Patent Publication Number: US-2023161355-A1

Title: Control system of dump truck

Description:
TECHNICAL FIELD 
     The present invention relates to a control system of a dump truck. 
     BACKGROUND ART 
     In mine operation in recent years, a request for operation of a dump truck of an autonomous travelling type (an autonomous travelling dump truck) that travels in an unmanned manner along a travelling route received via a satellite has been increasing for the purposes of reduction in labor cost and improvement in safety. As one of basic movements in a mine, there is loading work in which an excavator operated by an operator loads an autonomous travelling dump truck with a load. The excavator in the loading work exists on a platform called a face in many cases. Therefore, it is desirable for the autonomous travelling dump truck to come as close to this face as possible and stop, so that the excavator may easily carry out the loading work. 
     An autonomous travelling dump truck described in Patent Document 1 receives, by wireless communication, a route made toward a loading specified position specified by an operator (an excavator operator) of an excavator (a loading machine) in order to load the dump truck with a load and travels on the route. Further, Patent Document 1 proposes to compare the loading specified position with the position of a face detected by a rear-side recognizing device when the dump truck is to stop, and control the vehicle body to cause the dump truck to stop at a position closer to the excavator. By this control, the dump truck stops at a position that is as close to the loading specified position as possible, i.e., a position that allows the excavator operator to easily carry out loading work, without colliding with the face, and therefore, the loading work efficiency can improve. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: JP-2018-142113-A 
       
    
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     There are various situations in a mine environment. Thus, a travelling route that allows the dump truck to stop at the loading specified position in a direction with which the excavator operator easily carries out loading cannot necessarily be made. 
     The autonomous travelling dump truck of Patent Document 1 can come as close to the loading specified position as possible and stop without colliding with a face. However, the direction of the dump truck (a vessel) at the stop position is not necessarily a direction with which loading is easy for the excavator operator. For example, in loading the vessel of a dump truck with a load by an excavator, it is general to align a front-rear direction (a longitudinal direction) of a front work device with a front-rear direction of the vessel and carry out dumping operation of a bucket while moving the front work device along the front-rear direction of the vessel to thereby carry out the loading in such a manner that the load does not concentrate on one place on the vessel. At this time, if the autonomous travelling dump truck stops in such a manner that the front-rear direction of the vessel intersects the front-rear direction of the front work device of the excavator, when it is attempted to move the front work device along the front-rear direction of the vessel, a swing movement also needs to be combined simultaneously with it, and there is a concern that a rise in difficulty of operation, fatigue of the excavator operator, an increase in cycle time, and so forth are caused. 
     Thus, when the loading specified position is specified, it is desirable to make a route in as parallel to the front-rear direction of the front work device as possible and cause the relation between the direction of the vehicle body (the front-rear direction) and the front-rear direction of the front work device to come close to parallel when the autonomous travelling dump truck stops. However, the environment around the loading field can change successively, and therefore, it is difficult for an upper-level map generation system (as a specific example, a server), which has a role of transmitting a map to autonomous travelling dump trucks, to set the travelling route of each autonomous travelling dump truck with changes in the surroundings of the loading field all recognized. 
     Therefore, in the case of attempting to stop the autonomous travelling dump truck in such a manner that the front-rear direction of the front work device of the excavator and the front-rear direction of the autonomous travelling dump truck come close to parallel as described above, the route needs to be adjusted according to the circumstances while the external world is recognized by the autonomous travelling dump truck itself. 
     Based on the above, the present invention intends to provide a control system of a dump truck of an autonomous travelling type that can stop at a loading specified position in a direction with which an operator of a loading machine easily carries out loading. 
     Means for Solving the Problem 
     The present application includes multiple means to solve the above-described problem. As one example thereof, there is provided a control system of a dump truck of an autonomous travelling type, the system including a controller that outputs a control signal to the dump truck to control the dump truck in such a manner that the dump truck travels on a travelling route and stops at a loading specified position, on a basis of data of the travelling route and position data of the dump truck, the traveling route including, as an end point of the travelling route, the loading specified position specified as a position at which a loading machine loads a vessel of the dump truck with a load. The controller is configured to compute a first stop direction on a basis of the data of the travelling route, the first stop direction being a front-rear direction of the dump truck when the dump truck has travelled on the travelling route and stopped at the loading specified position, and correct the travelling route to compute a post-correction travelling route that is a travelling route obtained by correcting the travelling route and includes the loading specified position as an end point, in such a manner that the loading machine is located on an extension line of a second stop direction that is the front-rear direction of the dump truck when the dump truck has travelled on the post-correction travelling route and stopped at the loading specified position, on a basis of the computed first stop direction, position data of the loading specified position, and position data of the loading machine. 
     Advantages of the Invention 
     According to the present invention, the dump truck of the autonomous travelling type can be stopped at the loading specified position in the direction with which an operator of the loading machine easily carries out loading. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an appearance diagram of an autonomous travelling dump truck that is one example of a haulage vehicle according to an embodiment of the present invention. 
         FIG.  2    is a schematic configuration diagram of a control system of the dump truck according to the embodiment of the present invention. 
         FIG.  3    is a functional block diagram of a controller according to the embodiment of the present invention. 
         FIG.  4    is an explanatory diagram of a travelling route of the dump truck of the autonomous travelling type. 
         FIG.  5    is a geometric explanatory diagram for explaining logic of generation of a post-correction travelling route by a corrected route generating section  31 . 
         FIG.  6    is a top view of an excavator  200  held with such a posture that a movement plane  56  of a front work device  50  passes through a loading specified position P0. 
         FIG.  7    is an explanatory diagram of detection ranges of LIDARs (obstacle sensors). 
         FIG.  8    is a diagram illustrating a case in which an obstacle is detected during travelling of the dump truck  100  on a pre-correction travelling route  61  after a post-correction travelling route  62  is generated. 
         FIG.  9    is a diagram illustrating a case in which an obstacle that has not been sensed during travelling on the pre-correction travelling route  61  is detected when the dump truck  100  is about to travel on the post-correction travelling route  62  or during travelling of the dump truck  100  on the post-correction travelling route  62 . 
         FIG.  10    is a functional block diagram of a travelling control section  33 . 
         FIG.  11    is one example of a flowchart of processing executed by the controller  30  according to the present embodiment. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be described below by using the drawings. 
       FIG.  1    is an appearance diagram (a perspective view) of an autonomous travelling dump truck that is one example of a haulage vehicle according to the embodiment of the present invention. A dump truck  100  of  FIG.  1    includes a vehicle body frame  2 , a vessel (vessel)  3  pivotally supported on the vehicle body frame  2  by a support shaft (not illustrated), a cabin  4  attached to a front side on the vehicle body frame  2 , multiple front wheels  5  attached to the front side of the vehicle body frame  2 , and multiple rear wheels  6  attached to a rear side of the vehicle body frame  2 . 
     The cabin  4  has a driver&#39;s seat (not illustrated) provided therein. An operator (a driver) sits on the driver&#39;s seat to carry out operation of a brake pedal, an accelerator pedal, and so forth out in some cases. That is, the dump truck  100  is subjected to manned manual operation in some cases. Onto the vessel  3 , earth and sand that is a load (a hauled object) is loaded by a loading machine (a construction machine) such as a hydraulic excavator or a wheel loader. Further, at a hauling destination of the dump truck  100  (a dumping site), the load loaded on the vessel  3  can be discharged from a rear end of the vessel  3  by extending a vessel cylinder  15  (see  FIG.  2   ) to raise a front end of the vessel  3  and incline the vessel  3  while causing the vessel  3  to pivot around the support shaft at the rear end of the vessel  3 . 
     The front wheels  5  ( 5 L,  5 R) are rotatably provided on a lower side of a front part of the vehicle body frame  2 . The front wheel  5 L is disposed on a left side of the vehicle body frame  2 , and the front wheel  6 R is disposed on a right side of the vehicle body frame  2 . The left and right front wheels  5 L and  5 R configure steering wheels a steering angle θ of which is changed by a steering device. The left and right front wheels  5 L and  5 R are subjected to steering operation by the steering device according to a rotation angle of a steering wheel of the dump truck  100 . 
     The rear wheels  6  ( 6 L,  6 R) are rotatably provided on a rear part side of the vehicle body frame  2 . The rear wheel  6 L is disposed on the left side of the vehicle body frame  2 , and the rear wheel  6 R is disposed on the right side of the vehicle body frame  2 . The left and right rear wheels  6 L and  6 R configure drive wheels of the dump truck  100  and are rotationally driven by left and right electrically driven travelling motors  19 L and  19 R (see  FIG.  2   ). By rotationally driving the left and right rear wheels  6 L and  6 R, the dump truck  100  is driven to travel. 
     Major constituent elements such as the electrically driven motors  19  (see  FIG.  2   ) that are accelerating-decelerating devices for controlling acceleration and deceleration of the rear wheels  6  and a suspension (a suspension device) that supports the front wheels  5  and the rear wheels  6  in a vertically movable manner are further mounted in the vehicle body frame  2 , and a configuration that allows the vehicle to freely travel on a road surface with use of the front wheels  5  and the rear wheels  6  is adopted. 
       FIG.  2    is a schematic configuration diagram of a control system of a dump truck according to the embodiment of the present invention. The autonomous travelling dump truck  100  includes an engine  11 , an alternator (an electric generator)  12  and a hydraulic pump  13  that are driven by the engine  11 , a hydraulic circuit  14  that controls flow of a hydraulic operating fluid (a hydraulic fluid) supplied from the hydraulic pump  13  to respective hydraulic actuators (for example, a vessel cylinder  15 , steering cylinders  16 ), the vessel cylinder  15  that raises or lowers the vessel  3  by extending or contracting through reception of supply of the hydraulic operating fluid from the hydraulic circuit  14 , and an electrically driven steering motor  17  that inputs steering torque to a column shaft (not illustrated) coupled to the steering wheel (not illustrated) to actuate a steering valve (not illustrated). The autonomous travelling dump truck  100  also includes left and right steering cylinders  16  that change the steering angle of the left and right front wheels  5 L and  5 R by the hydraulic operating fluid supplied and discharged through the steering valve, the left and right electrically driven travelling motors  19  ( 19 L,  19 R) that apply torque to the left and right rear wheels  6  ( 6 L,  6 R) to control acceleration and deceleration of the dump truck  100 , an inverter  18  that supplies power generated by the alternator  12  to the left and right electrically driven travelling motors  19 , the electrically driven steering motor  17 , and so forth on the basis of a control signal from a controller  30 , and the controller  30  that outputs a control signal to the inverter  18  and so forth on the basis of various kinds of input information. 
     (Controller  30 ) 
     The controller (controller)  30  is a controller (for example, a microcomputer) including a computation processing device (for example, a processor such as a CPU), a storage device (for example, a semiconductor memory such as a ROM or a RAM), an input-output circuit, and a communication circuit and is configured to be capable of executing various kinds of processing prescribed by a program stored in the storage device by executing the program by the computation processing device. The controller  30  carries out control of the electrically driven travelling motors  19 L and  19 R and the electrically driven steering motor  17  (i.e., control of acceleration, deceleration, and steering of the dump truck  100 ) by outputting the control signal to the inverter  18  for execution of autonomous travelling of the dump truck  100 , correction processing of the travelling route used when the dump truck  100  autonomously travels, and so forth. 
     The controller  30  is connected to a wireless device  83  (see  FIG.  3   ) and is thus capable of executing wireless communication mutually with external terminals (for example, a server (a computer)  300  installed in a control center and a controller mounted in an excavator  200  (see  FIG.  6   )). The wireless device  83  transmits data output from the controller  30  from a wireless device antenna (not illustrated). Meanwhile, the wireless device  83  inputs data (for example, travelling route data to be described later) received by the wireless device antenna to the controller  30 . 
     The following kinds of data are input to the controller  30 : swing center position data that is position data of the excavator  200  as a loading machine, obstacle position data that is position data (obstacle coordinates) of an obstacle that is sensed by an obstacle sensor (for example, a LIDAR (see  FIGS.  3 ,  4   , and so forth))  21  and is located in an advancing direction (a rear side) of the dump truck  100 , position data of the dump truck (self-position data) computed by a GNSS receiver  84  mounted in the dump truck  100 , posture data of the dump truck  100  (including orientation data of the dump truck) computed based on output of an IMU (not illustrated) and the GNSS receiver  84  mounted in the dump truck  100 , steering angle data acquired by a steering angle sensor  81  mounted in the dump truck  100 , velocity data acquired by a velocity sensor  82  mounted in the dump truck  100 , and so forth. 
     The controller computes the drive torque of the left and right travelling motors  19  and the electrically driven steering motor  17  in such a manner as to cause the dump truck  100  to travel on the travelling route on the basis of travelling route data for the dump truck  100  wirelessly received from the server  300  in the control center, the position data (the swing center position data) of the excavator  200 , the position data of an obstacle detected by the obstacle sensor  21  that senses an obstacle existing in the advancing direction of the dump truck  100 , the position data of the dump truck  100  computed by the GNSS receiver  84 , the posture data (the orientation data) of the dump truck  100  computed from a positioning result of the GNSS receiver  84  using multiple GNSS antennas (not illustrated), the travelling velocity of the dump truck  100  sensed by the velocity sensor  82 , the steering angle of the front wheels  5  sensed by the steering angle sensor  81 , and so forth, and controls the inverter  18  to cause the respective motors  17  and  19  to operate according to the computation result. Power generated by the alternator  12  is supplied to the respective motors  17  and  19  through the inverter  18 , and the respective motors  17  and  19  carry out operation based on a command. The hydraulic fluid delivered from the hydraulic pump  13  is supplied to the vessel cylinder  15  and the steering cylinders  16  through the hydraulic circuit  14 . In particular, a configuration is adopted in which steering of the front wheels  5  is carried out when the steering valve in the hydraulic circuit  14  is operated due to driving of the electrically driven steering motor  17  and a hydraulic line from the hydraulic pump  13  to the steering cylinders  16  is opened. 
       FIG.  3    is a functional block diagram in which computations carried out in the controller  30  are illustrated in such a manner as to be classified by blocks. The controller  30  functions as a corrected route generating section  31 , a rear-side obstacle determining section  32 , and a travelling control section  33 . 
     The corrected route generating section  31  corrects a travelling route  61  (see  FIG.  5   ) prescribed by the travelling route data received from the server  300  to generate a post-correction travelling route  62  (see  FIG.  5   ) on the basis of the travelling route data, the position data (swing center position data) of the excavator  200 , and the position data and the posture data of the dump truck  100  in such a manner as to allow the dump truck  100  to stop with a position and a direction (an orientation) with which the excavator  200  easily carries out loading work. 
     The rear-side obstacle determining section  32  determines whether or not there is a possibility that the dump truck  100  collides with an obstacle if it travels on the post-correction travelling route  62  generated in the corrected route generating section  31 , on the basis of the position data of an obstacle sensed by the obstacle sensor  21  that senses an obstacle existing in the advancing direction of the dump truck  100  and data of the post-correction travelling route  62  (corrected travelling route data) generated in the corrected route generating section  31 . When it is determined that there is a possibility of contact with an obstacle in this determination, the rear-side obstacle determining section  32  outputs, to the travelling control section  33 , information indicating that the post-correction travelling route  62  cannot be used as the travelling route of the dump truck  100  (corrected route use determination). 
     The travelling control section  33  computes a target velocity and a target steering angle of the dump truck  100  to cause the dump truck  100  to travel on the pre-correction travelling route  61  or the post-correction travelling route  62 , generates a torque command to the left and right electrically driven travelling motors  19 L and  19 R and the electrically driven steering motor  17  to implement the computed velocity and angle, and outputs the generated torque command to the corresponding motors  19 L,  19 R, and  17 . 
     The pre-correction and post-correction travelling routes  61  and  62  are given as strings of points referred to as nodes. That is, a collection of pieces of position data of multiple nodes that configure each travelling route becomes the travelling route data. The position of each node can be defined on an orthogonal coordinate system (a site coordinate system) in which the east is defined as the +x direction, the north is defined as the +y direction, and a certain point in a mine is the origin, for example.  FIG.  4    is an explanatory diagram of the travelling route. As in this diagram, for each node n (n is a natural number) in the travelling route data, not only coordinates (Xn, Yn) thereof but also a target velocity Vn for the dump truck  100  to pass the node n is set. The controller  30  carries out control of acceleration or deceleration of the electrically driven travelling motors  19  on the basis of deviation between the actual velocity acquired by the velocity sensor  82  and the target velocity Vn. 
     (Corrected Route Generating Section  31 ) 
     Next, generation processing of the post-correction travelling route  62  executed in the corrected route generating section  31  will be described in more detail by using  FIG.  5   .  FIG.  5    is a geometric explanatory diagram for explaining logic of the corrected route generating section  31 . Multiple large black points in the diagram each indicate the node of the original travelling route  61  received from the server  300 . 
     A point P0 in the diagram represents the node of the loading specified position. The loading specified position P0 is a point specified by an operator of the excavator  200  as a reference position at the time when the excavator  200  loads the vessel  3  of the dump truck  100  with a load by using a front work device  51  (see  FIG.  6   ), and is directly or indirectly transmitted in a wireless manner to the controller  30  from the controller of the excavator  200 . 
     Further, in  FIG.  5   , the position of the right rear wheel  6 R and the position of the left rear wheel  6 L in a case in which the dump truck  100  has travelled on the travelling route  61  and stopped at the loading specified position P0 (in the example of the diagram, a case in which a center of an axle of the rear wheels  6  (a rear axle) of the dump truck  100  is located on the loading specified position P0) are defined as PR and PL, respectively, and the axle that connects the left and right rear wheels  6 L and  6 R to each other is drawn by a solid line that connects the two points PR and PL to each other. A distance between the point PR and the point PL will be sometimes referred to as an inter-rear-wheel distance, and the distance is defined as 1. Further, the front-rear direction of the dump truck  100  in this case (the case in which the dump truck  100  has travelled on the travelling route  61  and stopped at the loading specified position P0) will be sometimes referred to as a first stop direction. The first stop direction is a straight line that passes through a center of the dump truck  100  in the longitudinal direction of the dump truck  100  and passes through the loading specified position P0 on an xy plane in the site coordinate system. The first stop direction is also a line of intersection between a plane orthogonal to the rear axle of the dump truck  100  and the xy plane in the site coordinate system. Moreover, the first stop direction is also a straight line L1 obtained by extending a line segment that connects the loading specified position P0 that is the node of the end point of the travelling route  61  to a node Pz previous to the end point. The first stop direction can be computed based on the travelling route data (for example, position data of the loading specified position P0 and the node Pz included in the travelling route data). 
     Here, as a point relating to the excavator  200 , a swing center position Ps and a point Ps&#39; will be described by using  FIG.  6   .  FIG.  6    is a top view of the excavator  200  held with such a posture that a movement plane  56  of the front work device  50  passes through the loading specified position P0. The excavator  200  of  FIG.  6    includes a lower track structure  55 , an upper swing structure  54  swingably attached onto the lower track structure  55 , and the front work device  50  that is attached to the upper swing structure  54  and includes a boom  51 , an arm  52 , and a bucket  53 . The movement plane  56  of the front work device  50  is a plane in which all front components  51 ,  52 , and  53  that configure the front work device  50  can move, and passes through a center of the front work device  50  in the left-right direction in the example of  FIG.  6   . The point Ps is a position of a swing center of the upper swing structure  54 . The point Ps&#39; is a foot of a perpendicular drawn from the swing center position Ps to the movement plane  56  of the front work device  50 . Here, a length of the perpendicular is defined as m. The swing center position Ps and the point Ps&#39; illustrated in  FIG.  5    are obtained when the front work device  50  is kept in such a posture that the movement plane  56  passes through the loading specified position P0. 
     In the present embodiment, the position of the excavator  200  is defined with the swing center position Ps. However, the position may be any position as long as it is a point whose position with respect to two GNSS antennas (not illustrated) attached to the upper swing structure  54  is known. The swing center position Ps and the orientation of the front work device  50  (the upper swing structure  54 ) can be computed based on signals (navigation signals) received from multiple positioning satellites by the two GNSS antennas in a GNSS receiver (not illustrated) mounted in the excavator  200 . 
     Referring back to  FIG.  5   , a straight line L2 illustrated by a dashed line is a straight line that is defined on the xy plane in the site coordinate system and connects the loading specified position P0 and the point Ps&#39; to each other at the time when the front work device  50  of the excavator  200  is kept in such a posture that the movement plane  56  passes through the loading specified position P0. The position of the right rear wheel  6 R and the position of the left rear wheel  6 L in a case in which this straight line L2 coincides with the front-rear direction of the dump truck  100  when the dump truck  100  has stopped at the loading specified position P0 (referred to as a “second stop direction”) are defined as PR′ and PL′, respectively, and the axle at the time is drawn by a dotted line that connects the two points PR′ and PL′ to each other. 
     In a case in which the swing center position of the excavator  200  is located at the point Ps in  FIG.  5    and the dump truck  100  is stopped at the loading specified position P0, if the dump truck  100  is stopped with the direction thereof kept aligned with the second stop direction (the straight line L2), the movement plane  56  of the front work device  50  coincides with the front-rear direction of the dump truck  100  on the xy plane, and therefore, loading work by the excavator  200  becomes easy. 
     Thus, the corrected route generating section  31  in the present embodiment corrects the travelling route  61  to generate the post-correction travelling route  62  in such a manner that the front-rear direction (the second stop direction) of the dump truck  100  in a case in which the dump truck  100  has travelled (moved rearward) on the post-correction travelling route  62  and stopped at the loading specified position P0 coincides with the straight line L2 (the movement plane  56  that passes through the loading specified position P0) or an angle formed by the second stop direction and the straight line L2 comes close to zero. More specifically, before the dump truck  100  reaches the loading specified position P0, the corrected route generating section  31  computes, based on the travelling route data, the first stop direction L1 that is the front-rear direction of the dump truck  100  in the case in which the dump truck  100  has travelled (moved rearward) on the pre-correction travelling route  61  and stopped at the loading specified position P0. The corrected route generating section  31  then corrects the travelling route  61  to compute the post-correction travelling route  62  on the basis of the computed first stop direction L1, the position data of the loading specified position P0, and the position data (in the example of  FIG.  5   , the data of the swing center position) Ps of the excavator  200  in such a manner that the second stop direction coincides with the straight line L2 (the movement plane  56  that passes through the loading specified position P0) or the angle formed by the second stop direction and the straight line L2 comes close to zero. 
     When correcting the travelling route  61  to the post-correction travelling route  62 , the corrected route generating section  31  in the present embodiment uses dl (a first distance) and d2 (a second distance) that are two distances illustrated in  FIG.  5   . d1 (the first distance) is a distance (deviation) in the first stop direction (the direction orthogonal to the rear axle) between PR (a first position) and PR′ (a second position) in the case in which the dump truck  100  has travelled on the pre-correction travelling route  61  and stopped at the loading specified position P0, the first position PR being the position of one rear wheel (a first rear wheel)  6 R in the left-right direction of the dump truck, the second position PR′ being the position of the one rear wheel (the first rear wheel)  6 R in the case in which the dump truck  100  has travelled on the post-correction travelling route  62  and stopped at the loading specified position P0. d2 (the second distance) is a distance (deviation) in a direction orthogonal to the first stop direction (the direction of the rear axle) between the first position PR and the second position PR′. Next, a computation process of d1 (the first distance) and d2 (the second distance) by the corrected route generating section  31  will be described. 
     An angle formed by the straight line L1 (the first stop direction) and the straight line L2 (the movement plane  56  that passes through the loading specified position P0) is defined as θ. Where coordinates of the loading specified position P0 are (x0, y0), coordinates of the node Pz are (x1, y1), coordinates of the swing center position Ps are (xs, ys), coordinates of the foot Ps&#39; of the perpendicular drawn from the swing center position Ps to the movement plane  56  are (xs′, ys′), the length of the perpendicular is m, an angle formed by the straight line L1 and the y-axis is 01, and an angle formed by the straight line L2 and the y-axis is θ2, θ is a difference between θ1 and θ2 and can be computed by the following expression (1). 
     
       
         
           
             
               
                 
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                     3 
                     ) 
                   
                 
               
             
           
         
       
     
     The corrected route generating section  31  computes a point P1 (a first point) separate from the loading specified position P0 by the distance d1 (the first distance) on the pre-correction travelling route  61 , a point P2 (a second point) further separate from the point P1 (the first point) by a predetermined distance X1 on the same travelling route  61 , and P3 (a third point) further separate from the point P2 (the second point) by a predetermined distance X2 on the same travelling route  61 . Then, the corrected route generating section  31  translates the travelling route  61  between the point P1 (the first point) and the point P2 (the second point) in the direction orthogonal to the first stop direction by the distance d2 (the second distance) and deems the points on the post-correction travelling route  62  resulting from the translation of the two points P1 and P2 as P1′ and P2′. Then, the corrected route generating section  31  computes, as the post-correction travelling route  62 , a route obtained by connecting the point P1′ to the loading specified position P0 by a circular arc having the point PR′ as the center of the circle and smoothly connecting the point P2′ to the point P3 (a line that connects the point P3, the point P2′, the point P1′, and the point P0 to each other). 
     The target velocity prescribed for each node on the post-correction travelling route  62  can be taken over from the node corresponding to each node on the pre-correction travelling route  61 . The target velocity for a node newly generated in the post-correction travelling route  62  can be set by interpolating based on values for the nodes the target velocity of which is known, for example. Furthermore, it is preferable that X1 and X2 used in the above be set to lengths with which steering can be sufficiently completed when the dump truck  100  attempts to travel on the post-correction travelling route  62 , in view of the fact that the vehicle body travels at a very low velocity at the time of position adjustment with a rearward movement and the steering performance of the vehicle body. 
     (Rear-side Obstacle Determining Section  32 ) 
     The rear-side obstacle determining section  32  receives rear-side obstacle coordinates (obstacle position data) from the obstacle sensor  21 , determines whether or not the dump truck  100  gets contact with an obstacle when travelling on the post-correction travelling route  62  or during travelling on the post-correction travelling route  62  on the basis of the rear-side obstacle coordinates and the position data of the post-correction travelling route  62 , and outputs the corrected route use determination (TRUE or FALSE) according to the determination result. The corrected route use determination is used for determination about which travelling route of the pre-correction travelling route  61  and the post-correction travelling route  62  the dump truck  100  is made to travel on. It is desirable that the obstacle sensor  21  be a sensor that can detect an obstacle in a wide range. In the present embodiment, as in  FIG.  7   , two LIDARs that can each scan a range of ½× vehicle body width W+α[m] in the vehicle body front-rear direction (the longitudinal direction) are mounted as the obstacle sensors  21 . Double lines in the diagram represent scan planes of the LIDARs. 
       FIG.  8    illustrates a case in which an obstacle is detected by the obstacle sensor  21  during travelling of the dump truck  100  on the pre-correction travelling route  61  after the post-correction travelling route  62  is generated. When a length of a perpendicular drawn from rear-side obstacle coordinates Pol, which is received from the obstacle sensor  21 , to the post-correction travelling route  62  is equal to or shorter than the vehicle body width W of the dump truck  100  as in  FIG.  8   , the rear-side obstacle determining section  32  determines that there is a fear that the dump truck  100  collides with the relevant obstacle if it travels on the post-correction travelling route  62 , and outputs FALSE as the corrected route use determination. That is, the dump truck  100  is controlled to travel on the pre-correction travelling route  61 . On the other hand, the rear-side obstacle determining section  32  outputs TRUE as the corrected route use determination when the length of the perpendicular is larger than the vehicle body width W or when no obstacle is detected by the obstacle sensor  21 . 
       FIG.  9    illustrates a case in which an obstacle that has not been sensed during travelling on the pre-correction travelling route  61  is detected by the obstacle sensor  21  when the dump truck  100  is about to travel on the post-correction travelling route  62  or during travelling of the dump truck  100  on the post-correction travelling route  62 . Also in this case, similarly to the case of  FIG.  8   , the rear-side obstacle determining section  32  determines that there is a fear that the dump truck  100  collides with the relevant obstacle if it travels on the post-correction travelling route  62 , and outputs FALSE as the corrected route use determination. That is, the dump truck  100  is controlled to travel on the pre-correction travelling route  61 . Further, similarly to the case of  FIG.  8   , the rear-side obstacle determining section  32  outputs TRUE as the corrected route use determination when the length of the perpendicular is larger than the vehicle body width W or when no obstacle is detected by the obstacle sensor  21 . 
     While, in this example, the rear-side obstacle determining section  32  determines that there is a possibility of collision when the length of the perpendicular is equal to or shorter than the vehicle body width W, the vehicle body width W is merely one example, and another threshold may be used. Moreover, here, the corrected route use determination is carried out with focus only on the distance from the post-correction travelling route  62  (the length of the perpendicular). However, when the distance from the post-correction travelling route  62  is equal to or shorter than the vehicle body width W (when the dump truck  100  is to collide with an obstacle if it travels on the post-correction travelling route  62 ), it may be determined whether or not the distance between the relevant rear-side obstacle coordinates Pol and the pre-correction travelling route  61  is equal to or shorter than the vehicle body width W, and travelling on the pre-correction travelling route  61  may be allowed when the distance is larger than the vehicle body width W. When the dump truck  100  is to collide with an obstacle even if it travels on the pre-correction travelling route  61 , the dump truck  100  may be stopped before reaching the obstacle. 
     (Travelling Control Section  33 ) 
     The travelling control section  33  uses the post-correction travelling route  62  when the corrected route use determination output by the rear-side obstacle determining section  32  is TRUE and uses the pre-correction travelling route  61  when the corrected route use determination is FALSE, and controls travelling of the dump truck  100 . 
       FIG.  10    is a functional block diagram of the travelling control section  33 . As illustrated in this diagram, the travelling control section  33  includes a steering control section  41  that controls the steering angle of the dump truck  100  and a velocity control section  42  that controls the velocity of the dump truck  100 . 
     (A) Case of Travelling to Point P0 on Travelling Route  61  or to Point P1′ on Post-correction Travelling Route  62   
     Velocity control and steering control by the travelling control section  33  when the dump truck  100  is caused to travel to the loading specified position P0 on the pre-correction travelling route  61  or to the point P1′ on the post-correction travelling route  62  are carried out as follows. 
     The velocity control section  42  carries out feedback control based on the actual velocity of the dump truck  100  computed from the sensor value (the velocity data) of the velocity sensor  82  and the target velocity prescribed for each node of the travelling route, and computes the torque of the left and right electrically driven travelling motors  19 L and  19 R to cause the actual velocity of the dump truck  100  to come close to the target velocity. However, it is assumed here that position adjustment is carried out with a rearward movement, and therefore, the lowest velocity of the vehicle body is assumed as the target velocity, and the target velocity is set to 5 [km/h], for example. Further, when the dump truck  100  has reached the vicinity of the loading specified position P0, the target velocity is set to 0 [km/h] and the full brake is driven, to thereby stop the dump truck  100  at a desired position. 
     The steering control section  41  deems, as a target, a point (a front-side gaze point) on the route separate forward from the present position in the advancing direction of the dump truck  100  by a certain distance (a front-side gaze distance), and decides a target value of steering on the basis of an angle formed by a present yaw angle of the vehicle body and a straight line that connects the present position to the front-side gaze point. Here, the front-side gaze distance is set to 10 [m] in consideration of the fact that the vehicle velocity is slow. With the target value of steering decided, the steering control section  41  computes a torque command of the electrically driven steering motor  17  by feedback control of the steering target value and the present steering angle. 
     By outputting the travelling electrically driven motor torque command and the electrically driven steering motor torque command computed in the above to the inverter and driving the respective motors, the dump truck  100  travels without departing from the route. 
     (B) Case of Travelling from Point P1′ on Post-correction Travelling Route  62  to Point P0 
     Velocity control in the case of travelling from the point P1′ to the loading specified position P0 on the post-correction travelling route  62  is carried out as follows. 
     At the time when the dump truck  100  reaches the point P1′ on the post-correction travelling route  62 , either one of the left and right rear wheels  6  has reached the above-described point PL′ or point PR′. Thus, the velocity control section  42  sets the target velocity of the rear wheel  6  that has not yet reached the point to 5 [km/h] and sets the target velocity of the rear wheel  6  that has reached the point to 0 [km/h] and computes the torque of the left and right electrically driven travelling motors  19 L and  19 R. Simultaneously with this, the steering control section  41  outputs a torque command of the electrically driven steering motor  17  to cause the steering angle to become parallel to the direction of the vehicle body of the dump truck  100 . At this time, the dump truck  100  makes circular motion around the one rear wheel  6  that has reached the point PL′ or the point PR′, and the other rear wheel  6  that has not yet reached the point PL′ or the point PR′ gets closer to the point PL′ or the point PR′. Eventually, at the time when both of the left and right rear wheels  6  have reached the respective points PL′ and PR′ and the steering angle has become parallel to the vehicle body, the steering control section  41  sets the torque command of the respective electrically driven travelling motors  19 L and  19 R to 0 to complete the stop. 
     On the other hand, in the case in which the dump truck  100  is travelling on the post-correction travelling route  62  in the state in which the corrected route use determination is TRUE, when the corrected route use determination is switched to FALSE, the travelling route is immediately returned to the pre-correction travelling route  61 , and the above-described control is similarly carried out. 
     Furthermore, in the velocity control section  42 , the rear-side obstacle coordinates and the present coordinates (the position data) of the dump truck  100  are compared with each other irrespective of whether the travelling route is the post-correction travelling route  62 . When the distance between the rear-side obstacle coordinates and the present coordinates of the dump truck  100  has become equal to or shorter than a certain distance, the dump truck  100  is immediately stopped by the full brake to avoid collision with the rear-side obstacle. 
     (Flowchart) 
     Here, one example of control flow of the dump truck  100  carried out by the controller  30  configured as described above will be described.  FIG.  11    is one example of a flowchart of processing executed by the controller  30  according to the present embodiment. The controller  30  carries out the flow of  FIG.  11    at a predetermined cycle. 
     In S 101 , the controller  30  (the corrected route generating section  31 ) receives the travelling route data from the server  300  in the control center through the wireless device  83 . 
     In S 102 , the controller  30  (the corrected route generating section  31 ) determines whether or not the node of the termination of the travelling route indicated by the travelling route data received in S 101  is the loading specified position P0. The controller  30  proceeds to S 103  when it is determined that the node of the termination is the loading specification P0, and ends the processing if this is not the case. 
     In S 103 , the controller  30  (the corrected route generating section  31 ) receives the position data of the excavator  200  (the coordinates (xs, ys) of the swing center position Ps) from, for example, the excavator  200  and computes the coordinates (xs′, ys′) of the point Ps&#39; from the coordinates (xs, ys) and the coordinates (x0, y0) of the loading specified position P0. Then, the controller  30  (the corrected route generating section  31 ) computes θ from the computed coordinates (xs′, ys′) of the point Ps′, the coordinates (x0, y0) of the loading specified position P0, the coordinates (x1, y1) of the node Pz, and the above-described expression (1). Needless to say, the coordinates (x0, y0) of the loading specified position P0 and the coordinates (x1, y1) of the node Pz that define the straight line L1 (the first stop direction) are included in the travelling route data received in S 101 . 
     In S 104 , the controller  30  (the corrected route generating section  31 ) determines whether or not 0 computed in S 103  is 0. When it is determined that θ≠0, the controller  30  proceeds to S 105 . In the case of θ≠0, the travelling route does not need to be corrected, and therefore, the controller  30  ends the processing. 
     In S 105 , the controller  30  (the corrected route generating section  31 ) computes the distances d1 and d2 by using θ computed in S 103  and the above-described expressions (2) and (3) and generates the post-correction travelling route  62  from the travelling route  61  by using the method described in the above. 
     In S 106 , the controller  30  (the rear-side obstacle determining section  32 ) receives the rear-side obstacle coordinates (the obstacle position data) from the obstacle sensor  21 , and determines whether or not the dump truck  100  is to collide with an obstacle if it is caused to travel on the post-correction travelling route  62 , on the basis of the position data of the post-correction travelling route  62  generated in S 105  and the rear-side obstacle coordinates. The controller  30  proceeds to S 107  when it is determined that the dump truck  100  is to collide with an obstacle if it is caused to travel on the post-correction travelling route  62 , but proceeds to S 116  when it is determined that the dump truck  100  is not to collide with an obstacle. 
     In a step S 111 , the controller  30  (the travelling control section  33 ) causes the dump truck  100  to travel along the post-correction travelling route  62  and controls the travelling of the dump truck  100  until either one of the left and right rear wheels  6  reaches the point PL′ or the point PR′ (see  FIG.  5   ). 
     In a step S 112 , the controller  30  (the travelling control section  33 ) stops the driving of one of the left and right rear wheels  6  that has first reached the point PL′ or the point PR′ (see  FIG.  5   ) and drives the other rear wheel  6  that has not reached the point according to the target velocity ( 5  [km/h]). When the other rear wheel  6  reaches the point PL′ or the point PR′, the controller  30  stops the dump truck (S 113 ) and ends the processing. This can stop the dump truck  100  at the loading stop position P0 with the front-rear direction of the dump truck  100  aligned with the straight line L2, so that loading work by the excavator  200  becomes easy. 
     On the other hand, when it is determined in S 106  that the dump truck  100  is to collide with an obstacle if it is caused to travel on the post-correction travelling route  62 , the controller  30  discards the post-correction travelling route  62  (S 107 ) and proceeds to a step S 108 . 
     In the step S 108 , the controller  30  (the rear-side obstacle determining section  32 ) determines whether or not the dump truck  100  is to collide with an obstacle if it is caused to travel on the pre-correction travelling route  61  received in S 101 , on the basis of the position data of the travelling route  61  and the rear-side obstacle coordinates. The controller  30  proceeds to S 109  when it is determined that the dump truck  100  is to collide with an obstacle if it is caused to travel on the travelling route  61 , but proceeds to S 110  when it is determined that the dump truck  100  is not to collide with an obstacle. 
     In the step S 109 , the controller  30  (the travelling control section  33 ) causes the dump truck  100  to travel along the pre-correction travelling route  61  and stops the dump truck  100  before reaching the rear-side obstacle to end the processing. 
     In the step S 110 , the controller  30  (the travelling control section  33 ) causes the dump truck  100  to travel along the pre-correction travelling route  61  and stops the dump truck  100  at the loading specified position P0 to end the processing. 
     In the flowchart of  FIG.  11   , the processing in the case in which the post-correction travelling route  62  is discarded due to the existence of an obstacle and the pre-correction travelling route  61  is used (S 106 , S 107 , S 108 , S 109 , S 110 ) is also included. However, this processing can be omitted when it is obvious that no obstacle exists. 
     (Effects) 
     According to the present embodiment described above, the following operation and effects can be obtained. 
     (1) In the present embodiment, the post-correction travelling route  62  is generated in such a manner that the movement plane  56  (the straight line L2) of the front work device  50  (the bucket  53 ) of the excavator  200  at the time when the front work device  50  is moved to the loading specified position P0 coincides with the front-rear direction (the second stop direction) of the dump truck  100  at the loading specified position P0, and the dump truck is controlled to travel on the post-correction travelling route  62  and stop at the loading specified position P0. This can alleviate difficulty of work and fatigue for the excavator operator who carries out loading work and prevent an unnecessary increase in cycle time. 
     However, the second stop direction and the movement plane  56  (the straight line L2) do not need to be made to coincide with each other completely, and it is sufficient if the angle formed by them on the xy plane is brought close to zero. According to this viewpoint, as long as the excavator  200  is located on an extension line of the second stop direction (the straight line L2), the loading work by the excavator  200  becomes easy compared with other cases. That is, the corrected route generating section  31  may compute, based on the travelling route data, the first stop direction L1 that is the front-rear direction of the dump truck  100  in the case in which the dump truck  100  has travelled (moved rearward) on the pre-correction travelling route  61  and stopped at the loading specified position P0, and may correct the travelling route  61  to compute the post-correction travelling route  62  in such a manner that the excavator  200  is located on an extension line of the second stop direction L2 that is the front-rear direction of the dump truck  100  in the case in which the dump truck  100  has travelled (moved rearward) on the post-correction travelling route  62  and stopped at the loading specified position P0, on the basis of the computed first stop direction L1, the position data of the loading specified position P0, and the position data (in the example of  FIG.  5   , the data of the swing center position) Ps of the excavator  200 . 
     (2) In the present embodiment, the post-correction travelling route  62  is generated by employing, as a reference, a line segment obtained by translating a partial section of the pre-correction travelling route  61 . This can generate the post-correction travelling route  62  through the minimum route correction, and the possibility of travelling on a route completely different from the pre-correction travelling route  61  is reduced. Thus, the possibility of contact with an obstacle that is not assumed originally can be suppressed. 
     (3) In the present embodiment, when an obstacle is sensed during travelling of the dump truck  100  on the pre-correction travelling route  61 , it is determined whether or not there is a possibility that the dump truck  100  gets contact with the obstacle when travelling on the post-correction travelling route  62 , and the dump truck  100  is caused to travel on the original travelling route  61  without travelling on the post-correction travelling route  62  when there is the possibility of contact. This can avoid the possibility of contact with the obstacle due to travelling on the post-correction travelling route  62  and occurrence of a situation in which, in order to avoid contact with the obstacle, the dump truck  100  needs to be stopped before reaching the obstacle. 
     (4) In the present embodiment, when an obstacle is sensed during travelling of the dump truck  100  on the post-correction travelling route  62 , it is determined whether or not there is a possibility that the dump truck  100  gets contact with the obstacle during the travelling on the post-correction travelling route  62 , and the travelling route is switched to the original travelling route  61  when there is the possibility of contact. This can avoid the possibility of contact with the obstacle due to travelling on the post-correction travelling route  62  and occurrence of a situation in which, in order to avoid contact with the obstacle, the dump truck  100  needs to be stopped before reaching the obstacle. 
     (Others) 
     The present invention is not limited to the above-described embodiment, and various modification examples in such a range as not to depart from the gist thereof are included. For example, the present invention is not limited to what includes all the configurations explained in the above-described embodiment, and what is obtained by deleting some of the configurations is also included. Further, it is possible that part of a configuration according to a certain embodiment is added to or substituted for a configuration according to another embodiment. 
     In the above, the case in which the controller  30  that controls the dump truck  100  is mounted in the dump truck  100  has been described. However, the controller  30  does not need to be mounted in the dump truck  100 . For example, a configuration may be adopted in which the controller  30  is installed in the control center  300  and vehicle control of the dump truck  100  is wirelessly carried out. 
     In the above, when the dump truck  100  is to be stopped at the loading stop position P0, the dump truck  100  is controlled in such a manner as to cause a midpoint of the rear axle to be located on the loading stop position P0. However, the dump truck  100  may be controlled based on another point other than the midpoint of the rear axle. 
     Further, regarding the respective configurations, functions of the respective configurations, execution processing, and so forth relating to the above-described controller  30 , part or all of them may be implemented by hardware (for example, logic that carries out the respective functions may be designed by an integrated circuit). Moreover, for configurations relating to the above-described controller  30 , such a program (software) that the respective functions relating to the configurations of the controller  30  are implemented through reading-out and execution of the program by a computation processing device (for example, a CPU) may be employed. Information relating to this program can be stored in a semiconductor memory (a flash memory, an SSD, and so forth), a magnetic storage device (a hard disk drive and so forth), a recording medium (a magnetic disc, an optical disc, and so forth), and so forth. 
     Furthermore, in the explanation of the above-described respective embodiments, as control lines and information lines, what are interpreted to be necessary for the explanation of the embodiments are illustrated. However, all control lines and all information lines relating to a product are not necessarily illustrated. It may be interpreted that almost all the configurations are mutually connected in actual products. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
           2 : Vehicle body frame 
           3 : Vessel (vessel) 
           5 : Front wheel 
           6 : Rear wheel 
           11 : Engine 
           12 : Alternator (electric generator) 
           13 : Hydraulic pump 
           14 : Hydraulic circuit 
           15 : Vessel cylinder 
           16 : Steering cylinder 
           17 : Electrically driven steering motor 
           18 : Inverter 
           19 : Electrically driven travelling motor 
           21 : Obstacle sensor 
           30 : Controller (controller) 
           31 : Corrected route generating section 
           32 : Rear-side obstacle determining section 
           33 : Travelling control section 
           41 : Steering control section 
           42 : Velocity control section 
           50 : Front work device 
           51 : Boom 
           52 : Arm 
           53 : Bucket 
           54 : Upper swing structure 
           55 : Lower track structure 
           56 : Movement plane 
           61 : Pre-correction travelling route 
           62 : Post-correction travelling route 
           81 : Steering angle sensor 
           82 : Velocity sensor 
           83 : Wireless device 
           84 : GNSS receiver 
           100 : Autonomous travelling dump truck 
           200 : Excavator 
           300 : Server