Patent Publication Number: US-2018040129-A1

Title: Trailer articulation calculating system and method for calculating articulation angle of trailer

Description:
FIELD 
     The present disclosure relates to a trailer articulation calculating system and a method for calculating an articulation angle of a trailer. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     The trucking industry has utilized a plurality of tractors and trailers in combinations according to transporting plans. There are variety of types of trailers in their sizes and usages, and even each trailer changes its weight, its destination, and so on, depending on loads in the trailer. Such information may be shared with surrounding vehicles through, e.g., a DSRC network. 
     An articulating vehicle such as a tractor-trailer dynamically changes its articulation when right/left-turning, curving, lane-changing, or the like. Therefore, for DSRC communications, an articulation angle of an articulating vehicle would be necessarily detected on a real-time basis to obtain complete dimensional information. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. The present disclosure provides a trailer articulation calculating system. 
     The system includes a fiducial object, a camera, and an articulation calculator. The fiducial object is disposed in a front side of a trailer. The camera is disposed in a rear side of a tractor. The camera captures image data of the fiducial object. The articulation calculator calculates an articulation angle of the trailer relative to the tractor based on the image data captured by the camera. 
     The present disclosure further provides a method for calculating an articulation angle of a trailer. The method includes capturing, by camera, image data of a fiducial object disposed in a front side of the trailer, and calculating the articulation angle based on the image data. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a high level system diagram of a trailer articulation calculating system according to a first embodiment; 
         FIG. 2  is a top view of a tractor and a trailer that is in a default orientation; 
         FIG. 3  is a top view of the tractor and the trailer that is rotated relative to the tractor; 
         FIG. 4  is a side view of the tractor and the trailer that is connected to the tractor; 
         FIG. 5  is a block diagram of an angle calculation unit; 
         FIG. 6  is a side view of the tractor and the trailer when the tractor is being connected to the trailer; 
         FIG. 7  is a flowchart for an assist control by a microprocessor; 
         FIG. 8  is a flowchart for an articulation calculation control by the microprocessor; 
         FIG. 9  is a top view of a tractor and a trailer that is in a default orientation according to a third embodiment; and 
         FIG. 10  is a top view of the tractor and the trailer that is rotated relative to the tractor according to the third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A plurality of embodiments of the present disclosure will be described hereinafter referring to drawings. In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts may be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments may be combined, provided there is no harm in the combination. 
     First Embodiment 
       FIG. 1  depicts a high level system diagram of a trailer articulation calculating system  10  and a method for calculating an articulation angle θ of a trailer according to the present embodiment.  FIG. 1  shows a tractor  12  is towing a trailer  14  and is entering into a main road at a T junction by turning left. The trailer  14  has loads (not shown) loaded therein. The trailer articulation calculating system  10  dynamically calculates and outputs an articulation angle θ of the trailer  14  relative to the tractor  12  on a real-time basis, as will be described below. 
     The trailer articulation calculating system  10  generally includes a two-dimensional (2D) barcode  16  as a fiducial object, a camera  18 , and a microprocessor  20  as an articulation calculator and a distance calculator. 
     The trailer  14  has a rectangular parallelepiped shape and is connected to the tractor  12  through a kingpin  50 . It is understood that the trailer connection is not strictly limited to a kingpin  50 , and it could be a heavy-duty hitch as well. For example on a dual tandem trailer rig, the  s second trailer is pulled by the first trailer by a hitch. The trailer  14  is rotatable relative to the tractor  12  about the kingpin  50  as shown in  FIGS. 2 and 3 . The two-dimensional barcode  16  such as a QR code (a registered trademark) is attached to a front surface (front side) of the trailer  14  such that the two-dimensional barcode  16  can be scanned on the front surface. As shown in  FIGS. 2 and 4 , the two-dimensional barcode  16  is positioned around the center of the front surface of the trailer  14 . More detail, the two-dimensional barcode  16  is at the center of both the width and the height of the trailer  14 . However, the position of the two-dimensional barcode  16  is not limited to the center of the surface of the trailer  14 . For example, the two-dimensional barcode  16  may be positioned at a very lower side of the surface of the trailer  14 . 
     The two-dimensional barcode  16  stores (i.e., encodes) identification data associated with the trailer  14  and the loads in the trailer  14 . The identification data includes, for example, an ID number of the trailer  14 , information of the loads, gross weight of the trailer  14  including the loads, a dimension of the trailer  14  (i.e., width, length, and height of the trailer  14 ), a destination of the trailer  14 , a VIN (Vehicle Identification Number), a manufacturer of the trailer  14 , a model of the trailer  14 , an owner serialization, and other unique identifying information as to the trailer  14  or the loads. In the present embodiment, the identification data further includes a default size of the two-dimensional barcode  16 . The default size is defined as a size (or a shape) of the two-dimensional barcode  16 . 
     The camera  18  is a vehicle mounted camera and is disposed in a rear side of the tractor  12  to face backward. The camera  18  serves as a barcode reader to scan the two-dimensional barcode  16 . The camera  18  also serves as a digital camera to capture image data of the two-dimensional barcode  16 . The camera  18  is positioned on the rear side of the tractor  12  such that the camera  18  faces (i.e., aligned with) the two-dimensional barcode  16  when the trailer  14  is not angled relative to the tractor  12  (see  FIG. 2 ). In other words, when the trailer  14  is not angled relative to the tractor  12 , the position of the camera  18  in a vertical direction in gravity (see  FIG. 4 ) and a lateral direction along the width of the trailer  14  (see  FIG. 2 ) is substantially the same as the two-dimensional barcode  16 . 
     Here, an imaginary referential plane RP is defined as an imaginary plane on which the camera  18  and the kingpin  50  are positioned. When the trailer  14  is not angled relative to the trailer  12 , the two-dimensional barcode  16  is also positioned on the imaginary referential plane RP as shown in  FIG. 2 . That is, when the trailer  14  is not rotated, the camera  18 , the two-dimensional barcode  16 , and the kingpin  50  are aligned with each other along a straight line. An imaginary trailer plane TP is defined as an imaginary plane on which the kingpin  50  and the two-dimensional barcode  16  are positioned (see  FIG. 3 ). In this disclosure, an articulation angle θ is defined as an angle between the imaginary referential plane RP and the imaginary trailer plane TP. It should be understood that the imaginary referential plane RP and the imaginary trailer plane TP are overlapped each other (i.e., the articulation angle θ is zero) when the trailer  14  is not angled relative to the tractor  12 . Hereinafter, the orientation of the trailer  14  where the trailer  14  is not angled relative to the tractor  12  is referred to as a “default orientation”. 
     When the trailer  14  is angled relative to the tractor  12 , a minimum distance between the two-dimensional barcode  16  and an axis X (see  FIG. 4 ) of the kingpin  50  is defined as a referential distance RD. In the present embodiment, the information of the referential distance RD is stored (i.e., encoded) in the two-dimensional barcode  16  as the identification data of the trailer  14 . 
     The camera  18  is configured to automatically scan and capture the two-dimensional barcode  16  when the two-dimensional barcode  16  comes into a specified readable range of the camera  18 . The camera  18  is connected to an angle calculation unit  24  in the tractor  12 , more specifically connected to the microprocessor  20  in the angle calculation unit  24 , through Ethernet, for example. The camera  18  transmits the image data and the identification data retrieved from the two-dimensional barcode  16  to the microprocessor  20  though the Ethernet. 
     The angle calculation unit  24  is configured to form a V2X (Vehicle-to-everything) subsystem for the trailer articulation calculating system  10 . As shown in  FIG. 5 , the angle calculation unit  24  includes the microprocessor  20 , a DSRC (Dedicated Short-Range Communications) transceiver, a memory  30 , and, a CAN (Controller Area Network) bus  32 . The microprocessor  20  is connected to all other components  28 ,  30 ,  32  in the angle calculation unit  24 . 
     The DSRC transceiver  28  is configured to wirelessly communicate with surrounding vehicles  26  through DSRC network such as DSRC RSEs (Road Side Equipment)  36 . The DSRC transceiver  28  receives information, such as traffic information, safety warnings, identity information of the surrounding vehicles  26 , or the like. The DSRC transceiver  28  is also connected to the microprocessor  20 . The DSRC transceiver  28  receives information including the identity information and the articulation angle θ calculated by the microprocessor  20  and transmits such information to surrounding vehicles  26  through the DSRC network (the DSRC RSE  36 ). Although, in this present embodiment, the communication between the tractor  12  and the surrounding vehicles  26  are conducted through the DSRC network, the communication may be performed through other a V2X network system. 
     The memory  30  is a form of computer data storage and includes a ROM and a RAM. The memory  30  stores programs executed by the microprocessor  20 . Furthermore, the memory  30  tentatively stores the default size of the two-dimensional barcode  16  and the referential distance RD retrieved by the camera  18 . 
     The CAN bus  32  is connected to both an electronic control unit (ECU, not illustrated) for controlling an engine of the tractor  12  and the microprocessor  20 . The ECU and the microprocessor  20  are allowed to communicate with each other through the CAN bus  32 . The ECU sends operating condition of the engine to the microprocessor  20 , whereas the microprocessor  20  sends controlling signals to the ECU. The CAN bus  32  is also connected to a display controller that controls a display (not shown) in an interior of the tractor  12 . 
     In the present embodiment, the microprocessor  20  provides an assist control to assist a driver of the tractor  12  when connecting the tractor  12  to the trailer  14  and an articulation calculation control to calculate the articulation angle θ of the trailer  14 . The microprocessor  20  performs these controls by executing the programs stored in the memory  30 , as will be described below. In addition, the microprocessor  20  also controls operation of the engine according to traffic conditions and operational information of the surrounding vehicles  26  obtained from the DSRC transceiver  28 . The microprocessor  20  generates and sends controlling signals to the ECU through the CAN bus  32  to control the engine of the tractor  12 . 
     The microprocessor  20  is programmed to execute the assist control when a driver is connecting the tractor  12  to the trailer  14  (see  FIG. 6 ). The microprocessor  20  assists the driver by displaying the distance to the trailer  14  from the tractor  12  (i.e., the camera  18 ) on the display. The microprocessor  20  calculates the distance to the trailer  14  based on the image data captured by the camera  18 . More specifically, the microprocessor  20  obtains a current size of the two-dimensional barcode  16  based on the image data currently captured by the camera  18 . Then the microprocessor  20  calculates the distance to the trailer  14  by comparing the current size of the two-dimensional barcode  16  to the default size stored in the memory  30 . The microprocessor  20  outputs the distance to the trailer  14  to the display controller, and then the display controller controls the display to notify the driver of the distance to the trailer  14 . 
     The microprocessor  20  performs the articulation calculation control when the tractor  12  is in operation. The microprocessor  20  calculates the articulation angle θ of the trailer  14  based on the image data of the two-dimensional barcode  16  captured by the camera  18 . More specifically, the microprocessor  20  obtains a deviation D of the two-dimensional barcode  16  from the image data. The deviation D is defined as a minimum distance between the two-dimensional barcode  16  and the imaginary referential plane RP as shown in  FIG. 3 . Then the microprocessor  20  calculates the articulation angle θ based on the deviation D currently obtained and the referential distance RD using, e.g., a trigonometric function. The microprocessor  20  outputs the articulation angle θ to the DSRC transceiver  28  and then the articulation angle θ is sent to the surrounding vehicles  26  from the DSRC transceiver  28  through the DSRC network. 
     Next, operation of the trailer articulation calculating system  10  and the method for the articulation angle θ will be described below. When connecting the tractor  12  to the trailer  14 , the system  10  executes the assist control according to the flowchart of  FIG. 7 . When the microprocessor  20  detects driver&#39;s intention to connect the tractor  12  to the trailer  14  (by detecting, e.g., a reverse gear signal), the camera  18  starts scanning for the two-dimensional barcode  16  at Step  10 . When the two-dimensional barcode  16  comes into a readable range (Step  12 : Yes), the camera  18  automatically reads the two-dimensional barcode  16  and retrieves the identification data of the trailer  14  including the default size of the two-dimensional barcode  16  and the referential distance RD (Step  14 ). The default size and the referential distance RD are stored in the memory  30  through the CAN bus  32 . 
     Next, the microprocessor  20  obtains the current size of the two-dimensional barcode  16  from the image data currently captured by the camera  18  at Step  16 . Then, the microprocessor  20  calculates the distance to the trailer  14  by comparing the current size of the two-dimensional barcode  16  to the default size stored in the memory  30  at Step  18 . Next, the microprocessor  20  outputs the distance to the display through the CAN bus  32 , and then the driver is informed of the distance to the trailer  14  on the display. 
     The processes of Steps  16  to  20  are repeated until the tractor  12  is connected to the trailer  14 . When the tractor  12  is connected to the trailer  14  (Step  22 : YES), the microprocessor  20  terminates the assist control. As described above, since the driver is notified of the distance to the trailer  14 , the driver can safely connect the tractor  12  to the trailer  14 . 
     During operation of the tractor  12  towing the trailer  14 , the microprocessor  20  executes the articulation calculation control according to the flowchart of  FIG. 8 . It should be noted that the referential distance RD has been already retrieved and stored in the memory  30  at Step  14  of  FIG. 7 . When the tractor  12  is in operation, the camera  18  captures the image data of the two-dimensional barcode  16  as Step  30 . Then, the microprocessor  20  calculates the deviation D of the two-dimensional barcode  16  at Step based on the image data captured at Step  30 . Next, the microprocessor  20  calculates the articulation angle θ based on the deviation D with the referential distance RD stored in the memory  30  at Step  34 . Then, the microcomputer outputs the articulation angle θ of the trailer  14  to the DSRC network (the DSRC RSE  36 ) through the DSRC transceiver  28  at Step  36 . The articulation angle θ output from the tractor  12  is shared with surrounding vehicles  26 . In this way, the calculation of the articulation angle θ according to Steps  30  to  36  is repeated while the tractor  12  is in operation. When the tractor  12  stops operation (Step  38 : NO), the microprocessor  20  terminates the articulation calculation control. 
     As described above, the system  10  can dynamically calculate and output the articulation angle θ of the trailer  14 . Therefore, the surrounding vehicles  26  can obtain the articulation angle θ of the trailer  14  relative to the tractor  12  on a real-time basis. Thus, even if the tractor  12  is turning at a T junction as described in  FIG. 1 , the surrounding vehicles  26  can obtain information of complete dimensional data of the tractor-trailer. 
     Second Embodiment 
     In the first embodiment, the microprocessor  20  calculates the articulation angle θ based on the deviation D of the two-dimensional barcode  16 . Alternatively, the microprocessor  20  may calculate the articulation angle θ based on other elements relating to the two-dimensional barcode  16 . For example, the microprocessor  20  may calculate the articulation angle θ based on an aspect ratio of the two-dimensional barcode  16 . The aspect ratio of the two-dimensional barcode  16  viewed from the camera  18  varies as the trailer  14  rotates relative to the tractor  12 . Therefore, the articulation angle θ can be calculated based on the change in the aspect ratio of the two-dimensional barcode  16 . 
     For example, the two-dimensional barcode  16  may encode a default aspect ratio of the trailer  14 . The default aspect ratio is an aspect ratio determined based on the default size of the two-dimensional barcode  16 . The default aspect ratio is retrieved by the camera, and then is stored in the memory  30 . During operation of the tractor  12 , the microprocessor  20  obtains an aspect ratio (hereinafter referred to as a “current aspect ratio”) of the two-dimensional barcode  16  from the image data currently captured by the camera  18 . Then, the microprocessor  20  calculates the articulation angle θ by comparing the current aspect ratio to the default aspect ratio stored in the memory  30 . For example, the microprocessor  20  may calculate the articulation angle θ using a map representing a relationship between the default aspect ratio and the current aspect ratio. Such a map may be prepared in advance through experimentations. Alternatively, the articulation angle θ may be calculated using an equation with the current aspect ratio and the default aspect ratio. 
     Third Embodiment 
     In the first and second embodiments, the microprocessor  20  calculates the articulation angle θ based on information relating to the two-dimensional barcode  16 . In the third embodiment, two rivets  52  among a plurality of rivets  52  disposed in the front surface of the trailer  14  are used as the fiducial object (two fiducial elements). The two rivets  52  are positioned at the same level in height of the trailer  14 . In the present embodiment, the distance of the two rivets  52  viewed from the camera  18  when the trailer  14  is in the default orientation is defined as a default space distance DSD (see  FIG. 9 ). As shown in the  FIG. 10 , when the trailer  14  rotates relative to the tractor  12 , a distance between the two rivets  52  viewed from the camera  18  (hereinafter referred to as a “space distance SD”) is shorter than the default space distance DSD. In other words, the space distance SD between the two rivets  52  viewed from the camera  18  varies as the trailer  14  rotates relative to the tractor  12 . Hence, in the third embodiment, the microprocessor  20  calculates the articulation angle θ based the change in the space distance SD between the two rivets  52 . 
     For example, the two-dimensional barcode  16  encodes the default space distance DSD of the two rivets  52 . The default space distance DSD is retrieved by the camera  18  when the trailer  14  is connected to the tractor  12 , and then is stored in the memory  30 . During operation of the tractor  12 , the microprocessor  20  obtains the space distance SD of the two rivets  52  from the image data captured by the camera  18 . Then, the microprocessor  20  calculates the articulation angle θ by comparing the space distance SD currently obtained to the default space distance DSD stored in the memory  30 . For example, the microprocessor  20  may calculate the articulation angle θ using a map representing a relationship between the space distance SD and the default space distance DSD. Such a map is prepared in advance through experimentations. Alternatively, the articulation angle θ may be calculated using an equation with the space distance SD and the default space distance DSD. It should be understood that two brackets disposed in the front surface of the trailer  14  may be used as the fiducial object (the fiducial elements) in place of the rivets  52 . 
     Other Embodiments 
     In the first embodiment, the microprocessor  20  executes the assist control and the articulation calculation control. In other words, the microprocessor  20  serves as an articulation calculator and a distance calculator. However, the microprocessor  20  only executes the articulation calculation control and the assist control may be eliminated. 
     In the first embodiment, the two-dimensional barcode  16  is used as the fiducial object in addition to a function as a barcode to store information of the trailer  14 . However, another configuration may be applied to the fiducial object other than the two-dimensional barcode. For example, an additional component may be disposed to the front side of the trailer  14  as the fiducial object without using the two-dimensional barcode  16 . 
     In the first embodiment, the assist control provides showing of the distance to the trailer  14  to a driver. In addition, the assist control may provide left-right alignment and/or angular alignment information to the driver during trailer connection. For example, alignment information while backing the tractor  12  toward the trailer may be displayed to the driver  14  in addition to distance information. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
     Example embodiments are provided so that this disclosure will be thorough, and will convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.