Patent Publication Number: US-2020291606-A1

Title: Shovel

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of International Application No. PCT/JP2018/045181 filed on Dec. 7, 2018, and designated the U.S., which is based upon and claims priority to Japanese Patent Application No. 2017-235556, filed on Dec. 7, 2017, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a shovel. 
     2. Description of the Related Art 
     A shovel that enables an operator to recognize whether a shovel faces a target construction surface, such as a slope, straight, has been known. The shovel displays an image representing an extending direction of the target construction surface or a direction perpendicular to the extending direction of the target construction surface, superimposed on a camera image, so as to enable the operator to recognize whether the shovel faces the target construction surface straight. The camera image is an overhead image generated by combining images obtained by multiple cameras mounted to the shovel. 
     SUMMARY 
     According to one aspect of an embodiment, a shovel includes a lower traveling body, an upper swiveling body that is rotatably mounted on the lower traveling body, and a controller configured to perform straight facing control by which an actuator is operated to cause the upper swiveling body to face a target construction surface straight, based on information related to the target construction surface and information related to a direction of the upper swiveling body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a shovel according to an embodiment of the present invention; 
         FIG. 2  is a block diagram illustrating a configuration example of a driving system of the shovel of  FIG. 1 ; 
         FIG. 3  is a schematic diagram illustrating a configuration example of a hydraulic system mounted to the shovel of  FIG. 1 ; 
         FIG. 4A  is a diagram of a part extracted from the hydraulic system mounted to the shovel of  FIG. 1 ; 
         FIG. 4B  is a diagram of a part extracted from the hydraulic system mounted to the shovel of  FIG. 1 ; 
         FIG. 4C  is a diagram of a part extracted from the hydraulic system mounted to the shovel of  FIG. 1 ; 
         FIG. 5  is a block diagram illustrating another configuration example of a driving system of the shovel of  FIG. 1 ; 
         FIG. 6  is a flowchart of a straight facing process; 
         FIG. 7A  is a top view of the shovel when the straight facing process is performed; 
         FIG. 7B  is a top view of the shovel when the straight facing process is performed; 
         FIG. 8A  is a perspective view of the shovel when the straight facing process is performed; 
         FIG. 8B  is a perspective view of the shovel when the straight facing process is performed; 
         FIG. 9A  is a top view of the shovel when the straight facing process is performed; 
         FIG. 9B  is a top view of the shovel when the straight facing process is performed; and 
         FIG. 10  is a diagram illustrating a configuration example of an operation system including an electric operation device. 
     
    
    
     DETAILED DESCRIPTION 
     The above-described shovel only enables the operator to recognize whether the shovel faces the target construction surface straight. Thus, when the shovel does not face the target construction surface straight, the operator who wants the shovel to face the target construction surface straight needs to perform a swiveling operation. In this point, the above-described shovel might annoy the operator. 
     Therefore, it is desired to provide a shovel that can reduce annoyance at causing the shovel to face the target construction surface straight. 
       FIG. 1  is a side view of a shovel  100  as an excavator according to an embodiment of the present invention. An upper swiveling body  3  is rotatably mounted on a lower traveling body  1  of the shovel  100  through a swiveling mechanism  2 . A boom  4  is attached to the upper swiveling body  3 . An arm  5  is attached to a front end of the boom  4 , and a bucket  6  as an end attachment is attached to a front end of the arm  5 . 
     The boom  4 , the arm  5 , and the bucket  6  form an excavation attachment as an example of the attachment. The boom  4  is driven by a boom cylinder  7 , the arm  5  is driven by an arm cylinder  8 , and the bucket  6  is driven by a bucket cylinder  9 . A boom angle sensor S 1  is mounted to the boom  4 , an arm angle sensor S 2  is mounted to the arm  5 , and a bucket angle sensor S 3  is mounted to the bucket  6 . 
     The boom angle sensor S 1  is configured to detect the rotation angle of the boom  4 . In the present embodiment, the boom angle sensor S 1  is an acceleration sensor, and the rotation angle of the boom  4  with respect to the upper swiveling body  3  (which will be hereinafter referred to as the “boom angle”) can be detected. The boom angle is, for example, the minimum angle when the boom  4  is moved down at a lowest position and the boom angle increases as the boom  4  is raised. 
     The arm angle sensor S 2  is configured to detect the rotation angle of the arm  5 . In the present embodiment, the arm angle sensor S 2  is an acceleration sensor, and the rotation angle of the arm  5  with respect to the boom  4  (which will be hereinafter referred to as the “arm angle”) can be detected. The arm angle is, for example, the minimum angle when the arm  5  is closed at most and the arm angle increases as the arm  5  is opened. 
     The bucket angle sensor S 3  is configured to detect the rotation angle of the bucket  6 . In the present embodiment, the bucket angle sensor S 3  is an acceleration sensor, and the rotation angle of the bucket  6  with respect to the arm  5  (which will be hereinafter referred to as the “bucket angle”) can be detected. The bucket angle is, for example, the minimum angle when the bucket  6  is closed at most and increases as the bucket  6  is opened. 
     The boom angle sensor S 1 , the arm angle sensor S 2 , and the bucket angle sensor S 3  each may be a potentiometer using a variable resistor, a stroke sensor that detects a stroke amount of a corresponding hydraulic cylinder, a rotary encoder that detects the rotation angle around a coupling pin, a gyro sensor, or a combination of an acceleration sensor and a gyro sensor. 
     A cab  10 , which is an operation room, is provided in the upper swiveling body  3  and a power source such as an engine  11  is mounted to the upper swiveling body  3 . A controller  30 , a display device  40 , an input device  42 , a sound output device  43 , a storage device  47 , a machine body tilt sensor S 4 , a swivel angular velocity sensor S 5 , a camera S 6 , a communication device T 1 , and a positioning device P 1  are mounted to the upper swiveling body  3 . 
     The controller  30  is configured to function as a main controller for drive control of the shovel  100 . In the present embodiment, the controller  30  is formed by a computer including a CPU, a RAM, and a ROM. Various functions of the controller  30  are achieved by, for example, the CPU executing a program stored in the ROM. The various functions include, for example, a machine guidance function that guides an operator to perform a manual operation of the shovel  100  and a machine control function that automatically assists the operator to perform the manual operation of the shovel  100 . A machine guidance device  50  included in the controller  30  is configured to perform the machine guidance function and the machine control function. 
     The display device  40  is configured to display various information. The display device  40  may be connected to the controller  30  through a communication network such as CAN or may be connected to the controller  30  through a private network. 
     The input device  42  is configured to enable an operator to input various information to the controller  30 . The input device  42  includes a touch panel, a knob switch, and a membrane switch that are mounted in the cab  10 . 
     The sound output device  43  is configured to output a sound. The sound output device  43  may be, for example, an on-board speaker connected to the controller  30  or an alarm such as a buzzer. According to the present embodiment, the sound output device  43  is configured to output the sound indicating various information in response to a sound output command from the controller  30 . 
     The storage device  47  is configured to store various information. The storage device  47  is, for example, a non-volatile storage medium, such as a semiconductor memory. The storage device  47  may store information output by the various devices during operation of the shovel  100  and may store information obtained through the various devices before the operation of the shovel  100  is started. For example, the storage device  47  may store information related to the target construction surface obtained through the communication device T 1  or the like. The target construction surface may be set by the operator of the shovel  100 , a construction manager, or the like. 
     The machine body tilt sensor S 4  is configured to detect the tilt of the upper swiveling body  3  with respect to a virtual horizontal plane. In the present embodiment, the machine body tilt sensor S 4  is an acceleration sensor that detects the tilt angle around the front and rear axis of the upper swiveling body  3  and the tilt angle around the left and right axis of the upper swiveling body  3 . The front and rear axis and the left and right axis of the upper swiveling body  3  are orthogonal to each other at the center point of the shovel, which is a point on the swiveling axis of the shovel  100 , for example. 
     The swivel angular velocity sensor S 5  is configured to detect the swivel angular velocity of the upper swiveling body  3 . The swivel angular velocity sensor  55  may be configured to detect or calculate the rotation angle of the upper swiveling body  3 . In the present embodiment, the swivel angular velocity sensor S 5  is a gyro sensor. The swivel angular velocity sensor S 5  may be a resolver, a rotary encoder, or the like. 
     The camera S 6  is an example of a spatial recognition device and is configured to obtain an image around the shovel  100 . In the present embodiment, the camera S 6  includes a front camera S 6 F that images a space in front of the shovel  100 , a left camera S 6 L that images a space on the left of the shovel  100 , a right camera S 6 R that images a space on the right of the shovel  100 , and a rear camera S 6 B that images a space at the rear of the shovel  100 . 
     The camera S 6  is, for example, a monocular camera having an imaging element such as a CCD or CMOS, and outputs a taken image to the display device  40 . The camera S 6  may be a stereo camera, a distance image camera, or the like. The camera S 6  may be replaced by another spatial recognition device, such as an ultrasonic sensor, a millimeter wave radar, a LIDAR sensor, or an infrared sensor, and may be replaced by a combination of another spatial recognition device and a camera. 
     The front camera S 6 F is mounted to, for example, a ceiling of the cab  10 , that is, inside the cab  10 . However, the front camera S 6 F may be mounted to a roof of the cab  10 , that is, outside the cab  10 . The left camera S 6 L is mounted to a left end of the upper surface of the upper swiveling body  3 , the right camera S 6 R is mounted to a right end of the upper surface of the upper swiveling body  3 , and the rear camera S 6 B is mounted to a rear end of the upper surface of the upper swiveling body  3 . 
     The communication device T 1  controls communication with an external device outside the shovel  100 . In the present embodiment, the communication device T 1  controls communication with an external device through a satellite communication network, a cellular phone communication network, the Internet, or the like. The external device may be, for example, a management device such as a server installed in an external facility or an assistant device such as a smartphone carried by a worker around the shovel  100 . The external device, for example, is configured to manage construction information about one or more shovels  100 . The construction information includes, for example, information related to at least one of operation time, fuel consumption, and a workload of the shovel  100 . The workload is, for example, the amount of excavated earth and sand and the amount of earth and sand loaded onto a dump truck platform. The shovel  100  is configured to send the construction information related to the shovel  100  to the external device through the communication device T 1  at a predetermined time interval. 
     The positioning device P 1  is configured to measure the position of the upper swiveling body  3 . The positioning device P 1  may be configured to measure a direction of the upper swiveling body  3 . In the present embodiment, the positioning device P 1  is, for example, a GNSS compass. The positioning device P 1  detects the position and direction of the upper swiveling body  3  and outputs a detected value to the controller  30 . Therefore, the positioning device P 1  can function as a direction detecting device that detects the direction of the upper swiveling body  3 . The direction detecting device may be a direction sensor mounted to the upper swiveling body  3 . 
       FIG. 2  is a block diagram illustrating a configuration example of a driving system of the shovel  100 , and a mechanical power system, a hydraulic oil line, a pilot line, and an electric control system are illustrated with double lines, a solid line, a dashed line, and a dotted line, respectively. 
     The driving system of the shovel  100  mainly includes the engine  11 , a regulator  13 , a main pump  14 , a pilot pump  15 , a control valve  17 , an operation device  26 , a discharge pressure sensor  28 , an operation pressure sensor  29 , the controller  30 , and a proportional valve  31 . 
     The engine  11  is a driving source of the shovel  100 . In the present embodiment, the engine  11  is, for example, a diesel engine that is operated to maintain a predetermined rotation speed. Output shafts of the engine  11  are coupled to respective input shafts of the main pump  14  and pilot pump  15 . 
     The main pump  14  is configured to supply hydraulic oil to the control valve  17  through the hydraulic oil line. In the present embodiment, the main pump  14  is a swash plate variable displacement hydraulic pump. 
     The regulator  13  is configured to control the discharge amount of the main pump  14 . In the present embodiment, the regulator  13  controls the discharge amount of the main pump  14  by adjusting the swash plate tilt angle of the main pump  14  in response to a control command from the controller  30 . For example, the controller  30  receives an output of the operation pressure sensor  29  for example, and outputs a control command to the regulator  13  as needed to change the discharge amount of the main pump  14 . 
     The pilot pump  15  supplies the hydraulic oil through the pilot line to various hydraulic control devices, including the operation device  26  and the proportional valve  31 . In the present embodiment, the pilot pump  15  is a fixed displacement hydraulic pump. However, the pilot pump  15  may be omitted. In this case, the function performed by the pilot pump  15  may be achieved by the main pump  14 . That is, the main pump  14  may be provided with a circuit other than a function supplying the hydraulic oil to the control valve  17 , and may provide a function supplying the hydraulic oil to the operation device  26  or the like after the supply pressure of the hydraulic oil is lowered by restriction or the like. 
     The control valve  17  is a hydraulic controller that controls a hydraulic system in the shovel  100 . In the present embodiment, the control valve  17  includes control valves  171  to  176 . The control valve  17  may selectively supply the hydraulic oil discharged by the main pump  14  to one or more hydraulic actuators through the control valves  171  to  176 . The control valves  171  to  176  are configured to control the flow rate of the hydraulic oil flowing from the main pump  14  to the hydraulic actuator and the flow rate of the hydraulic oil flowing from the hydraulic actuator to a hydraulic oil tank. The hydraulic actuator includes the boom cylinder  7 , the arm cylinder  8 , the bucket cylinder  9 , a left-side traveling hydraulic motor  1 L, a right-side traveling hydraulic motor  1 R, and a swiveling hydraulic motor  2 A. The swiveling hydraulic motor  2 A may be a swiveling motor generator as an electric actuator. 
     The operation device  26  is a device used by an operator for operating the actuator. The actuator includes at least either the hydraulic actuator or the electric actuator. In the present embodiment, the operation device  26  supplies the hydraulic oil discharged by the pilot pump  15  through a pilot line to the pilot port of the corresponding control valve in the control valve  17 . The pressure of the hydraulic oil supplied to each of the pilot ports (i.e., the pilot pressure) is basically a pressure in accordance with the direction and amount of the operation of the operation device  26  corresponding to each of the hydraulic actuators. At least one of the operation devices  26  is configured to supply the hydraulic oil discharged by the pilot pump  15  to the pilot port of a corresponding control valve in the control valve  17  through the pilot line and a shuttle valve  32 . 
     The discharge pressure sensor  28  is configured to detect the discharge pressure of the main pump  14 . In the present embodiment, the discharge pressure sensor  28  outputs a detected value to the controller  30 . 
     The operation pressure sensor  29  is configured to detect an operation content of the operator using the operation device  26 . In the present embodiment, the operation pressure sensor  29  detects the direction and amount of the operation of the operation device  26  corresponding to each of the actuators in the form of the pressure, and outputs a detected value to the controller  30 . The operation content of the operation device  26  may be detected using a sensor other than the operation pressure sensor. 
     The proportional valve  31 , which functions as a machine control valve, is disposed in a conduit connecting the pilot pump  15  and the shuttle valve  32  and is configured to change the flow area of the conduit. In the present embodiment, the proportional valve  31  operates in response to a control command output by the controller  30 . Thus, the controller  30  can supply the hydraulic oil discharged by the pilot pump  15  to the pilot port of the corresponding control valve in the control valve  17  through the proportional valve  31  and the shuttle valve  32 , independently of the operation of the operation device  26  by the operator. 
     The shuttle valve  32  includes two inlet ports and one outlet port. One of the two inlet ports is connected to the operation device  26  and the other is connected to the proportional valve  31 . The outlet port is connected to a pilot port of a corresponding control valve in the control valve  17 . Thus, the shuttle valve  32  can apply higher one of either the pilot pressure generated by the operation device  26  or the pilot pressure generated by the proportional valve  31  to the corresponding pilot port of the control valve. 
     With this configuration, the controller  30  can operate the hydraulic actuator corresponding to the specific operation device  26  even when no operation is performed on the specific operation device  26 . 
     Next, the machine guidance device  50  included in the controller  30  will be described. The machine guidance device  50  is configured to perform, for example, a machine guidance function. In the present embodiment, the machine guidance device  50  communicates work information to the operator, such as the distance between the target construction surface and a working part of the attachment. Information related to the target construction surface is stored in the storage device  47  in advance, for example. The machine guidance device  50  may obtain the information related to the target construction surface from the external device through the communication device T 1 . The information related to the target construction surface is represented in a frame of reference, for example. The frame of reference is, for example, the World Geodetic System. The World Geodetic System is a three-dimensional orthogonal XYZ coordinate system in which the origin is located at the Earth&#39;s center of mass, the X-axis is in the direction toward the intersection of the Greenwich meridian and the equator, the Y-axis is in the direction of 90 degrees east longitude, and the Z-axis is in the direction toward the Arctic. The target construction surface may be set based on a relative positional relationship to a reference point. In this case, the operator may define any given point of the construction site as the reference point. The working part of the attachment is, for example, the toe of the bucket  6  or the back of the bucket  6 . The machine guidance device  50  may be configured to guide the operation of the shovel  100  by communicating operational information to the operator through the display device  40  or the sound output device  43 , for example. 
     The machine guidance device  50  may perform a machine control function that automatically assists the manual operation of the shovel  100  performed by the operator. For example, the machine guidance device  50  may automatically operate at least one of the boom  4 , the arm  5  and the bucket  6 , so that the target construction surface coincides with the position of the tip of the bucket  6  when the operator manually performs an excavating operation. 
     In the present embodiment, the machine guidance device  50  is incorporated into the controller  30 , but may be a controller separately provided from the controller  30 . In this case, the machine guidance device  50 , for example, is formed by a computer including, a CPU and an internal memory, in a manner similar to the controller  30 . The various functions of the machine guidance device  50  are achieved by the CPU executing a program stored in the internal memory. The machine guidance device  50  and the controller  30  are communicably connected to each other through a communication network such as CAN. 
     Specifically, the machine guidance device  50  obtains information from the boom angle sensor S 1 , the arm angle sensor S 2 , the bucket angle sensor S 3 , the machine body tilt sensor S 4 , the swivel angular velocity sensor S 5 , the camera S 6 , the positioning device P 1 , the communication device T 1 , and the input device  42 , for example. The machine guidance device  50 , for example, calculates the distance between the bucket  6  and the target construction surface based on the obtained information and communicates the distance between the bucket  6  and the target construction surface to the operator of the shovel  100  by at least either sound or image display. 
     Therefore, the machine guidance device  50  includes a position calculating unit  51 , a distance calculating unit  52 , an information communication unit  53 , and an automatic controller  54 . 
     The position calculating unit  51  is configured to calculate a position of a positioning object. In the present embodiment, the position calculating unit  51  calculates a coordinate point in the reference frame of the working part of the attachment. Specifically, the position calculating unit  51  calculates the coordinate point of the toe of the bucket  6  from the respective rotation angles of the boom  4 , the arm  5 , and the bucket  6 . The position calculating unit  51  may calculate not only the coordinate point of the center of the toe of the bucket  6  but also the coordinate point of the left end of the toe of the bucket  6  and the coordinate point of the right end of the toe of the bucket  6 . 
     The distance calculating unit  52  is configured to calculate the distance between two positioning objects. In the present embodiment, the distance calculating unit  52  calculates the vertical distance between the toe of the bucket  6  and the target construction surface. The distance calculating unit  52  may calculate distances between the respective coordinate points of the left end and right end of the toe of the bucket  6  and the target construction surface (for example, the vertical distances) so that the machine guidance device  50  can determine whether the shovel  100  faces the target construction surface straight. 
     The information communication unit  53  is configured to communicate various information to the operator of the shovel  100 . In the present embodiment, the information communication unit  53  communicates various distances calculated by the distance calculating unit  52  to the operator of the shovel  100 . Specifically, the vertical distance between the toe of the bucket  6  and the target construction surface is communicated to the operator of the shovel  100  using at least either visual information or audio information. 
     For example, the information communication unit  53  may communicate the vertical distance between the toe of the bucket  6  and the target construction surface to the operator using an intermittent sound generated by the sound output device  43 . In this case, the information communication unit  53  may shorten an interval of the intermittent sound as the vertical distance decreases. The information communication unit  53  may use a continuous sound and may change at least one of a pitch of the sound, strength of the sound, and the like to indicate a difference in the vertical distance. The information communication unit  53  may issue an alarm when the toe of the bucket  6  is lower than the target construction surface. The alarm is, for example, a continuous sound that is significantly greater than the intermittent sound. 
     The information communication unit  53  may display the vertical distance between the toe of the bucket  6  and the target construction surface as the work information on the display device  40 . The display device  40  displays, for example, the work information received from the information communication unit  53  with image data received from the camera S 6 , on the screen. The information communication unit  53  may communicate the vertical distance to the operator using an image of an analog meter or an image of a bar graph indicator, for example. 
     The automatic controller  54  automatically operates the actuator to automatically assist the manual operation of the shovel  100  performed by the operator. For example, the automatic controller  54  may automatically extend and retract at least one of the boom cylinder  7 , the arm cylinder  8 , and the bucket cylinder  9  so that the target construction surface coincides with the position of the toe of the bucket  6  when the operator manually performs a closing operation of the arm. In this case, the operator can close the arm  5  with the toe of the bucket  6  coinciding with the target construction surface by simply operating an arm operation lever in a closing direction, for example. The automatic control may be configured to be performed when a predetermined switch, which is one of the input devices  42 , is pressed. The predetermined switch is, for example, a machine control switch (which will be hereinafter referred to as the “MC switch”), and may be disposed as a knob switch at an end of the operation device  26 . 
     The automatic controller  54  may automatically rotate the swiveling hydraulic motor  2 A in order to cause the upper swiveling body  3  to face the target construction surface straight when the predetermined switch, such as the MC switch, is pressed. In this case, the operator can cause the upper swiveling body  3  to face the target construction surface straight by simply pressing the predetermined switch or operating a swiveling operation lever while pressing the predetermined switch. Alternatively, the operator can cause the upper swiveling body  3  to face the target construction surface straight and start the machine control function by simply pressing the predetermined switch. In the following, the control of causing the upper swiveling body  3  to face the target construction surface straight is referred to as the “straight facing control”. In the straight facing control, the machine guidance device  50  determines that the shovel  100  faces the target construction surface straight when the vertical distance at the left end, which is the vertical distance between the coordinate point at the left end of the toe of the bucket  6  and the target construction surface, is equal to the vertical distance at the right end, which is the vertical distance between the coordinate point at the right end of the toe of the bucket  6  and the target construction surface. However, the machine guidance device  50  may determine that the shovel  100  faces the target construction surface straight when the difference between the vertical distance at the left end and the vertical distance at the right end is smaller than or equal to a predetermined value, which is not when the vertical distance at the left end is equal to the vertical distance at the right end, that is not when the difference between the vertical distance at the left end and the vertical distance at the right end is zero. The machine guidance device  50  may inform the operator that the straight facing control has been completed, using at least either the visual information or the audio information when the machine guidance device  50  determines that the shovel  100  faces the target construction surface straight after automatically rotating the swiveling hydraulic motor  2 A. That is, the machine guidance device  50  may inform the operator that the upper swiveling body  3  faces the target construction surface straight. 
     In the present embodiment, the automatic controller  54  can automatically operate each actuator by individually and automatically adjusting the pilot pressure applied to the control valve corresponding to each actuator. For example, in the straight facing control, the automatic controller  54  may operate the swiveling hydraulic motor  2 A based on the difference between the vertical distance at the left end and the vertical distance at the right end. Specifically, when the swiveling operation lever is operated while the predetermined switch is pressed, the automatic controller  54  determines whether the swiveling operation lever is operated in a direction in which the upper swiveling body  3  faces the target construction surface straight. For example, when the swiveling operation lever is operated in a direction in which the vertical distance between the toe of the bucket  6  and the target construction surface (i.e., the backslope) is increased, the automatic controller  54  does not perform the straight facing control. With respect to the above, when the swiveling operation lever is operated in a direction in which the vertical distance between the toe of the bucket  6  and the target construction surface (i.e., the backslope) is reduced, the automatic controller  54  performs the straight facing control. As a result, the automatic controller  54  can operate the swiveling hydraulic motor  2 A so that the difference between the vertical distance at the left end and vertical distance at the right end becomes small. Thereafter, the automatic controller  54  stops the swiveling hydraulic motor  2 A when the difference is smaller than or equal to the predetermined value, or is zero. Alternatively, the automatic controller  54  may set the rotation angle at which the difference is smaller than or equal to the predetermined value or is zero as a target angle, and perform rotation angle control so that a difference of the angle between the target angle and the present rotation angle (the detected value) becomes zero. In this case, the rotation angle is, for example, the angle of a front and rear axis of the upper swiveling body  3  with respect to the reference direction. 
     When an operation with respect to the target construction surface, such as an excavating operation or a slope finishing operation, is performed, the automatic controller  54  may automatically operate the actuator so that the upper swiveling body  3  maintains to face the target construction surface straight. For example, when the direction of the upper swiveling body  3  is changed due to excavation reaction forces or the like and the upper swiveling body  3  does not face the target construction surface straight, the automatic controller  54  may automatically operate the swiveling hydraulic motor  2 A to cause the upper swiveling body  3  to immediately face the target construction surface straight. Alternatively, when the operation with respect to the target construction surface is being performed, the automatic controller  54  may proactively operate the actuator to prevent the direction of the upper swiveling body  3  from being changed due to excavation reaction forces or the like. 
     Next, a configuration example of the hydraulic system mounted to the shovel  100  will be described with reference to  FIG. 3 .  FIG. 3  is a schematic diagram illustrating the configuration example of the hydraulic system mounted to the shovel  100  of  FIG. 1 . As in  FIG. 2 ,  FIG. 3  illustrates the mechanical power system, the hydraulic oil line, the pilot line, and the electric control system with double lines, a solid line, a dashed line, and a dotted line, respectively. 
     The hydraulic system circulates the hydraulic oil from main pumps  14 L and  14 R driven by the engine  11  to the hydraulic oil tank through at least one of center bypass conduits  40 L and  40 R, and parallel conduits  42 L and  42 R. The main pumps  14 L and  14 R correspond to the main pump  14  of  FIG. 2 . 
     The center bypass conduit  40 L is a hydraulic oil line passing through control valves  171 ,  173 ,  175 L, and  176 L disposed in the control valve  17 . The center bypass conduit  40 R is a hydraulic oil line passing through control valves  172 ,  174 ,  175 R, and  176 R disposed in the control valve  17 . The control valves  175 L and  175 R correspond to the control valve  175  of  FIG. 2 . The control valves  176 L and  176 R correspond to the control valve  176  of  FIG. 2 . 
     The control valve  171  is a spool valve that supplies the hydraulic oil discharged by the main pump  14 L to the left-side traveling hydraulic motor  1 L and switches the flow of the hydraulic oil in order to discharge the hydraulic oil discharged by the left-side traveling hydraulic motor  1 L to the hydraulic oil tank. 
     The control valve  172  is a spool valve that supplies the hydraulic oil discharged by the main pump  14 R to the right-hand traveling hydraulic motor  1 R and switches the flow of the hydraulic oil in order to discharge the hydraulic oil discharged by the right-hand traveling hydraulic motor  1 R to the hydraulic oil tank. 
     The control valve  173  is a spool valve that supplies the hydraulic oil discharged by the main pump  14 L to the swiveling hydraulic motor  2 A and switches the flow of hydraulic oil in order to discharge the hydraulic oil discharged by the swiveling hydraulic motor  2 A to the hydraulic oil tank. 
     The control valve  174  is a spool valve that supplies the hydraulic oil discharged by the main pump  14 R to the bucket cylinder  9  and switches the flow of the hydraulic oil in order to discharge the hydraulic oil in the bucket cylinder  9  to the hydraulic oil tank. 
     The control valves  175 L and  175 R are spool valves that supply the hydraulic oil discharged by the main pumps  14 L and  14 R to the boom cylinder  7  and switch the flow of the hydraulic oil in order to discharge the hydraulic oil in the boom cylinder  7  to the hydraulic oil tank. 
     The control valves  176 L and  176 R are spool valves that supply the hydraulic oil discharged by the main pumps  14 L and  14 R to the arm cylinder  8  and switch the flow of the hydraulic oil in order to discharge the hydraulic oil in the arm cylinder  8  to the hydraulic oil tank. 
     The parallel conduit  42 L is a hydraulic oil line parallel to the center bypass conduit  40 L. The parallel conduit  42 L is configured to supply hydraulic oil to a downstream control valve when the flow of hydraulic oil passing through the center bypass conduit  40 L is restricted or blocked by either of the control valves  171 ,  173 , and  175 L. The parallel conduit  42 R is a hydraulic oil line parallel to the center bypass conduit  40 R. The parallel conduit  42 R is configured to supply the hydraulic oil to a downstream control valve when the flow of the hydraulic oil passing through the center bypass conduit  40 R is restricted or blocked by either of the control valves  172 ,  174 , and  175 R. 
     Regulators  13 L and  13 R control the discharge amount of the main pumps  14 L and  14 R by adjusting the swash plate tilt angles of the main pumps  14 L and  14 R in accordance with the discharge pressures of the main pumps  14 L and  14 R. The regulators  13 L and  13 R correspond to the regulator  13  in  FIG. 2 . The regulator  13 L, for example, adjusts the swash plate tilt angle of the main pump  14 L in response to an increase in the discharge pressure of the main pump  14 L to reduce the discharge amount. The same applies to the regulator  13 R. This is to prevent absorption power (i.e., absorption horsepower) of the main pump  14 , which is represented as a product of the discharge pressure and the discharge amount, from exceeding output power (i.e., output horsepower) of the engine  11 . 
     A discharge pressure sensor  28 L is an example of the discharge pressure sensor  28 . The discharge pressure sensor  28 L detects the discharge pressure of the main pump  14 L, and outputs a detected value to the controller  30 . The same applies to a discharge pressure sensor  28 R. 
     Here, a negative control employed in the hydraulic system of  FIG. 3  will be described. 
     In the center bypass conduit  40 L, a throttle  18 L is arranged between the control valve  176 L, which is located most downstream, and the hydraulic oil tank. The flow of the hydraulic oil discharged by the main pump  14 L is restricted by the throttle  18 L. The throttle  18 L generates control pressure for controlling the regulator  13 L. A control pressure sensor  19 L is a sensor for detecting the control pressure and outputs a detected value to the controller  30 . Similarly, in the center bypass conduit  40 R, a throttle  18 R is arranged between the control valve  176 R, which is located most downstream, and the hydraulic oil tank. The flow of the hydraulic oil discharged by the main pump  14 R is restricted by the throttle  18 R. The throttle  18 R generates control pressure for controlling the regulator  13 R. A control pressure sensor  19 R is a sensor for detecting the control pressure and outputs a detected value to the controller  30 . 
     The controller  30  controls the discharge amount of the main pump  14 L by adjusting the swash plate tilt angle of the main pump  14 L in accordance with the control pressure detected by the control pressure sensor  19 L. The controller  30  decreases the discharge amount of the main pump  14 L as the control pressure is increased, and increases the discharge amount of the main pump  14 L as the control pressure is decreased. 
     Specifically, as illustrated in  FIG. 3 , in a standby state in which none of the hydraulic actuators in the shovel  100  is operated, the hydraulic oil discharged by the main pump  14 L reaches the throttle  18 L through the center bypass conduit  40 L. The flow of the hydraulic oil discharged by the main pump  14 L increases the control pressure generated upstream from the throttle  18 L. As a result, the controller  30  reduces the discharge amount of the main pump  14 L to the allowable minimum discharge amount and suppresses pressure loss (i.e., pumping loss) when the discharged hydraulic oil passes through the center bypass conduit  40 L. 
     When any of the hydraulic actuators is operated, the hydraulic oil discharged by the main pump  14 L flows into a hydraulic actuator to be operated through a control valve corresponding to the hydraulic actuator to be operated. The flow of the hydraulic oil discharged by the main pump  14 L decreases or removes the amount of the hydraulic oil reaching the throttle  18 L, thereby lowering the control pressure generated upstream from the throttle  18 L. As a result, the controller  30  increases the discharge amount of the main pump  14 L and circulates the sufficient hydraulic oil in the hydraulic actuator to be operated to stably perform the operation of the hydraulic actuator to be operated. The description of the main pump  14 L above similarly applies to the main pump  14 R as well. 
     With the configuration described above, the hydraulic system of  FIG. 3  can reduce excessive energy consumption in the main pumps  14 L and  14 R in the standby state. The excessive energy consumption includes the pumping loss generated in the center bypass conduits  40 L and  40 R by the hydraulic oil discharged by the main pumps  14 L and  14 R. Additionally, in the hydraulic system of  FIG. 3 , the necessary and sufficient hydraulic oil can be supplied from the main pumps  14 L and  14 R to the hydraulic actuator to be operated when the hydraulic actuator is operated. 
     Next, a configuration for automatically operating the actuator will be described with reference to  FIGS. 4A to 4C .  FIGS. 4A to 4C  are diagrams of parts extracted from the hydraulic system. Specifically,  FIG. 4A  is a diagram extracting a hydraulic system part related to the operation of the boom cylinder  7 ,  FIG. 4B  is a diagram extracting a hydraulic system part related to the operation of the bucket cylinder  9 , and  FIG. 4C  is a diagram extracting a hydraulic system part related to the operation of the swiveling hydraulic motor  2 A. 
     A boom operation lever  26 A of  FIG. 4A  is an example of the operation device  26  and is used to operate the boom  4 . The boom operation lever  26 A utilizes the hydraulic oil discharged by the pilot pump  15  to apply the pilot pressure corresponding to the operation content to the pilot ports of the control valves  175 L and  175 R. Specifically, when the boom operation lever  26 A is operated in a boom raising direction, the boom operation lever  26 A applies the pilot pressure in accordance with the amount of the operation to the right pilot port of the control valve  175 L and the left pilot port of the control valve  175 R. When the boom operation lever  26 A is operated in a boom lowering direction, the boom operation lever  26 A applies the pilot pressure in accordance with the amount of the operation to the right pilot port of the control valve  176 R. 
     An operation pressure sensor  29 A is an example of the operation pressure sensor  29 . The operation pressure sensor  29 A detects the operation content of the operator to the boom operation lever  26 A in the form of pressure and outputs a detected value to the controller  30 . The operation content includes, for example, an operation direction and an operation amount (or an operation angle). 
     Proportional valves  31 AL and  31 AR are examples of the proportional valve  31 , and shuttle valves  32 AL and  32 AR are examples of the shuttle valve  32 . The proportional valve  31 AL operates in response to a current command output by the controller  30 . The proportional valve  31 AL then adjusts the pilot pressure generated by the hydraulic oil introduced into the right pilot port of the control valve  175 L and the left pilot port of the control valve  175 R from the pilot pump  15  through the proportional valve  31 AL and the shuttle valve  32 AL. The proportional valve  31 AR operates in response to a current command output by the controller  30 . The proportional valve  31 AR then adjusts the pilot pressure generated by hydraulic oil introduced into the right pilot port of the control valve  175 R from the pilot pump  15  through the proportional valve  31 AR and the shuttle valve  32 AR. The proportional valves  31 AL and  31 AR can adjust the pilot pressure so that the control valves  175 L and  175 R can be stopped at a desired valve position. 
     With this configuration, the controller  30  can supply the hydraulic oil discharged by the pilot pump  15  to the right pilot port of the control valve  175 L and the left pilot port of the control valve  175 R through the proportional valve  31 AL and the shuttle valve  32 AL, independently of the boom raising operation by the operator, for example. That is, the controller  30  can automatically raise the boom  4 . The controller  30  can also supply the hydraulic oil discharged by the pilot pump  15  to the right pilot port of the control valve  175 R through the proportional valve  31 AR and the shuttle valve  32 AR, independently of the boom lowering operation by the operator. That is, the controller  30  can automatically lower the boom  4 . 
     A bucket operation lever  26 B of  FIG. 4B  is an example of the operation device  26  and is used to operate the bucket  6 . The bucket operation lever  26 B utilizes the hydraulic oil discharged by the pilot pump  15  to apply the pilot pressure corresponding to the operation content to the pilot port of the control valve  174 . Specifically, when the bucket operation lever  26 B is operated in a bucket opening direction, the bucket operation lever  26 B applies the pilot pressure in accordance with the amount of the operation to the right pilot port of the control valve  174 . When the bucket operation lever  26 B is operated in a bucket closing direction, the bucket operation lever  26 B applies the pilot pressure in accordance with the amount of the operation to the left pilot port of the control valve  174 . 
     An operation pressure sensor  29 B is an example of the operation pressure sensor  29 . The operation pressure sensor  29 B detects the operation content of the operator to the bucket operation lever  26 B in the form of pressure and outputs a detected value to the controller  30 . 
     Proportional valves  31 BL and  31 BR are examples of the proportional valve  31 , and shuttle valves  32 BL and  32 BR are examples of the shuttle valve  32 . The proportional valve  31 BL operates in response to a current command output by the controller  30 . The proportional valve  31 BL then adjusts the pilot pressure generated by hydraulic oil introduced into the left pilot port of the control valve  174  from the pilot pump  15  through the proportional valve  31 BL and the shuttle valve  32 BL. The proportional valve  31 BR operates in response to a current command output by the controller  30 . The proportional valve  31 BR then adjusts the pilot pressure generated by hydraulic oil introduced into the right pilot port of the control valve  174  from the pilot pump  15  through the proportional valve  31 BR and the shuttle valve  32 BR. The proportional valves  31 BL and  31 BR can adjust the pilot pressure so that the control valve  174  can be stopped at a desired valve position. 
     This configuration enables the controller  30  to supply the hydraulic oil discharged by the pilot pump  15  to the left pilot port of the control valve  174  through the proportional valve  31 BL and the shuttle valve  32 BL, independently of the bucket closing operation by the operator. That is, the controller  30  can automatically close the bucket  6 . The controller  30  can also supply the hydraulic oil discharged by the pilot pump  15  to the right pilot port of the control valve  174  through the proportional valve  31 BR and the shuttle valve  32 BR, independently of the bucket opening operation by the operator. That is, the controller  30  can automatically open the bucket  6 . 
     A swiveling operation lever  26 C in  FIG. 4C  is an example of the operation device  26  and is used to swivel the upper swiveling body  3 . The swiveling operation lever  26 C utilizes the hydraulic oil discharged by the pilot pump  15  to apply the pilot pressure corresponding to the operation content to the pilot port of the control valve  173 . Specifically, when the swiveling operation lever  26 C is operated in a left swivel direction, the swiveling operation lever  26 C applies the pilot pressure in accordance with the amount of the operation to the left pilot port of the control valve  173 . When the swiveling operation lever  26 C is operated in a right swivel direction, the swiveling operation lever  26 C applies the pilot pressure in accordance with the amount of the operation to the right pilot port of the control valve  173 . 
     An operation pressure sensor  29 C is an example of the operation pressure sensor  29 . The operation pressure sensor  29 C detects the operation content of the operation to the swiveling operation lever  26 C in the form of pressure and outputs a detected value to the controller  30 . 
     Proportional valves  31 CL and  31 CR are examples of the proportional valve  31 , and shuttle valves  32 CL and  32 CR are examples of the shuttle valve  32 . The proportional valve  31 CL operates in response to a current command output by the controller  30 . The proportional valve  31 CL then adjusts the pilot pressure generated by the hydraulic oil introduced into the left pilot port of the control valve  173  from the pilot pump  15  through the proportional valve  31 CL and the shuttle valve  32 CL. The proportional valve  31 CR operates in response to a current command output by the controller  30 . The proportional valve  31 CR then adjusts the pilot pressure generated by the hydraulic oil introduced into the right pilot port of the control valve  173  from the pilot pump  15  through the proportional valve  31 CR and the shuttle valve  32 CR. The proportional valves  31 CL and  31 CR can adjust the pilot pressure so that the control valve  173  can be stopped at a desired valve position. 
     This configuration enables the controller  30  to supply the hydraulic oil discharged by the pilot pump  15  to the left pilot port of the control valve  173  through the proportional valve  31 CL and the shuttle valve  32 CL, independently of the left swiveling operation by the operator. That is, the controller  30  can automatically swivel the upper swiveling body  3  to the left. The controller  30  can also supply the hydraulic oil discharged by the pilot pump  15  to the right pilot port of the control valve  173  through the proportional valve  31 CR and the shuttle valve  32 CR, independently of the right swiveling operation by the operator. That is, the controller  30  can automatically swivel the upper swiveling body  3  to the right. 
     The shovel  100  may be configured to automatically open and close the arm  5  and to automatically move the lower traveling body  1  forward and backward. In this case, the hydraulic system part related to the operation of the arm cylinder  8 , the hydraulic system part related to the operation of the left-side traveling hydraulic motor  1 L, and the hydraulic system part related to the operation of the right-side traveling hydraulic motor  1 R may be configured in a manner similar to the hydraulic system part related to the operation of the boom cylinder  7 . 
     Next, another configuration example of the machine guidance device  50  will be described with reference to  FIG. 5 .  FIG. 5  is a block diagram illustrating another configuration example of a driving system of the shovel  100  and corresponds to  FIG. 2 . The drive system of  FIG. 5  differs from the drive system of  FIG. 2  in that the machine guidance device  50  includes a rotation angle calculating unit  55  and a relative angle calculating unit  56 , but the drive system of  FIG. 5  and the drive system of  FIG. 2  are common in other points. Thus, the description of the common parts will be omitted, and the different parts will be described in detail. 
     The rotation angle calculating unit  55  calculates the rotation angle of the upper swiveling body  3 . This is to determine the current direction of the upper swiveling body  3 . In the present embodiment, the rotation angle calculating unit  55  calculates the angle of the front and rear axis of the upper swiveling body  3  with respect to the reference direction based on an output of the GNSS compass as the positioning device P 1 , as the rotation angle. The rotation angle calculating unit  55  may calculate the rotation angle based on an output of the swivel angular velocity sensor S 5 . When the reference point is set in the construction site, the rotation angle calculating unit  55  may use a direction in which the reference point is viewed from a swiveling axis as the reference direction. 
     The rotation angle indicates a direction in which the attachment operation surface extends. The attachment operation surface is, for example, a virtual plane that crosses the attachment in a longitudinal direction and is positioned perpendicular to a swiveling plane. The swiveling plane is, for example, a virtual plane including a bottom surface of a swiveling frame perpendicular to the swiveling axis. The machine guidance device  50 , for example, determines that the upper swiveling body  3  faces the target construction surface straight when the machine guidance device  50  determines that an attachment operation plane AF (see  FIG. 8A ) includes a normal to the target construction surface. 
     The relative angle calculating unit  56  calculates the relative angle as the rotation angle necessary to cause the upper swiveling body  3  to face the target construction surface straight. The relative angle is a relative angle formed between a direction of the front and rear axis of the upper swiveling body  3  when the upper swiveling body  3  faces the target construction surface straight and a present direction of the front and rear axis of the upper swiveling body  3 , for example. In the present embodiment, the relative angle calculating unit  56  calculates the relative angle based on the information related to the target construction surface stored in the storage device  47  and the rotation angle calculated by the rotation angle calculating unit  55 . 
     When the swiveling operation lever is operated while the predetermined switch is pressed, the automatic controller  54  determines whether the swiveling operation lever is operated in a direction of causing the upper swiveling body  3  to face the target construction surface straight. When the automatic controller  54  determines that the swiveling operation lever is operated in the direction of causing the upper swiveling body  3  to face the target construction surface, the automatic controller  54  sets the relative angle calculated by the relative angle calculating unit  56  as the target angle. When the change of the rotation angle after the rotation operation lever has been operated reaches the target angle, the automatic controller  54  determines that the upper swiveling body  3  faces the target construction surface straight, and stops a movement of the swiveling hydraulic motor  2 A. 
     As described, the machine guidance device  50  of  FIG. 5  can cause the upper swiveling body  3  to face the target construction surface straight, in a manner similar to the machine guidance device  50  of  FIG. 2 . 
     Next, with reference to  FIGS. 6, 7A, 7B, 8A, and 8B , an example of a process in which the controller  30  causes the upper swiveling body  3  to face the target construction surface straight (which will be hereinafter referred to as the “straight facing process”) will be described.  FIG. 6  is a flowchart of the straight facing process. The controller  30  performs the straight facing process when the MC switch is pressed.  FIGS. 7A and 7B  are top views of the shovel  100  when the straight facing process is performed, and  FIGS. 8A and 8B  are perspective views of the shovel  100  when the straight facing process is performed, and when the shovel  100  is viewed from the left rear. Specifically,  FIGS. 7A and 8A  illustrate a state in which the upper swiveling body  3  does not face the target construction surface straight, and  FIGS. 7B and 8B  illustrate a state in which the upper swiveling body  3  faces the target construction surface straight. In  FIGS. 7A, 7B, 8A and 8B , the target construction surface is a backslope BS as illustrated in  FIG. 1 , for example. A region NS represents a state in which the backslope BS is not completed, that is, a state in which a ground surface ES is not matched with the backslope BS as illustrated in  FIG. 1 , and a region CS represents a state in which the backslope BS is completed, that is, the ground surface ES is matched with the backslope BS. 
     The state in which the upper swiveling body  3  faces the target construction surface straight, includes, for example, a state in which an angle α formed between a line segment L 1  representing the direction (an extending direction) of the target construction surface and a line segment L 2  representing the front and rear axis of the upper swiveling body  3  is 90 degrees on a virtual horizontal plane, as illustrated in  FIG. 7B . The extending direction of the slope as the direction of the target construction surface, which is represented by the line segment L 1 , is a direction orthogonal to a slope length direction, for example. The slope length direction is, for example, a direction along a virtual line segment connecting the top (shoulder) and the bottom (foot) of the slope at the shortest distance. A state in which the upper swiveling body  3  faces the target construction surface straight may be defined as a state in which an angle β (see  FIG. 9A ) formed between the line segment L 2  representing the front and rear axis of the upper swiveling body  3  and a line segment L 3  perpendicular to the direction (the extending direction) of the target construction surface is 0 degrees on the virtual horizontal plane. A direction represented by the line segment L 3  corresponds to a direction of a horizontal component of a perpendicular line drawn to the target construction surface. 
     A virtual cylinder CB of  FIGS. 8A and 8B  represents a portion of the normal to the target construction surface (i.e., the backslope BS), a dash-dotted line represents a portion of a virtual swivel plane SF, and a dotted line represents a portion of the virtual attachment operation plane AF. The attachment operation plane AF is arranged to be perpendicular to the swivel plane SF. As illustrated in  FIG. 8B , when the upper swiveling body  3  is in a state of facing the target construction surface straight, the attachment operation plane AF is arranged so that the attachment operation plane AF includes the portion of the normal as represented by the virtual cylinder CB, that is, the attachment operation plane AF extends along the portion of the normal. 
     The automatic controller  54 , for example, sets the rotation angle formed when the attachment operation plane AF and the target construction surface (i.e., the backslope BS) are perpendicular to each other, as the target angle. The automatic controller  54  detects the current rotation angle based on the output of the positioning device P 1  or the like and calculates a difference between the target angle and the current rotation angle (i.e., a detected value). The automatic controller  54  operates the swiveling hydraulic motor  2 A so that the difference is smaller than or equal to a predetermined value or is zero. Specifically, when the difference between the target angle and the current rotation angle is smaller than or equal to the predetermined value or is zero, the automatic controller  54  determines that the upper swiveling body  3  faces the target construction surface straight. When the swiveling operation lever is operated while the predetermined switch is pressed, the automatic controller  54  determines whether the swiveling operation lever is operated in a direction of causing the upper swiveling body  3  to face the target construction surface straight. For example, when the swiveling operation lever is operated in a direction in which the difference between the target angle and the current rotation angle increases, the automatic controller  54  determines that the swiveling operation lever is not operated in a direction of causing the upper swiveling body  3  to face the target construction surface straight, and does not perform the straight facing control. When the swiveling operation lever is operated in a direction in which the difference between the target angle and the current rotation angle decreases, the automatic controller  54  determines that the swiveling operation lever is operated in a direction of causing the upper swiveling body  3  to face the target construction surface straight, and performs the straight facing control. As a result, the swiveling hydraulic motor  2 A can be operated so that the difference between the target angle and the current rotation angle decreases. Thereafter, the automatic controller  54  stops the swiveling hydraulic motor  2 A when the difference between the target angle and the current rotation angle is smaller than or equal to the predetermined value or is zero. 
     The example illustrated in  FIG. 7B  is an example indicating a state in which the attachment operation plane AF includes the normal (i.e., the virtual cylinder CB), and the angle α formed between the line segment L 1  representing the direction of the target construction surface and the line segment L 2  representing the front and rear axis of the upper swiveling body  3  is 90 degrees. However, as long as the attachment operation plane AF is in a state of including the normal (i.e., the virtual cylinder CB), the angle α is not required to be 90 degrees. For example, since the shovel  100  is often installed on a ground with large relief, even when the attachment operation plane AF is in the state of including the normal (i.e., the virtual cylinder CB), the angle α is not necessarily 90 degrees. 
     On a basis of the above description of  FIGS. 7A, 7B, 8A, and 8B , a flow of the straight facing control will be described with reference to  FIG. 6  again. First, the machine guidance device  50  included in the controller  30  determines whether a shift from facing straight has occurred (in step ST 1 ). In the present embodiment, the machine guidance device  50  determines whether a shift from facing straight has occurred based on the information related to the target construction surface previously stored in the storage device  47  and the output of the positioning device P 1  as the direction detecting device. The information related to the target construction surface includes information related to the direction of the target construction surface. The positioning device P 1  outputs information related to the direction of the upper swiveling body  3 . For example, as illustrated in  FIG. 8A , in a state in which the attachment operation plane AF does not include the normal to the target construction surface, the machine guidance device  50  determines that a shift from facing the target construction surface straight from the shovel  100  has occurred. In such a state, as illustrated in  FIG. 7A , the angle α formed between the line segment L 1  representing the direction of the target construction surface and the line segment L 2  representing the direction of the upper swiveling body  3  is an angle other than 90 degrees. 
     Here, the machine guidance device  50  may determine whether a shift from facing straight has occurred based on an image taken by the camera S 6 . For example, the machine guidance device  50  may, by performing various image processing on the image taken by the camera S 6  to derive information related to the shape of the slope to be worked on, determine whether a shift from facing straight has occurred based on the derived information. Alternatively, the machine guidance device  50  may determine whether a shift from facing straight has occurred based on an output of a spatial recognition device other than camera S 6 , such as ultrasonic sensors, a millimeter wave radar, a distance image sensor, a LIDAR sensor, or an infrared sensor. 
     When it is determined that a shift from facing straight has not occurred (NO in step ST 1 ), the machine guidance device  50  terminates the current straight facing process without performing the straight facing control. 
     When it is determined that a shift from facing straight has occurred (YES in step ST 1 ), the machine guidance device  50  determines whether no obstacle is present around the shovel  100  (in step ST 2 ). In the present embodiment, the machine guidance device  50  performs image recognition processing on the image taken by the camera S 6  to determine whether an image related to a predetermined obstacle exists in the taken image. The predetermined obstacle is at least one of a person, an animal, a machine, and a building, for example. Then, when it is determined that no image related to the predetermined obstacle exists in an image related to a predetermined area that is set around the shovel  100 , it is determined that no obstacle is present around the shovel  100 . The predetermined area includes, for example, an area in which there can be an object that comes into contact with the shovel  100  when the shovel  100  is moved to cause the upper swiveling body  3  to face the target construction surface straight. An area RA, which is represented by a cross hatching pattern in  FIG. 7A , is an example of the predetermined area. However, the predetermined area may be set as a wider area, such as an area within a predetermined distance from a swiveling axis  2 X, for example. 
     The machine guidance device  50  may determine whether no obstacle is present around the shovel  100  based on an output of a spatial recognition device other than the camera S 6 , such as an ultrasonic sensor, a millimeter wave radar, a distance image sensor, a LIDAR sensor, or an infrared sensor. 
     When it is determined that an obstacle is present around the shovel  100  (NO in step ST 2 ), the machine guidance device  50  terminates the current straight facing process without performing the straight facing control. This is to prevent the shovel  100  from contacting the obstacle by performing the straight facing control. In this case, the machine guidance device  50  may output an alarm. The machine guidance device  50  may send information related to the obstacle, such as the presence or absence of the obstacle, the location of the obstacle, and the type of the obstacle, to the external device through the communication device T 1 . The machine guidance device  50  may receive information related to the obstacle obtained by another shovel through the communication device T 1 . 
     When it is determined that no obstacle is present around the shovel  100  (YES in step ST 2 ), the machine guidance device  50  performs the straight facing control (in step ST 3 ). In the examples of  FIGS. 7A, 7B, 8A, and 8B , the automatic controller  54  of the machine guidance device  50  outputs a current command to the proportional valve  31 CL (see  FIG. 4C ). The pilot pressure generated by the hydraulic oil passing through the proportional valve  31 CL and the shuttle valve  32 CL from the pilot pump  15  is applied to the left pilot port of the control valve  173 . The control valve  173  receiving the pilot pressure at the left pilot port is displaced in the right direction to cause the hydraulic oil discharged by the main pump  14 L to flow into a first port  2 A 1  of the swiveling hydraulic motor  2 A. The control valve  173  causes the hydraulic oil that flows out from a second port  2 A 2  of the swiveling hydraulic motor  2 A to flow out to the hydraulic oil tank. As a result, the swiveling hydraulic motor  2 A rotates in a forward direction and swivels the upper swiveling body  3  in the left direction around the swiveling axis  2 X as illustrated by the arrow in  FIG. 7A . Thereafter, as illustrated in  FIG. 7B , the automatic controller  54  stops the output of the current command to the proportional valve  31 CL at 90 degrees of the angle α or at 0 degrees of the angle β and reduces the pilot pressure applied to the left pilot port of the control valve  173 . The control valve  173  is displaced in the left direction to return to a neutral position, and blocks the flow of the hydraulic oil from the main pump  14 L toward the first port  2 A 1  of the swiveling hydraulic motor  2 A. The control valve  173  also blocks the flow of the hydraulic oil from the second port  2 A 2  of the swiveling hydraulic motor  2 A toward the hydraulic oil tank. As a result, the swiveling hydraulic motor  2 A stops the rotation in the forward direction and stops swiveling the upper swiveling body  3  in the left direction. 
     As described above, the shovel  100  according to the embodiment of the present invention includes the lower traveling body  1 , the upper swiveling body  3  that is rotatably mounted on the lower traveling body  1 , and the controller  30  as a controller that can perform the straight facing control by which the actuator is operated to cause the upper swiveling body  3  to face the target construction surface straight, based on information related to the target construction surface and information related to the direction of the upper swiveling body  3 . The target construction surface includes, for example, at least one of a foreslope, a backslope, a horizontal surface, and a vertical surface. The information related to the target construction surface includes, for example, information related to the direction of the target construction surface. The direction of the target construction surface is determined based on at least either an extending direction of the target construction surface or a direction of the horizontal component of the perpendicular line drawn to the target construction surface, for example. This configuration enables the shovel  100  to reduce annoyance felt by the operator of the shovel  100  when causing the shovel  100  to face the target construction surface straight. The operator of the shovel  100  does not need to manually operate the actuator such as the swiveling hydraulic motor  2 A in order to cause the upper swiveling body  3  to face the target construction surface straight. Further, the operator of the shovel  100  does not need to check whether the upper swiveling body  3  faces the target construction surface straight by viewing an image, such as a Facing Angle Compass displayed on the display device  40 . 
     The controller  30  may be configured to perform the straight facing control when a predetermined switch is operated. For example, the controller  30  may be configured to perform the straight facing control when the MC switch is operated. In this case, the controller  30  can automatically cause the upper swiveling body  3  to face the target construction surface straight when the MC switch for starting the machine control function is pressed. That is, the controller  30  can perform the straight facing control as part of the machine control function. Thus, the controller  30  can reduce annoyance felt by the operator of the shovel  100  when causing the shovel  100  to face the target construction surface straight in performing the machine control function. As a result, the controller  30  can improve the operational efficiency of the shovel  100 . 
     When the swiveling operation lever  26 C is operated while the straight facing control is performed, the controller  30  may stop performing the straight facing control. This is to prioritize manual operation by the operator. This configuration enables the operator to manually operate the actuator through the operation device  26 , even when the straight facing control is being performed, that is, even when the actuator is being automatically operated. 
     Even when the controller  30  determines that a shift from facing straight has occurred in step ST 1 , the controller  30  may not perform the straight facing control when a shift from facing straight is large. Specifically, the automatic controller  54  may be configured so as not to perform the straight facing control when the angle α at the time when it is determined that a shift from facing straight has occurred, is smaller than a first threshold value, that is, when the angle β is larger than a second threshold value (i.e., a value obtained by subtracting the first threshold value from 90 degrees). This is to prevent the operator from being anxious about too large an operation amount of the shovel  100  performed by automatic control in a state in which the operation device  26  is not operated. 
     In other words, the controller  30  may be configured to perform the straight facing control only when the angle between the direction of the target construction surface and the direction of the upper swiveling body  3  is within a predetermined angle range. For example, the controller  30  may be configured to perform the straight facing control only when the angle α is larger than or equal to the first threshold and is smaller than or equal to 90 degrees, or only when the angle β is larger than or equal to 0 degrees and is smaller than or equal to the second threshold, as illustrated in  FIG. 7A . 
     The controller  30  may be configured to perform the straight facing control when it is confirmed that no obstacle is present around the upper swiveling body  3 . This is to prevent the contact between the upper swiveling body  3  and the obstacle when the straight facing control is being performed. 
     The preferred embodiment of the present invention has been described in detail above. However, the invention is not limited to the embodiments described above. Various modifications, substitutions, and the like can be applied to the embodiments described above without departing from the scope of the invention. Also, the characteristics described separately may be combined as long as a technical inconsistency is not caused. 
     For example, in the above-described embodiment, the controller  30  automatically operates the swiveling hydraulic motor  2 A to cause the upper swiveling body  3  to face the target construction surface straight. However, the controller  30  may automatically operate the swivel motor generator to cause the upper swiveling body  3  to face the target construction surface straight. 
     Additionally, the controller  30  may operate another actuator to cause the upper swiveling body  3  to face the target construction surface straight. For example, as illustrated in  FIGS. 9A and 9B , the controller  30  may automatically operate the left-side traveling hydraulic motor  1 L and the right-side traveling hydraulic motor  1 R to cause the upper swiveling body  3  to face the target construction surface straight. 
       FIGS. 9A and 9B  are top views of the shovel  100  when the straight facing process is performed and correspond to  FIGS. 7A and 7B . That is,  FIG. 9A  illustrates a state in which the upper swiveling body  3  does not face the target construction surface straight, and  FIG. 9B  illustrates a state in which the upper swiveling body  3  faces the target construction surface straight. 
     In the examples of  FIGS. 9A and 9B , the controller  30  performs a spin turn by rotating the right-side traveling hydraulic motor  1 R in a forward direction and rotating the left-side traveling hydraulic motor  1 L in a reverse direction to cause the upper swiveling body  3  to face the target construction surface straight. 
     In the above-described embodiments, a hydraulic operation device is employed as the operation device  26 , but an electric operation device may be employed.  FIG. 10  illustrates a configuration example of an operation system including the electric operation device. Specifically, the operation system illustrated in  FIG. 10  is an example of a boom operation system. The boom operation system mainly includes the pilot pressure operated control valve  17 , the boom operation lever  26 A as the electric operation lever, the controller  30 , a solenoid valve  60  for a boom raising operation, and a solenoid valve  62  for a boom lowering operation. The operating system of  FIG. 10  may also be applied to an arm operation system, a bucket operation system, and the like. 
     The pilot pressure operated control valve  17  includes the control valves  175 L and  175 R for the boom cylinder  7 , as illustrated in  FIG. 3 . The solenoid valve  60  is configured to adjust a flow path area of an oil path connecting the pilot pump  15  to the right pilot port of the control valve  175 L and connecting the pilot pump  15  to the left pilot port of the control valve  175 R. The solenoid valve  62  is configured to adjust a flow path area of an oil path connecting the pilot pump  15  to the right pilot port of the control valve  175 R. 
     When the manual operation is performed, the controller  30  generates a boom raising operation signal (i.e., an electrical signal) or a boom lowering operation signal (i.e., an electrical signal) in response to an operation signal (i.e., an electrical signal) output by the operation signal generator of the boom operation lever  26 A. The operation signal output by the operation signal generator of the boom operation lever  26 A is an electrical signal that varies in accordance with the operation amount and the operation direction of the boom operation lever  26 A. 
     Specifically, when the boom operation lever  26 A is operated in the boom raising direction, the controller  30  outputs the boom raising operation signal (i.e., the electrical signal) in accordance with the amount of the lever operation to the solenoid valve  60 . The solenoid valve  60  adjusts the flow path area in accordance with the boom raising operation signal (i.e., the electrical signal) to control the pilot pressure applied to the right pilot port of the control valve  175 L and the left pilot port of the control valve  175 R. Similarly, when the boom operation lever  26 A is operated in the boom lowering direction, the controller  30  outputs the boom lowering operation signal (i.e., the electrical signal) in accordance with the amount of the lever operation to the solenoid valve  62 . The solenoid valve  62  adjusts the flow path area in accordance with the boom lowering operation signal (i.e., the electrical signal) to control the pilot pressure applied to the right pilot port of the control valve  175 R. 
     When the automatic control is performed, the controller  30  generates the boom raising operation signal (i.e., the electrical signal) or the boom lowering operation signal (i.e., the electrical signal) in accordance with a correction operation signal (i.e., the electrical signal) instead of the operation signal output by the operation signal generator of the boom operation lever  26 A. The correction operation signal may be an electrical signal generated by the machine guidance device  50  or an electrical signal generated by a controller other than the machine guidance device  50 . 
     It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.