EXCAVATOR

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2023-211876, filed on Dec. 15, 2023, the contents of which are incorporated herein by reference in their entirety.

BACKGROUND

Technical Field

The present disclosure relates to an excavator.

Description of Related Art

Conventionally, in excavators, what is referred to as facing control has been known, in which an upper turning body is caused to directly face a target work surface.

SUMMARY

An excavator according to one aspect of the present invention includes

• • a lower traveling body;
  • an upper turning body mounted on the lower traveling body in a turnable manner; and
  • a control device configured to perform facing control such that the upper turning body faces a target work surface, by applying a turning force to the lower traveling body or the upper turning body to turn the lower traveling body or the upper turning body, wherein
  • the control device controls a turning speed of the lower traveling body or the upper turning body based on a turning angle required for the upper turning body to face the target work surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an excavator as an excavating machine according to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating an example of the configuration of the drive system of the excavator;

FIG. 3 is a schematic diagram illustrating an example of the configuration of the hydraulic system mounted on the excavator of FIG. 1;

FIG. 4A is a partial view of the hydraulic system;

FIG. 4B is a partial view of the hydraulic system;

FIG. 4C is a partial view of the hydraulic system;

FIG. 5 is a block diagram illustrating another configuration example of the excavator drive system;

FIG. 6 is a flowchart illustrating the processing of the facing control;

FIG. 7A is a top view of the excavator when the facing control is executed;

FIG. 7B is a top view of the excavator when the facing control is executed;

FIG. 8A is a perspective view of the excavator viewed from the rear left when facing control is executed;

FIG. 8B is a perspective view of the excavator viewed from the rear left when facing control is executed;

FIG. 9A is a flowchart for explaining an example of processing added to facing control;

FIG. 9B is a flowchart for explaining an example of how to limit the turning speed of the upper turning body;

FIG. 9C is a flowchart for explaining another example of processing added to facing control;

FIG. 10A is a top view of an excavator when facing control is executed;

FIG. 10B is a top view of an excavator when facing control is executed; and

FIG. 11 illustrates a configuration example of an operation system including an electric operation device.

DETAILED DESCRIPTION

In work performed by using an excavator, by improving the accuracy of the positioning the excavator to directly face a target, the work can be performed accurately and the work efficiency can be improved.

Therefore, it is preferable to provide an excavator capable of improving the accuracy of facing control for causing the upper turning body to directly face a target work surface.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of an excavator 100 as an excavating machine according to an embodiment of the present invention.

An upper turning body 3 is mounted on the lower traveling body 1 of the excavator 100 so as to be able to turn through a turning mechanism 2. A boom 4 is attached to the upper turning body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 as an end attachment is attached to the tip of the arm 5.

The boom 4, the arm 5 and the bucket 6 constitute an excavation attachment as an example of an 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 S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a bucket angle sensor S3 is attached to the bucket 6.

The boom angle sensor S1 is configured to detect the rotation angle of the boom 4. In the present embodiment, the boom angle sensor S1 is an acceleration sensor and can detect the rotation angle (hereinafter referred to as “boom angle”) of the boom 4 with respect to the upper turning body 3. The boom angle is, for example, the minimum angle when the boom 4 is lowered most, and increases as the boom 4 is raised.

The arm angle sensor S2 is configured to detect the rotation angle of the arm 5. In the present embodiment, the arm angle sensor S2 is an acceleration sensor and can detect the rotation angle (hereinafter referred to as “arm angle”) of the arm 5 with respect to the boom 4. The arm angle is, for example, the minimum angle when the arm 5 is closed most, and increases as the arm 5 is opened.

The bucket angle sensor S3 is configured to detect the rotation angle of the bucket 6. In the present embodiment, the bucket angle sensor S3 is an acceleration sensor and can detect the rotation angle (hereinafter referred to as “bucket angle”) of the bucket 6 with respect to the arm 5. For example, the bucket angle becomes the minimum angle when the bucket 6 is closed the most and increases as the bucket 6 is opened.

The boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 may be a potentiometer using a variable resistor, a stroke sensor for detecting the stroke amount of the corresponding hydraulic cylinder, a rotary encoder for detecting the rotation angle around the connecting pin, a gyro sensor, or a combination of an acceleration sensor and a gyro sensor.

The upper turning body 3 is provided with a cabin 10 which is a driving room, and a power source such as the engine 11 is mounted. The upper turning body 3 also has attached 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 S4, a turning angular speed sensor S5, a camera S6, a communication device T1, and a positioning device P1.

The controller 30 is configured to function as a main control part for controlling the drive of the excavator 100. In the present embodiment, the controller 30 is composed of a computer including a CPU, a RAM, a ROM, and the like. Various functions of the controller 30 are implemented, for example, by the CPU executing a program stored in the ROM. The various functions include, for example, a machine guidance function for guiding the manual operation of the excavator 100 by an operator, and a machine control function for automatically supporting the manual operation of the excavator 100 by an operator. The machine guidance device 50 included in the controller 30 is configured to execute the machine guidance function and the machine control function.

The display device 40 is configured to display various kinds of information. The display device 40 may be connected to the controller 30 via a communication network such as CAN, or may be connected to the controller 30 via an exclusive-use line. Further, when the upper turning body 3 is likely to exceed the position facing the target work surface or when the upper turning body 3 exceeds the position facing the target work surface, the display device 40 can, under the control of the controller 30, report this fact by a warning or the like using characters or images, in the facing control described later.

The input device 42 is configured such that an operator can input various kinds of information to the controller 30. The input device 42 includes a touch panel, a knob switch, a membrane switch and the like installed in the cabin 10.

The sound output device 43 is configured to output information by sound. The sound output device 43 may be, for example, an in-vehicle speaker connected to the controller 30 or an alarm such as a buzzer. In the present embodiment, the sound output device 43 is configured to output various kinds of information by sound in response to a sound output instruction from the controller 30. Further, under the control of the controller 30, the sound output device 43 can report a fact by an alarm or the like, when the upper turning body 3 is likely to exceed the position facing the target work surface, or when the upper turning body 3 exceeds the position facing the target work surface, in the facing control described later.

The storage device 47 is configured to store various kinds of information. The storage device 47 is, for example, a nonvolatile storage medium such as a semiconductor memory. The storage device 47 may store information output from various kinds of devices during the operation of the excavator 100, or it may store information acquired through various kinds of devices before the operation of the excavator 100 starts. The storage device 47 may store, for example, information on the target work surface acquired through the communication device T1 or the like. The target work surface may be set by the operator of the excavator 100 or set by the work manager or the like.

The machine body tilt sensor S4 is configured to detect the tilt of the upper turning body 3 with respect to the virtual horizontal plane. In the present embodiment, the machine body tilt sensor S4 is an acceleration sensor for detecting the tilt angle of the upper turning body 3 around the longitudinal axis and the tilt angle of the upper turning body 3 around the lateral axis. The longitudinal axis and the lateral axis of the upper turning body 3 are orthogonal to each other at the excavator center point which is a point on the turning axis of the excavator 100, for example.

The turning angular speed sensor S5 is configured to detect the turning angular speed of the upper turning body 3. The turning angular speed sensor S5 may be configured to detect or calculate the turning angle of the upper turning body 3. In the present embodiment, the turning angular speed sensor S5 is a gyro sensor. The turning angular speed sensor S5 may be a resolver, a rotary encoder, or the like.

The camera S6 is an example of a space recognition device and is configured to acquire an image of the area around the excavator 100. In the present embodiment, the camera S6 includes a front camera S6F for capturing the space in front of the excavator 100, a left camera S6L for capturing the space to the left of the excavator 100, a right camera S6R for capturing the space to the right of the excavator 100, and a rear camera S6B for capturing the space behind the excavator 100.

The camera S6 is, for example, a monocular camera having an imaging element such as CCD or CMOS, and outputs a captured image to the display device 40. The camera S6 may be a stereo camera, a distance image camera, or the like. The camera S6 may be replaced by other spatial recognition devices such as an ultrasonic sensor, a millimeter wave radar, a LIDAR, or an infrared sensor, or may be replaced by a combination of other spatial recognition devices and the camera.

The front camera S6F is, for example, mounted on the ceiling of the cabin 10, i.e., inside the cabin 10. However, the front camera S6F may be attached to the roof of the cabin 10, that is, to the outside of the cabin 10. The left camera S6L is attached to the left end of the upper surface of the upper turning body 3, the right camera S6R is attached to the right end of the upper surface of the upper turning body 3, and the rear camera S6B is attached to the rear end of the upper surface of the upper turning body 3.

The communication device T1 controls communication with an external device located outside the excavator 100. In the present embodiment, the communication device T1 controls communication with the external device via a satellite communication network, a cellular telephone communication network, or an Internet network. The external device may be, for example, a management device such as a server installed in an external facility, or a support device such as a smartphone carried by a worker around the excavator 100. The external device is configured to manage, for example, work information related to one or more excavators 100. The work information includes, for example, information related to at least one of operation time, fuel consumption, and the work amount of the excavator 100. The work amount includes, for example, the amount of excavated earth and sand, and the amount of loaded earth and sand on the bed of a dump truck. The excavator 100 is configured to transmit work information related to the excavator 100 to the external device at predetermined time intervals via the communication device T1.

The positioning device P1 is configured to measure the position of the upper turning body 3. The positioning device P1 may be configured to measure the orientation of the upper turning body 3. In the present embodiment, the positioning device P1 is, for example, a GNSS compass, which detects the position and orientation of the upper turning body 3 and outputs the detected value to the controller 30. Therefore, the positioning device P1 can function as an orientation detecting device for detecting the orientation of the upper turning body 3. The orientation detecting device may be an azimuth sensor attached to the upper turning body 3.

FIG. 2 is a block diagram illustrating an example of the configuration of the driving system of the excavator 100, and the mechanical power system, the hydraulic oil line, the pilot line, and the electric control system are indicated by double lines, solid lines, dashed lines, and dotted lines, respectively.

The driving system of the excavator 100 mainly includes an 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, a controller 30, and a proportional valve 31.

The engine 11 is a driving source of the excavator 100. In the present embodiment, the engine 11 is, for example, a diesel engine operating to maintain a predetermined rotation speed. The output shaft of the engine 11 is connected to the respective input shafts of the main pump 14 and the pilot pump 15.

The main pump 14 is configured to supply hydraulic oil to the control valve 17 via a hydraulic oil line. In the present embodiment, the main pump 14 is a swash plate type 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 according to a control instruction from the controller 30. For example, the controller 30 receives the output of the operation pressure sensor 29 and the like, and outputs a control instruction to the regulator 13 as necessary to change the discharge amount of the main pump 14.

The pilot pump 15 supplies hydraulic oil to various hydraulic control devices including the operation device 26 and the proportional valve 31 via the pilot line. In the present embodiment, the pilot pump 15 is a fixed-capacity hydraulic pump. However, the pilot pump 15 may be omitted. In this case, the function of the pilot pump 15 may be implemented by the main pump 14. That is, the main pump 14 may be provided with a circuit separate from the function of supplying hydraulic oil to the control valve 17, and may be provided with a function of supplying hydraulic oil to the operation device 26 after lowering the hydraulic oil supply pressure by a aperture or the like.

The control valve 17 is a hydraulic control device for controlling the hydraulic system in the excavator 100. In the present embodiment, the control valve 17 includes control valves 171 to 176. The control valve 17 can selectively supply hydraulic oil discharged from 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 hydraulic oil flowing from the main pump 14 to the hydraulic actuator and the flow rate of hydraulic oil flowing from the hydraulic actuator to the hydraulic oil tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left-side travel hydraulic motor 1L, a right-side travel hydraulic motor 1R, and a turning hydraulic motor 2A. The turning hydraulic motor 2A may be a turning electric generator functioning as an electric actuator.

The operation device 26 is a device used by an operator to operate the actuator. The actuator includes at least one of a hydraulic actuator and an electric actuator. In the present embodiment, the operation device 26 supplies hydraulic oil discharged from the pilot pump 15 to the pilot port of the corresponding control valve in the control valve 17 via the pilot line. The pressure (pilot pressure) of the hydraulic oil supplied to each of the pilot ports is, in principle, the pressure corresponding to the operation direction and the operation amount of the operation device 26 corresponding to each of the hydraulic actuators. At least one of the operation devices 26 is configured to supply hydraulic oil discharged from the pilot pump 15 to the pilot port of the corresponding control valve in the control valve 17 via the pilot line and the 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 the detected value to the controller 30.

The operation pressure sensor 29 is configured to detect the operation contents of an operator using the operation device 26. In the present embodiment, the operation pressure sensor 29 detects the operation direction and the operation amount of the operation device 26 corresponding to each actuator in the form of pressure, and outputs the detected value to the controller 30. The operation contents of the operation device 26 may be detected by using sensors other than the operation pressure sensor.

The proportional valve 31 functioning as a control valve for machine control is arranged in a pipeline connecting the pilot pump 15 and the shuttle valve 32, and is configured to change the flow path area of the pipeline. In the present embodiment, the proportional valve 31 operates according to a control instruction output from the controller 30. Therefore, the controller 30 can supply hydraulic oil discharged from the pilot pump 15 to the pilot port of the corresponding control valve in the control valve 17 via the proportional valve 31 and the shuttle valve 32, regardless of the operation of the operation device 26 by the operator.

The shuttle valve 32 has two inlet ports and one outlet port. One of the two inlet ports is connected to the operation device 26, and the other port is connected to the proportional valve 31. The outlet port is connected to the pilot port of the corresponding control valve in the control valve 17. Therefore, the shuttle valve 32 can apply the higher of the pilot pressure generated by the operation device 26 and the pilot pressure generated by the proportional valve 31 to the pilot port of the corresponding control valve.

With this configuration, the controller 30 can operate the hydraulic actuator corresponding to a specific operation device 26 even when the specific operation device 26 is not operated.

Next, the machine guidance device 50 included in the controller 30 will be described.

The machine guidance device 50 is configured to execute, for example, a machine guidance function. In the present embodiment, the machine guidance device 50 transmits, for example, work information such as a distance between the target work surface and the work part of the attachment to the operator. Information on the target work surface is stored in advance, for example, in the storage device 47. The machine guidance device 50 may acquire information on the target work surface from an external device via the communication device T1. Information on the target work surface is expressed by, for example, a reference coordinate system. The reference coordinate system is, for example, the world geodetic system. The world geodetic system is a three-dimensional orthogonal XYZ coordinate system with the origin at the center of gravity of the earth, the X-axis in the direction of the intersection of the Greenwich meridian and the equator, the Y-axis in the direction of longitude 90 degrees east, and the Z-axis in the direction of the North Pole. The target work surface may be set based on the relative positional relationship with the reference point. In this case, the operator may designate any point at the work site as the reference point. The work part of the attachment is, for example, the claw tip 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 excavator 100 by transmitting work information to the operator via the display device 40, the sound output device 43, or the like. Further, the machine guidance device 50 provides a report when the upper turning body 3 is likely to exceed the position facing the target work surface or when the upper turning body 3 exceeds the position facing the target work surface, in the facing control. The reference on the excavator 100 side for determining whether or not the upper turning body 3 is facing the target work surface is, for example, the claw tip of the bucket 6 or the back of the bucket 6. The machine guidance device 50 may be configured to make a report when the upper turning body 3 is likely to exceed the position facing the target work surface or when the upper turning body 3 exceeds the position facing the target work surface via the display device 40, the sound output device 43, or the like, in the facing control.

The machine guidance device 50 may execute a machine control function that automatically supports the operator's manual operation of the excavator 100. For example, the machine guidance device 50 may automatically operate at least one of the boom 4, the arm 5, and the bucket 6 such that the target work surface and the tip of the bucket 6 coincide with each other when the operator is performing a manual excavation operation.

In the present embodiment, the machine guidance device 50 is incorporated in the controller 30, but may be a control device provided separately from the controller 30. In this case, the machine guidance device 50 is composed of a computer including a CPU and an internal memory, for example, similar to the controller 30. Various functions of the machine guidance device 50 are implemented by the CPU executing programs stored in the internal memory. Further, 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 acquires information from a boom angle sensor S1, an arm angle sensor S2, a bucket angle sensor S3, a machine body tilt sensor S4, a turning angular speed sensor S5, a camera S6, a positioning device P1, a communication device T1, and an input device 42. The machine guidance device 50 calculates, for example, the distance between the bucket 6 and the target work surface based on the acquired information, and transmits the magnitude of the distance between the bucket 6 and the target work surface to the operator of the excavator 100 by at least one of sound or image display. Further, the machine guidance device 50 limits the turning speed of the upper turning body 3 when the turning speed of the upper turning body 3 exceeds a predetermined speed at the time of starting the facing control described later. Further, the machine guidance device 50 determines, based on the calculated distance, whether the upper turning body 3 is likely to exceed the position facing the target work surface or whether the upper turning body 3 has exceeded the position facing the target work surface, and provides a report, by at least one of sound or display, if the upper turning body 3 is likely to exceed the position facing the target work surface or the upper turning body 3 has exceeded the position facing the target work surface.

Therefore, the machine guidance device 50 has a position calculation part 51, a distance calculation part 52, an information transmission part 53, an automatic control part 54, and a turning speed calculation part 57.

The position calculation part 51 is configured to calculate the position of the positioning object. In the present embodiment, the position calculation part 51 calculates a coordinate point in the reference coordinate system of the work part of the attachment. Specifically, the position calculation part 51 calculates the coordinate point of the claw tip of the bucket 6 from the respective rotation angles of the boom 4, the arm 5, and the bucket 6. The position calculation part 51 may calculate not only the coordinate point of the center of the claw tip of the bucket 6, but also the coordinate point of the left end of the claw tip of the bucket 6, and the coordinate point of the right end of the claw tip of the bucket 6, in order to determine whether or not the upper turning body 3 is likely to exceed the position facing the target work surface or whether the upper turning body 3 has exceeded the position facing the target work surface. The position calculation part 51 may also calculate the turning angle of the upper turning body 3 based on the position of the bucket 6.

The distance calculation part 52 is configured to calculate the distance between the two positioning objects. In the present embodiment, the distance calculation part 52 calculates the vertical distance between the claw tip of the bucket 6 and the target work surface. The distance calculation part 52 may calculate the distance (for example, the vertical distance) between the coordinate points of the left and right ends of the claw tip of the bucket 6 and the corresponding target work surface such that the machine guidance device 50 can determine whether or not the excavator 100 is facing to the target work surface.

The turning speed calculation part 57 calculates the turning speed of the upper turning body 3 based on the turning angle of the upper turning body 3 calculated by the position calculation part 51. Specifically, the turning speed calculation part 57 calculates the turning speed of the upper turning body 3 by time-differentiating the turning angle of the upper turning body 3 calculated by the position calculation part 51.

The information transmission part 53 is configured to transmit various kinds of information to the operator of the excavator 100. In the present embodiment, the information transmission part 53 transmits the magnitudes of the various distances calculated by the distance calculation part 52 to the operator of the excavator 100. Specifically, the magnitude of the vertical distance between the claw tip of the bucket 6 and the target work surface is transmitted to the operator of the excavator 100 by using at least one of visual information or auditory information. The information transmission part 53 also reports, to the operator of the excavator 100, when the upper turning body 3 is likely to exceed the position facing the target work surface or when the upper turning body 3 exceeds the position facing the target work surface.

For example, the information transmission part 53 may transmit the magnitude of the vertical distance between the claw tip of the bucket 6 and the target work surface to the operator by using intermittent sound generated by the sound output device 43. In this case, the information transmission part 53 may shorten the interval between intermittent sounds as the vertical distance becomes smaller. The information transmission part 53 may use a continuous sound, and may change at least one of the pitch or the intensity of the sound to indicate the difference in the magnitude of the vertical distance. Further, the information transmission part 53 may issue an alarm when the claw tip of the bucket 6 becomes lower than the target work surface. The alarm is, for example, a continuous sound that is significantly larger than the intermittent sound. Further, when the upper turning body 3 is likely to exceed the position facing the target work surface or when the upper turning body 3 exceeds the position facing the target work surface, the information transmission part 53 may use the sound from the sound output device 43 to report this to the operator.

Further, the information transmission part 53 may cause the display device 40 to display the magnitude of the vertical distance between the claw tip of the bucket 6 and the target work surface as work information. The display device 40 displays, for example, the image data received from the camera S6 and the work information received from the information transmission part 53 on the screen. The information transmission part 53 may use, for example, an image of an analog meter or an image of a bar graph indicator to inform the operator of the magnitude of the vertical distance. Further, when the upper turning body 3 is likely to exceed the position facing to the target work surface, or when the upper turning body 3 exceeds the position facing to the target work surface, the information transmission part 53 may report this to the operator via the display device 40 by using characters or images.

The automatic control part 54 automatically supports the manual operation of the excavator 100 by the operator by automatically operating the actuator. For example, the automatic control part 54 may automatically extend and contract at least one of the boom cylinder 7, the arm cylinder 8, or the bucket cylinder 9 such that the target work surface matches the position of the claw tip of the bucket 6 when the operator manually performs the arm closing operation. In this case, the operator can close the arm 5 while aligning the claw tip of the bucket 6 with the target work surface by simply operating the arm operating lever in the closing direction, for example. This automatic control may be executed when a predetermined switch, which is one of the input devices 42, is pressed. The predetermined switch may be, for example, a machine control switch (hereinafter referred to as “MC switch”) and may be arranged at the tip of the operation device 26 as a knob switch.

The automatic control part 54 may automatically rotate the turning hydraulic motor 2A in order to make the upper turning body 3 face the target work surface when a predetermined switch such as the MC switch is pressed. In this case, the operator can make the upper turning body 3 face the target work surface only by pressing the predetermined switch or by operating the turning operation lever while the predetermined switch is pressed. Alternatively, the operator can make the upper turning body 3 face the target work surface and start the machine control function only by pressing the predetermined switch. At this time, the automatic control part 54 may automatically rotate the turning hydraulic motor 2A to make the upper turning body 3 face the target work surface on the condition that the work surface is located right below the bucket 6 based on the position of the bucket 6 calculated by the position calculation part 51. Hereinafter, the control to make the upper turning body 3 face the target work surface is referred to as “facing control”. In the facing control, the machine guidance part 50 determines that the excavator 100 is facing the target work surface when the left end vertical distance, which is the vertical distance between the coordinate point at the left end of the claw tip of the bucket 6 and the target work surface, and the right end vertical distance, which is the vertical distance between the coordinate point at the right end of the claw tip of the bucket 6 and the target work surface, become equal. However, it may be determined that the excavator 100 is facing the target work surface, not when the left end vertical distance and the right end vertical distance become equal, i.e., not when the difference between the left end vertical distance and the right end vertical distance becomes zero, but when the difference becomes less than or equal to a predetermined value. When the machine guidance part 50 determines that the excavator 100 is facing the target work surface after automatically rotating the turning hydraulic motor 2A, the machine guidance part 50 may inform the operator that the facing control is completed by using at least one of visual information or auditory information. That is, the machine guidance part 50 may inform the operator that the upper turning body 3 has been made to face the target work surface.

In the present embodiment, the automatic control part 54 can automatically operate each actuator by individually and automatically adjusting the pilot pressure acting on the control valve corresponding to each actuator. For example, in the facing control, the automatic control part 54 may operate the turning hydraulic motor 2A based on the difference between the left end vertical distance and the right end vertical distance. Specifically, when the turning operation lever is operated in a state where a predetermined switch is pressed, the automatic control part 54 determines whether the turning operation lever is operated in a direction to make the upper turning body 3 face the target work surface. For example, when the turning operation lever is operated in a direction in which the vertical distance between the claw tip of the bucket 6 and the target work surface (uphill slope) increases, the automatic control part 54 does not execute the facing control. On the other hand, when the turning operation lever is operated in a direction in which the vertical distance between the claw tip of the bucket 6 and the target work surface (uphill slope) decreases, the automatic control part 54 executes the facing control. As a result, the automatic control part 54 can operate the turning hydraulic motor 2A such that the difference between the left end vertical distance and the right end vertical distance decreases. After that, the automatic control part 54 stops the turning hydraulic motor 2A when the difference becomes a predetermined value or less or zero. Alternatively, the automatic control part 54 may set the turning angle in which the difference becomes a predetermined value or less or zero, as a target angle, and perform the turning angle control such that the angular difference between the target angle and the current turning angle (detected value) becomes zero. In this case, the turning angle is, for example, the angle of the longitudinal axis of the upper turning body 3 with respect to the reference direction.

Further, the automatic control part 54 may automatically operate the actuator such that the state in which the upper turning body 3 faces the target work surface is maintained when an operation related to the target work surface such as an excavation operation or a slope finishing operation is performed. For example, the automatic control part 54 may automatically operate the turning hydraulic motor 2A such that the upper turning body 3 faces the target work surface immediately when the orientation of the upper turning body 3 changes due to excavation reaction force or the like and the upper turning body 3 does not face the target work surface. Alternatively, the automatic control part 54 may preemptively operate the actuator such that the orientation of the upper turning body 3 does not change due to an excavation reaction force or the like when an operation related to the target work surface is performed.

Further, when the turning speed of the upper turning body 3 calculated by the turning speed calculation part 57 exceeds a predetermined speed, the automatic control part 54 limits the rotation speed of the turning hydraulic motor 2A in the facing control to limit the turning speed of the upper turning body 3. The automatic control part 54 obtains a predetermined speed that acts as a condition for limiting the rotation speed of the turning hydraulic motor 2A, by using the turning angle of the upper turning body 3 calculated by the position calculation part 51 and the distance between the claw tip of the bucket 6 and the target work surface calculated by the distance calculation part 52. Specifically, the automatic control part 54 calculates a turning angle required for the upper turning body 3 to face the target work surface by using the turning angle of the upper turning body 3 calculated by the position calculation part 51 and the distance between the claw tip of the bucket 6 and the target work surface calculated by the distance calculation part 52, and obtains the predetermined speed based on the calculated turning angle. For example, when the turning angle required for the upper turning body 3 to face the target work surface is large, because the turning angle is large at the limited turning speed, even if the turning speed before the limitation is high, the turning speed is sufficiently reduced by the time the upper turning body 3 faces the target work surface, and the possibility that the upper turning body 3 exceeds the position facing the target work surface is reduced, the predetermined speed acting as a condition for limiting the rotation speed of the hydraulic motor 2A is made high. On the other hand, when the turning angle required for the upper turning body 3 to face the target work surface is small, because the turning angle is small at the limited turning speed, if the turning speed before the limitation is high, the turning speed is not sufficiently reduced by the time the upper turning body 3 faces the target work surface, and the possibility that the upper turning body 3 exceeds the position facing the target work surface is increased, the predetermined speed acting as a condition for limiting the rotation speed of the hydraulic motor 2A is reduced. In this way, the automatic control part 54 controls the turning speed of the upper turning body 3 based on the turning angle required for the upper turning body 3 to face the target work surface. In addition to the turning angle described above, the amount of the turning operation with respect to the operation device 26 may be used to set the predetermined speed. Specifically, when the amount of operation with respect to the operation device 26 is large, even if the turning speed is limited by the predetermined speed obtained based on the turning angle, the turning speed reaches the predetermined speed while the turning speed is accelerated such that the turning speed exceeds the predetermined speed, and the possibility that the upper turning body 3 exceeds the position facing the target work surface is increased. Therefore, when the amount of operation with respect to the operation device 26 is large, the predetermined speed may be smaller than the predetermined speed obtained based on the turning angle. On the other hand, when the amount of operation with respect to the operation device 26 is small, if the turning speed is limited by the predetermined speed at the predetermined speed obtained based on the turning angle, the turning speed will be sufficiently reduced until the upper turning body 3 faces the target work surface, and the possibility that the upper turning body 3 will exceed the position facing the target work surface will be reduced, and, therefore, there is no need to reduce the predetermined speed, which has been obtained based on the turning angle, according to the turning operation amount.

Next, with reference to FIG. 3, a configuration example of the hydraulic system mounted on the excavator 100 will be described.

FIG. 3 is a schematic view illustrating a configuration example of the hydraulic system mounted on the excavator 100 illustrated in FIG. 1. Similarly to FIG. 2, FIG. 3 illustrates the mechanical power system, the hydraulic oil line, the pilot line, and the electric control system by double lines, solid lines, dashed lines, and dotted lines, respectively.

The hydraulic system circulates hydraulic oil from the main pumps 14L and 14R driven by the engine 11 to the hydraulic oil tank through at least one of center bypass pipelines 40L and 40R and parallel pipelines 42L and 42R. The main pumps 14L and 14R correspond to the main pump 14 illustrated in FIG. 2.

The center bypass pipeline 40L is a hydraulic oil line passing through the control valves 171, 173, 175L, and 176L arranged in the control valve 17. The center bypass pipeline 40R is a hydraulic oil line passing through the control valves 172, 174, 175R, and 176R arranged in the control valve 17. The control valves 175L and 175R correspond to the control valve 175 illustrated in FIG. 2. The control valves 176L and 176R correspond to the control valve 176 illustrated in FIG. 2.

The control valve 171 is a spool valve that supplies the hydraulic oil discharged from the main pump 14L to the left-side travel hydraulic motor 1L and switches the flow of the hydraulic oil to discharge the hydraulic oil discharged from the left-side travel hydraulic motor 1L to the hydraulic oil tank.

The control valve 172 is a spool valve that supplies the hydraulic oil discharged from the main pump 14R to the right-side travel hydraulic motor 1R and switches the flow of the hydraulic oil to discharge the hydraulic oil discharged from the right-side travel hydraulic motor 1R to the hydraulic oil tank.

The control valve 173 is a spool valve that supplies the hydraulic oil discharged from the main pump 14L to the turning hydraulic motor 2A and switches the flow of the hydraulic oil to discharge the hydraulic oil discharged from the turning hydraulic motor 2A to the hydraulic oil tank.

The control valve 174 is a spool valve that supplies the hydraulic oil discharged from the main pump 14R to the bucket cylinder 9 and switches the flow of the hydraulic oil to discharge the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

The control valves 175L and 175R are spool valves that supply the hydraulic oil discharged from the main pumps 14L and 14R to the boom cylinder 7 and switches the flow of the hydraulic oil to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

The control valves 176L and 176R are spool valves that supply the hydraulic oil discharged from the main pumps 14L and 14R to the arm cylinder 8 and switches the flow of the hydraulic oil to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

The parallel pipeline 42L is a hydraulic oil line parallel to the center bypass pipeline 40L. The parallel pipeline 42L is configured to supply the hydraulic oil to the downstream control valve when the flow of the hydraulic oil through the center bypass pipeline 40L is limited or interrupted by any of the control valves 171, 173, 175L. The parallel pipeline 42R is a hydraulic oil line parallel to the center bypass pipeline 40R. The parallel pipeline 42R is configured to supply hydraulic oil to the downstream control valve when the flow of hydraulic oil through the center bypass pipeline 40R is limited or cut off by one of the control valves 172, 174, 175R.

The regulators 13L and 13R control the discharge amount of the main pumps 14L and 14R by adjusting the swash plate tilt angle of the main pumps 14L and 14R according to the discharge pressure of the main pumps 14L and 14R. The regulators 13L and 13R correspond to the regulator 13 illustrated in FIG. 2. The regulator 13L reduces the discharge amount by adjusting the swash plate tilt angle of the main pump 14L according to an increase in the discharge pressure of the main pump 14L, for example. The same applies to the regulator 13R. This is to ensure that the absorption power (absorption horsepower) of the main pump 14 expressed as a product of the discharge pressure and the discharge amount, does not exceed the output power (output horsepower) of the engine 11.

The discharge pressure sensor 28L is an example of the discharge pressure sensor 28 and detects the discharge pressure of the main pump 14L and outputs the detected value to the controller 30. The same applies to the discharge pressure sensor 28R.

The negative control adopted in the hydraulic system illustrated in FIG. 3 will now be described.

In the center bypass pipeline 40L, an aperture 18L is arranged between the control valve 176L located at the most downstream and the hydraulic oil tank. The flow of hydraulic oil discharged from the main pump 14L is limited by the aperture 18L. The aperture 18L generates a control pressure for controlling the regulator 13L. The control pressure sensor 19L is a sensor for detecting the control pressure and outputs the detected value to the controller 30. Similarly, in the center bypass pipeline 40R, an aperture 18R is arranged between the control valve 176R located at the most downstream and the hydraulic oil tank. The flow of the hydraulic oil discharged from the main pump 14R is limited by the aperture 18R. The aperture 18R generates the control pressure for controlling the regulator 13R. The control pressure sensor 19R is a sensor for detecting the control pressure, and outputs the detected value to the controller 30.

The controller 30 controls the discharge amount of the main pump 14L by adjusting the swash plate tilt angle of the main pump 14L according to the control pressure detected by the control pressure sensor 19L. The controller 30 decreases the discharge amount of the main pump 14L as the control pressure increases, and increases the discharge amount of the main pump 14L as the control pressure decreases.

Specifically, as illustrated in FIG. 3, when the hydraulic actuator of the excavator 100 is in a standby state where none of the hydraulic actuators is operated, the hydraulic oil discharged from the main pump 14L reaches the aperture 18L through the center bypass pipeline 40L. The flow of the hydraulic oil discharged from the main pump 14L increases the control pressure generated upstream of the aperture 18L. As a result, the controller 30 decreases the discharge amount of the main pump 14L to the allowable minimum discharge amount, and reduces the pressure loss (pumping loss) when the discharged hydraulic oil passes through the center bypass pipeline 40L.

On the other hand, when any hydraulic actuator is operated, the hydraulic oil discharged from the main pump 14L flows into the hydraulic actuator that is the operation target via a control valve corresponding to the hydraulic actuator that is the operation target. Then, the flow of the hydraulic oil discharged from the main pump 14L reduces or eliminates the flow to the aperture 18L, thereby lowering the control pressure generated upstream of the aperture 18L. As a result, the controller 30 increases the discharge amount of the main pump 14L, circulates sufficient hydraulic oil to the hydraulic actuator that is the operation target, and ensures the drive of the hydraulic actuator that is the operation target. The above description of the main pump 14L also applies to the main pump 14R.

With the above-described configuration, the hydraulic system of FIG. 3 can reduce wasteful energy consumption in the main pumps 14L and 14R in the standby state. The wasteful energy consumption includes pumping losses generated in the center bypass pipelines 40L and 40R by the hydraulic oil discharged by the main pumps 14L and 14R. When the hydraulic actuator is operated, the hydraulic system of FIG. 3 can supply necessary and sufficient hydraulic oil from the main pumps 14L and 14R to the hydraulic actuator that is the operation target.

Next, referring to FIGS. 4A to 4C, a configuration for automatically operating the actuator will be described.

FIGS. 4A to 4C are diagrams illustrating a part of the hydraulic system. Specifically, FIG. 4A illustrates a part of the hydraulic system relating to the operation of the boom cylinder 7, FIG. 4B illustrates a part of the hydraulic system relating to the operation of the bucket cylinder 9, and FIG. 4C illustrates a part of the hydraulic system relating to the operation of the turning hydraulic motor 2A.

The boom operating lever 26A in FIG. 4A is an example of the operation device 26 and is used to operate the boom 4. The boom operating lever 26A uses hydraulic oil discharged from the pilot pump 15 to cause the pilot pressure corresponding to the operation contents to act on the pilot ports of the control valves 175L and 175R. Specifically, when the boom operating lever 26A is operated in the boom raising direction, the pilot pressure corresponding to the operation amount acts on the right pilot port of the control valve 175L and the left pilot port of the control valve 175R. When the boom operating lever 26A is operated in the boom lowering direction, the pilot pressure corresponding to the operation amount acts on the right pilot port of the control valve 176R.

The operation pressure sensor 29A is an example of the operation pressure sensor 29, and detects the operation contents of the operator with respect to the boom operating lever 26A in the form of pressure, and outputs the detected value to the controller 30. The operation contents are, for example, the operation direction and the operation amount (operation angle).

Proportional valves 31AL and 31AR are examples of the proportional valve 31, and shuttle valves 32AL and 32AR are examples of the shuttle valve 32. The proportional valve 31AL operates according to a current instruction output from the controller 30. The proportional valve 31AL adjusts pilot pressure by hydraulic oil introduced from the pilot pump 15 to the right pilot port of the control valve 175L and the left pilot port of the control valve 175R via the proportional valve 31AL and the shuttle valve 32AL. The proportional valve 31AR operates according to a current instruction output from the controller 30. The proportional valve 31AR adjusts pilot pressure by the hydraulic oil introduced from the pilot pump 15 to the right pilot port of the control valve 175R via the proportional valve 31AR and the shuttle valve 32AR. The proportional valves 31AL and 31AR can adjust the pilot pressure such that the control valves 175L and 175R can be stopped at any valve position.

With this configuration, the controller 30 can supply hydraulic oil discharged from the pilot pump 15 to the right pilot port of control valve 175L and the left pilot port of the control valve 175R via the proportional valve 31AL and the shuttle valve 32AL, for example, regardless of a boom raising operation by an operator. That is, the controller 30 can automatically raise the boom 4. Further, the controller 30 can supply hydraulic oil discharged from the pilot pump 15 to the right pilot port of the control valve 175R via the proportional valve 31AR and the shuttle valve 32AR, regardless of the boom lowering operation by the operator. That is, the controller 30 can automatically lower the boom 4.

The bucket operating lever 26B in FIG. 4B is an example of the operation device 26 and is used to operate the bucket 6. The bucket operating lever 26B uses hydraulic oil discharged from the pilot pump 15 to apply a pilot pressure corresponding to the operation content to the pilot port of the control valve 174. Specifically, when the bucket operating lever 26B is operated in the bucket opening direction, the pilot pressure corresponding to the operation amount is applied to the right pilot port of the control valve 174. When the bucket operating lever 26B is operated in the bucket closing direction, the pilot pressure corresponding to the operation amount is applied to the left pilot port of the control valve 174.

The operation pressure sensor 29B is an example of the operation pressure sensor 29, and detects the operation content of the operator to the bucket operating lever 26B in the form of pressure, and outputs the detected value to the controller 30.

The proportional valves 31BL and 31BR are examples of the proportional valve 31, and the shuttle valves 32BL and 32BR are examples of the shuttle valve 32. The proportional valve 31BL operates according to a current instruction output from the controller 30. The proportional valve 31BL adjusts a pilot pressure caused by hydraulic oil introduced from the pilot pump 15 to the left pilot port of the control valve 174 via the proportional valve 31BL and the shuttle valve 32BL. The proportional valve 31BR operates according to a current instruction output from the controller 30. The proportional valve 31BR adjusts pilot pressure caused by hydraulic oil introduced from the pilot pump 15 to the right pilot port of the control valve 174 via the proportional valve 31BR and the shuttle valve 32BR. The proportional valves 31BL and 31BR can adjust pilot pressure such that the control valve 174 can be stopped at an arbitrary valve position.

With this configuration, the controller 30 can supply hydraulic oil discharged from the pilot pump 15 to the left pilot port of the control valve 174 via the proportional valve 31BL and the shuttle valve 32BL, regardless 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 hydraulic oil discharged from the pilot pump 15 to the right pilot port of the control valve 174 via the proportional valve 31BR and the shuttle valve 32BR, regardless of the bucket opening operation by the operator. That is, the controller 30 can automatically open the bucket 6.

The turning operation lever 26C in FIG. 4C is an example of the operation device 26 and is used to turn the upper turning body 3. The turning operation lever 26C uses hydraulic oil discharged from the pilot pump 15 to apply pilot pressure corresponding to the operation content to the pilot port of the control valve 173. Specifically, when the turning operation lever 26C is operated in the left turning direction, the pilot pressure corresponding to the operation amount is applied to the left pilot port of the control valve 173. When the turning operation lever 26C is operated in the right turning direction, the pilot pressure corresponding to the operation amount is applied to the right pilot port of the control valve 173.

The operation pressure sensor 29C is an example of the operation pressure sensor 29, and detects the operation content of the operator to the turning operation lever 26C in the form of pressure, and outputs the detected value to the controller 30.

The proportional valves 31CL and 31CR are examples of the proportional valve 31, and the shuttle valves 32CL and 32CR are examples of the shuttle valve 32. The proportional valve 31CL operates according to the current instruction output from the controller 30. The proportional valve 31CL adjusts the pilot pressure caused by the hydraulic oil introduced from the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31CL and the shuttle valve 32CL. The proportional valve 31CR operates according to the current instruction output from the controller 30. The proportional valve 31CR adjusts the pilot pressure caused by the hydraulic oil introduced from the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31CR and the shuttle valve 32CR. The proportional valves 31CL and 31CR can adjust the pilot pressure such that the control valve 173 can be stopped at an arbitrary valve position.

With this configuration, the controller 30 can supply the hydraulic oil discharged from the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31CL and the shuttle valve 32CL, regardless of the left turning operation by the operator. That is, the controller 30 can automatically turn the upper turning body 3 to the left. Also, the controller 30 can supply the hydraulic oil discharged from the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31CR and the shuttle valve 32CR, regardless of the right turning operation by the operator. That is, the controller 30 can automatically turn the upper turning body 3 to the right.

The excavator 100 may be provided with a configuration in which the arm 5 is automatically opened and closed, and a configuration in which the lower traveling body 1 is automatically moved forward and backward. In this case, the hydraulic system portion relating to the operation of the arm cylinder 8, the hydraulic system portion relating to the operation of the left-side travel hydraulic motor 1L, and the hydraulic system portion relating to the operation of the right-side travel hydraulic motor 1R may be configured in the same manner as the hydraulic system portion relating 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 the drive system of the excavator 100, and corresponds to FIG. 2. The drive system of FIG. 5 is different from the drive system of FIG. 2 in that the machine guidance device 50 includes a turning angle calculation part 55 and a relative angle calculation part 56, but is common in other respects. Therefore, the description of the common parts will be omitted and the differences will be described in detail.

The turning angle calculation part 55 calculates the turning angle of the upper turning body 3. This is to identify the current orientation of the upper turning body 3. In the present embodiment, the turning angle calculation part 55 calculates the angle of the longitudinal axis of the upper turning body 3 with respect to the reference direction as the turning angle, based on the output of the GNSS compass serving as the positioning device P1. The turning angle calculation part 55 may calculate the turning angle based on the output of the turning angular speed sensor S5. Further, if the reference point is set at the work site, the turning angle calculation part 55 may use the direction in which the reference point is viewed from the turning axis as the reference direction.

The turning angle indicates the direction in which the attachment operating surface extends. The attachment operating surface is, for example, a virtual plane that traverses the attachment and is arranged so as to be perpendicular to the turning plane. The turning plane is, for example, a virtual plane that includes the bottom surface of the turning frame perpendicular to the turning axis. When the machine guidance device 50 determines that the attachment operating surface AF (see FIG. 8A) includes a line orthogonal to the target working surface, for example, it determines that the upper turning body 3 faces the target working surface.

The relative angle calculation part 56 calculates a relative angle as a turning angle necessary for making the upper turning body 3 face the target work surface. The relative angle is, for example, a relative angle formed between the direction of the longitudinal axis of the upper turning body 3 when the upper turning body 3 faces the target work surface and the current direction of the longitudinal axis of the upper turning body 3. In the present embodiment, the relative angle calculation part 56 calculates a relative angle based on information about the target work surface stored in the storage device 47 and the turning angle calculated by the turning angle calculation part 55.

When the turning operation lever is operated while a predetermined switch is pressed, the automatic control part 54 determines whether or not the turning operation lever is operated in a direction to make the upper turning body 3 face the target work surface. When it is determined that the turning operation lever is operated in a direction to make the upper turning body 3 face the target work surface, the automatic control part 54 sets the relative angle calculated by the relative angle calculation part 56 as the target angle. When the change in the turning angle after the turning operation lever is operated reaches the target angle, it is determined that the upper turning body 3 has faced the target work surface, and the movement of the turning hydraulic motor 2A is stopped. Further, the automatic control part 54 obtains a predetermined speed as a condition for limiting the rotation speed of the turning hydraulic motor 2A in the facing control, by using the turning angle of the upper turning body 3 calculated by the turning angle calculation part 55 and the relative angle calculated by the relative angle calculation part 56.

In this way, the machine guidance device 50 of FIG. 5 can make the upper turning body 3 face the target work surface in the same manner as the machine guidance device 50 of FIG. 2.

Next, with reference to FIGS. 6, 7A, 7B, 8A, and 8B, an example of the facing control in which the controller 30 makes the upper turning body 3 face the target work surface will be described.

FIG. 6 is a flowchart illustrating the process of the facing control. The controller 30 executes this process when the MC switch is pressed. FIGS. 7A and 7B are top views of the excavator 100 when the facing control is executed, and FIGS. 8A and 8B are perspective views of the excavator 100 when the excavator 100 is viewed from the left rear when the facing control is executed. Specifically, FIGS. 7A and 8A illustrate a state in which the upper turning body 3 does not face the target work surface, and FIGS. 7B and 8B illustrate a state in which the upper turning body 3 faces the target work surface. The target work surface in FIGS. 7A, 7B, 8A, and 8B is, for example, the uphill slope BS as illustrated in FIG. 1. The region NS represents a state in which the uphill slope BS is not completed, that is, a state in which the ground surface ES does not coincide with the uphill slope BS as illustrated in FIG. 1, and the region CS represents a state in which the uphill slope BS is completed, that is, a state in which the ground surface ES coincides with the uphill slope BS.

The state in which the upper turning body 3 faces the target work surface includes, for example, a state in which the angle α formed between the line segment L1 representing the direction (extension direction) of the target work surface and the line segment L2 representing the longitudinal axis of the upper turning body 3 on the virtual horizontal plane is 90 degrees, as illustrated in FIG. 7B. The extension direction of the slope as the direction of the target work surface represented by the line segment L1 is, for example, a direction perpendicular to the slope length direction. The slope length direction is, for example, a direction along an imaginary line segment connecting the upper end (slope top) and the lower end (slope toe) of the slope with the shortest distance. The state in which the upper turning body 3 faces the target work surface may be defined as a state in which the angle β (see FIG. 7A) formed between the line segment L2 representing the longitudinal axis of the upper turning body 3 and the line segment L3 perpendicular to the direction (extension direction) of the target work surface is zero degrees on the virtual horizontal plane. The direction represented by the line segment L3 corresponds to the direction of the horizontal component of the perpendicular line drawn down to the target work surface.

The virtual cylinder CB in FIGS. 8A and 8B represents a part of the line perpendicular to the target work surface (uphill slope BS), the dash-dot line represents a part of the virtual turning plane SF, and the dashed line represents a part of the virtual attachment operating surface AF. The attachment operating surface AF is arranged so as to be perpendicular to the turning plane SF. As illustrated in FIG. 8B, when the upper turning body 3 faces the target work surface, the attachment operating surface AF is arranged so as to include a part of the orthogonal line represented by the virtual cylinder CB, that is, the attachment operating surface AF extends along a part of the orthogonal line.

The automatic control part 54 sets, for example, a turning angle, at which the attachment operating surface AF and the target work surface (uphill slope BS) are perpendicular, as the target angle. Then, the automatic control part 54 detects the current turning angle based on the output of the positioning device P1 or the like, and calculates the difference between the target angle and the current turning angle (detected value). Then, the automatic control part 54 operates the turning hydraulic motor 2A such that the difference becomes a predetermined value or less or zero. Specifically, the automatic control part 54 determines that the upper turning body 3 faces the target work surface when the difference between the target angle and the current turning angle becomes a predetermined value or less or zero. When the turning operation lever is operated while a predetermined switch is pressed, the automatic control part 54 determines whether or not the turning operation lever is operated in the direction to make the upper turning body 3 face the target work surface. For example, if the turning operation lever is operated in the direction in which the difference between the target angle and the current turning angle becomes large, the automatic control part 54 determines that the turning operation lever is not operated in the direction to make the upper turning body 3 face the target work surface and does not execute the facing control. On the other hand, if the turning operation lever is operated in the direction in which the difference between the target angle and the current turning angle becomes small, the automatic control part 54 determines that the turning operation lever is operated in the direction to make the upper turning body 3 face the target work surface and executes the facing control. As a result, the turning hydraulic motor 2A can be operated such that the difference between the target angle and the current turning angle becomes small. Thereafter, the automatic control part 54 stops the turning hydraulic motor 2A when the difference between the target angle and the current turning angle becomes a predetermined value or less or zero.

The example illustrated in FIG. 7B is one example indicating the state where the attachment operating surface AF includes the orthogonal line (virtual cylindrical body CB), and the angle π formed between the line segment L1 indicating the orientation of the target work surface and the line segment L2 indicating the longitudinal axis of the upper turning body 3 is 90 degrees. However, if the attachment operating surface AF includes the orthogonal line (virtual cylindrical body CB), the angle π does not necessarily have to be 90 degrees. For example, because the ground where the excavator 100 is installed is often a highly undulating ground, the angle α does not necessarily have to be 90 degrees even if the attachment operating surface AF includes the orthogonal line (virtual cylindrical body CB).

With reference to FIG. 7A, FIG. 7B, FIG. 8A, and FIG. 8B, the flow of the facing processing will be described with reference to FIG. 6.

First, the machine guidance device 50 included in the controller 30 determines whether or not displacement from the facing position has occurred. In the present embodiment, the machine guidance device 50 determines whether or not the displacement from the facing position has occurred based on the information on the target work surface previously stored in the storage device 47 and the output of the positioning device P1 serving as the orientation detecting device. The information on the target work surface includes information on the orientation of the target work surface. The positioning device P1 outputs information about the orientation of the upper turning body 3. For example, as illustrated in FIG. 8A, when the attachment operating surface AF does not include the line orthogonal to the target work surface, the machine guidance device 50 determines that displacement from the facing position has occurred between the target work surface and the excavator 100. In such a state, as illustrated in FIG. 7A, the angle α formed between the line segment L1 representing the orientation of the target work surface and the line segment L2 representing the orientation of the upper turning body 3 is an angle π other than 90 degrees.

Note that the machine guidance device 50 may determine whether or not the displacement from the facing position has occurred based on the image captured by the camera S6. For example, the machine guidance device 50 may perform various kinds of image processing on the image captured by the camera S6 to derive information about the shape of the slope that is the work target, and determine whether or not the displacement from the facing position has occurred based on the derived information. Alternatively, the machine guidance device 50 may determine whether or not the displacement from the facing position has occurred based on the output of another spatial recognition device other than the camera S6 such as an ultrasonic sensor, a millimeter wave radar, a distance image sensor, LIDAR, or an infrared sensor.

When it is determined that the displacement from the facing position has occurred, the machine guidance device 50 determines whether or not the turning operation lever is operated in the direction to make the upper turning body 3 face the target work surface while a predetermined switch is pressed (steps ST1 and ST2).

In a state where a predetermined switch is pressed (YES in step ST1) and the turning operation lever is operated in a direction to make the upper turning body 3 face the target work surface (YES in step ST2), the machine guidance device 50 determines whether or not the target work surface is located directly under the bucket 6 based on the position of the bucket 6 calculated by the position calculation part 51 (step ST3).

At this time, it may be determined whether or not an obstacle exists around the excavator 100. For example, the machine guidance device 50 performs image recognition processing on the image captured by the camera S6 to determine whether or not an image related to a predetermined obstacle exists in the captured image. The predetermined obstacle is, for example, at least one of a person, an animal, a machine, a building, or the like. When it is determined that no image related to a predetermined obstacle exists in the image related to the predetermined range set around the excavator 100, it is determined that no obstacle exists around the excavator 100. The predetermined range includes, for example, a range where an object that comes into contact with the excavator 100 may exist when the excavator 100 is moved to make the upper turning body 3 face the target work surface. The range RA represented by the cross-hatching pattern in FIG. 7A is an example of the predetermined range. However, the predetermined range may be set as a wider range, for example, within a range of a predetermined distance from the turning shaft 2X.

The machine guidance device 50 may determine whether or not an obstacle exists around the excavator 100 based on the output of other spatial recognition devices other than the camera S6, such as an ultrasonic sensor, a millimeter wave radar, a distance image sensor, LIDAR, or an infrared sensor.

When the turning operation lever is operated in a direction to make the upper turning body 3 face the target work surface while a predetermined switch is pressed, and the target work surface is directly under the bucket 6 (YES in step ST3), the machine guidance device 50 executes the facing control (step ST4). In the examples of FIGS. 7A, 7B, 8A, and 8B, the automatic control part 54 of the machine guidance device 50 outputs a current instruction to the proportional valve 31CL (see FIG. 4C). Then, the pilot pressure generated by the hydraulic oil coming out of the pilot pump 15 and passing through the proportional valve 31CL and the shuttle valve CL acts on 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, and the hydraulic oil discharged from the main pump 14L flows into the first port 2A1 of the turning hydraulic motor 2A. The control valve 173 also causes the hydraulic oil flowing out of the second port 2A2 of the turning hydraulic motor 2A to flow into the hydraulic oil tank. As a result, the turning hydraulic motor 2A rotates in the forward direction, and as indicated by the arrow in FIG. 7A, the turning force is applied to the upper turning body 3 around the turning shaft 2X to turn the upper turning body 3 in the left direction. Then, the automatic control part 54 stops the output of the current instruction to the proportional valve 31CL when the angle α becomes 90 degrees or when the angle β becomes zero degrees, as illustrated in FIG. 7B, and reduces the pilot pressure acting on the left pilot port of the control valve 173. The control valve 173 is displaced in the left direction, returns to the neutral position, and blocks the flow of the hydraulic oil from the main pump 14L to the first port 2A1 of the turning hydraulic motor 2A. The control valve 173 blocks the flow of hydraulic oil from the second port 2A2 of the turning hydraulic motor 2A to the hydraulic oil tank. As a result, the turning hydraulic motor 2A stops rotating in the forward direction and stops the upper turning body 3 from rotating in the left direction.

In the case of determining whether or not an obstacle exists around the excavator 100, when it is determined that an obstacle exists around the excavator 100, the machine guidance device 50 may terminate the current facing processing without executing the facing control. This is to prevent the excavator 100 from coming into contact with the obstacle by executing the facing control. In this case, the machine guidance device 50 may output an alarm. Further, the machine guidance device 50 may transmit information about the obstacle such as the presence or absence of the obstacle, the position of the obstacle, and the type of the obstacle to an external device via the communication device T1. The machine guidance device 50 may also receive information about the obstacle acquired by another excavator via the communication device T1.

In this way, the controller 30 can perform the facing control in which the upper turning body 3 is caused to face the target work surface by applying a turning force to the upper turning body 3 to turn the upper turning body 3.

Also, as described above, the controller 30 is configured to execute the facing control when a predetermined switch is operated. For example, when the MC switch is operated, the controller 30 may be configured to perform facing control. In this case, the controller 30 can automatically make the upper turning body 3 face the target work surface when the MC switch for starting the machine control function is pressed. That is, the controller 30 can execute the facing control as a part of the machine control function. Therefore, the controller 30 can reduce annoyance felt by the operator of the excavator 100 when making the excavator 100 face the target work surface when executing the machine control function. As a result, the controller 30 can improve the work efficiency of the excavator 100. As described above, it is also possible to have a configuration in which the facing control is performed when the operation for turning the upper turning body 3 is performed while the predetermined switch is operated and the target work surface is located below the operating element of the excavator 100 for working on the target work surface, such as the bucket 6. Thus, it is possible to support the operator to make the upper turning body 3 face the target work surface only when the target work surface is located below the operating element of the excavator 100 for working on the target work surface, such as the bucket 6. Further, if the switch for pressing when performing the automatic control of the attachment other than facing control, and the switch for pressing when executing the facing control, are the same switch, the facing control is performed by operating the turning operation lever while pressing the switch to make the upper turning body 3 face the target work surface, and then the automatic control can be performed by operating another lever while continuously pressing the switch. Thus, the facing control and the automatic control can be performed in a series of operations.

In the facing control described above, by improving the accuracy of the facing, the work can be performed accurately and the work efficiency can be improved. Therefore, the control for improving the accuracy of the facing will be described below.

FIG. 9A is a flowchart for explaining an example of the process added to the facing control.

In this process, when starting the facing control, the automatic control part 54 determines whether the turning speed of the upper turning body 3 calculated by the turning speed calculation part 57 exceeds a predetermined speed (step ST11). As described above, the facing control is started when the target work surface is located directly under the bucket 6. Therefore, even if the turning speed of the upper turning body 3 in the facing control is predetermined, the turning speed of the upper turning body 3 may be high when the target work surface is not located directly under the bucket 6. In this case, if the facing control is continued, the upper turning body 3 may not be able to stop at the position facing the target work surface. Therefore, when starting the facing control, the automatic control part 54 first calculates the turning angle required for the upper turning body 3 to face the target work surface, by using the turning angle of the upper turning body 3 calculated by the position calculation part 51 and the distance between the claw tip of the bucket 6 and the target work surface calculated by the distance calculation part 52. When the turning angle required for the upper turning body 3 to face the target work surface is small, the turning angle at the limited turning speed is small, so if the turning speed before the limitation is high, the turning speed will not decrease sufficiently before the upper turning body 3 faces the target construction surface, thereby increasing the possibility that the upper turning body 3 will exceed the position facing the target work surface. On the other hand, when the turning angle required for the upper turning body 3 to face the target work surface is large, the turning angle at the limited turning speed is large, and even if the turning speed before the limitation is high, the turning speed is sufficiently reduced by the time the upper turning body 3 faces the target work surface, and the possibility that the upper turning body 3 exceeds the position facing the target work surface is low. Therefore, the automatic control part 54 sets a predetermined speed as a condition for limiting the turning speed of the upper turning body 3 such that the smaller the turning angle of the upper turning body 3 becomes, the faster the predetermined speed becomes.

The turning speed calculation part 57 calculates the turning speed of the upper turning body 3 by time-differentiating the turning angle of the upper turning body 3 calculated by the position calculation part 51. Therefore, the automatic control part 54 can determine whether the turning speed of the upper turning body 3 calculated by the turning speed calculation part 57 exceeds the predetermined speed obtained according to the turning angle required for the upper turning body 3 to face the target work surface.

If the turning speed of the upper turning body 3 exceeds the predetermined speed (YES in step ST11), the automatic control part 54 limits the turning speed of the upper turning body 3 (step ST12). Specifically, the automatic control part 54 changes the pilot pressure exiting the pilot pump 15 and exerted on the control valve 173 via the proportional valve 31CL and the shuttle valve CL, thereby reducing the amount of hydraulic oil flowing into the turning hydraulic motor 2A. As a result, the turning force applied to the upper turning body 3 becomes small, and the turning speed of the upper turning body 3 becomes slow. The degree to which the automatic control part 54 slows the turning speed of the upper turning body 3 may be set according to the turning angle required for the upper turning body 3 to face the target work surface, or according to the type and size of the excavator 100. Further, instead of slowing the turning speed of the upper turning body 3 by changing the pilot pressure exiting the pilot pump 15 and exerted on the control valve 173 through the proportional valve 31CL and the shuttle valve CL, the control may be performed so as to slow the turning speed of the upper turning body 3 by applying a resistance force toward the lever of the operation device 26 which is operated in the turning operation, in the direction opposite to the operation direction, and limiting the amount of the lever operation.

As described above, the excavator 100 in the present embodiment is provided with the lower traveling body 1, the upper turning body 3 mounted on the lower traveling body 1 so as to be able to turn, and the controller 30 which performs the facing control to make the upper turning body 3 face the target work surface by applying a turning force to the upper turning body 3 to turn, and the controller 30 controls the turning speed of the upper turning body 3 based on the turning angle required for the upper turning body 3 to face the target work surface. As a result, in the facing control to make the upper turning body 3 face the target work surface, the upper turning body 3 is prevented from exceeding the position facing the target work surface, and the accuracy of the facing control can be improved. For example, the controller 30 can improve the accuracy of the facing control by limiting the turning speed of the upper turning body 3 when the turning speed of the upper turning body 3 exceeds a predetermined speed. In this case, the predetermined speed as a condition for limiting the turning speed of the upper turning body 3 is obtained based on the turning angle required for the upper turning body 3 to face the target work surface, such that the upper turning body 3 is prevented from exceeding the position facing the target work surface in the facing control of making the upper turning body 3 face the target work surface, regardless of the magnitude of inertial force caused by the turning when the upper turning body 3 turns and faces the target work surface.

Further, the automatic control part 54 determines whether the upper turning body 3 is likely to exceed the position facing the target work surface in the facing control (step ST13). Here, the controller 30 calculates the distance between the claw tip of the bucket 6 and the target work surface by the distance calculation part 52. Therefore, based on the distance calculated by the distance calculation part 52, the automatic control part 54 always determines whether the upper turning body 3 is likely to exceed the position facing the target work surface.

If the upper turning body 3 is likely to exceed the position facing the target work surface (YES in step ST13), the information transmission part 53 reports, to the operator of the excavator 100, that the upper turning body 3 is likely to exceed the position facing the target work surface (step ST14). The reporting at this time may be performed by using, for example, sound from the sound output device 43. The reporting may also be performed by using characters or images via the display device 40. In this way, the controller 30 provides a report to the operator of the excavator 100 when the upper turning body 3 is likely to exceed the position facing the target work surface by turning, such that the operator of the excavator 100 can recognize the fact when the upper turning body 3 is likely to exceed the position facing the target work surface by turning in the facing control.

The automatic control part 54 always determines whether the upper turning body 3 has exceeded the position facing the target work surface based on the distance calculated by the distance calculation part 52 (step ST15).

Then, when the upper turning body 3 has exceeded the position facing the target work surface (YES in step ST15), the information transmission part 53 reports, to the operator of the excavator 100, that the upper turning body 3 has exceeded the position facing the target work surface (step ST16). The report at this time may be made by, for example, sound from the sound output device 43. Further, the reporting may be made by text or the like through the display device 40. In this way, the controller 30 provides a report to the operator of the excavator 100 when the upper turning body 3 has exceeded the position facing the target work surface by turning, such that the operator of the excavator 100 can recognize the fact when the upper turning body 3 has exceeded the position facing the target work surface by turning in the facing control.

Note that the information transmission part 53 may use different sounds when the upper turning body 3 is likely to exceed the position facing the target work surface and when the upper turning body 3 has exceeded the position facing the target work surface. For example, the information transmission part 53 may perform first reporting by using intermittent sounds through the sound output device 43 when the upper turning body 3 is likely to exceed the position facing the target work surface, and perform second reporting by using continuous sound through the sound output device 43 when the upper turning body 3 has exceeded the position facing the target work surface. Thus, the operator can distinguish and recognize when the upper turning body 3 is likely to exceed the position facing the target work surface and when the upper turning body 3 has exceeded the position facing the target work surface.

In the present embodiment, after limiting the turning speed of the upper turning body 3 in step ST12, it is determined whether or not the upper turning body 3 is likely to exceed the position facing the target work surface or has exceeded the position, and the reporting is performed in steps ST14 and ST16. However, it is possible to perform the reporting in steps ST14 and ST16 without limiting the turning speed of the upper turning body 3 in step ST12. In this case, in the flow illustrated in FIG. 9A, the processing in steps ST13 and ST15 may be performed without performing the processing in steps ST11 and ST12, or the processing may be shifted to steps ST13 and ST15 when the determination in step ST11 is NO. Even in this case, when the upper turning body 3 is likely to exceed the position facing the target work surface or when the upper turning body 3 exceeds the position facing the target work surface by turning in the facing control, the operator of the excavator 100 can be made to recognize this.

Next, an example of the method of limiting the turning speed of the upper turning body 3 will be described.

FIG. 9B is a flowchart for explaining an example of the method of limiting the turning speed of the upper turning body 3.

In this process, when starting the facing control, the automatic control part 54 determines whether the turning speed of the upper turning body 3 exceeds the predetermined speed (step ST21), and then determines whether the difference between the turning speed of the upper turning body 3 and the predetermined speed is greater than a predetermined value (step ST22).

When the difference between the turning speed of the upper turning body 3 and the predetermined speed is less than or equal to the predetermined value (NO in step ST22), the automatic control part 54 changes the pilot pressure exiting from the pilot pump 15 and applied to the control valve 173 via the proportional valve 31CL and the shuttle valve CL, as described above, thereby reducing the amount of hydraulic oil flowing into the turning hydraulic motor 2A. Thus, the turning force applied to the upper turning body 3 is reduced and the turning speed of the upper turning body 3 is slowed down (step ST23).

On the other hand, when the difference between the turning speed of the upper turning body 3 and the predetermined speed is greater than the predetermined value (YES in step ST22), there is a possibility that the turning speed of the upper turning body 3 cannot be slowed down to the target turning speed by the automatic control part 54. Therefore, when the difference between the turning speed of the upper turning body 3 and the predetermined speed is greater than the predetermined value, the automatic control part 54 applies the turning force opposite to the currently applied turning force to the upper turning body 3 (step ST24). Specifically, when the pilot pressure is applied to the left pilot port of the control valve 173 to turn the upper turning body 3, the pilot pressure generated by the hydraulic oil coming out of the pilot pump 15 and passing through the proportional valve 31CL and the shuttle valve CL is applied to the right pilot port of the control valve 173. The control valve 173, which receives the pilot pressure at the right pilot port, displaces in the left direction and causes the hydraulic oil discharged from the main pump 14L to flow into the second port 2A2 of the turning hydraulic motor 2A. The control valve 173 also causes the hydraulic oil flowing out of the first port 2A1 of the turning hydraulic motor 2A to flow into the hydraulic oil tank. As a result, the turning hydraulic motor 2A rotates in the opposite direction. At this time, the turning force in the opposite direction is applied to the upper turning body 3, but due to the inertia force caused by the turning of the upper turning body 3, the upper turning body 3 does not turn in the opposite direction for a certain amount of time.

After that, when the turning speed of the upper turning body 3 slows down to the target turning speed or approaches the target turning speed, the application of the turning force in the opposite direction to the upper turning body 3 is stopped.

Thus, in this example, when the difference between the current turning speed of the upper turning body 3 at the time of starting the facing control and the predetermined speed is greater than the predetermined value, the controller 30 applies the turning force in the opposite direction from the current turning force applied to the upper turning body 3 to which the turning force is applied. Thus, even when the difference between the current turning speed of the upper turning body 3 at the time of starting the facing control and the predetermined speed is greater than the predetermined value, the possibility that the automatic control part 54 cannot slow down the turning speed of the upper turning body 3 to the target turning speed can be reduced.

Next, another example of improving the accuracy of the facing will be described.

FIG. 9C is a flowchart for explaining another example of processing added to the facing control.

In this process, as in the flow illustrated in FIG. 9A, the automatic control part 54 determines whether or not the turning speed of the upper turning body 3 exceeds the predetermined speed when starting the facing control (step ST31), and limits the turning speed of the upper turning body 3 when the turning speed of the upper turning body 3 exceeds the predetermined speed (step ST32).

Also, as described above, the automatic control part 54 always determines whether or not the upper turning body 3 has exceeded the position facing the target work surface based on the distance calculated by the distance calculation part 52 (step ST33).

When the upper turning body 3 has exceeded the position facing the target work surface (YES in step ST33), the automatic control part 54 applies a turning force opposite to the turning force currently applied to the upper turning body 3. Specifically, when the pilot pressure is applied to the left pilot port of the control valve 173 to turn the upper turning body 3, the pilot pressure generated by the hydraulic oil exiting the pilot pump 15 and passing through the proportional valve 31CL and the shuttle valve CL is applied to the right pilot port of the control valve 173. The control valve 173, which has received the pilot pressure at the right pilot port, displaces in the left direction and causes the hydraulic oil discharged from the main pump 14L to flow into the second port 2A2 of the turning hydraulic motor 2A. The control valve 173 also causes the hydraulic oil discharged from the first port 2A1 of the turning hydraulic motor 2A to flow into the hydraulic oil tank. As a result, the turning hydraulic motor 2A rotates in the opposite direction. At this time, the turning force in the opposite direction is applied to the upper turning body 3. Further, because the turning speed of the upper turning body 3 is reduced by the speed limitation in step ST32, the upper turning body 3 turns in the opposite direction (step ST34).

Thereafter, the automatic control part 54 performs the facing control until the upper turning body 3 faces the target work surface (step ST35).

Thus, in this example, when the upper turning body 3 turns and exceeds the position facing the target work surface, the controller 30 turns the upper turning body 3 in the opposite direction until the upper turning body 3 faces the target work surface. Thus, even when the upper turning body 3 turns and exceeds the position facing the target work surface, the upper turning body 3 can be made to face the target work surface.

In this example, when the upper turning body 3 exceeds the position facing the target work surface, the upper turning body 3 is turned in the opposite direction under the control of the automatic control part 54. However, when the upper turning body 3 exceeds the position facing the target work surface, the upper turning body 3 may be turned in the opposite direction until the upper turning body 3 faces the target work surface by operating the operation device 26. In such a configuration, when the upper turning body 3 stops at the position facing the target work surface in the facing control, the upper turning body 3 maintains the facing state without turning even if the turning operation is performed by operating the lever while the predetermined switch is pressed. On the other hand, when the upper turning body 3 exceeds the position facing the target work surface, when the lever of the operation device 26 is operated to turn the upper turning body 3 in the direction facing the target work surface, the upper turning body 3 turns in the direction to face the target work surface.

In the present embodiment, when the turning speed of the lower traveling body 1 or the upper turning body 3 exceeds the predetermined speed at the time of starting the facing control, the controller 30 limits the turning speed of the lower traveling body 1 or the upper turning body 3. However, when the turning angle required for the upper turning body 3 to face the target work surface is large and the amount of turning operation for the operation device 26 is large, the inertia force due to turning increases, and the turning speed of the lower traveling body 1 or the upper turning body 3 may exceed the predetermined speed even during the execution of the facing control. Even in this case, as in the present embodiment, the controller 30 limits the turning speed of the lower traveling body 1 or the upper turning body 3.

Note that the controller 30 may cause the upper turning body 3 to face the target work surface by operating other actuators. For example, as illustrated in FIGS. 10A and 10B, the controller 30 may cause the upper turning body 3 to face the target work surface by automatically operating the left traveling hydraulic motor 1L and the right traveling hydraulic motor 1R.

FIGS. 10A and 10B are top views of the excavator 100 when the front facing processing is executed, and correspond to FIGS. 7A and 7B. That is, FIG. 10A illustrates a state in which the upper turning body 3 does not face the target work surface, and FIG. 10B illustrates a state in which the upper turning body 3 faces the target work surface.

In the examples of FIGS. 10A and 10B, the controller 30 performs spin turning by rotating the right traveling hydraulic motor 1R in forward direction and rotating the left traveling hydraulic motor 1L in opposite direction, such that the upper turning body 3 faces the target work surface.

In such a configuration, with the provision of the lower traveling body 1, the upper turning body 3 mounted on the lower traveling body 1 so as to be able to turn, and the controller 30 that performs facing control in which the upper turning body 3 faces the target work surface by turning the lower traveling body 1 by applying a turning force, the controller 30 limits the turning speed of the lower traveling body 1 when the current turning speed of the lower traveling body 1 exceeds a predetermined speed.

In the above embodiment, a hydraulic operation device is employed as the operation device 26, but an electric operation device may be employed.

FIG. 11 illustrates a configuration example of an operating system including an electric operation device.

Specifically, the operation system illustrated in FIG. 11 is an example of a boom operation system, and mainly consists of a pilot pressure-operated control valve 17, a boom operation lever 26A as an electric operation lever, a controller 30, a solenoid valve 60 for boom-raising operation, and a solenoid valve 62 for boom-lowering operation. The operation system illustrated in FIG. 11 can similarly be applied to an arm operation system, a bucket operation system, and the like.

As illustrated in FIG. 3, the pilot pressure-operated control valve 17 includes control valves 175L and 175R for the boom cylinder 7. The solenoid valve 60 is configured to adjust the flow path area of the oil passage connecting the pilot pump 15 and the right pilot port of the control valve 175L and the left pilot port of the control valve 175R, respectively. The solenoid valve 62 is configured to adjust the flow path area of the oil passage connecting the pilot pump 15 and the right pilot port of the control valve 175R.

When manual operation is performed, the controller 30 generates a boom raising operation signal (electric signal) or a boom lowering operation signal (electric signal) according to the operation signal (electric signal) output by the operation signal generation part of the boom operating lever 26A. The operation signal output by the operation signal generation part of the boom operating lever 26A is an electric signal which changes according to the operation amount and the operation direction of the boom operating lever 26A.

Specifically, when the boom operation lever 26A is operated in the boom raising direction, the controller 30 outputs, to the solenoid valve 60, a boom raising operation signal (electric signal) corresponding to the lever operation amount. The solenoid valve 60 adjusts the flow path area according to the boom raising operation signal (electric signal) and controls the pilot pressure acting on the right pilot port of the control valve 175L and the left pilot port of the control valve 175R. Similarly, when the boom operation lever 26A is operated in the boom lowering direction, the controller 30 outputs, to the solenoid valve 62, a boom lowering operation signal (electric signal) corresponding to the lever operation amount. The solenoid valve 62 adjusts the flow path area according to the boom lowering operation signal (electric signal) and controls the pilot pressure acting on the right pilot port of the control valve 175R.

When automatic control is executed, the controller 30 generates a boom raising operation signal (electric signal) or a boom lowering operation signal (electric signal) according to the correction operation signal (electric signal) instead of the operation signal output by the operation signal generation part of the boom operation lever 26A. The correction operation signal may be an electric signal generated by the machine guidance device 50 or an electric signal generated by a control device other than the machine guidance device 50.

According to the present disclosure, the accuracy of the facing control for causing the upper turning body to face the target work surface can be improved.