute coordinates.

[0048] Here, the tractor position P1 is determined based on, for example, a center point of the pair of rear wheels 14R that are drive wheels of the tractor 10, that is, a center point of an axle of the rear wheels 14R. The trailer position P2 is determined based on, for example, a center point of the pair of wheels 24 of the trailer 20, that is, a center point of an axle of the wheels 24.

[0049] However, in the case of a two-axle trailer including two pairs of wheels, the trailer position may be determined, for example, with reference to a center point of a first axle or a second axle or with reference to any point between the center point of the first axle and the center point of the second axle.

[0050] The X-direction position X1, the Y-direction position Y1, and the yaw angle ψ1 of the tractor 10 in absolute coordinates can be detected, for example, using the steering angle sensor 61, the shift sensor 62, and the wheel speed sensor 63. The X-direction position X2, the Y-direction position Y2, and the yaw angle ψ2 of the trailer 20 in absolute coordinates can be specified based on the tractor position P1 and a trailer hitch angle φ.

[0051] As in Fig. 5, the trailer coupling angle φ is an angle formed by a line that is a center line of the trailer 20 in the left-right direction and is a line obtained by extending a line that coincides with an extension direction of the coupling member 22 further forward along the coupling member 22 and a center line of the tractor 10 in the left-right direction. The trailer coupling angle φ can be determined, for example, by analyzing the image captured by the imaging unit 12 described above. The method is not limited to image recognition, and alternatively, for example, a sensor for detecting the trailer coupling angle φ may be provided for the trailer coupling ball 19.

[0052] In this way, the tractor position P1, such as the X-direction position X1, the Y-direction position Y1, and the yaw angle ψ1 of the tractor 10, and the trailer hitch angle φ are specified. Furthermore, by using a distance between the front and rear wheels 14F and 14R of the tractor 10, a distance from each rear wheel 14R of the tractor 10 to the trailer hitch ball 19, and a distance from the trailer hitch ball 19 to each wheel 24 of the trailer 20, which are known values, the trailer position P2, such as the X-direction position X2, the Y-direction position Y2, and the yaw angle ψ2 of the trailer 20, are specified.

[0053] The nearest point calculation unit 303 calculates a deviation of a current position of the trailer 20 from the target path based on the target path of the trailer 20 calculated by the target path calculation unit 301 and the trailer position P2 acquired by the trailer position acquisition unit 302, and further calculates a target curvature κ 2FF of the trailer 20.

[0054] Fig. 6 shows a nearest point P n , which is calculated by the towing assistance device 30 according to the embodiment. As in Fig. 6, the deviation of the current position of the trailer 20 from the target path is determined, for example, by the nearest point P n a target path TP of the trailer 20 relative to the trailer position P2. That is, the nearest point P nis a point on the target path TP where the distance to the trailer position P2 is the shortest, and an intersection point when a perpendicular line from the trailer position P2 falls on a tangent line of the curved target path TP. The nearest point P n is determined by the lateral deviation e y between the trailer position P2 and the target path TP and the yaw angle deviation e θ between the trailer position P2 and the target path TP.

[0055] The target curvature κ 2FF of the trailer 20 is the target curvature of the trailer 20 when a forward control is performed to move the position of the trailer 20 along the target path TP, and is calculated based on the nearest point P n , which is caused by the lateral deviation e y and the yaw angle deviation e θ of the trailer 20 is calculated.

[0056] The target curvature κ 2FFof the trailer 20, which is used for the forward control to maintain the trailer position P2 on the target path TP, is an example of a first target curvature.

[0057] The tractor curvature conversion unit 304 converts the target curvature κ 2FF of the trailer 20, which is calculated by the nearest point calculation unit 303, into the target curvature κ 1FF of the tractor 10 um. The target curvature κ 1FF of the tractor 10 is a target curvature of the tractor 10 when the forward control is performed to maintain the position of the trailer 20 on the target path TP, and is calculated using the following equation (1) using the target curvature κ 2FF of the trailer 20 and the trailer coupling angle φ, which is also used to indicate the trailer position P2. κ1FF=tanφ−κ2FFl2κ2FFlhl2tanφ+lh

[0058] Fig. 7 shows the distances I h and I2 in equation (1).

[0059] Fig. 7 shows the distances I1, I h and I2 used by the towing assistance device 30 according to the embodiment. As shown in Fig. 7, the distance I1 is a wheelbase of the tractor 10, ie a distance between the front and rear wheels 14F and 14R. The distance I h is a distance from the tractor position P1, i.e. the center of the axle of the rear wheels 14R of the tractor 10, to the trailer coupling ball 19. The distance I2 is a distance from the trailer coupling ball 19 to the trailer position P2, i.e. the center of the axle of the wheels 24 of the trailer 20.

[0060] The distances I h and I2 are used to determine the target curvature κ 1FF of the tractor 10 using the above equation (1), and the distances I1, I hand I2 are also used when the trailer position acquiring unit 302 specifies the trailer position P2 based on the tractor position P1 and the trailer hitch angle φ as described above.

[0061] A conversion equation from the target curvature κ 2FF of the trailer 20 to the target curvature κ 1FF of the tractor 10 shown in the above equation (1) is determined based on a geometric model in a tractor-trailer system and can be easily derived.

[0062] The tractor curvature conversion unit 304 is an example of a first conversion unit, and the target curvature κ 1FF of the tractor 10, which is determined by converting the target curvature κ 2FF of the trailer 20 is an example of a second target curvature.

[0063] The feedback control unit 305 calculates the target curvature κ 1FBof the tractor 10 using the lateral deviation e y and the yaw angle deviation e θ of the trailer 20 at the nearest point P n , which is calculated by the calculation unit for the nearest point 303. The target curvature κ 1FB of the tractor 10 is the target curvature of the tractor 10 when a feedback control is performed to return the position of the trailer 20, at which the deviation occurs, to the target path TP. The target curvature κ calculated by the feedback control unit 305 1FB the tractor 10 is an approximate value.

[0064] The target curvature κ 1FB of the tractor 10, which is used for the feedback control to correct the trailer position P2 based on the lateral deviation e y and the yaw angle deviation e θ of the trailer 20 is an example of a third target curvature.

[0065] The steering angle conversion unit 306 calculates a target steering angle δ* SW of the tractor 10 based on the target curvature κ*1 of the tractor 10, which is calculated by summing the target curvature κ 1FF the tractor 10, which is used for forward control to correct the trailer position P2, and the target curvature κ 1FB of the tractor 10 used for feedback control and outputs the calculated target steering angle δ* SW to the tractor 10. The target steering angle δ* SW of the tractor 10 is a steering angle that the tractor 10 must adopt in order to cause the tractor 10 to travel on a path with the target curvature κ*1.

[0066] The steering angle conversion unit 306 is an example of a second conversion unit.

[0067] The tractor 10 is accordingly controlled in such a way that it achieves the target steering angle δ* SWand moves on a path with the target curvature κ*1. Accordingly, the position of the trailer 20 can be maintained on the target path TP. overview

[0068] The towing assist device assists the tractor when towing the trailer. For example, when the trailer is being towed backward by the tractor, the towing assist device calculates the target path for the trailer and controls the tractor so that the trailer moves along the target path. Therefore, in the case of reversing assistance, the forward control and feedback control for steering the tractor become complex.

[0069] According to the towing assist device of the embodiment, the target curvature κ used for forward control is 2FF of the trailer 20 based on the target path TP into the target curvature κ 1FFof the tractor 10, and the target curvature κ 1FF is converted into the target steering angle δ* SW of the tractor 10. Accordingly, it is possible to assist in reversing the tractor 10 with simple steering control logic. Accordingly, the computation costs of the towing assistance device 30 can be reduced.

[0070] According to the towing assistance device of the embodiment, the lateral deviation e y and the yaw angle deviation e θ from the target path TP of the trailer 20 from the coordinates of the trailer 20 and the trailer coupling angle φ, which is the coupling angle between the trailer 20 and the tractor 10, and the target curvature κ 1FF , to which the target curvature κ 1FB of the tractor 10 used for feedback control is added based on the lateral deviation ey and the yaw angle deviation e θof the trailer 20 to the target steering angle δ* SW the tractor 10.

[0071] By performing the forward control and the feedback control in this way, it is possible to assist more precisely when towing the tractor 10 backward. Since the feedback control is only based on the lateral deviation e y and the yaw angle deviation e θ of the trailer 20, the gain adjustment is facilitated. modification

[0072] Next, a towing assist device 130 according to a modification of the embodiment is described with reference to Fig. 8. The towing assistance device 130 of the modification differs from the above-described embodiment in that the target curvature of the tractor 10 is determined based on the target curvature κ 2FBthe feedback control for the trailer 20 in addition to the trailer coupling angle φ, which is the coupling angle between the tractor 10 and the trailer 20, and the target curvature κ 2FF the forward control for trailer 20 is calculated.

[0073] Fig. Fig. 8 is a block diagram showing an example of a functional configuration of the towing assist device 130 according to the modification of the embodiment. Fig. 8, configurations similar to those in the above-described embodiment are designated by the same reference numerals, and a description thereof may be omitted.

[0074] As in Fig. 8, the towing assist device 130 includes a tractor curvature conversion unit 314 and a feedback control unit 315 as functional units instead of the tractor curvature conversion unit 304 and the feedback control unit 305.

[0075] The feedback control unit 315 of the modification calculates and outputs the target curvature κ 2FB of the trailer 20 instead of the target curvature κ 1FB of the tractor 10, which is calculated by the feedback control unit 305 in the embodiment described above.

[0076] The target curvature κ 2FB of the trailer 20 is the target curvature of the trailer 20 when the feedback control for correcting the trailer position P2 (see the above-described Fig. 5) and is calculated using the following equation (2) using the lateral deviation e y and the yaw angle deviation e θof the trailer 20, which is in the nearest point P n which is calculated by the calculation unit for the nearest point 303. κ2FB=κ1ey+κ2eθ

[0077] A gain k1 in equation (2) is a value that represents the lateral deviation e y of the trailer 20 when the feedback control is performed to correct the trailer position P2. A gain k2 in equation (2) is a value that represents the yaw angle deviation e θ of the trailer 20 is amplified when the feedback control is performed to correct the trailer position P2.

[0078] The gains k1 and k2 can be varied in different situations, and fixed values ​​for the gains k1 and k2 can be used. The gains k1 and k2 can be values ​​that represent the lateral deviation e y or the yaw angle deviation e θ reduce.

[0079] The target curvature κ 2FB of the trailer 20, which is used for the feedback control to correct the trailer position P2 based on the lateral deviation e y and the yaw angle deviation e θ of the trailer 20 is an example of a fourth target curvature.

[0080] The tractor curvature conversion unit 314 of the modification converts the target curvature κ*2 of the trailer 20 obtained by summing the target curvature κ 2FF of the trailer 20, which is used for forward control to correct the trailer position P2, and the target curvature κ 2FB of the trailer 20, which is used for the feedback control, into the target curvature κ**1 of the tractor 10.

[0081] The target curvature κ**1 of the tractor 10 is calculated using the following equation (3) using the target curvature κ*2 of the trailer 20 and the trailer coupling angle φ, which is the coupling angle between the tractor 10 and the trailer 20. κ1**=tanφ−κ2*l2κ2*lhl2tanφ+lh

[0082] As described above, the distances I h and I2 in equation (3) is the distance from the center of the axle of the rear wheels 14R of the tractor 10 to the trailer coupling ball 19 or the distance from the trailer coupling ball 19 to the center of the axle of the wheels 24 of the trailer 20 (see the above-described Fig. 7).

[0083] The tractor curvature conversion unit 314 is an example of the first conversion unit, and the target curvature κ**1 of the tractor 10 obtained from the target curvature κ 2FF and the target curvature κ 2FBof the trailer 20 is an example of the fourth target curvature.

[0084] The steering angle conversion unit 306 calculates a target steering angle δ** SW of the tractor 10 based on the target curvature κ**1 of the tractor 10 and outputs the target steering angle δ** SW to the tractor 10, as in the embodiment described above. The target steering angle δ** SW of the tractor 10 is a steering angle that the tractor 10 must adopt in order to allow the tractor 10 to travel on a path with the target curvature κ**1.

[0085] A difference between the target steering angle δ** SW and the target steering angle δ* SW in the embodiment described above is that the target steering angle δ* described above SW based on the target curvature κ 1FF and κ 1FB of the tractor 10 is calculated, while the target steering angle δ** SWthe modification based on the target curvature κ 2FF and κ 2FB of the trailer 20 is calculated.

[0086] In other words, in the above-described embodiment, the towing assistance device 30 calculates the target curvature κ*1 of the tractor 10 based on the target curvature κ 1FF and κ 1FB of the tractor 10 and converts the target curvature κ*1 into the target steering angle δ* SW of the tractor 10, while the towing assistance device 130 of the modification calculates the target curvature κ**1 of the tractor 10 based on the target curvature κ 2FF and κ 2FB of the trailer 20 and the target curvature κ**1 is converted into the target steering angle δ** SW the tractor 10.

[0087] According to the towing assistance device 130 of the modification, the lateral deviation e y and the yaw angle deviation e θfrom the target path TP of the trailer 20 from the coordinates of the trailer 20 and the trailer coupling angle φ, which is the coupling angle between the trailer 20 and the tractor 10, and the target curvature κ 2FF of the trailer 20, which is used for forward control, to which the target curvature κ 2FB of the trailer 20, which is used for feedback control, is added based on the lateral deviation e y and the yaw angle deviation e θ of the trailer 20 to the target steering angle δ** SW the tractor 10.

[0088] In this way, the tractor 10 is based on the target curvature κ 2FF and the target curvature κ 2FB of the trailer 20 with respect to the forward control and the feedback control, and thus more precise assistance can be provided when reversing the tractor 10. By adding the target curvature κ 2FFof the trailer 20 with respect to the feedback control, it is possible to perform appropriate feedback control according to a size of the trailer 20 and improve the stability of the movement of the trailer 20 according to the target path.

[0089] The principles, preferred embodiment, and mode of operation of the present invention are set forth in the foregoing description. However, the invention which is intended to be protected is not to be construed as limited to the specifically disclosed embodiments. Furthermore, the embodiments described herein are to be considered as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents may be substituted, without departing from the spirit and scope of the present invention. Accordingly, it is expressly intended to embrace all such variations, changes, and equivalents which fall within the spirit and scope of the present invention as defined by the claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-107175A

[0003]

Claims

[1] Towing assistance device (30, 130) which assists in the reversing of a towing vehicle (10) towing a towed vehicle (20), the towing assistance device comprising: a target path calculation unit (301) configured to calculate a target path on which the towed vehicle is to be moved; an acquisition unit (302) configured to acquire coordinates of the towed vehicle in a plane coordinate system and a coupling angle between the towed vehicle and the towing vehicle; a calculation unit (303) configured to calculate a first target curvature (κ 2FF ), which is a target curvature of the towed vehicle used for forward control, based on the target path; a first conversion unit (304, 314) configured to convert the first target curvature into a second target curvature (κ1FF ), which is the target curvature of the towing vehicle; and a second conversion unit (306) configured to convert the second target curvature into a target steering angle (δ* SW , δ** SW ) of the towing vehicle. [2] Towing assistance device according to claim 1, wherein the calculation unit based on the coordinates of the towed vehicle and the coupling angle a deviation (e y , e θ ) of the towed vehicle from the target path, the towing assistance device further comprises a feedback control unit (305) configured to determine a third target curvature (κ 1FB ), which is a target curvature of the towing vehicle used for feedback control, based on the deviation of the towed vehicle, and the second conversion unit converts the second target curvature, to which the third target curvature is added, into the target steering angle. [3] Towing assistance device according to claim 1, wherein the calculation unit calculates a deviation of the towed vehicle from the target path based on the coordinates of the towed vehicle and the coupling angle, the towing assistance device further comprises a feedback control unit (315) configured to determine a fourth target curvature (κ 2FB , κ**1), which is a target curvature of the towed vehicle used for feedback control, based on the deviation of the towed vehicle, and the first conversion unit converts the first target curvature, to which the fourth target curvature is added, into the second target curvature.

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