Abstract:
A dump truck having a periphery monitoring apparatus is adapted to display an image of surroundings of the dump truck on a display apparatus. A rearward camera is attached to a vehicle body of the dump truck underneath a vessel of the dump truck and positioned forward of a rear edge portion of the vessel. A rearward camera image captured by the rearward camera includes the rear edge portion of the vessel, an area below the vessel, and an area rearward of the vehicle body. A display control section is configured to display the rear edge portion of the vessel in an upper region of the rearward camera image, to display a ground surface below the vessel in a lower region of the rearward camera image, and to display a vehicle body outer edge line obtained by vertically projecting an outer edge of the vessel onto the ground surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a division of U.S. patent application Ser. No. 13/818,323 filed on Feb. 22, 2013, which is a U.S. National phase application of International Application No. PCT/JP2012/063255, filed on May 24, 2012, which claims priority to Japanese Patent Application No. 2011-127478 filed on Jun. 7, 2011. The disclosures U.S. patent application Ser. No. 13/818,323 and Japanese Patent Application No. 2011-127478 are hereby incorporated herein by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a dump truck, and in particular, to a dump truck having a periphery monitoring apparatus which displays a camera image of the surroundings of the large dump truck on a display apparatus. 
       BACKGROUND ART 
       [0003]    Extra-large dump trucks are used for carrying crushed rock at a mine or the like are known. In dump trucks of this type, it is difficult for a driver to grasp the circumstances in the surroundings using side mirrors and the like since the vehicle width is remarkably wide in comparison with a typical truck or the like, and in addition, the length from the front to back is long. 
         [0004]    Therefore, in Hitachi Construction Machinery Co., Ltd. press release “Joint Development of ‘Overview Monitor System’ with Clarion Co., Ltd.”, (online), Jan. 24, 2011, (retrieved on Jun. 1, 2011), link &lt;URL: http://www.hitachi-kenki.co.jp/news/press/PR20110121113934973.html&gt;, a periphery monitoring apparatus is proposed where bird&#39;s-eye images for the front, left, and right of the work vehicle and a camera image of the rear of the work vehicle are displayed on a display apparatus with an object of a driver simply grasping the circumstances in the periphery. Specifically, the periphery monitoring apparatus of the above-noted Hitachi Construction Machinery Co., Ltd. press release is provided with three cameras which video the front, left, and right of the work vehicle and one rear camera which videos the rear of the work vehicle. The rear camera is disposed below the vehicle body which has a vessel and the ground surface at the rear of the work vehicle appears in the camera image. 
       SUMMARY 
       [0005]    However, in the camera image of the above-noted Hitachi Construction Machinery Co., Ltd. press release, grasping of the positional relationship of the vehicle body and objects in the periphery of the vehicle body (for example, a person, a vehicle, a building, or the like) is not easy since the vehicle body exists upward of the rear camera. That is, it is difficult to determine using the camera image if a person has entered the space below the vehicle body, to what extent that the vehicle body has approached a building, or the like. 
         [0006]    The present invention has been carried out in consideration of the circumstances described above and has an object of providing a dump truck having a periphery monitoring apparatus where it is possible to easily grasp the positional relationship of the vehicle body and objects in the periphery of the vehicle body using a camera image. 
         [0007]    A dump truck includes a vehicle body, a vessel movably connected to the vehicle body and a periphery monitoring apparatus. The periphery monitoring apparatus is adapted to display an image of the surroundings of the dump truck on a display apparatus. The periphery monitoring apparatus includes a plurality of cameras configured and arranged to capture camera images of the surroundings of the dump truck and a display control section. The plurality of cameras includes a rearward camera that is attached to a vehicle body of the dump truck so as to be disposed underneath a vessel of the dump truck and positioned forward of a rear edge portion of the vessel. The rearward camera is configured and arranged such that a rearward camera image captured by the rearward camera includes the rear edge portion of the vessel, an area below the vessel, and an area rearward of the vehicle body. The display control section is configured to display the rear edge portion of the vessel in an upper region of the rearward camera image, to display a ground surface below the vessel in a lower region of the rearward camera image, and to display a vehicle body outer edge line obtained by vertically projecting an outer edge of the vessel onto the ground surface. 
         [0008]    According to dump truck having the periphery monitoring apparatus of the first aspect, it is possible for the driver to easily grasp the positional relationship of the vehicle body which is positioned above the camera and objects in the periphery of the vehicle body (for example, a person, a vehicle, a building, or the like) with the vehicle body outer edge line as a reference. As a result, it is possible to easily determine using the camera image, for example, if a person has entered the space below the vehicle body, to what extent that the vehicle body has approached a building, or the like. As a result, it is possible for the driver to simply grasp the circumstances in the periphery of the work vehicle. 
         [0009]    A dump truck of a second aspect is related to the first aspect such that the display control section is further configured to display a bird&#39;s eye image of the surroundings of the dump truck based on the camera images captured by the plurality of cameras, and to display a selected one of the camera images adjacent to the bird&#39;s eye image. 
         [0010]    A dump truck of a third aspect is related to the first aspect such that a horizon line is captured in the rearward camera image. The rear edge portion of the vessel is displayed above the horizon line in the rearward camera image, and the vehicle body outer edge line is displayed below the horizon line in the rearward camera image 
         [0011]    A dump truck of a fourth aspect is related to the first aspect such that a trapezoidal shape is displayed on the rearward camera image. The trapezoidal shape is formed by the vehicle body outer edge line, a pair of reference lines indicating a vehicle width, and a warning line spaced from the vehicle body outer edge line by a prescribed distance in an outward direction. 
         [0012]    A dump truck of a fifth aspect is related to the first aspect such that the vehicle body outer edge line is spaced from the rear edge portion of the vessel in the rearward camera image. 
         [0013]    According to the present invention, it is possible to provide a dump truck having a periphery monitoring apparatus where it is possible to easily determine the positional relationship of the vehicle body and objects in the periphery of the vehicle body using a camera image. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]    The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
           [0015]      FIG. 1  is a perspective diagram illustrating an overall configuration of a dump truck. 
           [0016]      FIG. 2  is a block diagram illustrating a configuration of a periphery monitoring apparatus. 
           [0017]      FIG. 3  is a planar diagram of a dump truck which illustrates mounting positions of six cameras and two-dimensional videoing ranges. 
           [0018]      FIG. 4  is a perspective diagram of a dump truck which illustrates three-dimensional imaging ranges using six cameras. 
           [0019]      FIG. 5  is a perspective diagram illustrating an attachment state of six cameras. 
           [0020]      FIG. 6  is a schematic diagram illustrating a configuration of a monitor. 
           [0021]      FIG. 7  is a schematic diagram illustrating a configuration of a monitor. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0022]    Below, an embodiment of the present invention will be described by referencing the diagrams. Here, in the description below, “front, back, left, and right” are terms with an operator who is sitting in a driver&#39;s seat as a reference, and “vehicle width direction” has the same meaning as “left and right direction”. 
       Overall Configuration of Dump Truck 
       [0023]      FIG. 1  is a perspective diagram illustrating an overall configuration of a dump truck  1  which is provided with a periphery monitoring apparatus according to an embodiment of the present invention. The dump truck  1  is a self-propulsion type of extra-large work vehicle which is used in mining operations and the like. 
         [0024]    The dump truck  1  is mainly provided with a vehicle body frame  2 , a cab  3 , a vessel  4 , two front wheels  5 , two rear wheels  6 , and a base  7 . In addition, the dump truck  1  is provided with a periphery monitoring apparatus  10  which displays an image of the surroundings of the vehicle on a monitor. The configuration of the periphery monitoring apparatus  10  will be described later. 
         [0025]    The vehicle body frame  2  supports a diesel engine, a driving mechanism such as a transmission unit, other auxiliary units, and the like which are not shown. In addition, the front wheels  5  (only the right front wheel is shown in the diagram in  FIG. 1 ) are supported in the left and right of the front portion of the vehicle body frame  2 , and the rear wheels  6  (only the right rear wheel is shown in the diagram in  FIG. 1 ) are supported in the left and right of the rear portion of the vehicle body frame  2 . The vehicle body frame  2  has a lower deck  2 A at a side which is close to the ground surface and has an upper deck  2 B above the lower deck  2 A. Two movable ladders  2 C are provided between the lower deck  2 A and the ground surface and a sloping ladder  2 D is provided between the lower deck  2 A and the upper deck  2 B. Hand rails with a palisade shape are fixed in the left and right of the front portion, the side portion, and a portion of the back portion on the upper deck  2 B. 
         [0026]    The cab  3  is disposed to be lateralized towards the left side from the center in the vehicle width direction above the upper deck  2 B. A driver&#39;s seat, a shift lever, a controller, a monitor, a handle, an acceleration pedal, a brake pedal, and the like are provided in the cab  3 . As will be described later, the controller, the monitor, and the shift level configure a portion of the periphery monitoring apparatus  10 . 
         [0027]    The vessel  4  is a container for hauling heavy materials such as crushed rocks. A bottom portion at the rear side of the vessel  4  is connected to a rear edge portion of the vehicle body frame  2  so as to be able to rotate via a rotation pin (which is not shown). Due to this, it is possible for the vessel  4  to take an erect posture, where loading materials are discharged by the front portion being rotated upward using an actuator such as a hydraulic cylinder which is not shown, and a hauling posture where the front portion is position at an upper portion of the cab as shown in  FIG. 1 . 
         [0028]    The base  7  is disposed above the upper deck  2 B. The base  7  is a power supply apparatus for positioning a pantograph which receives electrical power from a bird&#39;s-eye wire such as a trolley. 
         [0029]    Here, the vehicle body frame  2  and the vessel  4  configure the “vehicle body” of the dump truck  1  in the embodiment. 
       Configuration of Periphery Monitoring Apparatus 
       [0030]      FIG. 2  is a block diagram illustrating a configuration of the periphery monitoring apparatus  10  which is provided in the dump truck  1 . 
         [0031]    The periphery monitoring apparatus  10  has six cameras  11  to  16 , six frame memories  11 A to  16 A, an operator switch  20 , a monitor  30 , and a display control section  40 . 
       Cameras 
       [0032]      FIG. 3  is a planar diagram of the dump truck  1  which illustrates mounting positions of the six cameras  11  to  16  and two-dimensional videoing ranges.  FIG. 4  is a perspective diagram of the dump truck  1  which illustrates three-dimensional imaging ranges using the six cameras  11  to  16 .  FIG. 5  is a perspective diagram illustrating an attachment state of the six cameras  11  to  16 . The six cameras  11  to  16  are mounted on the outside of the dump truck  1  and acquire images of the surroundings of the dump truck  1 . 
         [0033]    A first camera  11  is disposed at an upper edge portion of the sloping ladder  2 D and is fixed toward the front of the vehicle. A first videoing range  11 R of the first camera  11  is the front of the vehicle. 
         [0034]    A second camera  12  is disposed at a right edge portion on a front side surface of the upper deck  2 B and is fixed toward the front right diagonal of the vehicle. A second videoing range  12 R of the second camera  12  is the front right diagonal of the vehicle. 
         [0035]    A third camera  13  is disposed at a position which is left and right symmetrical with the second camera  12 , that is, a left edge portion on a front side surface of the upper deck  2 B and is fixed toward the front left diagonal of the vehicle. A third videoing range  13 R of the third camera  13  is the front left diagonal. 
         [0036]    A fourth camera  14  is disposed at a front edge portion on a right side surface of the upper deck  2 B and is fixed toward the rear right diagonal of the vehicle. A fourth videoing range  14 R of the fourth camera  14  is the rear right diagonal. 
         [0037]    A fifth camera  15  is disposed at a position which is left and right symmetrical with the fourth camera  14 , that is, a front edge portion on a left side of the upper deck  2 B and is fixed toward the rear left diagonal of the vehicle. A fifth videoing range  15 R of the fifth camera  15  is the rear left diagonal. 
         [0038]    A sixth camera  16  is disposed to be beneath the vessel  4  as shown in  FIG. 5  and is fixed toward the rear of the vehicle. Specifically, the sixth camera  16  is fixed by a bracket  9   a  which is attached to a cross bar  9  above a rear axel  8 . The sixth camera  16  is fixed diagonally downward toward the rear and a sixth imaging range  16 R of the sixth camera  16  is the rear of the vehicle below the vessel  4 . Here, in the embodiment, the vehicle body itself (the rear edge portion of the vessel  4 ) is included in the sixth imaging range  16 R of the sixth camera  16  (refer to  FIG. 6 ) which is different to the imaging range images of the other cameras. 
         [0039]    Images of substantially the entire surroundings of the dump truck  1  are acquired using the six cameras  11  to  16  above. Each of the six cameras  11  to  16  respectively transmit camera image data, which indicates the camera image which is videoed by the apparatus itself, to the frame memories  11 A to  16 A. 
       Frame Memories 
       [0040]    The six frame memories  11 A to  16 A are connected to the six cameras  11  to  16 . The six frame memories  11 A to  16 A temporarily store the camera image data which is received from the six cameras  11  to  16 . The six frame memories  11 A to  16 A transmit the camera image data which has been stored to the display control section  40 . 
       Operator Switch 
       [0041]    The operator switch  20  is an operating member for specifying the camera image, which is to be displayed on the monitor  30 , out of the camera images from each of the six cameras  11  to  16 . It is possible for a desired camera image to the displayed on the monitor  30  by the driver operating the operator switch  20 . The operator switch  20  notifies the display control section  40  whether any of the camera images has been selected. 
       Monitor 
       [0042]      FIG. 6  and  FIG. 7  are schematic diagrams illustrating a configuration of the monitor  30 . 
         [0043]    The monitor  30  is disposed in front of the driver&#39;s seat in the cab  3 . The monitor  30  has a display region  30   a  which displays the camera image as shown in  FIG. 6  and  FIG. 7 . Here,  FIG. 6  shows an appearance where a camera image  16 G of the sixth camera  16  and a bird&#39;s-eye image F are displayed in the display region  30   a .  FIG. 7  shows an appearance where a camera image  150  of the fifth camera  15  and the bird&#39;s-eye image F are displayed in the display region  30   a.    
         [0044]    Here, a plurality of camera images may be displayed in the display region  30   a  or only the bird&#39;s-eye image F may be displayed in the display region  30   a . In this manner, the display of the monitor  30  may be automatically switched according to the movement state of the dump truck  1 . For example, it is possible for the camera image of the first camera and the bird&#39;s-eye image F to be displayed during forward progression and when stationary and only the camera image  16 G of the sixth camera  16  to be displayed during backward progression. Furthermore, the camera image  16 G and the bird&#39;s-eye image F may be displayed during backward progression and the camera image  16 G and another camera image may be displayed during backward progression. 
       Display Control Section 
       [0045]    The display control section  40  selects camera image data which corresponds to the camera image which has been selected based on the notification from the operator switch  20 . In addition, the display control section  40  generates bird&#39;s-eye image data where the plurality of images are videoed from a predetermined projected plane due to conversion of the coordinates of the camera image data of the six cameras  11  to  16  and which shows the bird&#39;s-eye image F which encompasses the entire surroundings of the dump truck  1 . The display control section  40  generates two-screen data which corresponds to a two-screen image where the camera image which has been selected and the bird&#39;s-eye image F are lined up due to the combination of the camera image data and the bird&#39;s-eye image data. 
         [0046]    In addition, the display control section  40  generates vehicle body outer edge line data which corresponds to a vehicle body outer edge line BL showing the outer edges of the vehicle body (including the vehicle body frame  2  and the vessel  4 ) which is vertically projected with regard to the ground surface in the camera image which has been selected. The display control section  40  generates the vehicle body outer edge line data according to distortions of the camera image of a target camera in accordance with a sequence which will be described next. 
         [0047]    First, the display control section  40  defines three vectors Ra, Rb, and Rc which indicate the orientation of the target cameras based on the following formulae (1) to (3). 
         [0000]    
       
         
           
             
               
                 
                   Formulae 
                    
                   
                       
                   
                    
                   
                     ( 
                     1 
                     ) 
                   
                    
                   
                       
                   
                    
                   to 
                    
                   
                       
                   
                    
                   
                     ( 
                     3 
                     ) 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   Ra 
                   = 
                   
                     ( 
                     
                       
                         
                           1 
                         
                         
                           0 
                         
                         
                           0 
                         
                       
                       
                         
                           0 
                         
                         
                           ca 
                         
                         
                           sa 
                         
                       
                       
                         
                           0 
                         
                         
                           
                             - 
                             sa 
                           
                         
                         
                           ca 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
             
               
                 
                   Rb 
                   = 
                   
                     ( 
                     
                       
                         
                           cb 
                         
                         
                           0 
                         
                         
                           
                             - 
                             sb 
                           
                         
                       
                       
                         
                           0 
                         
                         
                           1 
                         
                         
                           0 
                         
                       
                       
                         
                           sb 
                         
                         
                           0 
                         
                         
                           cb 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
             
               
                 
                   Rc 
                   = 
                   
                     ( 
                     
                       
                         
                           cc 
                         
                         
                           sc 
                         
                         
                           0 
                         
                       
                       
                         
                           
                             - 
                             sc 
                           
                         
                         
                           cc 
                         
                         
                           0 
                         
                       
                       
                         
                           0 
                         
                         
                           0 
                         
                         
                           1 
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
         [0048]    Here, 
         [0049]    ca=cos(roll), sa=sin(roll) 
         [0050]    cb=cos(pitch), sb=sin(pitch) 
         [0051]    cc=cos(yaw), sc=sin(yaw) 
         [0000]    where 
         [0052]    roll is the deflection angle of the target camera around an axis which is parallel with the front and back direction, 
         [0053]    pitch is the deflection angle of the target camera around an axis which is parallel with the vehicle width direction, 
         [0054]    yaw is the deflection angle of the target camera around an axis which is parallel with the vertical direction, and 
         [0055]    pitch, roll, and yaw are stored in a memory which is built into the display control section  40 . 
         [0056]    Next, the display control section  40  converts the three-dimensional coordinates (Xr, Yr, Zr) at one point on the outer edge of the vehicle body, which is vertically projected with regard to the ground surface, in a physical coordinates system to three-dimensional coordinates (x, y, z) in a camera coordinates system where the orientation and the position of the target camera is a reference as an Euler angle in the vertical direction—front and back direction—vehicle width direction based on the following formula (4). 
         [0000]    
       
         
           
             
               
                 
                   Formula 
                    
                   
                       
                   
                    
                   
                     ( 
                     4 
                     ) 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     ( 
                     
                       
                         
                           x 
                         
                       
                       
                         
                           y 
                         
                       
                       
                         
                           z 
                         
                       
                     
                     ) 
                   
                   = 
                   
                     RaRbRc 
                      
                     
                       ( 
                       
                         
                           ( 
                           
                             
                               
                                 Xr 
                               
                             
                             
                               
                                 Yr 
                               
                             
                             
                               
                                 Zr 
                               
                             
                           
                           ) 
                         
                         - 
                         
                           ( 
                           
                             
                               
                                 tx 
                               
                             
                             
                               
                                 ty 
                               
                             
                             
                               
                                 tz 
                               
                             
                           
                           ) 
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
         [0057]    Here, (tx, ty, tz) are coordinates in the physical coordinates system of the target camera. 
         [0058]    Next, the display control section  40  converts the three-dimensional coordinates (x, y, z) in the camera coordinates system to two-dimensional coordinates (u, v) in the display region  30   a  of the monitor  30  based on the following formulae (5) to (11). 
         [0000]      Formulae (5) to (11) 
         [0000]        x 2= x/z   (5)
 
         [0000]        y 2= y/z   (6)
 
         [0000]        r   2   =x 2 2   +y 2 2   (7)
 
         [0000]        x 3 =x 2(1+ k 1* r   2   +k 2* r   4   +k 3* r   6 ) +2* p 1* x 2* y 2 +p 2( r   2 +2* x 2 2 )  (8)
 
         [0000]        y 3 =y 2(1+ k 1* r   2   +k 2* r   4   +k 3* r   6 ) + p 1( r   2 +2* y 2 2 )+2* p 2* x 2* y 2  (9)
 
         [0000]        u=fx*x 3 +cx   (10)
 
         [0000]        v=fy*y 3 +cy   (11)
 
         [0059]    Here, k1, k2, and k3 are radial direction strain coefficients, 
         [0060]    P1 and p2 are shear direction strain coefficients, 
         [0061]    fx and fy are camera focal distances, and 
         [0062]    cx and cy are camera coordinate systems with the focal direction of the camera as the Z axis, the imaging plane direction as the X axis and the Y axis. 
         [0063]    In this manner, the display control section  40  acquires the two-dimensional coordinates (u, v) at one point on the outer edge of the vehicle, which is vertically projected with regard to the ground surface, in the display region  30   a . The display control section  40  generates the vehicle body outer edge line data which corresponds to the vehicle body outer edge line BL with a desired form (a dashed line, a chain line, or the like) by acquiring the two-dimensional coordinates in the same manner with regard to a plurality of points on the outer edges of the vehicle body. 
         [0064]    In addition, the display control section  40  generates warning line data which corresponds the a first to a third warning lines L 1  to L 3  which indicate positions with predetermined distances on the outside from the vehicle body outer edge line BL using the formulae (1) to (11) described above in the same manner. In the embodiment, the first warning line L 1  is a line which is 3 m to the outside of the vehicle body outer edge line BL, the second warning line L 2  is a line which is 5 m to the outside of the vehicle body outer edge line BL, and the third warning line L 3  is a line which is 7 m to the outside of the vehicle body outer edge line BL. 
         [0065]    The display control section  40  generates display image data by overlapping the two-screen data which has been generated, the vehicle body outer edge line data which has been generated, and the warning line data which has been generated. The display control section  40  transmits the display image data which has been generated to the monitor  30 . Due to this, the vehicle body outer edge line BL, which indicates the outer edges of the vehicle body which is vertically projected with regard to the ground surface, and the first to the third warning lines L 1  to L 3 , which indicates the lines which are 3 m, 5 m, and 7 m more to the outside of the vehicle body than the vehicle body outer edge line BL, are displayed along with the camera images  15 G and  16 G on the monitor  30  as shown in  FIG. 6  and  FIG. 7 . 
       Actions and Effects 
       [0066]    (1) The periphery monitoring apparatus  10  is provided with the display control section  40  which displays the camera image and the vehicle body outer edge line BL, which indicates the outer edges of the vehicle body (including the vessel  4 ) which is vertically projected with regard to the ground surface in the camera image, on the monitor  30 . 
         [0067]    Accordingly, it is possible for the driver to easily grasp the positional relationship of the vehicle body which is positioned above the camera and an object (for example, a person, a vehicle, a building, or the like) in the periphery of the vehicle body with the vehicle body outer edge line as a reference. As a result, it is possible to easily determine using the camera image, for example, if a person has entered the space below the vehicle body, to what extent that the vehicle body has approached a building, or the like. As a result, it is possible for the driver to simply grasp the circumstances in the periphery of the dump truck  1 . 
         [0068]    (2) The display control section  40  displays the first to the third warning lines L 1  to L 3 , which indicate positions with predetermined distances from the vehicle body outer edge line BL, on the monitor  30 . 
         [0069]    Accordingly, it is possible for the driver to more easily grasp the positional relationship of the vehicle body and objects in the periphery of the vehicle body since to what extent objects in the periphery of the vehicle body are separated from the vehicle body is shown in a stepped manner with the vehicle body outer edge line BL as a reference. 
         [0070]    (3) The ground surface is included in the lower part of the screen in the imaging range  16 R of the sixth camera  16  as shown in  FIG. 6 , and the lower surface side of the rear edge portion of the vessel  4  which configures a portion of the vehicle body is included in an upper part of the screen which opposes the ground surface. 
         [0071]    Accordingly, it is possible for the driver to more clearly grasp the positional relationship of the vessel and objects in the periphery of the vessel since it is possible for the rear edge portion of the vessel  4  to be directly confirmed in the camera image  16 G. 
       Other Embodiments 
       [0072]    The present invention is not limited to the embodiment as described above and various changes and modifications which do not depart from the scope of the invention are possible. 
         [0073]    (A) In the embodiment described above, the display control section  40  displays the first to the third warning lines L 1  to L 3  on the monitor  30  but the present invention is not limited to this. The display control section  40  may display any of the first to the third warning lines L 1  to L 3 , and in addition, may display four or more warning lines. 
         [0074]    (B) In the embodiment described above, the display control section  40  shows the vehicle body outer edge line BL and the first to the third warning lines L 1  to L 3  with dashed lines but the present invention is not limited to this. The display control section  40  may show the vehicle body outer edge line BL and the first to the third warning lines L 1  to L 3  with a solid line, a chain line, or the like. In addition, the display control section  40  may show each of the vehicle body outer edge line BL and the first to the third warning lines L 1  to L 3  with different colors. 
         [0075]    (C) In the embodiment described above, the case is described where the vehicle body outer edge line BL is displayed along with the camera image  16 G of the sixth camera  16  or the camera image  15 G of the fifth camera  15  using  FIG. 6  and  FIG. 7  but the present invention is not limited to this. The vehicle body outer edge line BL may be displayed along with the camera images of the first to the fourth cameras in a case where the driver specifies any of the first to the fourth cameras  11  to  14 . 
         [0076]    (D) In the embodiment described above, the dump truck  1  is provided with the base  7  but need not be provided with the base  7 . 
         [0077]    (E) In the embodiment described above, the dump truck  1  is provided with six cameras  11  to  16  but the present invention is not limited to this. The dump truck  1  may be provided with one to five cameras or may be provided with seven or more cameras.