Patent Publication Number: US-2021165414-A1

Title: System including conveyance vehicle and work macihne that loads materials onto conveyance vehicle, method and work machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National stage application of International Application No. PCT/JP2019/036532, filed on Sep. 18, 2019. This U.S. National stage application claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2018-191789, filed in Japan on Oct. 10, 2018, the entire contents of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present invention relates to a technique for controlling a conveyance vehicle and a work machine that loads materials onto the conveyance vehicle. 
     Background Information 
     There is work which involves digging materials such as soil and the like by a work machine such as a hydraulic excavator and loading the materials onto a conveyance vehicle such as a dump truck. The conveyance vehicle is loaded with the materials at a predetermined loading position. The conveyance vehicle travels to a predetermined dumping position and dumps the materials at the dumping position. The conveyance vehicle then returns to the loading position and materials are loaded again by the work machine onto the conveyance vehicle. 
     Conventionally, a technique for performing the above loading work by the work machine with automatic control is known. For example, Japanese Patent Laid-Open No. 2000-192514 indicates that the digging position and the unloading position are previously learned by a controller of the work machine. The controller controls the work machine so as to perform digging at the digging position, cause the work machine to rotate from the digging position toward the unloading position, and unload materials at the unloading position. 
     SUMMARY 
     According to the above technique, the loading work can be performed by the work machine with automatic control. However, the loading work is performed not only by the work machine but also in cooperation with the conveyance vehicle. Therefore, it is important to perform the work while appropriately coordinating the work machine and the conveyance vehicle in order to efficiently perform the loading work. 
     An object of the present invention is to perform loading work onto the conveyance vehicle by the work machine with automatic control and appropriately coordinate the work machine and the conveyance vehicle. 
     A system according to a first aspect is a system including a conveyance vehicle and a work machine that loads materials onto the conveyance vehicle. The work machine includes a first position sensor and a first processor. The first position sensor detects a position of the work machine. The first processor acquires data indicative of the position of the work machine detected by the first position sensor. The first processor acquires data indicative of a target offset distance of the conveyance vehicle with respect to the work machine. The first processor determines a target stop position of the conveyance vehicle based on the position of the work machine and the target offset distance. The conveyance vehicle includes a communication device, a second position sensor, and a second processor. The communication device communicates with the work machine. The second position sensor detects a position of the conveyance vehicle. The second processor acquires data indicative of the target stop position from the work machine. The second processor controls the conveyance vehicle so as to move the conveyance vehicle to the target stop position. 
     A method according to a second aspect is a method executed by one or more processors in order to control a conveyance vehicle and a work machine that loads materials onto the conveyance vehicle. The method includes the following processes. A first process is to acquire data indicative of a position of the work machine. A second process is to acquire data indicative of a target offset distance of the conveyance vehicle with respect to the work machine. A third process is to determine a target stop position of the conveyance vehicle based on the position of the work machine and the target offset distance. A fourth process is to acquire data indicative of a position of the conveyance vehicle. A fifth process is to control the conveyance vehicle so as to move the conveyance vehicle to the target stop position. 
     A work machine according to a third aspect is a work machine including a first position sensor, a first processor, and a communication device. The first position sensor detects a position of the work machine. The first processor acquires data indicative of the position of the work machine detected by the first position sensor. The first processor acquires data indicative of a target offset distance of a conveyance vehicle with respect to the work machine. The first processor determines a target stop position of the conveyance vehicle based on the position of the work machine and the target offset distance. The communication device transmits the target stop position to the conveyance vehicle. 
     According to the present invention, the target stop position of the conveyance vehicle is determined based on the position of the work machine and the target offset distance. Further, the conveyance vehicle is controlled so as to move to the target stop position. As a result, it is possible to perform loading work onto the conveyance vehicle by the work machine with the automatic control and appropriately coordinate the work machine and the conveyance vehicle. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view illustrating an example of a work site where a work machine and a conveyance vehicle are used. 
         FIG. 2  is a side view of the work machine. 
         FIG. 3  is a block diagram illustrating a configuration of the work machine. 
         FIG. 4  is a side view of the conveyance vehicle. 
         FIG. 5  is a block diagram illustrating a configuration of the conveyance vehicle. 
         FIG. 6  is a flowchart illustrating a process of automatic control of the work machine. 
         FIG. 7  is a flowchart illustrating a process of automatic control of the work machine. 
         FIG. 8  is a flowchart illustrating a process of automatic control of the conveyance vehicle. 
         FIG. 9  is a flowchart illustrating a process of automatic control of the conveyance vehicle. 
         FIG. 10  is a plan view schematically illustrating conditions of the work site in an automatic control mode. 
         FIG. 11  is a plan view schematically illustrating conditions of the work site in the automatic control mode. 
         FIG. 12  is a plan view schematically illustrating conditions of the work site in the automatic control mode. 
         FIG. 13  is a plan view schematically illustrating conditions of the work site in the automatic control mode. 
         FIG. 14  is a plan view illustrating an example of an allowable stop range. 
         FIG. 15  is a plan view illustrating adjustment to a rotation angle of a bed of the conveyance vehicle. 
         FIG. 16  is a plan view illustrating an example of a current topography and a digging path. 
         FIG. 17  is a side view illustrating an example of a cross section of the current topography and the digging path. 
         FIG. 18  is a plan view schematically illustrating conditions of the work site in the automatic control mode. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENT(S) 
     A control system of a work machine and a conveyance vehicle according to an embodiment will now be described with reference to the drawings.  FIG. 1  is a plan view illustrating an example of a work site where a work machine  1  and a conveyance vehicle  2  according to the embodiment are used. The work machine  1  and the conveyance vehicle  2  are disposed at the work site. The work machine  1  and the conveyance vehicle  2  perform work in cooperation with each other under automatic control. 
     In the present embodiment, the work machine  1  is a hydraulic excavator. The conveyance vehicle  2  is a dump truck. The work machine  1  is disposed beside a predetermined digging position L 1  in the work site. The conveyance vehicle  2  travels back and forth between a predetermined loading position L 2  and a predetermined dumping position L 3  in the work site. The work machine  1  digs the digging position L 1  with automatic control and loads materials such as soil and the like as an object to be dug onto the conveyance vehicle  2  that is stopped at the loading position L 2 . The conveyance vehicle  2  loaded with the materials travels to the dumping position L 3  and unloads the materials at the dumping position L 3 . Another work machine  3  such as a bulldozer is disposed at the dumping position L 3  and spreads the materials unloaded at the dumping position L 3 . The conveyance vehicle  2  that has unloaded the materials travels to the loading position L 2 , and the work machine  1  again loads the materials onto the conveyance vehicle  2  that is stopped at the loading position L 2 . The materials of the digging position L 1  are transported to the dumping position L 3  by repeating the above work. 
       FIG. 2  is a side view of the work machine  1 . As illustrated in  FIG. 2 , the work machine  1  includes a vehicle body  11  and a work implement  12 . The vehicle body  11  includes a rotating body  13  and a support body  14 . The rotating body  13  is rotatably attached to the support body  14 . A cab  15  is disposed on the rotating body  13 . However, the cab  15  may be omitted. The support body  14  includes crawler belts  16 . The crawler belts  16  are driven by driving force of an engine  24  described later, whereby the work machine  1  travels. 
     The work implement  12  is attached to the front part of the vehicle body  11 . The work implement  12  includes a boom  17 , an arm  18 , and a bucket  19 . The boom  17  is attached to the rotating body  13  so as to allow movement in the up and down direction. The arm  18  is movably attached to the boom  17 . The bucket  19  is movably attached to the arm  18 . The work implement  12  includes a boom cylinder  21 , an arm cylinder  22 , and a bucket cylinder  23 . The boom cylinder  21 , the arm cylinder  22 , and the bucket cylinder  23  are hydraulic cylinders and are driven by hydraulic fluid supplied from a hydraulic pump  25  described later. The boom cylinder  21  actuates the boom  17 . The arm cylinder  22  actuates the arm  18 . The bucket cylinder  23  actuates the bucket  19 . 
       FIG. 3  is a block diagram illustrating a configuration of a control system of the work machine  1 . As illustrated in  FIG. 3 , the work machine  1  includes an engine  24 , a hydraulic pump  25 , a power transmission device  26 , and a controller  27 . 
     The engine  24  is controlled by command signals from the controller  27 . The hydraulic pump  25  is driven by the engine  24  to discharge hydraulic fluid. The hydraulic fluid discharged from the hydraulic pump  25  is supplied to the boom cylinder  21 , the arm cylinder  22 , and the bucket cylinder  23 . 
     The work machine  1  includes a rotation motor  28 . The rotation motor  28  is a hydraulic motor and is driven by hydraulic fluid from the hydraulic pump  25 . The rotation motor  28  rotates the rotating body  13 . The hydraulic pump  25  is a variable displacement pump. Although one hydraulic pump  25  is illustrated in  FIG. 3 , a plurality of hydraulic pumps may be included. A pump control device  29  is connected to the hydraulic pump  25 . The pump control device  29  controls the inclination angle of the hydraulic pump  25 . The pump control device  29  includes, for example, an electromagnetic valve and is controlled by command signals from the controller  27 . The controller  27  controls the displacement of the hydraulic pump  25  by controlling the pump control device  29 . 
     The hydraulic pump  25 , the cylinders  21  to  23 , and the rotation motor  28  are connected to each other by means of a hydraulic circuit via a control valve  31 . The control valve  31  is controlled by command signals from the controller  27 . The control valve  31  controls the flow rate of hydraulic fluid supplied from the hydraulic pump  25  to the cylinders  21  to  23  and the rotation motor  28 . The controller  27  controls the operation of the work implement  12  by controlling the control valve  31 . The controller  27  also controls the rotation of the rotating body  13  by controlling the control valve  31 . 
     The power transmission device  26  transmits driving force of the engine  24  to the support body  14 . The power transmission device  26  may be, for example, a torque converter or a transmission having a plurality of transmission gears. Alternatively, the power transmission device  26  may be another type of transmission such as a hydro static transmission (HST) or a hydraulic mechanical transmission (HMT). 
     The controller  27  is programmed so as to control the work machine  1  based on acquired data. The controller  27  causes the work machine  1  to travel by controlling the engine  24 , the support body  14 , and the power transmission device  26 . The controller  27  causes the work implement  12  to operate by controlling the engine  24 , the hydraulic pump  25 , and the control valve  31 . 
     The controller  27  includes a first processor  271  such as a CPU or a GPU, and a memory  272 . The first processor  271  performs a process for automatic control of the work machine  1 . The memory  272  stores data and programs for the automatic control of the work machine  1 . For example, the memory  272  includes a volatile memory and a non-volatile memory. 
     The work machine  1  includes load sensors  32   a  to  32   c . The load sensors  32   a  to  32   c  detect a load applied to the work implement  12  and output load data indicative of the load. In the present embodiment, the load sensors  32   a  to  32   c  are hydraulic pressure sensors and detect each hydraulic pressure of the cylinders  21  to  23 . The load data indicates the hydraulic pressures of the cylinders  21  to  23 . The controller  27  is communicatably connected to the load sensors  32   a  to  32   c  by wire or wirelessly. The controller  27  receives the load data from the load sensors  32   a  to  32   c.    
     The work machine  1  includes a first position sensor  33 , work implement sensors  34   a  to  34   c , and a rotation angle sensor  39 . The first position sensor  33  detects a position of the work machine  1  and outputs position data indicative of the position of the work machine  1 . The first position sensor  33  includes a global navigation satellite system (GNSS) receiver and an inertial measurement unit (IMU). The GNSS receiver is, for example, a receiver for a global positioning system (GPS). The position data includes data indicative of the position of the work machine  1  output by the GNSS receiver and data indicative of a posture of the vehicle body  11  output by the IMU. The posture of the vehicle body  11 , for example, includes an angle (pitch angle) with respect to the horizontal in the longitudinal direction of the work machine  1  and an angle (roll angle) with respect to the horizontal in the lateral direction of the work machine  1 . 
     The work implement sensors  34   a  to  34   c  detects a posture of the work implement  12  and output posture data indicative of the posture of the work implement  12 . The work implement sensors  34   a  to  34   c  are, for example, stroke sensors that detect the stroke amounts of the cylinders  21  to  23 . The posture data of the work implement  12  includes the stroke amounts of the cylinders  21  to  23 . Alternatively, the work implement sensors  34   a  to  34   c  may be other sensors such as sensors that detect each rotation angle of the boom  17 , the arm  18 , and the bucket  19 . The rotation angle sensor  39  detects the rotation angle of the rotating body  13  with respect to the support body  14  and outputs rotation angle data indicative of the rotation angle. 
     The controller  27  is communicatably connected to the first position sensor  33 , the work implement sensors  34   a  to  34   c , and the rotation angle sensor  39  by wire or wirelessly. The controller  27  receives the position data of the work machine  1 , the posture data of the work implement  12 , and the rotation angle data from the first position sensor  33 , the work implement sensors  34   a  to  34   c , and the rotation angle sensor  39 , respectively. The controller  27  calculates a blade tip position of the bucket  19  from the position data, the posture data, and the rotation angle data. For example, the position data of the work machine  1  indicates the global coordinates of the first position sensor  33 . The controller  27  calculates the global coordinates of the blade tip position of the bucket  19  from the global coordinates of the first position sensor  33  based on the posture data of the work implement  12  and the rotation angle data. 
     The work machine  1  includes a topography sensor  35 . The topography sensor  35  measures a topography at the surroundings of the work machine  1  and outputs topography data indicative of the topography measured by the topography sensor  35 . In the present embodiment, the topography sensor  35  is attached to a side part of the rotating body  13 . The topography sensor  35  measures the topography located to the side of the rotating body  13 . The topography sensor  35  is, for example, a laser imaging detection and ranging (LIDAR) device. The LIDAR device measures distances to a plurality of measurement points on the topography by irradiating a laser and measuring the reflected light thereof. The topography data indicates the positions of the measurement points with respect to the work machine  1 . 
     The work machine  1  includes a first camera  36  and a plurality of the second cameras  37 . The first camera  36  is facing forward from the rotating body  13  and is attached to the rotating body  13 . The first camera  36  captures toward the front of the rotating body  13 . The first camera  36  is a stereo camera. The first camera  36  outputs first image data indicative of the captured moving images. 
     The plurality of second cameras  37  are facing left, right, and rear from the rotating body  13  and are attached to the rotating body  13 . The second cameras  37  output second image data indicative of the captured moving images. The second cameras  37  may be single-lens cameras. Alternatively, the second cameras  37  may be stereo cameras in the same way as the first camera  36 . The controller  27  is communicatably connected to the first camera  36  and the second cameras  37  by wire or wirelessly. The controller  27  receives the first image data from the first camera  36 . The controller  27  receives the second image data from the second cameras  37 . 
     The work machine  1  includes a first communication device  38 . The first communication device  38  performs data communication with a device outside the work machine  1 . The first communication device  38  communicates with a remote computer device  4  outside the work machine  1 . The remote computer device  4  may be disposed at the work site. Alternatively, the remote computer device  4  may be disposed at a management center remote from the work site. The remote computer device  4  includes a display  401  and an input device  402 . 
     The display  401  displays images related to the work machine  1 . The display  401  displays images corresponding to signals received from the controller  27  via the first communication device  38 . The input device  402  is operated by an operator. The input device  402  may include, for example, a touch screen or may include hardware keys. The remote computer device  4  transmits signals indicative of commands input by the input device  402  to the controller  27  via the first communication device  38 . The first communication device  38  also performs data communication with the conveyance vehicle  2 . 
       FIG. 4  is a side view of the conveyance vehicle  2 . As illustrated in  FIG. 4 , the conveyance vehicle  2  includes a vehicle body  51 , a traveling body  52 , and a bed  53 . The vehicle body  51  is rotatably supported with respect to the traveling body  52 . The traveling body  52  includes crawler belts  54 . The crawler belts  54  are driven by driving force from an engine  55  described later, whereby the conveyance vehicle  2  travels. The bed  53  is supported by the vehicle body  51 . Accordingly, the bed  53  is supported so as to be rotatable together with the vehicle body  51  with respect to the traveling body  52 . The bed  53  is configured to move between a dumping posture and a conveying posture. In  FIG. 4 , the bed  53  indicated by solid lines indicates the position of the bed  53  in the conveying posture. A bed  53 ′ indicated by chain double-dashed lines indicates the position of the bed  53  in the dumping posture. In the conveying posture, the bed  53  is disposed approximately horizontally. In the dumping posture, the bed  53  is inclined with respect to the conveying posture. 
       FIG. 5  is a block diagram illustrating a configuration of a control system of the conveyance vehicle  2 . The conveyance vehicle  2  includes an engine  55 , a hydraulic pump  56 , a power transmission device  57 , a lift cylinder  58 , a rotation motor  59 , a controller  61 , and a control valve  62 . The controller  61  includes a second processor  611  such as a CPU or a GPU, and a memory  612 . The second processor  611  performs a process for automatic control of the conveyance vehicle  2 . The memory  612  stores data and programs for the automatic control of the conveyance vehicle  2 . For example, the memory  612  includes a volatile memory and a non-volatile memory. 
     The engine  55 , the hydraulic pump  56 , the power transmission device  57 , the controller  61 , and the control valve  62  have the same configurations as the engine  24 , the hydraulic pump  25 , the power transmission device  26 , the controller  27 , and the control valve  31  of the work machine  1 , respectively. Therefore, detailed explanations thereof are omitted. 
     The lift cylinder  58  is a hydraulic cylinder. The rotation motor  59  is a hydraulic motor. Hydraulic fluid discharged from the hydraulic pump  56  is supplied to the lift cylinder  58  and the rotation motor  59 . The lift cylinder  58  and the rotation motor  59  are driven by the hydraulic fluid from the hydraulic pump  56 . The lift cylinder  58  raises and lowers the bed  53 . Consequently, the posture of the bed  53  is switched between the conveying posture and the dumping posture. The rotation motor  59  causes the vehicle body  51  to rotate with respect to the traveling body  52 . The controller  61  controls the lift cylinder  58  by means of the control valve  62 , thereby controlling the operation of the bed  53 . In addition, the controller  61  controls the rotation motor  59  by means of the control valve  62 , thereby controlling the rotation of the vehicle body  51 . 
     The conveyance vehicle  2  includes a second position sensor  63 , a bed sensor  64 , and a rotation angle sensor  65 . The second position sensor  63  includes a GNSS receiver and an IMU in the same way as the first position sensor  33  of the work machine  1 . The second position sensor  63  outputs position data. The position data includes data indicative of a position of the conveyance vehicle  2  and data indicative of a posture of the vehicle body  51 . 
     The bed sensor  64  detects the posture of the bed  53  and outputs bed data indicative of the posture of the bed  53 . The bed sensor  64  is, for example, a stroke sensor that detects the stroke amount of the lift cylinder  58 . The bed data includes the stroke amount of the lift cylinder  58 . Alternatively, the bed sensor  64  may be another type of sensor such as a sensor that detects an inclination angle of the bed  53 . The rotation angle sensor  65  detects the rotation angle of the vehicle body  51  with respect to the traveling body  52  and outputs rotation angle data indicative of the rotation angle. 
     The controller  61  is communicatably connected to the second position sensor  63 , the bed sensor  64 , and the rotation angle sensor  65  by wire or wirelessly. The controller  61  receives the position data, the bed data, and the rotation angle data from the second position sensor  63 , the bed sensor  64 , and the rotation angle sensor  65 , respectively. 
     The conveyance vehicle  2  includes a second communication device  66 . The controller  61  of the conveyance vehicle  2  performs data communication with the controller  27  of the work machine  1  via the second communication device  66 . The controller  61  of the conveyance vehicle  2  transmits the position data of the conveyance vehicle  2 , the bed data, and the rotation angle data via the second communication device  66 . The controller  27  of the work machine  1  receives the position data of the conveyance vehicle  2 , the bed data, and the rotation angle data via the first communication device  38 . The controller  27  of the work machine  1  stores vehicle dimension data indicative of the dispositions and the dimensions of the vehicle body  51  of the conveyance vehicle  2  and the bed  53 . The controller  27  calculates a position of the bed  53  from the position data of the conveyance vehicle  2 , the bed data, the rotation angle data, and the vehicle dimension data. 
     Next, a process of an automatic control mode executed by the controller  27  of the work machine  1  and the controller  61  of the conveyance vehicle  2  will be described. In the automatic control mode, the controller  61  of the conveyance vehicle  2  controls the conveyance vehicle  2  so that the conveyance vehicle  2  automatically travels back and forth between the loading position L 2  and the predetermined dumping position L 3 . The controller  27  of the work machine  1  controls the work machine  1  so that the work machine  1  automatically performs the digging and loading work described above.  FIGS. 6 and 7  are flowcharts illustrating the process of the automatic control mode executed by the controller  27  of the work machine  1 .  FIGS. 8 and 9  are flowcharts illustrating the process of the automatic control mode executed by the controller  61  of the conveyance vehicle  2 . 
     Upon receiving a start command for starting the automatic control mode, the controller  27  of the work machine  1  executes the process of the automatic control mode illustrated in  FIG. 6 . As illustrated in  FIG. 10 , the start command for starting the automatic control mode is output from the abovementioned remote computer device  4  due to, for example, the operator operating the input device  402  of the remote computer device  4 . The controller  27  receives the start command via the first communication device  38 . The controller  61  of the conveyance vehicle  2  also receives the start command for starting the automatic control mode. Upon receiving the start command for starting the automatic control mode, the controller  61  of the conveyance vehicle  2  executes the process of the automatic control mode illustrated in  FIG. 8 . 
     In step S 101 , the controller  27  of the work machine  1  acquires the position of the work machine  1  as illustrated in  FIG. 6 . Here, the controller  27  acquires the position data of the work machine  1 , the posture data of the work implement  12 , and the rotation angle data from the first position sensor  33 , the work implement sensors  34   a  to  34   c , and the rotation angle sensor  39 , respectively. The controller  27  calculates the blade tip position of the bucket  19  from the position data, the work implement data, and the rotation angle data. The controller  27  continuously acquires and updates the position of the work machine  1  during the automatic control mode. 
     In step S 102 , the controller  27  determines a target stop position P 1  in the loading position L 2  of the conveyance vehicle  2  based on the position of the work machine  1 . Specifically, the controller  27  acquires data indicative of the direction of the loading position L 2  with respect to the work machine  1 . The controller  27  acquires the direction of the loading position L 2  with respect to the work machine  1  by calculation from the position of the work machine  1  and the loading position L 2 . Further, the controller  27  acquires data indicative of a target offset distance of the conveyance vehicle  2  with respect to the work machine  1 . For example, the target offset distance is stored in the memory  272 , and the controller  27  reads the target offset distance from the memory  272 . The controller  27  determines the target stop position P 1  of the conveyance vehicle  2  based on the direction of the loading position L 2 , the target offset distance, and the position of the work machine  1 . For example, the controller  27  determines, as the target stop position P 1  of the conveyance vehicle  2 , a position that is away from the position of the work machine  1  toward the direction of the loading position L 2  by the target offset distance. 
     In step S 103 , the controller  27  determines an allowable stop range A 1  of the conveyance vehicle  2 . As illustrated in  FIG. 10 , the allowable stop range A 1  is a range positioned in the direction of the loading position L 2  with respect to the work machine  1 , and includes the target stop position P 1 . The controller  27  determines the allowable stop range A 1  from the position of the work machine  1 . The allowable stop range A 1  will be described later. 
     In step S 104 , the controller  27  communicates with the conveyance vehicle  2 . Here, the controller  27  transmits the target stop position P 1  to the conveyance vehicle  2 . In step S 201 , the controller  61  of the conveyance vehicle  2  communicates with the work machine  1  as illustrated in  FIG. 8 . Here, the controller  61  of the conveyance vehicle  2  receives the target stop position P 1  transmitted by the controller  27  of the work machine  1  via the second communication device  66 . 
     In step S 202 , the controller  61  acquires the position of the conveyance vehicle  2 . Here, the controller  27  acquires the position data of the conveyance vehicle  2 , the bed data, and the rotation angle data from the second position sensor  63 , the bed sensor  64 , and the rotation angle sensor  65 , respectively. The controller  61  continuously acquires and updates the position of the conveyance vehicle  2  during the automatic control mode. 
     In step S 203 , the controller  61  acquires area data. The area data includes data indicative of the topography of the work site. The area data also includes data indicative of entry prohibition areas A 2  and A 3  of the conveyance vehicle  2  illustrated in  FIG. 11 . 
     In step S 204 , the controller  61  determines a target travel route R 1 . The target travel route R 1  is a route from a current position of the conveyance vehicle  2  to the target stop position P 1 . The controller  61  determines the target travel route R 1  from the abovementioned area data, the position data of the conveyance vehicle  2 , and the target stop position P 1 . The controller  61  determines the target travel route R 1  so as to avoid the entry prohibition areas A 2  and A 3 . For example, the controller  61  determines the target travel route R 1  so as to avoid the entry prohibition areas A 2  and A 3  and to minimize the moving distance of the conveyance vehicle  2 . The controller  61  may determine the target travel route R 1  in consideration of a factor other than the entry prohibition areas A 2  and A 3 . 
     In step S 205 , the controller  61  causes the conveyance vehicle  2  to start moving. The controller  61  controls the conveyance vehicle  2  so that the conveyance vehicle  2  moves along the target travel route R 1  to the target stop position P 1 . 
     In step S 206  illustrated in  FIG. 9 , the controller  61  determines whether the conveyance vehicle  2  is positioned in the entry prohibition area A 2  or A 3 . The controller  61  determines whether the conveyance vehicle  2  is positioned in the entry prohibition area A 2  or A 3  from the abovementioned current position of the conveyance vehicle  2  indicated by the position data of the conveyance vehicle  2  and the entry prohibition areas A 2  and A 3  indicated by the area data. 
     When the conveyance vehicle  2  is positioned in the entry prohibition area A 2  or A 3 , the controller  61  transmits a stop command for stopping the automatic control to the work machine  1  in step S 214 . In step S 215 , the controller  61  stops the work of the conveyance vehicle  2 . For example, the controller  61  causes the conveyance vehicle  2  to stop. Alternatively, the controller  61  may cause the conveyance vehicle  2  to return to the dumping position L 3 . 
     As illustrated in  FIG. 7 , upon receiving the stop command for stopping the automatic control from the conveyance vehicle  2  in step S 105 , the controller  27  of the work machine  1  stops the work of the work machine  1  in step S 111 . For example, the controller  61  causes the work machine  1  to stop. 
     As illustrated in  FIG. 9 , in step S 207 , the controller  61  determines whether a deviation distance D 1  is greater than a predetermined threshold Th 1 . As illustrated in  FIG. 12 , the deviation distance D 1  is a distance that the conveyance vehicle  2  is deviated from the target travel route R 1 . The controller  61  calculates the deviation distance D 1  from the abovementioned current position of the conveyance vehicle  2  indicated by the position data of the conveyance vehicle  2  and the target travel route R 1 . The predetermined threshold Th 1  is stored in the memory  612 , for example. When the deviation distance D 1  is greater than the predetermined threshold Th 1 , similarly to the mentioned above, the controller  61  transmits the stop command for stopping the automatic control to the work machine  1  in step S 214 . In step S 215 , the controller  61  stops the work. 
     In step S 208 , the controller  61  determines whether the conveyance vehicle  2  has reached the target stop position P 1 . The controller  61  determines whether the conveyance vehicle  2  has reached the target stop position P 1  from the abovementioned current position of the conveyance vehicle  2  indicated by the position data of the conveyance vehicle  2  and the target stop position P 1 . For example, the controller  27  determines that the conveyance vehicle  2  has reached the target stop position P 1  when the position of a reference point P 2  included in the conveyance vehicle  2  matches or substantially matches the target stop position P 1 . For example, the reference point P 2  of the conveyance vehicle  2  is a rotation center of the bed  53 . However, the reference point P 2  of the conveyance vehicle  2  may be another position of the conveyance vehicle  2 . For example, the reference point P 2  of the conveyance vehicle  2  may be a center point in the longitudinal direction and the width direction of the conveyance vehicle  2 . As illustrated in  FIG. 13 , when the conveyance vehicle  2  has reached the target stop position P 1 , the controller  61  causes the conveyance vehicle  2  to stop in step S 209 . 
     As illustrated in  FIG. 7 , in step S 106 , the controller  27  of the work machine  1  determines whether the conveyance vehicle  2  has stopped. For example, the controller  27  determines whether the conveyance vehicle  2  has stopped from the position data of the conveyance vehicle  2  received from the conveyance vehicle  2 . Alternatively, the controller may determine whether the conveyance vehicle  2  has stopped with image recognition technology based on the first image data output from the first camera  36  and/or the second image data output from the second cameras  37 . When the conveyance vehicle  2  has stopped, the process proceeds to step S 107 . 
     In step S 107 , the controller  27  determines whether the conveyance vehicle  2  is positioned in the allowable stop range A 1 . As described above, the allowable stop range A 1  is the range that includes the target stop position P 1 , and the controller  27  determines the allowable stop range A 1  from the position of the work machine  1 .  FIG. 14  is a view illustrating an example of the allowable stop range A 1 . The controller  27  determines the allowable stop range A 1  based on the digging position L 1  and the distance from the work machine  1 . 
     Specifically, as illustrated in  FIG. 14 , the allowable stop range A 1  is the range in which a distance from a rotation center C 1  of the rotating body  13  is equal to or less than a first distance threshold Td 1 . The allowable stop range A 1  is the range in which a distance from the rotation center C 1  of the rotating body  13  is equal to or greater than a second distance threshold Td 2 . For example, the first distance threshold Td 1  is the maximum value of the distance that the blade tip of the bucket  19  can reach. The second distance threshold Td 2  is the minimum value of the distance that the blade tip of the bucket  19  can reach. 
     The allowable stop range A 1  is the range in which an absolute value of the angle formed by a direction X 1  of the loading position L 2  with respect to the work machine  1  and a vector connecting any position in the allowable stop range A 1  and the rotation center C 1  is equal to or less than an angle threshold Tal. The support body  14  of the work machine  1  is disposed facing the direction X 1 . For example, the angle threshold Tal is a value within a range in which the topography sensor  35  can appropriately measure the topography of the digging position L 1  during the loading. In  FIG. 14 , the direction X 1  of the loading position L 2  with respect to the work machine  1  is zero degrees and the counterclockwise direction is a positive value. 
     When the reference point P 2  of the conveyance vehicle  2  is positioned in the allowable stop range A 1 , the controller  27  determines that the conveyance vehicle  2  is positioned in the allowable stop range A 1 . For example, the controller  27  determines that a position  2 _ 1  of the conveyance vehicle  2  indicated in  FIG. 14  is positioned in the allowable stop range A 1 . The controller  27  determines that a position  2 _ 2  and a position  2 _ 3  of the conveyance vehicle  2  indicated in  FIG. 14  are not positioned in the allowable stop range A 1 . 
     In step S 107 , when the conveyance vehicle  2  is not positioned in the allowable stop range A 1 , the process proceeds to step S 112 . In step S 112 , the controller  27  transmits a redo command to the conveyance vehicle  2 . As illustrated in  FIG. 9 , when the controller  61  of the conveyance vehicle  2  receives the redo command in step S 210 , the process returns to step S 205 , and the conveyance vehicle  2  again moves to the target stop position P 1 . 
     When the conveyance vehicle  2  is positioned in the allowable stop range A 1  in step S 107 , in step S 211 , the controller  61  of the conveyance vehicle  2  adjusts the rotation angle of the bed  53  while keeping the conveyance vehicle  2  stopped. The controller  61  determines the rotation angle of the bed  53  with respect to the traveling body  52  based on the position of the work machine  1  and the position of the conveyance vehicle  2 . Specifically, as illustrated in  FIG. 15 , the controller  61  determines the rotation angle of the bed  53  with respect to the traveling body  52  so that the bed  53  faces a straight line X 2  connecting a rotation center C 2  of the bed  53  and the rotation center C 1  of the work machine  1 , and causes the bed  53  to rotate. In other words, the controller  61  determines the rotation angle of the bed  53  with respect to the traveling body  52  so that the longitudinal direction of the bed  53  matches the direction of the straight line X 2  connecting the rotation center C 2  of the bed  53  and the rotation center C 1  of the work machine  1 , and causes the bed  53  to rotate. As a result, the rear end of the bed  53  is disposed facing the work machine  1  in the direction from the rotation center C 2  of the bed  53  toward the rotation center C 1  of the work machine  1 . 
     Upon finishing the adjustment of the rotation angle of the bed  53  of the conveyance vehicle  2 , the controller  27  of the work machine  1  starts digging materials and loading the materials onto the conveyance vehicle  2  in step S 108 . Here, the controller  27  acquires topography data indicative of a current topography T 1  of the digging position L 1  measured by the topography sensor  35 . The controller  27  determines a digging path PA 1  from the current position of the work machine  1  and the topography data. The digging path PA 1  is a target trajectory of the blade tip position of the bucket  19 .  FIG. 16  is a plan view illustrating an example of the current topography T 1  and the digging path PA 1 .  FIG. 17  is a side view illustrating an example of a cross section of the current topography T 1  and the digging path PA 1 . The controller  27  determines the digging path PA 1  so that the amount of the materials to be dug by the work implement  12  such as the volume or the weight matches a target value. 
     As illustrated in  FIG. 17 , the controller  27  determines the digging path PA 1  so that the volume between the surface of the current topography T 1  and the digging path PA 1  (the hatched portion in  FIG. 17 ) matches the target value. The target value is determined based on the capacity of the bucket  19 , for example. The digging path PA 1  includes a digging start point S 1  and a digging end point E 1 . The digging start point S 1  and the digging end point E 1  are intersections of the surface of the topography T 1  and the digging path PA 1 . 
     The controller  27  determines a target rotation angle at the time of down rotating. The controller  27  determines the target rotation angle at the time of the down rotating from a current blade tip position of the bucket  19  and a straight line X 3  connecting the rotation center C 1  of the work machine  1  and the digging start point S 1 . In the down rotating, the controller  27  causes the blade tip position of the bucket  19  to be lowered toward the height of the digging start point S 1 , while causing the rotating body  13  to be rotated toward the digging start point S 1 . Then, the controller  27  controls the work implement  12  so that the blade tip position of the bucket  19  moves along the digging path PA 1 . Accordingly, the materials are dug by the work implement  12 . 
     Further, the controller  27  determines a target rotation angle at the time of hoist rotating. The controller  27  determines the target rotation angle at the time of the hoist rotating from a current blade tip position of the bucket  19  after digging and the straight line X 2  connecting the rotation center C 1  of the work machine  1  and the rotation center C 2  of the bed  53 . In the hoist rotating, the controller  27  causes the blade tip position of the bucket  19  to be raised toward an unloading position P 3 , while causing the rotating body  13  to be rotated toward the unloading position P 3 . The unloading position P 3  is a position that is on the straight line X 2  connecting the rotation center C 1  of the work machine  1  and the rotation center C 2  of the bed  53  and is above the bed  53 . The controller  27  operates the work implement  12  so that the materials held by the bucket  19  are unloaded on the bed  53 . As a result, the materials are loaded onto the bed  53 . 
     In step S 109  illustrated in  FIG. 7 , the controller  27  determines whether the loading is finished. The controller  27  determines that the loading is finished when the amount of the materials loaded onto the bed  53  (hereinafter, referred to as “loading amount”) reaches an allowable amount. The loading amount may be a volume or a weight. The controller  27  calculates the loading amount from the load data. Specifically, the controller  27  calculates the amount of the dug materials from the load data. The controller  27  calculates the total value of the amount of the materials loaded onto the bed  53  as the loading amount. 
     When the controller  27  determines that the loading is not finished in step S 109 , the digging of the materials and the loading thereof onto the conveyance vehicle  2  are performed again. The digging of the materials and the loading thereof onto the conveyance vehicle  2  are repeated until it is determined that the loading is finished. When the controller  27  determines that the loading is finished in step S 109 , the process proceeds to step S 110 . In step S 110 , the controller  27  transmits a withdraw command for withdrawing from the loading position L 2  to the conveyance vehicle  2  as illustrated in  FIG. 18 . 
     As illustrated in  FIG. 9 , in step S 212 , the controller  61  of the conveyance vehicle  2  determines whether a withdraw command is received. When the controller  61  receives the withdraw command, the process proceeds to step S 213 . In step S 213 , the controller  61  controls the conveyance vehicle  2  to start moving from the loading position L 2  toward the dumping position L 3 . 
     With the control system according to the present embodiment described above, the target stop position P 1  of the conveyance vehicle  2  is determined based on the position of the work machine  1 . Then, the conveyance vehicle  2  is controlled to move to the target stop position P 1 . As a result, it is possible to perform the loading work onto the conveyance vehicle  2  by the work machine  1  with the automatic control and to appropriately coordinate the work machine  1  and the conveyance vehicle  2 . 
     When the stop position of the conveyance vehicle  2  is in the allowable stop range A 1 , the controller  27  of the work machine  1  starts loading the materials onto the conveyance vehicle  2 . Therefore, even if the position of the conveyance vehicle  2  is slightly deviated from the target stop position P 1 , it is possible to start loading the materials. When the position of the conveyance vehicle  2  is greatly deviated from the target stop position P 1 , the loading is not performed. Accordingly, the loading work onto the conveyance vehicle  2  by the work machine  1  can be performed efficiently. 
     When the conveyance vehicle  2  is positioned in the entry prohibition area A 2  or A 3 , the controller  61  of the conveyance vehicle  2  transmits, to the work machine  1 , the stop command for stopping the automatic control by the work machine  1 . When the deviation distance D 1  of the conveyance vehicle  2  from the target travel route R 1  is greater than the predetermined threshold ml, the controller  61  transmits, to the work machine  1 , the stop command for stopping the automatic control by the work machine  1 . Accordingly, it is possible to quickly stop the automatic control when the movement of the conveyance vehicle  2  is not performed appropriately. 
     The controller  61  of the conveyance vehicle  2  controls the rotation angle of the bed  53  with respect to the traveling body  52  based on the position of the work machine  1  and the position of the conveyance vehicle  2 . As a result, the loading work of the materials onto the conveyance vehicle  2  by the work machine  1  can be easily performed. 
     Although an embodiment of the present invention has been described so far, the present invention is not limited to the above embodiment and various modifications may be made within the scope of the invention. 
     The work machine  1  is not limited to a hydraulic excavator and may be another machine such as a wheel loader, a motor grader, or the like. The configuration of the work machine  1  is not limited to that of the above embodiment and may be changed. The work machine  1  may be a vehicle driven by an electric motor. For example, the support body  14  and/or the rotating body  13  may be driven by the electric motor. The configuration of the work implement  12  may be changed. For example, the work implement  12  is not limited to the bucket  19  and may include another loading attachment such as a grapple, a fork, a lifting magnet, or the like. 
     The conveyance vehicle  2  may be a vehicle other than the dump truck. The configuration of the conveyance vehicle  2  is not limited to that of the above embodiment and may be changed. For example, the conveyance vehicle  2  may be a vehicle driven by an electric motor. For example, the traveling body  52  and/or the bed  53  may be driven by the electric motor. The bed  53  of the conveyance vehicle  2  may not be rotatable. The traveling body  52  of the conveyance vehicle  2  may include tires instead of the crawler belts. 
     The configurations of the sensors included in the work machine  1  and the conveyance vehicle  2  are not limited to those of the above embodiment and may be changed. For example, the topography sensor  35  may be disposed in a part other than the side part of the rotating body  13 . The topography sensor  35  is not limited to the LIDAR device and may be another sensing device such as a radar device or the like. Alternatively, the topography sensor  35  may be a camera and the controller  27  may recognize the topography by analyzing the images captured by the camera. 
     In the above embodiment, the controller  27  calculates the loading amount with the load data detected by the load sensors  32   a  to  32   c . However, the controller  27  may calculate the loading amount based on the images of the bed  53  indicated by the first image data. 
     The controller  27  of the work machine  1  is not limited to one unit and may be divided into a plurality of controllers. The process executed by the controller  27  may be distributed and executed among the plurality of controllers. In such a case, a portion of the plurality of controllers may be disposed outside the work machine  1 . 
     The controller  61  of the conveyance vehicle  2  is not limited to one unit and may be divided into a plurality of controllers. The process executed by the controller  61  may be distributed and executed among the plurality of controllers. In such a case, a portion of the plurality of controllers may be disposed outside the conveyance vehicle  2 . 
     The controller  27  of the work machine  1  and the controller  61  of the conveyance vehicle  2  may communicate with each other via another controller instead of directly communicating with each other. The process of the automatic control mode executed by the controller  27  is not limited to that of the aforementioned embodiment and may be changed. 
     For example, the process of determining the target stop position P 1  may be executed by a remote controller disposed outside the work machine  1  and the conveyance vehicle  2  or by the controller  61  of the conveyance vehicle  2 . The process of determining the allowable stop range A 1  may be executed by the remote controller or the controller  61  of the conveyance vehicle  2 . The determination as to whether the conveyance vehicle  2  is positioned in the entry prohibition area A 2  or A 3  may be performed by the remote controller or the controller  27  of the work machine  1 . The determination as to whether the deviation distance D 1  of the conveyance vehicle  2  from the target travel route R 1  is greater than the predetermined threshold may be executed by the remote controller or the controller  27  of the work machine  1 . The determination of the target rotation angle of the bed  53  may be executed by the remote controller or the controller  27  of the work machine  1 . 
     In the above embodiment, the target stop position is given from the work machine  1  to the conveyance vehicle  2 . In addition to the target stop position, information related to a stop direction of the conveyance vehicle  2  may be given to the conveyance vehicle  2 . Since the bucket  19  of the work machine  1  moves between the digging position L 1  and the target stop position P 1  by the rotating operation, it is preferable that the front part of the conveyance vehicle  2  is not present in the moving range of the bucket  19 . Thus, giving the stop direction of the conveyance vehicle  2  to the conveyance vehicle  2  in advance to appropriately stop the conveyance vehicle  2  can reduce the influence on the loading operation by the conveyance vehicle  2 . This is particularly effective for the conveyance vehicle  2  including a stationary bed that does not rotate. 
     According to the present invention, it is possible to perform the loading work onto the conveyance vehicle by the work machine with the automatic control and appropriately coordinate the work machine and the conveyance vehicle.