Method and electronic device for estimating lateral sideslip of trailer in tow vehicle

Abstract

The present invention provides a method and electronic device for estimating the lateral sideslip of a trailer in a towing vehicle, which is applied to a combined vehicle of a tractor and a trailer, and the method comprises: obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point; obtaining a third speed of the tractor in the ground coordinate system; based on the third speed, converting the first speed and the second speed into a fourth speed and a fifth speed in the vehicle coordinate system of the tractor respectively; estimating the sideslip of the trailer based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer. The method can estimate the lateral sideslip of the trailer and provide a reference for the dynamic control model of the towing vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle control, and in particular to an estimation method and electronic equipment for lateral sideslip of a trailer in a tow vehicle. Background Art

[0002] The side slip of the truck trailer is a problem that the truck will inevitably encounter when turning. When the side slip is small, it generally does not affect the dynamic stability of the truck. If the steering is too radical or the steering speed is too fast, the side slip will increase and affect the overall stability of the truck.

[0003] Measuring the side slip of a truck trailer has always been a technical problem for autonomous trucks, and there is no practical and inexpensive solution to detect the side slip. In the prior art, in the field of autonomous driving, it is often estimated by using truck models and trailer mass, but this estimation lacks the support of actual measurement data and has poor accuracy. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method and electronic equipment for estimating the lateral sideslip of a trailer in a tow vehicle.

[0005] The present invention provides a method for estimating the lateral sideslip of a trailer in a tow vehicle, which is applied to a combined vehicle of a tractor and a trailer, and the method comprises:

[0006] Obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point;

[0007] Acquire a third speed of the tractor in the ground coordinate system;

[0008] Based on the third speed, converting the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively;

[0009] The side slip amount of the trailer is estimated based on the fourth speed and the fifth speed and the distribution positions of the first point and the second point on the trailer.

[0010] According to a method for estimating lateral sideslip of a trailer in a tow vehicle provided by the present invention, based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer, estimating the sideslip amount of the trailer includes:

[0011] Based on the fourth speed and the fifth speed, obtaining a first component and a second component of the fourth speed and the fifth speed in a horizontal axis direction of the vehicle coordinate system, respectively;

[0012] The sideslip amount of the trailer is estimated based on the first component and the second component and the distribution positions of the first point and the second point on the trailer.

[0013] According to a method for estimating lateral sideslip of a trailer in a towed vehicle provided by the present invention, the distribution positions of the first point and the second point on the trailer only include:

[0014] The distance between the projection points of the first point and the second point on the longitudinal axis of the trailer.

[0015] According to a method for estimating lateral sideslip of a trailer in a tow vehicle provided by the present invention, based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer, estimating the sideslip amount of the trailer includes:

[0016] Acquire a first distance between projection points of the first point and the second point on the longitudinal axis of the trailer;

[0017] Acquire a second distance between the second point and a projection point of the center of the rear wheel axle of the trailer on the longitudinal axis of the trailer;

[0018] Based on the first distance, the second distance, the fourth speed, and the fifth speed, it is determined whether the trailer is skidding.

[0019] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for estimating the lateral sideslip of a trailer in a tow vehicle as described in any one of the above items are implemented.

[0020] The present invention further provides a tractor, wherein the tractor comprises the electronic device.

[0021] The present invention further provides a vehicle, comprising the tractor and a trailer towed by the tractor.

[0022] According to a vehicle provided by the present invention, the trailer comprises:

[0023] A first optical flow sensor, wherein the first optical flow sensor is disposed at a first point on the bottom of the trailer chassis, and the first optical flow sensor is disposed toward the ground;

[0024] A second optical flow sensor, the second optical flow sensor is arranged at a second point on the bottom of the trailer chassis, and the second optical flow sensor is arranged toward the ground;

[0025] at least one distance sensor, wherein the distance sensor is disposed on the bottom of the trailer chassis and the distance sensor is disposed toward the ground;

[0026] in,

[0027] The first optical flow sensor is closer to the towing point of the trailer than the second optical flow sensor;

[0028] The first optical flow sensor, the second optical flow sensor, and the distance sensor are configured to send data to a same processor.

[0029] According to a vehicle provided by the present invention, the x-axis and y-axis of the first optical flow sensor and the x-axis and y-axis of the second optical flow sensor are respectively parallel.

[0030] According to a vehicle provided by the present invention, the first optical flow sensor and the second optical flow sensor are both arranged on the same side of the towing point in the longitudinal direction of the trailer.

[0031] The present invention also provides a system for estimating the lateral sideslip of a trailer, which is applied to a combined vehicle of a tractor and a trailer, and the system comprises:

[0032] A first acquisition module, used for acquiring a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point;

[0033] A second acquisition module, used for acquiring a third speed of the tractor in the ground coordinate system;

[0034] a conversion module, configured to convert the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively, based on the third speed;

[0035] An estimation module is used to estimate the sideslip amount of the trailer based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer.

[0036] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method for estimating the lateral sideslip of a trailer in a tow vehicle as described in any one of the above items are implemented.

[0037] The method for estimating the lateral sideslip of a trailer in a towing vehicle and the electronic device provided by the present invention can estimate the lateral sideslip of the trailer and provide a reference for a dynamic control model of the towing vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic flow chart of a method for estimating the lateral sideslip of a trailer in a tow vehicle provided by the present invention;

[0040] Figure 2 A schematic diagram of estimating the side slip amount of a trailer provided by the present invention;

[0041] Figure 3 A schematic diagram of a trailer provided by the present invention when turning without side slipping;

[0042] Figure 4 A schematic diagram of the structure of a system for estimating the lateral sideslip of a trailer provided by the present invention;

[0043] Figure 5 A schematic diagram of the physical structure of an electronic device provided by the present invention;

[0044] Figure 6 A schematic diagram of the structure of a trailer provided by the present invention;

[0045] Figure 7 This is a schematic diagram of the installation structure of the first optical flow sensor and the distance sensor provided by the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The following describes in detail the method for estimating the lateral sideslip of a trailer in a tow vehicle provided by the embodiment of the present application through specific embodiments and application scenarios in conjunction with the accompanying drawings.

[0048] Figure 1 A schematic flow chart of a method for estimating the lateral sideslip of a trailer in a tow vehicle provided by the present invention is shown as follows: Figure 1 As shown, the present invention provides a method for estimating the lateral sideslip of a trailer in a tow vehicle, which is applied to a combined vehicle of a tractor and a trailer, and the method may include the following steps.

[0049] Preferably, the estimation method of this embodiment is performed by a processor arranged on the vehicle side or a processor on the cloud side.

[0050] S100, obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point.

[0051] Preferably, the first point and the second point are both arranged on the longitudinal center axis of the trailer. Further, the first point is arranged at the front end of the trailer, and the second point is arranged at the rear end of the trailer.

[0052] It should be noted that the first speed and the second speed are both speed vectors with directions in the vehicle motion plane.

[0053] S200: Obtain a third speed of the tractor in the ground coordinate system.

[0054] It should be noted that the third speed is a speed vector with a direction in the vehicle motion plane.

[0055] S300: Based on the third speed, convert the first speed and the second speed into a fourth speed and a fifth speed in the vehicle coordinate system of the tractor, respectively.

[0056] S400: Estimate the side slip amount of the trailer based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer.

[0057] Optionally, estimating the sideslip amount of the trailer based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer includes:

[0058] Based on the fourth speed and the fifth speed, obtaining a first component and a second component of the fourth speed and the fifth speed in the horizontal axis direction in the vehicle coordinate system respectively;

[0059] The sideslip amount of the trailer is estimated based on the first component and the second component and the distribution positions of the first point and the second point on the trailer.

[0060] It should be noted that the horizontal axis in the vehicle coordinate system is the x-axis.

[0061] Optionally, the distribution positions of the first point and the second point on the trailer only include:

[0062] The distance between the projections of the first and second points onto the longitudinal axis of the trailer.

[0063] Preferably, Figure 2 The schematic diagram of estimating the trailer side slip provided by the present invention is as follows: Figure 2As shown, the first point 11 and the second point 12 are both distributed on the longitudinal center axis of the trailer, the first component Va.x at the first point 11 after the trailer towing point 6 is obtained, and the second component Vb.x at the second point 12 of the trailer is obtained. The distance between the first point 11 and the second point 12 is L1. The sideslip amount is represented by the sideslip angle ω of the trailer. The formula for estimating the sideslip amount of the trailer is as follows:

[0064] ω≈arctan[(V b.x -V a.x ) / L1]

[0065] By simplifying the estimation formula through geometric approximation, it is only necessary to obtain the distance between the preset first point 11 and the second point 12, and then combine the first component and the second component obtained by measurement analysis to quickly obtain the sideslip amount, thereby achieving rapid sideslip amount estimation.

[0066] Optionally, estimating the sideslip amount of the trailer based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer includes:

[0067] Obtaining a first distance between the projection points of the first point and the second point on the longitudinal axis of the trailer;

[0068] Obtaining a second distance between the second point and the projection point of the center of the rear wheel axle of the trailer on the longitudinal axis of the trailer;

[0069] Based on the first distance, the second distance, the fourth speed, and the fifth speed, it is determined whether the trailer is skidding.

[0070] Specifically, this embodiment is aimed at the conventional steering scenario of the towing vehicle during driving. Figure 3 A schematic diagram of a trailer provided by the present invention when turning without side slipping, such as Figure 3 As shown, when the trailer vehicle turns at a large angle, the first point 11 and the second point 12 will rotate along the rotation axis, which can be approximately identified as the center 9 of the rear axle of the trailer. In practice, there will be a certain offset, and the distance between the center 9 of the rear axle of the trailer and the second point 12 is L2. During the actual large-angle turn, if the trailer does not skid, the rotation axis will be stable near the center 9 of the rear axle of the trailer, and the first component and the second component approximately satisfy the following formula. When the formula is not satisfied, it means that skidding occurs.

[0071] V a.x =[(L1+L2) / L2]×V b.x

[0072] Preferably, whether or not sideslip occurs is first determined by the above formula, and when it is determined that sideslip occurs, the sideslip amount is specifically estimated.

[0073] This embodiment can estimate the lateral sideslip of the trailer and provide a reference for the dynamic control model of the towing vehicle.

[0074] The following is a description of a system for estimating the lateral sideslip of a trailer provided by the present invention. The system for estimating the lateral sideslip of a trailer described below and the method for estimating the lateral sideslip of a trailer described above can be referred to each other.

[0075] Figure 4 A schematic diagram of the structure of a system for estimating the lateral sideslip of a trailer provided by the present invention is shown in FIG. Figure 4 As shown, the present invention also provides a system for estimating the lateral sideslip of a trailer, which is applied to a combined vehicle of a tractor and a trailer, and the system comprises:

[0076] A first acquisition module is used to acquire a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point;

[0077] A second acquisition module is used to acquire a third speed of the tractor in the ground coordinate system;

[0078] a conversion module, configured to convert the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively, based on the third speed;

[0079] The estimation module is used for estimating the sideslip amount of the trailer based on the fourth speed and the fifth speed and the distribution positions of the first point and the second point on the trailer.

[0080] This embodiment can estimate the lateral sideslip of the trailer and provide a reference for the dynamic control model of the towing vehicle.

[0081] Figure 5 A schematic diagram of the physical structure of an electronic device provided by the present invention, such as Figure 5 As shown, the electronic device may include: a processor 510, a communication interface 520, a memory 530 and a communication bus 540, wherein the processor 510, the communication interface 520 and the memory 530 communicate with each other through the communication bus 540. The processor 510 may call the logic instructions in the memory 530 to execute an estimation method for the lateral sideslip of the trailer in the towing vehicle, which is applied to a combined vehicle of a tractor and a trailer, and the method includes:

[0082] Obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point;

[0083] Acquire a third speed of the tractor in the ground coordinate system;

[0084] Based on the third speed, converting the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively;

[0085] The side slip amount of the trailer is estimated based on the fourth speed and the fifth speed and the distribution positions of the first point and the second point on the trailer.

[0086] In addition, the logic instructions in the above-mentioned memory 530 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0087] On the other hand, the present invention further provides a tractor, which includes the above-mentioned electronic device.

[0088] On the other hand, the present invention further provides a vehicle, comprising the above-mentioned tractor and a trailer towed by the tractor.

[0089] Figure 6 A schematic diagram of a trailer structure provided by the present invention is shown in FIG. Figure 6 As shown, the present invention also provides a vehicle in which a trailer 7 is connected to a tractor 5 at the front, and the trailer 7 includes:

[0090] A first optical flow sensor 2, the first optical flow sensor 2 is arranged at a first point on the bottom of the trailer chassis, and the first optical flow sensor is arranged toward the ground;

[0091] A second optical flow sensor 8, the second optical flow sensor 8 is arranged at a second point on the bottom of the trailer chassis, and the second optical flow sensor is arranged toward the ground;

[0092] At least one distance sensor, the distance sensor is arranged on the bottom of the trailer chassis, and the distance sensor is arranged toward the ground;

[0093] in,

[0094] The first optical flow sensor 2 is closer to the towing point 6 of the trailer 7 than the second optical flow sensor 8;

[0095] The first optical flow sensor 2 , the second optical flow sensor 8 , and the distance sensor are configured to send data to the same processor.

[0096] Optionally, the x-axis and y-axis of the first optical flow sensor 2 are parallel to the x-axis and y-axis of the second optical flow sensor 8. By arranging that the x-axis and y-axis of the first optical flow sensor 2 and the x-axis and y-axis of the second optical flow sensor 8 are parallel, it is convenient to realize the subsequent speed calculation and speed coordinate system conversion, and reduce the computing power requirement of the processor.

[0097] Optionally, the first optical flow sensor 2 and the second optical flow sensor 8 are both arranged on the same side of the towing point 6 in the longitudinal direction of the trailer.

[0098] Preferably, the second optical flow sensor 2 is arranged at a predetermined distance in front of the center 9 of the rear wheel axle of the trailer.

[0099] Preferably, Figure 7 The schematic diagram of the installation structure of the first optical flow sensor and the distance sensor provided by the present invention is as follows: Figure 7 As shown, the first optical flow sensor 2 is arranged at the bottom of the trailer chassis 1, and the distance sensor 3 is arranged at the bottom of the trailer chassis 1. The first optical flow sensor 2 and the distance sensor 3 have the same installation height, and the measurement units of the two are in the same plane. The distance sensor 3 measures its height from the ground 4 as h.

[0100] The formula for obtaining the first speed V is as follows:

[0101] V=v×h / f

[0102] in,

[0103] v is the pixel plane velocity given by the first optical flow sensor; h is the height from the lens of the first optical flow sensor to the ground, given by the distance sensor; f is the phase plane focal length of the first optical flow sensor.

[0104] Similarly, the second speed can also be obtained.

[0105] Based on the sensing data of the first optical flow sensor, the second optical flow sensor and the distance sensor, the processor processes and obtains the aforementioned first speed and second speed.

[0106] On the other hand, the present invention further provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, when the program instructions are executed by a computer, the computer can execute the method for estimating the lateral sideslip of a trailer in a towed vehicle provided by the above methods, applied to a combination vehicle of a tractor and a trailer, the method comprising:

[0107] Obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point;

[0108] Acquire a third speed of the tractor in the ground coordinate system;

[0109] Based on the third speed, converting the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively;

[0110] The side slip amount of the trailer is estimated based on the fourth speed and the fifth speed and the distribution positions of the first point and the second point on the trailer.

[0111] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to execute the above-mentioned method for estimating the lateral sideslip of a trailer in a towed vehicle, which is applied to a combination vehicle of a tractor and a trailer, and the method comprises:

[0112] Obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point;

[0113] Acquire a third speed of the tractor in the ground coordinate system;

[0114] Based on the third speed, converting the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively;

[0115] The side slip amount of the trailer is estimated based on the fourth speed and the fifth speed and the distribution positions of the first point and the second point on the trailer.

[0116] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0117] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for estimating the lateral sideslip of a trailer in a tow vehicle, It is characterized in that Applied to a combination vehicle of a tractor and a trailer, the method comprises: Obtaining a first speed and a second speed corresponding to a first point and a second point on the trailer in a ground coordinate system, wherein the first point is closer to the towing point than the second point; Acquire a third speed of the tractor in the ground coordinate system; Based on the third speed, converting the first speed and the second speed into a fourth speed and a fifth speed in a vehicle coordinate system of the tractor, respectively; estimating a sideslip amount of the trailer based on the fourth speed and the fifth speed, and distribution positions of the first point and the second point on the trailer; Based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer, estimating the sideslip amount of the trailer includes: Based on the fourth speed and the fifth speed, obtaining a first component and a second component of the fourth speed and the fifth speed in a horizontal axis direction of the vehicle coordinate system, respectively; The sideslip amount of the trailer is estimated based on the first component and the second component and the distribution positions of the first point and the second point on the trailer.

2. The method for estimating the lateral sideslip of a trailer in a tow vehicle according to claim 1, It is characterized in that The distribution positions of the first point and the second point on the trailer only include: The distance between the projection points of the first point and the second point on the longitudinal axis of the trailer.

3. The method for estimating the lateral sideslip of a trailer in a tow vehicle according to claim 1, It is characterized in that Based on the fourth speed and the fifth speed, and the distribution positions of the first point and the second point on the trailer, estimating the sideslip amount of the trailer includes: Acquire a first distance between projection points of the first point and the second point on the longitudinal axis of the trailer; Acquire a second distance between the second point and a projection point of the center of the rear wheel axle of the trailer on the longitudinal axis of the trailer; Based on the first distance, the second distance, the fourth speed, and the fifth speed, it is determined whether the trailer is skidding.

4. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, It is characterized in that When the processor executes the program, the steps of the method for estimating the lateral sideslip of the trailer in the towed vehicle as described in any one of claims 1 to 3 are implemented.

5. A tractor, It is characterized in that The tractor comprises the electronic device of claim 4.

6. A vehicle, It is characterized in that The vehicle comprises the tractor according to claim 5 and a trailer towed by the tractor.

7. The vehicle according to claim 6, It is characterized in that The trailer comprises: A first optical flow sensor, wherein the first optical flow sensor is disposed at a first point on the bottom of the trailer chassis, and the first optical flow sensor is disposed toward the ground; A second optical flow sensor, the second optical flow sensor is arranged at a second point on the bottom of the trailer chassis, and the second optical flow sensor is arranged toward the ground; at least one distance sensor, wherein the distance sensor is disposed on the bottom of the trailer chassis and the distance sensor is disposed toward the ground; in, The first optical flow sensor is closer to the towing point of the trailer than the second optical flow sensor; The first optical flow sensor, the second optical flow sensor, and the distance sensor are configured to send data to a same processor.

8. The vehicle according to claim 7, It is characterized in that The x-axis and y-axis of the first optical flow sensor are parallel to the x-axis and y-axis of the second optical flow sensor.

9. The vehicle according to claim 7, It is characterized in that The first optical flow sensor and the second optical flow sensor are both arranged on the same side of the towing point in the longitudinal direction of the trailer.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the steps of the method for estimating the lateral sideslip of a trailer in a towed vehicle as claimed in any one of claims 1 to 3 are implemented.

Images