WO2021151516A1

WO2021151516A1 - A method for determining a trailer length of a vehicle

Info

Publication number: WO2021151516A1
Application number: PCT/EP2020/052507
Authority: WO
Inventors: Pierre-Yves CHAUVOT; Thibaut JEANPIERRE
Original assignee: Volvo Truck Corporation
Priority date: 2020-01-31
Filing date: 2020-01-31
Publication date: 2021-08-05

Abstract

The invention relates to a method for determining a trailer length of a vehicle comprising a cab and a trailer, the vehicle comprising a camera assembly comprising at least two cameras located on each side of the cab. The invention also relates to a system for determining a trailer length of a vehicle comprising a cab and a trailer. The invention further concerns a vehicle comprising such a system.

Description

A method for determining a trailer length of a vehicle

TECHNICAL FIELD

The invention relates to a method for determining a trailer length of a vehicle comprising a cab and a trailer, the vehicle comprising a camera assembly comprising at least two cameras located on each side of the cab. The invention also relates to a system for determining a trailer length of a vehicle comprising a cab and a trailer. The invention further concerns a vehicle comprising such a system. The invention is particularly well suited for heavy-duty vehicles, such as trucks, buses and construction equipment. The invention may also be used in other vehicles such as a car.

BACKGROUND

A trend in industrial vehicles is to replace conventional mirrors by a camera assembly which comprises a supporting arm mounted on the vehicle cab and a camera arranged on said supporting arm, for providing a captured image of an area located rearwards and along a vehicle side. An image, resulting from the processing of the captured image, can typically be displayed on a monitor inside the driver’s compartment.

The camera assembly must be arranged to provide to the vehicle driver an appropriate image displayed on the monitor, to ensure good visibility, hence safety. One of the most important information to know is the length of the trailer. This information is crucial for the driver and for the driver assistance system. Various systems have been provided to determine the trailer length based on wireless transmitters mounted on the rear side of the trailer, on radars or on lidars. The patent application US20180045823 discloses a trailer-detection system including a radar-sensor, a camera, and a controller. The radar-sensor is used to determine a range, and an azimuth-angle, of a radar-signal reflected by a feature of trailer towed by a host- vehicle. The camera is used to capture an image of the trailer. The controller is in communication with the radar-sensor and the camera. The controller is configured to determine a position in the image of a viewable-feature of the trailer, determine a trailer- width and a trailer-height of the trailer based on the position and a range and azimuth- angle to the viewable-feature indicated by the radar-sensor, and optionally determine the trailer-length based on the range and azimuth-angle of the radar-signal reflected by a hidden-feature.

However, under existing techniques, the value of the length of the trailer is not accurate enough. It can lead to erroneous data used for the driver assistance system and transmitted to the driver resulting in accidents. Moreover, the process of determining the trailer length of the vehicle from wireless transmitters, radars or lidars data is complicated to apply. Indeed, a significant computational power is needed to process the trailer length of the vehicle.

SUMMARY

An object of the invention is to provide an easy-to-implement solution to improve the determination of the length of a trailer for the driver and for the driver assistance system.

The object is achieved by a method for determining a trailer length of a vehicle comprising a cab and a trailer, the vehicle comprising a camera assembly comprising at least two cameras, each camera being located on each side of the cab.

The method comprises:

A) Determining the position of two targets (T1, T2) being located on each side of the back of the trailer (30) using at the least two cameras (C1, C2) capturing at least two images (41 , 42) of an area located rearwards and along each vehicle side,

B) Processing the trailer length (L) of the vehicle (1), using the position of the targets (T1, T2) detected in at least two captured images (41, 42), with the following formula (1):

Wherein L is the length of the trailer in meter, W1 is the width in meter between the at least two cameras (C1, C2), i.e. the width including the at least two cameras (C1, C2) and the cab,

W2 is the width in pixel of the at least two cameras (C1, C2), a is the angle of the field of vision of the at least two cameras (C1 , C2),

D1 is the distance in pixel between the target (T1) located on one side of the trailer and the camera (C1),

D2 is the distance in pixel between the target (T2) located on the other side of the trailer and the camera (C2) and

W3 is the width in meter of the cab, i.e. the width only including the cab.

By the provision of a method for determining a trailer length of a vehicle according to the present invention, the advantage is to provide a method allowing an automatic determination of the length of the trailer based on the captured images of the at least two cameras. Additionally, the computational power needed to process the trailer length of the vehicle is low. Finally, the value of the trailer length is more accurate since the pixel, i.e. the smallest unit of an image, is used.

In a preferred embodiment, the at least two cameras are stereoscopic cameras. It is believed that a stereoscopic camera is a type of camera with two or more lenses with a separate image sensor or film frame for each lens. This allows the camera to simulate human binocular vision, and therefore gives it the ability to capture three-dimensional images.

In a preferred embodiment, the targets are equidistant. In this case, it seems that the determination of the length of the trailer is even more precise.

In a preferred embodiment, the targets are rear side markers lamps on the trailer, rear wall corners of the trailer, ora vertical edge located at the rear of the trailer. It is believed that when the targets are located in the rear side of the trailer, the determination of the trailer length is more precise.

For example, when the targets are the rear side markets lamps, flickering commands can be sent to the rear side markets lamps to facilitate the detection of the targets by the at least two cameras. In an embodiment, in that steps A) and B) can be performed while the vehicle is moving forward or backward. Advantageously, the cab comprises a steering wheel having a steering wheel angle b.

Advantageously, the method further comprises transmitting at least two captured images data provided by said at least two cameras through a vehicle internal communication network.

Preferably, the camera assembly comprises two supporting arms mounted on each side of the vehicle, said at least two cameras being respectively arranged on each supporting arm. According to a second aspect, the invention relates to a system for determining a trailer length of a vehicle comprising a cab and a trailer, the vehicle comprising a camera assembly comprising at least two cameras, each camera being located on each side of the cab, the system comprising:

- at least two cameras located on each side of the cab; - a controller capable of receiving the target positions information from the at least two cameras, and of processing the trailer length of the vehicle, using the position of the targets detected in at least two captured images, with the following formula 1:

D2 is the distance in pixel between the target (T2) located on the other side of the trailer and the camera (C2) and W3 is the width in meter of the cab, i.e. the width only including the cab.

The system may further comprise a vehicle internal communication network, which links at least two cameras and the controller.

According to a third aspect, the invention relates to a vehicle comprising:

- a cab having front wheels and rear wheels;

- a camera assembly comprising at least two cameras located on each side of the cab, for providing at least two captured images of an area located rearwards and along each vehicle side;

- a vehicle internal communication network; characterized in that it further comprises a system, wherein the at least two cameras and the controller are linked by the vehicle internal communication network.

Preferably, the camera is fixed relative to the cab, in the use position. For example, in this embodiment, the supporting arm of the camera assembly is fixedly mounted on the cab (but can be folded along the cab side when the vehicle is stopped).

Each captured image may correspond to a field of vision having an angle a.

After the processing, the trailer length of the vehicle, using the position of the targets detected in at least two captured images, can be displayed on a monitor located in that the cab for the driver and/or directly transmitted to the vehicle internal communication network for the driver assistance system.

In an embodiment, the controller is part of a camera monitoring system including the camera assembly. In other words, in this embodiment, the controller is not the electrical control unit of the vehicle.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

In the drawings:

Fig. 1 is a perspective view of a vehicle according to the invention,

Fig. 2 is a perspective view forward from the interior of a vehicle, showing a camera assembly;

Fig. 3 is a top view of a vehicle, showing two different fields of vision for displaying two different images, according to an embodiment of the invention;

Fig. 4a and 4b show the images captured by two cameras located on each side of the cab.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

As illustrated in Figure 1 , the vehicle 1 comprises a cab 2 defining a driver’s compartment 3. The cab 2 has side walls 4 each comprising a door 5, a front wall 6 including a windscreen 7, a top wall 8 and a rear wall 9. The cab 2 further comprises front wheels 10, and rear wheels 11. There may be provided one rear wheel or several rear wheels on each side of the cab 2.

X is defined as the longitudinal direction of the vehicle 1, Y is defined as the transversal direction and Z is defined as the vertical direction of the vehicle 1.

The vehicle 1 may comprise an electrical control unit (ECU) 12 for controlling the various electric systems of the vehicle 1.

The vehicle 1 also comprises a camera assembly 13 mounted on the cab 2, typically above a front portion of the door 5, on both sidewalls 4 of the cab 2. Basically, the camera assembly 13 can comprise two supporting arms 14 and two cameras C1, C2 arranged respectively on each supporting arm 14, for providing two captured images 41, 42 of two areas surrounding the vehicle 1, more specifically an area located rearwards and along a vehicle side. The supporting arm 14 can be fixedly mounted on the cab 2, and can be equipped with a mechanism (not shown) allowing the camera assembly 13 to be:

- either in a parking position, when not in use (typically when the vehicle 1 is stopped), in which the camera assembly 13 is folded against the cab side wall 4 to prevent damages;

- or in a use position, in which the camera assembly 13 is protruding from the cab side wall 4, to allow the cameras C1, C2 to capture images (figures 1 and 2).

Such a camera assembly 13 can typically be part of a so-called camera monitoring system (CMS) 20 which can further include a monitor 21 inside the driver’s compartment 3 for displaying an image based on the two captured images 41 , 42 provided by the camera 13. The image can include the targets T1, T2 and the value of the trailer length. Thus, the vehicle 1 according to the invention can be devoid of side exterior mirrors, and possibly also devoid of an interior mirror. The camera monitoring system 20 also includes a controller 22. The controller 22 can be connected to the ECU 12.

Moreover, the vehicle 1 comprises a trailer 30 which can be mechanically and electrically connected to the cab 2, as shown in figure 1. The trailer 30 has side walls 31 , a top wall 32 and a rear wall 33. The trailer 30 further has rear wheels 34.

The vehicle 1 also can also comprise a vehicle CAN bus 23. This network 23 includes electrical wiring 24 of the vehicle 1 configured to establish electric connection and communication between the cab 2, the trailer 30 and various vehicle components. The bundle 24 of cables can typically be linked to the ECU 12. Alternatively or in addition, the value of the trailer length can directly transmitted to the vehicle internal communication network 23 for the driver assistance system.

According to the invention, the vehicle 1 can comprise a system 25 for adapting an image displayed on the monitor 21, based on the captured images 41, 42.

The cab 2 may further comprise a steering wheel 26 which commands the front and optionally the rear wheels. The steering wheel has a steering wheel angle b below or equal to 10°, preferably below or equal to 5° and more preferably above or equal to 0°. When the steering wheel angle is equal to 0°, the cab 2 and the trailer 30 are aligned. The system 25 comprises at the least two cameras C1 , C2 located on each side of the cab for determining the position of two targets T1 , T2 being located on each side of the back of the trailer. As shown in Figure 3, two cameras C1 , C2 capture two images of the area located rearwards and along each vehicle side. The cameras detect the targets T 1 , T2 and determine the position of these targets.

The controller 22, which is part of the system 25, is capable of receiving the targets T 1 , T2 position data from the camera assembly 13, in particular the targets T1, T2 position detecting in the two images captured by the two cameras C1, C2.

As shown in Figure 3, according to the targets position T1, T2 determined by the camera assembly 13 and the corresponding information provided to the controller 22, the controller 22 automatically processes the trailer length of the vehicle with the following formula (1):

Wherein L is the length of the trailer in meter,

W1 is the width in meter between the at least two cameras (C1, C2), i.e. the width including the at least two cameras (C1, C2) and the cab, W2 is the width in pixel of the at least two cameras (C1 , C2), a is the angle of the field of vision of the at least two cameras (C1 , C2),

W3 is the width in meter of the cab, i.e. the width only including the cab.

For that purpose, and because the camera 13 is preferably fixed relative to the cab 2, in the use position, the first captured image 41 corresponds to a first field of vision F1 of the camera 13 as illustrated in figure 3 in dotted lines, while the second image 42 corresponds to a second field of vision F2 of the camera 13 as illustrated in figure 3 in solid lines. The captured images 41 , 42 may respectively correspond to a field of vision F1 , F2 of a camera C1, C2 wherein a is between 1 and 179°, preferably between 20 and 160°, more preferably between 30 and 100° and for example between 30 and 50°.

With the method and the system according to the present invention, the length of a trailer is effectively determined for the driver and for the driver assistance system.

Although the invention has been described for a trailer truck, the invention can also be implemented to a straight truck.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

1. A method for determining a trailer length (L) of a vehicle (1) comprising a cab (2) and a trailer (30), the vehicle comprising a camera assembly (13) comprising at least two cameras (C1, C2), each camera (C1, C2) being located on each side of the cab (2), characterized in that the method comprises the following steps:

A) Determining the position of two targets (T1, T2) being located on each side of the back of the trailer (30) using at the least two cameras (C1, C2) capturing at least two images (41, 42) of an area located rearwards and along each vehicle side,

Wherein L is the length of the trailer in meter,

W1 is the width in meter between the at least two cameras (C1, C2), i.e. the width including the at least two cameras (C1, C2) and the cab, W2 is the width in pixel of the at least two cameras (C1, C2), a is the angle of the field of vision of the at least two cameras (C1 , C2),

W3 is the width in meter of the cab, i.e. the width only including the cab.

2. The method according to claim 1, characterized in that the at least two cameras (C1, C2) are stereoscopic cameras.

3. The method according to claim 1 or 2, characterized in that the targets (T1, T2) are equidistant.

4. The method according to anyone of claims 1 to 3, characterized in that the targets (T 1 , T2) are rear side markers lamps on the trailer, rear wall corners of the trailer, or a vertical edge located at the rear of the trailer.

5. The method according to claim 4, characterized in that when the targets (T1, T2) are the rear side markets lamps, flickering commands are sent to the rear side markets lamps to facilitate the detection of the targets (T 1 , T2) by the at least two cameras (C1 , C2).

6. The method according to anyone of claims 1 to 5, characterized in that steps A) and B) are performed while the vehicle (1) is moving forward or backward.

7. The method according to anyone of claims 1 to 6, characterized in that the cab (2) comprises a steering wheel (26) having a steering wheel angle (b) below or equal to 10

8. The method according to anyone of claims 1 to 7, characterized in that the method further comprises transmitting at least two captured images data provided by said at least two cameras (C1 , C2) through a vehicle internal communication network (23).

9. The method according to any one of claims 1 to 8, characterized in that the camera assembly (13) comprising two supporting arms (14) mounted on each side of the vehicle, said at least two cameras (C1, C2) being respectively arranged on each supporting arm (14).

10. A system for determining a trailer length (L) of a vehicle (1) comprising a cab (2) and a trailer (30), the vehicle comprising a camera assembly (13) comprising at least two cameras (C1, C2), each camera (C1, C2) being located on each side of the cab (2), characterized in that the system (25) comprises:

- at least two cameras (C1 , C2) located on each side of the cab (2);

- a controller (22) capable of receiving the target positions information from the at least two cameras (C1, C2), and of processing the trailer length (L) of the vehicle, using the position of the targets (T1, T2) detected in at least two captured images (41, 42), with the following formula (1):

W3 is the width in meter of the cab, i.e. the width only including the cab.

11. The system according to claim 10, characterized in that the system (25) further comprises a vehicle internal communication network (23) which links at least two cameras (C1 , C2) and the controller (22).

12. A vehicle (1) comprising:

- a cab (2) having front wheels (10) and rear wheels (11);

- a camera assembly (13) comprising at least two cameras (C1, C2), each camera (C1, C2) being located on each side of the cab (2), for providing at least two captured images (41, 42) of an area located rearwards and along each vehicle side;

- a vehicle internal communication network (23); characterized in that it further comprises a system (25) according to any one of claims 10 to 11 , wherein the at least two cameras (C1 , C2) and the controller (22) are linked by the vehicle internal communication network (23).

13. The vehicle according to claim 12, characterized in that the camera (13) is fixed relative to the cab (2), in the use position.

14. The vehicle according to claim 12 or claim 13, characterized in that each captured image (41, 42) corresponds respectively to a field of vision (F1, F2) of a camera (C1, C2) having an angle a between 1 and 179°.

15. The vehicle according to any one of claims 12 to 14, characterized in that the controller (22) is part of a camera monitoring system (20) including the camera assembly