EXCAVATOR, REMOTE OPERATION SYSTEM, AND CONTROL METHOD

Description

RELATED APPLICATIONS

This application is a continuation application of International Application No. PCT/JP2024/016508, filed on April 26, 2024, and designated the U.S., which claims priority to Japanese Patent Application No. 2023-074653, filed on April 28, 2023, the entire content of each of which is incorporated herein by reference.

BACKGROUND

TECHNICAL FIELD The present invention relates to an excavator, a remote operation system, and a control method. DESCRIPTION OF THE RELATED ART A technique has been proposed for shaping a slope having earth, sand, gravel, and the like heaped thereon by using an end attachment provided at the distal end of an attachment of an excavator. The slope is shaped by moving the end attachment along the slope from the top of the slope to the toe of the slope. In order to prevent the end attachment of the excavator from contacting the slope when the excavator swings near such a slope, a technique is generally employed in which a controller of the excavator decelerates the swinging of the excavator as the end attachment approaches the slope, and stops the swinging before the end attachment contacts the slope. However, in some cases, it is desired to shape a slope with a working portion of the end attachment by swinging the excavator to move the end attachment while the end attachment is in contact with the slope.

SUMMARY

An excavator according to an embodiment of the present invention includes an undercarriage, an upper structure swingably mounted on the undercarriage, a boom attached to the upper structure, an arm attached to the boom, an end attachment attached to the arm, and a control device that controls at least one of the boom, the arm, or the end attachment when a swing operation of the upper structure is performed in accordance with an operation by an operator, so that a working portion of the end attachment follows a construction surface after the working portion contacts the construction surface, the construction surface being a construction target of the end attachment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an excavator according to an embodiment;

FIG. 2 is a schematic diagram illustrating a configuration example of the excavator according to the embodiment;

FIG. 3 is a schematic view illustrating a configuration example of a hydraulic system of the excavator according to the embodiment;

FIG. 4 is a partial hydraulic circuit diagram of the hydraulic system relating to operation of a hydraulic swing motor according to the embodiment;

FIG. 5A is an explanatory view illustrating slope shaping work based on a swing operation by the excavator according to the embodiment;

FIG. 5B is an explanatory view illustrating the slope shaping work based on the swing operation by the excavator according to the embodiment;

FIG. 5C is an explanatory view illustrating the slope shaping work based on the swing operation by the excavator according to the embodiment;

FIG. 6 is a view illustrating, as an example, slope shaping with a working portion of a bucket according to the embodiment;

FIG. 7 is a flowchart showing a processing procedure of the slope shaping work by a machine guidance unit according to the embodiment when a swing operation of an upper structure is performed;

FIG. 8 is an explanatory view of operation control of an automatic control unit according to another modification; and

FIG. 9 is a schematic view illustrating an example of a remote operation system according to another embodiment.

DETAILED DESCRIPTION

An embodiment of the present invention provides a technique for improving work efficiency, in which work according to an operator's request is enabled by moving the end attachment by swinging the excavator while the end attachment is in contact with a slope.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are not intended to limit the invention but are exemplary, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention. The same or corresponding components are denoted by the same or corresponding reference signs throughout the drawings, and redundant descriptions thereof may be omitted.

In the following description of the embodiments of the present invention, an excavator is used as an example of a work machine. However, the present invention is not limited to the excavator. The present invention may also be applied to construction machines, standard machines, application machines, forestry machines, and transport machines based on hydraulic excavators.

First Embodiment

An overview of an excavator 100 according to the present embodiment will be described with reference FIG. 1. FIG. 1 to is a side view of the excavator 100 serving as a work machine according to the present embodiment.

The excavator 100 according to the present embodiment includes an undercarriage 1, an upper structure 3, a boom 4, an arm 5, a bucket 6, and a cab 10. The upper structure 3 is swingably mounted on the undercarriage 1 via a swing mechanism 2. The boom 4, the arm 5, and the bucket 6 form an attachment (work implement).

The undercarriage 1 causes the excavator 100 to travel by hydraulically driving a pair of left and right crawlers with respective hydraulic travel motors 1L and 1R (see FIG. 2 described later). That is, the pair of hydraulic travel motors 1L and 1R (an example of travel motors) drives the undercarriage 1 (crawler) serving as a driven unit.

The upper structure 3 swings relative to the undercarriage 1 by being driven with a hydraulic swing motor 2A (see FIG. 2 described later). That is, the hydraulic swing motor 2A is a swing drive unit that drives the upper structure 3 serving as a driven unit, and can change an orientation of the upper structure 3.

Note that the upper structure 3 may be driven electrically by an electric motor (hereinafter, referred to as an “electric swing motor”) instead of the hydraulic swing motor 2A. That is, similar to the hydraulic swing motor 2A, the electric swing motor is a swing drive unit that drives the upper structure 3 serving as a driven unit, and can change the orientation of the upper structure 3.

The boom 4 is pivotably mounted at a front center portion of the upper structure 3 so as to be pivotable in elevation. The arm 5 is pivotably mounted at a distal end of the boom 4 so as to be vertically movable. The bucket 6 serving as an end attachment is pivotably mounted at a distal end of the arm 5 so as to be vertically movable. The boom 4, the arm 5, and the bucket 6 are respectively hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, each serving as a hydraulic actuator.

Note that the bucket 6 is an example of the end attachment (work tool), and a different end attachment capable of slope shaping, such as a slope bucket, may be attached to the distal end of the arm 5 in place of the bucket 6 depending on work details or the like.

The cab 10, which serves as an operator’s compartment, is mounted on a front left side of the upper structure 3.

Configuration of Excavator

Next, a specific configuration of the excavator 100 according to the present embodiment will be described with reference to FIG. 2 in addition to FIG. 1.

FIG. 2 is a schematic diagram illustrating a configuration example of the excavator 100 according to the present embodiment.

In FIG. 2, a mechanical power system, a hydraulic line, a pilot line, and an electric control system are indicated by double lines, solid lines, broken lines, and dotted lines, respectively.

A drive system of the excavator 100 according to the present embodiment includes an engine 11, a regulator 13, a main pump 14, and a control valve 17. As described above, the hydraulic drive system of the excavator 100 according to the present embodiment includes hydraulic actuators such as the hydraulic travel motors 1L and 1R, the hydraulic swing motor 2A, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, which hydraulically drive the undercarriage 1, the upper structure 3, the boom 4, the arm 5, and the bucket 6, respectively.

The engine 11 is a main power source of the hydraulic drive system and is mounted, for example, at the rear of the upper structure 3. Specifically, the engine 11 rotates at a preset target rotational speed under direct or indirect control of a controller 30 described later, and drives the main pump 14 and a pilot pump 15. The engine 11 is, for example, a diesel engine that uses light oil as fuel.

The regulator 13 controls displacement of the main pump 14. For example, the regulator 13 adjusts an angle (tilt angle) of a swash plate of the main pump 14 in accordance with a control command from the controller 30. The regulator 13 includes, for example, regulators 13L and 13R as described later.

Similar to the engine 11, the main pump 14 is mounted, for example, at the rear of the upper structure 3, and supplies hydraulic fluid to the control valve 17 through a high-pressure hydraulic line. The main pump 14 is driven by the engine 11 as described above. The main pump 14 is, for example, a variable displacement pump, and as described above, the regulator 13 adjusts the tilt angle of the swash plate under the control of the controller 30, thereby adjusting a stroke length of the pistons and controlling a discharge flow rate (discharge pressure). The main pump 14 includes, for example, main pumps 14L and 14R as described later.

The control valve 17 is a hydraulic control device that controls a hydraulic system in the excavator 100. In the present embodiment, the control valve 17 includes individual control valves 171 to 176. The control valve 175 includes a control valve 175L and a control valve 175R, and the control valve 176 includes a control valve 176L and a control valve 176R. The control valve 17 selectively supplies hydraulic fluid 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 control, for example, the flow rates of hydraulic fluid flowing from the main pump 14 to the respective hydraulic actuators and the flow rate of hydraulic fluid flowing from the hydraulic actuators to a hydraulic reservoir. The hydraulic actuators include the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, the hydraulic travel motors 1L and 1R, and the hydraulic swing motor 2A. More specifically, the control valve 171 is for the left hydraulic travel motor 1L, the control valve 172 is for the right hydraulic travel motor 1R, and the control valve 173 is for the hydraulic swing motor 2A. The control valve 174 is for the bucket cylinder 9, the control valve 175 is for the boom cylinder 7, and the control valve 176 is for the arm cylinder 8. The control valve 175 includes, for example, the control valves 175L and 175R as described later. The control valve 176 includes, for example, the control valves 176L and 176R as described later. Details of the control valves 171 to 176 will be described later.

The pilot pump 15 is an example of a pilot-pressure generating device and supplies hydraulic fluid to hydraulic control devices via the pilot line. In the present embodiment, the pilot pump 15 is a fixed displacement pump. However, the pilot-pressure generating device may be realized by the main pump 14. That is, the main pump 14 may have a function of supplying hydraulic fluid to various hydraulic control devices via the pilot line in addition to a function of supplying hydraulic fluid to the control valve 17 via the hydraulic line. In this case, the pilot pump 15 may be omitted.

An operating device 26 is a device used by an operator to operate an actuator. The actuator includes at least one of a hydraulic actuator or an electric actuator.

A discharge pressure sensor 28 detects a 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 discharge pressure sensor 28 includes, for example, discharge pressure sensors 28L and 28R as described later.

An operation sensor 29 detects an operation detail by an operator using the operating device 26. In the present embodiment, the operation sensor 29 detects an operation direction and an operation amount of the operating device 26 associated with each actuator, and outputs the detected values to the controller 30. In the present embodiment, the controller 30 controls an opening area of a proportional valve 31 in accordance with the output of the operation sensor 29. Then, the controller 30 supplies hydraulic fluid discharged from the pilot pump 15 to a pilot port of a corresponding control valve included in the control valve 17. The pressure (pilot pressure) of the hydraulic fluid supplied to each pilot port is, in principle, a pressure corresponding to the operation direction and the operation amount of the operating device 26 associated with each hydraulic actuator. Thus, the operating device 26 supplies the hydraulic fluid discharged from the pilot pump 15 to a pilot port of a corresponding control valve included in the control valve 17.

The proportional valve 31, which serves as a control valve for machine control, is disposed in a conduit connecting the pilot pump 15 and a pilot port of the control valve included in the control valve 17, and changes a flow passage area of the conduit. In the present embodiment, the proportional valve 31 operates in accordance with a control command output from the controller 30. Therefore, the controller 30 can supply hydraulic fluid discharged from the pilot pump 15 to a pilot port of a control valve included in the control valve 17 via the proportional valve 31 independently of the operation of the operating device 26 performed by the operator. The proportional valve 31 includes, for example, proportional valves 31AL, 31AR, 31BL, 31BR, 31CL, and 31CR as described later.

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

A control system of the excavator 100 according to the present embodiment includes the controller 30, a display device 40, an input device 42, an audio output device 43, a storage device 47, a boom angle sensor S1, an arm angle sensor S2, a bucket angle sensor S3, a machine body tilt sensor (an example of an attitude detection unit) S4, a swing state sensor S5, an imaging device S6, a positioning device PS, and a communication device T1.

The controller 30 (an example of the control device) is provided, for example, in the cab 10 and performs drive control of the excavator 100. The functions of the controller 30 may be implemented by hardware, software, or a combination thereof. For example, the controller 30 is mainly formed of a microcomputer including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a nonvolatile auxiliary storage device, various input/output interfaces, and the like. The controller 30 implements various functions, for example, by executing, on the CPU, various programs stored in the ROM or the nonvolatile auxiliary storage device.

For example, the controller 30 sets a target rotational speed based on an operation or the like performed by an operator or the like, and performs drive control to rotate the engine 11 at a constant speed.

For example, the controller 30 outputs a control command to the regulator 13 as necessary to change displacement of the main pump 14.

For example, the controller 30 controls a machine guidance function of guiding the manual operation of the excavator 100 by an operator through the operating device 26. The controller 30 controls a machine control function of automatically assisting manual operation of the excavator 100 performed by an operator through the operating device 26. That is, the controller 30 includes a machine guidance unit 50 as a functional unit for the machine guidance function and the machine control function.

Note that some of the functions of the controller 30 may be implemented by a different controller (control device). That is, the functions of the controller 30 may be implemented in a distributed manner by a plurality of controllers. For example, the machine guidance function and the machine control function may be implemented by a dedicated controller (control device).

The display device 40 is provided in the cab 10 at a position easily visible from a seated operator, and displays various information images under the control of the controller 30. The display device 40 may be connected to the controller 30 via an in-vehicle communication network such as a controller area network (CAN), or may be connected to the controller 30 via a dedicated point-to-point line.

The input device 42 is provided within reach of the seated operator in the cab 10, receives various operation inputs from the operator, and outputs signals corresponding to the operation inputs to the controller 30. The input device 42 includes: a touch panel mounted on a display of the display device for displaying various information images; knob switches provided at distal ends of levers of lever devices 26A to 26C; button switches provided around the display device 40; levers; toggles; rotary dials; and the like. A signal corresponding to an operation detail to the input device 42 is input to the controller 30.

The audio output device 43 is provided, for example in the cab 10, is connected to the controller 30, and outputs audio under control of the controller 30. The audio output device 43 is, for example, a speaker, a buzzer, or the like. The audio output device 43 outputs various information in audio in accordance with an audio output command from the controller 30.

The storage device 47 is provided, for example, in the cab 10 and stores various information under the control of the controller 30. 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 devices during the operation of the excavator 100, or may store information acquired via various devices before the operation of the excavator 100 is started. The storage device 47 may store, for example, data on a target construction surface, which is acquired via the communication device T1 or the like or set through the input device 42 or the like. The target construction surface may be set (saved) by the operator of the excavator 100 or may be set by a construction manager or the like.

The boom angle sensor S1 is attached to the boom 4 and detects an elevation angle (hereinafter, referred to as a "boom angle") of the boom 4 relative to the upper structure 3, which is, for example, an angle, in side view, between a swing plane of the upper structure 3 and a straight line connecting both pivot points at opposite ends of the boom 4. The boom angle sensor S1 may include, for example, a rotary encoder, an acceleration sensor, a 6-axis sensor, an inertial measurement unit (IMU) or the like. The boom angle sensor S1 may also include a potentiometer using a variable resistor, a cylinder stroke sensor for detecting a stroke amount of a hydraulic cylinder (boom cylinder 7) corresponding to the boom angle, or the like. This similarly applies to the arm angle sensor S2 and the bucket angle sensor S3. A detection signal corresponding to the boom angle from the boom angle sensor S1 is input to the controller 30.

The arm angle sensor S2 is attached to the arm 5 and detects a rotation angle of the arm 5 relative to the boom 4 (hereinafter, referred to as an “arm angle”), which is, for example, an angle, in side view, between a straight line connecting both pivot points at opposite ends of the boom 4 and a straight line connecting both pivot points at opposite ends of the arm 5. A detection signal corresponding to the arm angle from the arm angle sensor S2 is input to the controller 30.

The bucket angle sensor S3 is attached to the bucket 6 and detects a rotation angle of the arm 5 relative to the bucket 6 (hereinafter, referred to as a “bucket angle”), which is, for example, an angle, in side view between a straight line connecting both pivot points at opposite ends of the arm 5 and a straight line connecting a pivot point and a distal end (tooth tip) of the bucket 6. A detection signal corresponding to the bucket angle from the bucket angle sensor S3 is input to the controller 30.

The machine body tilt sensor (an example of an attitude detection unit) S4 detects a tilt state of a machine body (the upper structure 3 or the undercarriage 1) relative to a horizontal plane. For example, the machine body tilt sensor S4 is attached to the upper structure 3 and detects tilt angles of the excavator 100 (i.e., the upper structure 3) about two axes, a longitudinal axis and a lateral axis. The tilt angles are hereinafter referred to as a longitudinal tilt angle and a lateral tilt angle. The machine body tilt sensor S4 may include, for example, a rotary encoder, an acceleration sensor, a 6-axis sensor, an IMU, or the like. Detection signals corresponding to the tilt angles from the machine body tilt sensor S4 are input to the controller 30.

The swing state sensor S5 outputs detection information on a swing state of the upper structure 3. The swing state sensor S5 detects, for example, a swing angular velocity and a swing angle of the upper structure 3. The swing state sensor S5 may include, for example, a gyroscope sensor, a resolver, a rotary encoder, or the like. Detection signals corresponding to the swing angle and the swing angular velocity of the upper structure 3 from the swing state sensor S5 are input to the controller 30.

The imaging device S6, which serves as a spatial recognition device, images the surroundings of the excavator 100. The imaging device S6 includes a camera S6F for imaging forward of the excavator 100, a camera S6L for imaging leftward of the excavator 100, a camera S6R for imaging rightward of the excavator 100, and a camera S6B for imaging rearward of the excavator 100.

The camera S6F is attached, for example, to the ceiling of the cab 10, that is, inside the cab 10. Moreover, the camera S6F may be attached outside the cab 10, such as on the roof of the cab 10 or on the side surface of the boom 4. The camera S6L is attached on the left end of the upper surface of the upper structure 3. The camera S6R is attached on the right end of the upper surface of the upper structure 3. The camera S6B is attached on the rear end of the upper surface of the upper structure 3.

The imaging device S6 (cameras S6F, S6B, S6L and S6R) is, for example, a monocular wide-angle camera having a very wide angle of view. The imaging device S6 may be a stereo camera, a range image camera, or the like. An image captured by the imaging device S6 is input to the controller 30 via the display device 40.

The imaging device S6, which serves as a spatial recognition device, may function as an object detection device. In this case, the imaging device S6 may detect an object present around the excavator 100. The object to be detected may include, for example, a person, an animal, a vehicle, a construction machine, a building, a hole, and the like. Further, the imaging device S6 may compute a distance from the imaging device S6 or the excavator 100 to the recognized object. The imaging device S6, which serves as an object detection device, may include, for example, a stereo camera, a range image sensor, and the like. The spatial recognition device may be, for example, a monocular camera having an imaging element such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and output a captured image to the display device 40. The spatial recognition device may compute a distance from the spatial recognition device or the excavator 100 to the recognized object. In addition to the imaging device S6, an additional object detection device such as, for example, an ultrasonic sensor, a millimeter-wave radar, a LIDAR, or an infrared sensor may be provided as the spatial recognition device. When a millimeter-wave radar, an ultrasonic sensor, a laser radar, or the like is used as the spatial recognition device, a large number of signals (such as laser beams) may be transmitted to the object, and the reflected signals thereof may be received, thereby detecting the distance and the direction of the object from the reflected signals.

The imaging device S6 may be directly connected to the controller 30 in a communicable manner.

A boom rod pressure sensor S7R and a boom bottom pressure sensor S7B are attached to the boom cylinder 7. An arm rod pressure sensor S8R and an arm bottom pressure sensor S8B are attached to the arm cylinder 8. A bucket rod pressure sensor S9R and a bucket bottom pressure sensor S9B are attached to the bucket cylinder 9. The boom rod pressure sensor S7R, the boom bottom pressure sensor S7B, the arm rod pressure sensor S8R, the arm bottom pressure sensor S8B, the bucket rod pressure sensor S9R, and the bucket bottom pressure sensor S9B are collectively referred to as a “cylinder pressure sensor.”

The boom rod pressure sensor S7R detects a pressure in a rod-side fluid chamber of the boom cylinder 7 (hereinafter, referred to as a “boom rod pressure”), and the boom bottom pressure sensor S7B detects a pressure in a bottom-side fluid chamber of the boom cylinder 7 (hereinafter, referred to as a “boom bottom pressure”). The arm rod pressure sensor S8R detects a pressure in a rod-side fluid chamber of the arm cylinder 8 (hereinafter, referred to as an “arm rod pressure”), and the arm bottom pressure sensor S8B detects a pressure in a bottom-side fluid chamber of the arm cylinder 8 (hereinafter, referred to as an “arm bottom pressure”). The bucket rod pressure sensor S9R detects a pressure in a rod-side fluid chamber of the bucket cylinder 9 (hereinafter, referred to as a “bucket rod pressure”), and the bucket bottom pressure sensor S9B detects a pressure in a bottom-side fluid chamber of the bucket cylinder 9 (hereinafter, referred to as a “bucket bottom pressure”).

The positioning device PS measures a position and an orientation of the upper structure 3. The positioning device PS is, for example, a global navigation satellite system (GNSS) compass and detects a position and an orientation of the upper structure 3, and the detection signals corresponding to the position and the orientation of the upper structure 3 are input to the controller 30. Among the functions of the positioning device PS, the function of detecting the orientation of the upper structure 3 of the positioning device PS may be replaced by an orientation sensor attached to the upper structure 3.

The communication device T1 communicates with an external device through a predetermined network including a mobile communication network having a base station as a terminal, a satellite communication network, an Internet network, and the like. The communication device T1 may be, for example, a mobile communication module compatible with mobile communication standards such as long term evolution (LTE), 4th generation (4G), and 5th generation (5G), or a satellite communication module for connecting to a satellite communication network, or the like.

Hydraulic System of Excavator

Next, the hydraulic system of the excavator 100 according to the present embodiment will be described with reference to FIG. 3.

FIG. 3 is a schematic diagram illustrating a configuration example of the hydraulic system of the excavator 100 according to the present embodiment.

Similar to FIG. 2 and the like, the mechanical power system, the hydraulic line, the pilot line, and the electric control system in FIG. 3 are indicated by double lines, solid lines, broken lines, and dotted lines, respectively.

A hydraulic system implemented by the hydraulic circuit circulates hydraulic fluid from the respective main pumps 14L and 14R driven by the engine 11, through center bypass fluid passages C1L and C1R and parallel fluid passages C2L and C2R, to the hydraulic reservoir.

The center bypass fluid passage C1L originates from the main pump 14L, sequentially passes through control valves 171, 173, 175L, and 176L disposed in the control valve 17, and reaches the hydraulic reservoir.

The center bypass fluid passage C1R originates from the main pump 14R, sequentially passes through control valves 172, 174, 175R, and 176R disposed in the control valve 17, and reaches the hydraulic reservoir.

The control valve 171 is a spool valve for supplying the hydraulic fluid discharged from the main pump 14L to the hydraulic travel motor 1L and returning the hydraulic fluid discharged from the hydraulic travel motor 1L to the hydraulic reservoir.

The control valve 172 is a spool valve for supplying the hydraulic fluid discharged from the main pump 14R to the hydraulic travel motor 1R and returning the hydraulic fluid discharged from the hydraulic travel motor 1R to the hydraulic reservoir.

The control valve 173 is a spool valve for supplying the hydraulic fluid discharged from the main pump 14L to the hydraulic swing motor 2A and returning the hydraulic fluid discharged from the hydraulic swing motor 2A to the hydraulic reservoir.

The control valve 174 is a spool valve for supplying the hydraulic fluid discharged from the main pump 14R to the bucket cylinder 9 and returning the hydraulic fluid in the bucket cylinder 9 to the hydraulic reservoir.

The control valves 175L and 175R are spool valves for supplying the hydraulic fluid discharged from the main pumps 14L and 14R to the boom cylinder 7 and returning the hydraulic fluid in the boom cylinder 7 to the hydraulic reservoir.

The control valves 176L and 176R are spool valves for supplying the hydraulic fluid discharged from the main pumps 14L and 14R to the arm cylinder 8 and returning the hydraulic fluid in the arm cylinder 8 to the hydraulic reservoir.

Each of the control valves 171, 172, 173, 174, 175L, 175R, 176L and 176R adjusts the flow rate of the hydraulic oil supplied to and discharged from the corresponding hydraulic actuator and switches the flow direction in accordance with the pilot pressure applied to the pilot port.

The parallel fluid passage C2L supplies the hydraulic fluid of the main pump 14L to the control valves 171, 173, 175L, and 176L in parallel with the center bypass fluid passage C1L. Specifically, the parallel fluid passage C2L branches from the center bypass fluid passage C1L upstream of the control valve 171 and supplies the hydraulic fluid of the main pump 14L in parallel to each of the control valves 171, 173, 175L, and 176L. Thus, when the flow of the hydraulic fluid through the center bypass fluid passage C1L is restricted or blocked by any of the control valves 171, 173, and 175L, the parallel fluid passage C2L can supply the hydraulic fluid to a control valve located further downstream.

The parallel fluid passage C2R supplies the hydraulic fluid of the main pump 14R to the control valves 172, 174, 175R, and 176R in parallel with the center bypass fluid passage C1R. Specifically, the parallel fluid passage C2R branches from the center bypass fluid passage C1R upstream of the control valve 172 and supplies the hydraulic fluid of the main pump 14R in parallel to each of the control valves 172, 174, 175R, and 176R. When the flow of the hydraulic fluid through the center bypass fluid passage C1R is restricted or blocked by any of the control valves 172, 174, and 175R, the parallel fluid passage C2R can supply the hydraulic fluid to a control valve located further downstream.

The regulators 13L and 13R adjust the tilt angles of the swash plates of the main pumps 14L and 14R, respectively, under the control of the controller 30, thereby adjusting displacements of the main pumps 14L and 14R.

The discharge pressure sensor 28L detects a discharge pressure of the main pump 14L, and a detection signal corresponding to the detected discharge pressure is input to the controller 30. This similarly applies to the discharge pressure sensor 28R. Accordingly, the controller 30 can control the regulators 13L and 13R based on discharge pressures of the main pumps 14L and 14R.

The center bypass fluid passages C1L and C1R are provided with negative control orifices 18L and 18R, respectively, between the respective lowermost downstream control valves 176L and 176R and the hydraulic reservoir. Accordingly, the flows of the hydraulic fluid discharged by the main pumps 14L and 14R are restricted by the negative control orifices 18L and 18R, respectively. Then, the negative control orifices 18L and 18R generate control pressures (hereinafter, referred to as "negative control pressures") for controlling the regulators 13L and 13R, respectively.

Negative control pressure sensors 19L and 19R detect the negative control pressures, and detection signals corresponding to the detected negative control pressures are input to the controller 30.

The controller 30 may adjust displacements of the main pumps 14L and 14R by controlling the regulators 13L and 13R based on discharge pressures of the main pumps 14L and 14R detected by the discharge pressure sensors 28L and 28R, respectively. For example, when a discharge pressure of the main pump 14L increases, the controller 30 may reduce a displacement of the main pump 14L by controlling the regulator 13L to adjust a tilt angle of the swash plate of the main pump 14L. This similarly applies to the regulator 13R. Accordingly, the controller 30 can perform total horsepower control of the main pumps 14L and 14R so that absorbed horsepower of the main pumps 14L and 14R, represented as a product of discharge pressure and discharge flow rate, does not exceed output horsepower of the engine 11.

The controller 30 may adjust displacements of the main pumps 14L and 14R by controlling the regulators 13L and 13R based on negative control pressures detected by the negative control pressure sensors 19L and 19R, respectively. For example, the controller 30 reduces displacements of the main pumps 14L and 14R as the negative control pressures increase, and increases displacements of the main pumps 14L and 14R as the negative control pressures decrease.

Specifically, in a standby state (state illustrated in FIG. 3) in which none of the hydraulic actuators of the excavator 100 is operated, the hydraulic fluid discharged from the main pumps 14L and 14R passes through the center bypass fluid passages C1L and C1R and reaches the negative control orifices 18L and 18R. The flows of the hydraulic fluid discharged from the main pumps 14L and 14R increase negative control pressures generated upstream of the negative control orifices 18L and 18R. As a result, the controller 30 reduces discharge flow rates of the main pumps 14L and 14R to allowable minimum discharge flow rates, thereby minimizing pressure losses (pumping losses) occurring when the discharged hydraulic fluid passes through the center bypass fluid passages C1L and C1R.

On the other hand, when any of the hydraulic actuators is operated through the operating device 26, the hydraulic fluid discharged from the main pumps 14L and 14R flows into a target hydraulic actuator through a control valve corresponding to the target hydraulic actuator. Then, the flow of the hydraulic fluid discharged from the main pumps 14L and 14R is reduced or eliminated before reaching the negative control orifices 18L and 18R, thereby lowering negative control pressures generated upstream of the negative control orifices 18L and 18R. As a result, the controller 30 can increase discharge flow rates of the main pumps 14L and 14R, circulate sufficient hydraulic fluid to the target hydraulic actuator, and reliably drive the target hydraulic actuator.

The operating device 26 includes a left control lever 26L, a right control lever 26R, and a travel lever 26D. The travel lever 26D includes a left travel lever 26DL and a right travel lever 26DR.

The left control lever 26L is used for a swing operation and an operation of the arm 5. When the left control lever 26L is operated in a forward or reverse direction, hydraulic fluid discharged from the pilot pump 15 is utilized to introduce a control pressure corresponding to a lever stroke amount into a pilot port of the control valve 176. When the left control lever 26L is operated in a leftward or rightward direction, hydraulic fluid discharged from the pilot pump 15 is utilized to introduce a control pressure corresponding to a lever stroke amount into a pilot port of the control valve 173.

Specifically, when the left control lever 26L is operated in an arm close direction, hydraulic fluid is introduced into a right pilot port of the control valve 176L and into a left pilot port of the control valve 176R. When the left control lever 26L is operated in an arm open direction, hydraulic fluid is introduced into a left pilot port of the control valve 176L and into a right pilot port of the control valve 176R. When the left control lever 26L is operated in a left swing direction, hydraulic fluid is introduced into a left pilot port of the control valve 173 and into a right polit port of the control valve 173.

The right control lever 26R is used for an operation of the boom 4 and an operation of the bucket 6. When the right control lever 26R is operated in a forward or reverse direction, hydraulic fluid discharged from the pilot pump 15 is utilized to introduce a control pressure corresponding to a lever stroke amount into a pilot port of the control valve 175. When the right control lever 26R is operated in a leftward or rightward direction, hydraulic fluid discharged from the pilot pump 15 is utilized to introduce a control pressure corresponding to a lever stroke amount into a pilot port of the control valve 174.

Specifically, when the right control lever 26R is operated in a boom down direction, hydraulic fluid is introduced into a left pilot port of the control valve 175R. When the right control lever 26R is operated in a boom up direction, hydraulic fluid is introduced into a right pilot port of the control valve 175L and into a left pilot port of the control valve 175R. When the right control lever 26R is operated in a bucket close direction, hydraulic fluid is introduced into a right pilot port of the control valve 174. When the right control lever 26R is operated in a bucket open direction, hydraulic fluid is introduced into a left pilot port of the control valve 174.

Hereinafter, the left control lever 26L operated in the leftward or rightward direction may be referred to as a “swing control lever,” and the left control lever 26L operated in the forward or reverse direction may be referred to as an “arm control lever.” The right control lever 26R operated in the leftward or rightward direction may be referred to as a “bucket control lever,” and the right control lever 26R operated in the forward or reverse direction may be referred to as a “boom control lever.”

The left travel lever 26DL is used for an operation of a left crawler 1CL and may be interlocked with a left travel pedal. When the left travel lever 26DL is operated in the forward or reverse direction, hydraulic fluid discharged from the pilot pump 15 is utilized to introduce a control pressure corresponding to a lever stroke amount into a pilot port of the control valve 171. The right travel lever 26DR is used for an operation of a right crawler 1CR and may be interlocked with a right travel pedal. When the right travel lever 26DR is operated in the forward or reverse direction, hydraulic fluid discharged from the pilot pump 15 is utilized to a control pressure corresponding to a lever stroke amount into a pilot port of the control valve 172.

The operation sensor 29 detects a detail of the operation of the operating device 26 by the operator. In the present embodiment, the operation sensor 29 detects an operation direction and an operation amount of the operating device 26 associated with each actuator, and outputs the detected values to the controller 30.

The operation sensor 29 includes operation sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. The operation sensor 29LA detects a detail of the operation of the left control lever 26L in the forward or reverse direction by the operator, and outputs the detected value to the controller 30. The detail of the operation is, for example, a lever stroke direction, a lever stroke amount (lever stroke angle), or the like.

The operation sensor 29LB similarly detects a detail of the operation of the left control lever 26L in the leftward or rightward direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29RA detects a detail of the operation of the right control lever 26R in the forward or reverse direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29RB detects a detail of the operation of the right control lever 26R in the leftward or rightward direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29DL detects a detail of the operation of the left travel lever 26DL in the forward or reverse direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29DR detects a detail of the operation of the right travel lever 26DR in the forward or reverse direction by the operator, and outputs the detected value to the controller 30.

The controller 30 receives the output of the operation sensor 29, outputs a control command to the regulator 13 as necessary, and changes the displacement of the main pump 14. The controller 30 also receives the output of the control pressure sensor 19 provided upstream of the orifice 18, outputs a control command to the regulator 13 as necessary, and changes the displacement of the main pump 14. The orifice 18 includes a left orifice 18L and a right orifice 18R, and the control pressure sensor 19 includes negative control pressure sensors 19L and 19R.

Details of Configuration of Excavator Related to Machine Control Function

Next, details of the configuration of the excavator 100 related to the machine control function will be described.

FIG. 4 is a partial hydraulic circuit diagram of the hydraulic system relating to operation of the hydraulic swing motor 2A according to the present embodiment.

As illustrated in FIG. 4, the hydraulic system includes the proportional valve 31. The proportional valve 31 includes individual proportional valves 31DL and 31DR.

The proportional valve 31 functions as a control valve for machine control. The proportional valve 31 is disposed in a conduit connecting the pilot pump 15 and a pilot port of a corresponding control valve included in the control valve 17, and changes a flow passage area of the conduit. In the present embodiment, the proportional valve 31 operates in accordance with a control command output from the controller 30. Thus, the controller 30 can supply hydraulic fluid discharged from the pilot pump 15 to a pilot port of a corresponding control valve included in the control valve 17 via the proportional valve 31 independently of the operation of the operating device 26 performed by the operator. Then, the controller 30 can apply 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 a hydraulic actuator corresponding to the specific operating device 26 even when the specific operating device 26 is not operated. Moreover, the controller 30 can forcibly stop the operation of the hydraulic actuator corresponding to the specific operating device 26 even when the specific operating device 26 is operated.

For example, as illustrated in FIG. 4, the left control lever 26L is also used to operate the swing mechanism 2. Specifically, the left control lever 26L utilizes pilot hydraulic fluid discharged from the pilot pump 15 to apply pilot pressure corresponding to the operation in the leftward or rightward direction to the pilot port of the control valve 173. More specifically, when the left control lever 26L is operated in the left swing direction (leftward direction), the pilot pressure corresponding to the stroke amount is applied to the left pilot port of the control valve 173. When the left control lever 26L is operated in the right swing direction (rightward direction), the pilot pressure corresponding to the stroke amount is applied to the right pilot port of the control valve 173.

The operation sensor 29LB detects the detail of the operation of the left control lever 26L in the leftward or rightward direction by the operator, and outputs the detected value to the controller 30.

The proportional valve 31DL operates in accordance with a control command (current command) output from the controller 30. Then, pilot pressure caused by pilot hydraulic fluid introduced from the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31DL is adjusted. The proportional valve 31DR operates in accordance with a control command (current command) output from the controller 30. Then, pilot pressure caused by pilot hydraulic fluid introduced from the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31DR is adjusted. The proportional valve 31DL can adjust pilot pressure such that the control valve 173 can be stopped at a desired valve position. The proportional valve 31DR can similarly adjust pilot pressure such that the control valve 173 can be stopped at a desired valve position.

With this configuration, the controller 30 can supply pilot hydraulic fluid discharged from the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31DL in accordance with a left-swing operation performed by the operator. The controller 30 can also supply pilot hydraulic fluid discharged from the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31DL independently of a left-swing operation performed by the operator. That is, the controller 30 can swing the swing mechanism 2 leftward in accordance with the left-swing operation performed by the operator or independently of the left-swing operation performed by the operator. Thus, the proportional valve 31DL functions as a “swing solenoid valve ” or a “left-swing solenoid valve.”

Moreover, the controller 30 can supply pilot hydraulic fluid discharged from the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31DR in accordance with a right-swing operation performed by the operator. The controller 30 can also supply pilot hydraulic fluid discharged from the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31DR independently of a right-swing operation performed by the operator. That is, the controller 30 can swing the swing mechanism 2 rightward in accordance with the right-swing operation performed by the operator or independently of the right-swing operation performed by the operator. Thus, the proportional valve 31DR functions as a “swing solenoid valve” or a “right-swing solenoid valve.”

The operating device 26 is provided with a switch SW. In the present embodiment, the switch SW includes a switch SW1 and a switch SW2. The switch SW1 is a push button switch provided at the distal end of the left control lever 26L. The operator can operate the left control lever 26L while pressing the switch SW1. The switch SW1 may be provided on the right control lever 26R or may be provided at a different position in the cab 10. The switch SW2 is a push button switch provided at the distal end of the left travel lever 26DL. The operator can operate the left travel lever 26DL while pressing the switch SW2. The switch SW2 may be provided on the right travel lever 26DR or may be provided at a different position in the cab 10.

The excavator 100 may cause a bucket tilt mechanism to automatically operate. In this case, a part of the hydraulic system related to the bucket tilt cylinder forming the bucket tilt mechanism may be configured in substantially the same manner as a part of the hydraulic system related to the operation of the boom cylinder 7.

Although an electric control lever has been described as a form of the operating device 26, a hydraulic control lever may be employed instead of the electric control lever. In this case, a lever stroke amount of the hydraulic control lever may be detected in the form of pressure by a pressure sensor and input to the controller 30. A solenoid valve may be disposed between the operating device 26 serving as the hydraulic control lever and the pilot port of each control valve. The solenoid valve operates in accordance with an electric signal from the controller 30. With this configuration, when a manual operation using the operating device 26 serving as the hydraulic control lever is performed, the operating device 26 can move each control valve by increasing or decreasing the pilot pressure in accordance with the lever stroke amount. Each control valve may be formed by an electromagnetic solenoid spool valve. In this case, the electromagnetic solenoid spool valve operates in accordance with an electric signal from the controller 30 corresponding to the lever stroke amount of the electric control lever.

Description of Swing Operation

When a swing operation is received from an operator, the excavator 100 according to the present embodiment performs slope shaping work with the working portion of the bucket 6.

Techniques have been proposed for restricting a movable region of an excavator or an end attachment so that the end attachment does not excessively dig a slope during a swing operation of the excavator, or for performing stop control so that the end attachment does not collide with the slope.

Meanwhile, when slope shaping is performed with an excavator, slope shaping is often performed generally from the top of the slope to the toe of the slope by a boom down operation of the excavator. However, there are cases where it is desirable to shape a slope by swinging the bucket, for example, when a side edge in a traveling direction at a back surface of the bucket is longer than a side edge in a width direction so that a swing operation can improve work efficiency, or when a distance from the top of the slope to the toe of the slope is short so that the slope is desired to be shaped by swinging.

Therefore, in the present embodiment, the machine guidance unit 50 controls so that a slope can be shaped with the working portion of the bucket 6 when a swing operation is performed by an operator.

Although the present embodiment describes a case where slope shaping is performed with the working portion of the bucket 6, the end attachment used for shaping the slope is not limited to the tooth tip or the back surface of the bucket 6. For example, a plate stuck to the bucket 6, a special end attachment having a shaped surface for performing slope shaping in a swing direction, or the like may be used. Moreover, the present embodiment does not limit the type of the bucket 6 for performing slope shaping, and, for example, a slope bucket or the like may be used.

Configuration of Machine Guidance Unit

Referring back to FIG. 2, the machine guidance unit 50 will be described. The machine guidance unit 50 executes, for example, control of the excavator 100 related to the machine guidance function. Target construction surface information 47A indicating data on a target construction surface is stored in advance in, for example, the storage device 47. The target construction surface indicated by the target construction surface information 47A is expressed, for example, in a reference coordinate system. The reference coordinate system is, for example, a world geodetic system. The world geodetic system is a three-dimensional orthogonal XYZ coordinate system in which an origin is set at the center of the earth, an X-axis is directed to an intersection of the Greenwich meridian and the equator, a Y-axis is directed to a direction of east longitude 90 degrees, and a Z-axis is directed to the north pole. An operator may define a point at a construction site as a reference point, and may set a target construction surface based on a relative positional relationship with the reference point through the input device 42.

The target construction surface information 47A according to the present embodiment may include a (flattened) slope after being shaped.

The machine guidance unit 50 acquires information from the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the machine body tilt sensor S4, the swing state sensor S5, the imaging device S6, the boom rod pressure sensor S7R, the boom bottom pressure sensor S7B, the arm rod pressure sensor S8R, the arm bottom pressure sensor S8B, the bucket rod pressure sensor S9R, the bucket bottom pressure sensor S9B, the positioning device PS, the operation sensor 29, the communication device T1, the input device 42, and the like. Then, the machine guidance unit 50 computes, for example, a distance between the bucket 6 and the target construction surface based on the acquired information, and automatically controls the operation of the attachment so that the working portion of the bucket 6, or the like can move along the target construction surface.

A configuration in which the machine guidance unit 50 controls slope shaping work will be described. The machine guidance unit 50 includes, as the machine guidance function and the machine control function, an acquisition unit 51, a position computing unit 52, a distance computing unit 53, a determination unit 54, and an automatic control unit 55 as detailed functional configurations for performing compaction work.

The acquisition unit 51 acquires detection information indicating detection results by various sensors in the excavator 100. For example, the acquisition unit 51 acquires detection information from the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the machine body tilt sensor S4, the swing state sensor S5, the imaging device S6, the boom rod pressure sensor S7R, the boom bottom pressure sensor S7B, the arm rod pressure sensor S8R, the arm bottom pressure sensor S8B, the bucket rod pressure sensor S9R, the bucket bottom pressure sensor S9B, and the positioning device PS.

Moreover, the acquisition unit 51 acquires operation information indicating a detail of the operation of the operating device 26 from the operation sensor 29, and acquires a signal corresponding to the operation input from the input device 42. Furthermore, the acquisition unit 51 acquires information received from an external device via the communication device T1. For example, when the excavator 100 is operated remotely, the acquisition unit 51 may acquire an operation signal received from an external device via the communication device T1.

The position computing unit 52 computes a position of a predetermined positioning target. For example, the position computing unit 52 computes the coordinate points of the distal end of the attachment, specifically, the working portion such as the tooth tip or the back surface of the bucket 6 in the reference coordinate system. Specifically, the position computing unit 52 computes the coordinate points of the working portion of the bucket 6 from the respective elevation angles (the boom angle, the arm angle, and the bucket angle) of the boom 4, the arm 5, and the bucket 6.

The distance computing unit 53 computes a distance between two positioning objects. For example, the distance computing unit 53 computes a distance between the distal end of the attachment, specifically, the working portion such as the tooth tip or the back surface of the bucket 6, and the target construction surface.

In the present embodiment, the distance between the target construction surface, which is expressed in the reference coordinate system indicated by the target construction surface information 47A, and the working portion of the bucket 6, which is expressed in the reference coordinate system, is computed. Moreover, the distance computing unit 53 may compute an angle (relative angle) between the target construction surface and the back surface serving as the working portion of the bucket 6. Based on the angle, the distance computing unit 53 may identify an end edge of the back surface of the bucket 6 closest to the target construction surface and compute a distance between the specified end edge and the target construction surface.

The determination unit 54 determines whether or not the working portion of the bucket 6 is in contact with the target construction surface when a swing operation of the upper structure 3 is performed in accordance with an operation from an operator via the operating device 26. In the present embodiment, it is determined whether or not the working portion of the bucket 6 is in contact with the target construction surface based on whether or not the distance between the target construction surface and the working portion of the bucket 6 computed by the distance computing unit 53 is “0.” Note that the present embodiment illustrates an example of a method of determining whether or not the working portion of the bucket 6 is in contact with the target construction surface, and is not limited to the determination method using the target construction surface information 47A, and other methods may be used.

In the present embodiment, the working portion of the bucket 6 in contact with the target construction surface is a lateral end edge of the back surface of the bucket 6 or the tooth tip of the bucket 6. Note that the present embodiment illustrates an example of the working portion of the bucket 6 for slope shaping, and slope shaping may be performed with a different working portion.

The automatic control unit 55 automatically assists, by automatically operating the actuators, the manual operation of the excavator 100 performed by the operator through the operating device 26. Specifically, as described later, the automatic control unit 55 can individually and automatically adjust pilot pressures applied to control valves (i.e., the control valve 173, the control valves 175L and 175R, and the control valve 174) corresponding to a plurality of hydraulic actuators (i.e., the hydraulic swing motor 2A, the boom cylinder 7, and the bucket cylinder 9). Accordingly, the automatic control unit 55 can automatically operate each of the hydraulic actuators. The control of the machine control function performed by the automatic control unit 55 may be executed, for example, when a predetermined switch included in the input device 42 is pressed. The predetermined switch is, for example, a machine control switch (hereinafter, referred to as a MC switch), and may be disposed as a knob switch at the distal end of a grip portion held by an operator of the operating device 26 (e.g., a lever device corresponding to the operation of the arm 5). Hereinafter, the description will proceed on the assumption that the machine control function is effective when the MC switch is pressed.

For example, when the MC switch or the like is pressed, the automatic control unit 55 controls any one or more of the boom 4, the arm 5, or the bucket 6 so that the working portion follows the target construction surface after the determination unit 54 has determined that the working portion of the bucket 6 is in contact with the target construction surface.

Slope Shaping Work Using Swing Operation

Next, slope shaping work using a swing operation of the excavator 100 will be described. FIGS. 5A to 5C are explanatory views illustrating the slope shaping work based on the swing operation by the excavator 100 according to the present embodiment. In the present embodiment, the case where the excavator 100 performs a left swing is described. However, the slope shaping work can also be performed when the excavator 100 performs a right swing.

FIG. 5A illustrates a state before the excavator 100 starts swinging. In an example illustrated in FIG. 5A, the excavator 100 is grounded on a ground surface GS. Then, the excavator 100 performs slope shaping work on a slope BS present leftward of the excavator 100. In the example illustrated in FIG. 5A, slope shaping is performed between a toe of slope FS and a top of slope TS. The present embodiment illustrates an example in which the ground surface GS substantially coincides with a horizontal plane.

In the present embodiment, the operator tilts the left control lever 26L in the left-swing direction (leftward direction) while the MC switch or the like is pressed. This starts a left swing of the upper structure 3 of the excavator 100.

FIG. 5B illustrates a state in which the determination unit 54 has determined that the working portion of the bucket 6 of the excavator 100 is in contact with the target construction surface. When it is determined that the working portion is in contact with the target construction surface, the automatic control unit 55 starts control of the boom 4, the arm 5, and the bucket 6 so that the working portion follows the target construction surface. FIG. 5B illustrates a region CS and a region NS. The region CS is where the bucket 6 is in contact with the slope BS and slope shaping work is performed, and the region NS is where slope shaping work is not performed.

FIG. 5C is a view illustrating a state in which the automatic control unit 55 controls the boom 4, the arm 5, and the bucket 6 so that the working portion follows the target construction surface. In an example illustrated in FIG. 5C, the region CS where slope shaping work is performed is illustrated. That is, in the present embodiment, as illustrated in the region CS, slope shaping work is performed in a horizontal region of the slope BS.

In the present embodiment, when the bucket 6 moves along the target construction surface in accordance with the left swing of the upper structure 3, a distance between the bucket 6 and the swing mechanism 2 may be reduced. Accordingly, the automatic control unit 55 performs a close operation of the arm 5. However, if only the close operation of the arm 5 is performed, the bucket 6 will be lowered. Therefore, the automatic control unit 55 controls the close operation of the arm 5 as well as an up operation of the boom 4. This control maintains the height of the bucket 6 from the ground surface GS.

When the bucket 6 moves along the target construction surface and, after the distance between the swing mechanism 2 and the bucket 6 has become the shortest, a left swing of the upper structure 3 continues, the automatic control unit 55 controls the attachment so as to maintain the bucket 6 in contact with the target construction surface. Specifically, the automatic control unit 55 controls the open operation of the arm 5 as well as a down operation of the boom 4. This control maintains the height of the bucket 6 from the ground surface GS.

As described above, the automatic control unit 55 controls the boom 4 and the arm 5 so that the bucket 6 is maintained at substantially the same height from the ground surface GS where the excavator is grounded. Therefore, the machine guidance unit 50 can perform the slope shaping work by the swing operation while the bucket 6 is maintained at substantially the same height. That is, in the present embodiment, slope shaping work can be performed in a region in the horizontal direction (substantially the same height) relative to the slope BS. In the slope shaping work, after the completion of the slope shaping in the horizontal direction, the operator controls the bucket 6 to come to a height at which the next shaping work is performed, and then performs a swing operation so that the slope shaping work can be performed in the horizontal direction in the region at the height. The operator can perform the slope shaping work in all regions of the slope BS by repeating the swing operation and the height adjustment of the bucket 6. In the present embodiment, when the slope shaping work is performed in the horizontal direction by the swing operation, the bucket 6 is maintained at substantially the same height so that the operator can intuitively grasp the region where the slope shaping work is performed. Therefore, the work efficiency can be improved.

As illustrated in the region CS in FIG. 5C, the slope shaping is performed by the working portion of the bucket 6 on a surface-by-surface basis in the present embodiment. Next, control for performing the slope shaping on a surface-by-surface basis will be described.

FIG. 6 is a view illustrating, as an example, slope shaping with the working portion of the bucket 6 according to the present embodiment. In an example illustrated in FIG. 6, since a left end edge 6L of the back surface of the bucket 6 is in contact with the slope BS, the slope shaping is performed in the region CS having a length corresponding to the left end edge 6L. In FIG. 6, a region NS is a region where the slope shaping is not performed.

As illustrated in FIG. 6, the automatic control unit 55 controls the bucket angle so that the left end edge 6L of the back surface of the bucket 6 contacts the target construction surface in a substantially parallel state. In the present embodiment, an inclination angle of the target construction surface is included in the target construction surface information 47A. Therefore, the automatic control unit 55 controls the bucket angle so that an angle of the left end edge 6L of the back surface of the bucket 6 corresponding to a horizontal plane becomes the inclination angle of the target construction surface.

Note that the present embodiment is not limited to the method of controlling the bucket angle based on the inclination angle of the target construction surface included in the target construction surface information 47A. For example, the automatic control unit 55 may control the bucket angle so that the bucket angle becomes the inclination of the slope BS imaged by the imaging device S6. As described above, the present embodiment illustrates an example of the control of the end attachment, and any control of the end attachment may be employed as long as a lateral end edge of the back surface of the bucket 6 contacts the target construction surface in a substantially parallel state.

That is, in the present embodiment, since the automatic control unit 55 adjusts the bucket angle so that the left end edge 6L of the back surface of the bucket 6 contacts the slope BS, the slope shaping can be performed on a surface-by-surface basis, in which a surface has a side corresponding to a lateral end edge (e.g., the left end edge 6L) of the back surface of the bucket 6. Thus, compared with a case where a tooth tip of the bucket 6 contacts the target construction surface, the region in which work can be performed is increased, thereby improving work efficiency.

The present embodiment is not limited to the method of performing the slope shaping with a lateral end edge of the back surface of the bucket 6, and the slope shaping may be performed with the tooth tip of the bucket 6. For example, when the slope BS is hard and the slope shaping is difficult to be performed with the lateral end edge of the back surface, the slope shaping may be performed with the tooth tip of the bucket 6.

That is, when the operator performs the shaping work by a swing operation, the method of the slope shaping may be different depending on the hardness of the slope BS, or the like. Therefore, the machine guidance unit 50 according to the present embodiment switches the method of the slope shaping in accordance with an operation performed by the operator.

FIG. 7 is a flowchart showing a processing procedure of the slope shaping work by the machine guidance unit 50 according to the present embodiment when a swing operation is performed with the upper structure 3.

First, the machine guidance unit 50 starts a swing operation of the upper structure 3 in accordance with a swing operation from the operating device 26 (S1701).

The position computing unit 52 computes current coordinate points of the working portion of the bucket 6, such as the tooth tip or the back surface, in the reference coordinate system (S1702).

The distance computing unit 53 computes a distance between the current coordinate points of the working portion of the bucket 6, such as the tooth tip or the back surface, which has been computed in S1702, and the target construction surface indicated by the target construction surface information 47A (S1703).

Based on the distance computed in S1703, the determination unit 54 determines whether or not the working portion is in contact with the target construction surface (S1704). When the determination unit 54 determines that the working portion is not in contact with the target construction surface (S1704: NO), the process of S1708 is performed.

On the other hand, when the determination unit 54 determines that the working portion and the target construction surface are in contact with each other (S1704: YES), the determination unit 54 determines whether or not the angle between the end edge of the back surface of the bucket 6 and the target construction surface (| angle of the end edge of the back surface of the bucket 6 - angle of the target construction surface |) is equal to or less than a threshold (an example of a predetermined angle) (S1705). That is, when the angle between the end edge of the back surface of the bucket 6 and the target construction surface is equal to or less than the threshold, it is determined that the operator has performed the operation to perform the slope shaping with the end edge of the back surface of the bucket 6. When the angle between the end edge of the back surface of the bucket 6 and the target construction surface is greater than the threshold, it is determined that the operator has performed the operation to perform the slope shaping with something other than end edge of the back surface of the bucket 6, such as the tooth tip of the bucket 6. In the present embodiment, the threshold serving as a reference for determining whether or not to control the bucket angle for performing the slope shaping with the back surface may be set to an appropriate angle depending on embodiments, and may be set to, for example, 10 degrees, or the like.

When the determination unit 54 determines that the angle between the end edge of the back surface of the bucket 6 and the target construction surface is equal to or less than the threshold (S1705: YES), the automatic control unit 55 controls the boom angle, the arm angle, and the bucket angle so that the end edge of the back surface of the bucket 6 and the target construction surface are in contact with each other in a substantially parallel state and the bucket 6 is maintained at substantially the same height from the ground surface GS (S1706).

On the other hand, when the determination unit 54 determines that the angle between the end edge of the back surface of the bucket 6 and the target construction surface is greater than the threshold (S1705: NO), the automatic control unit 55 reduces the control of the bucket angle that causes the end edge of the back surface of the bucket 6 and the target construction surface to be in contact with each other in a substantially parallel state, and controls the boom angle and the arm angle so that the tooth tip of the bucket 6 is maintained to be in contact with the target construction surface and the bucket 6 is maintained at substantially the same height from the ground surface GS (S1707).

Thereafter, the machine guidance unit 50 determines whether or not a swing operation of the upper structure 3 has been ended in accordance with the swing operation from the operating device 26 (S1708). When it is determined that the swing operation of the upper structure 3 has not been ended (S1708: NO), the process starts again from S1702.

On the other hand, when the machine guidance unit 50 determines that the swing operation of the upper structure 3 has been ended (S1708: YES), the machine guidance unit 50 ends the control.

In the present embodiment, when the operator first operates the bucket angle so that (the end edge of) the back surface of the bucket 6 follows the target construction surface, the automatic control unit 55 controls the bucket angle so that the end edge of the back surface of the bucket 6 and the target construction surface are in contact with each other in a substantially parallel state during swinging. Thus, the automatic control is performed so that the end edge of the back surface of the bucket 6 is in contact with the target construction surface in a substantially parallel state, thereby improving operability.

In the present embodiment, when the swing operation of the upper structure 3 is performed, slope shaping can be performed with the tooth tip of the bucket 6 as necessary. Thus, the construction mode can be switched depending on the state of the slope BS. Moreover, even if the slope BS includes a hard object, slope shaping can be appropriately performed with the tooth tip of the bucket 6.

First Modification

In the above embodiment, since the ground surface GS on which the excavator 100 is grounded coincides with the horizontal plane, the automatic control unit 55 can control the boom 4 and the arm 5 so that the working portion of the bucket 6 is maintained at substantially the same height from the ground surface GS of the excavator 100. In the present modification, a case where the ground surface on which the excavator 100 is grounded is inclined from a horizontal plane will be described.

In this case, the automatic control unit 55 controls the operation of the arm 5 and the boom 4 in consideration of the inclination of the excavator 100.

When it is determined that the machine body (the upper structure 3 or the undercarriage 1) is inclined relative to a horizontal plane based on detection information from the machine body tilt sensor S4, the automatic control unit 55 according to the present modification controls the operation of the arm 5 and the boom 4 so as to draw a trajectory inclined by the inclination angle detected from the horizontal plane during the operation of swinging the upper structure 3.

That is, the automatic control unit 55 controls at least one of the boom 4, the arm 5, or the bucket 6 so that the working portion of the bucket 6 moves along a trajectory obtained by the intersection between the target construction surface and a plane including the position of the working portion of the bucket 6 and inclined by the inclination angle from the horizontal plane (i.e., a plane including the position of the working portion of the bucket 6 and substantially parallel to a ground-contact surface of the excavator 100).

Thus, in the present modification, slope shaping is performed in a direction of inclination by the inclination angle detected with respect to the slope BS. In the present modification, by the control, even when the excavator 100 is inclined, slope shaping can be easily performed through control of at least one of the boom 4, the arm 5, and the bucket 6 by the automatic control unit 55.

Second Modification

In the above-described embodiment and modification, the case where the operation of the arm 5 and the boom 4 is controlled together with the swing operation of the upper structure 3 to perform slope shaping has been described. However, the above-described embodiment and modification are not limited to this method. In the present modification, a case where only an operation of the arm 5 is controlled will be described.

FIG. 8 is an explanatory view of operation control of the automatic control unit 55 according to the present modification. An arrow 1801 illustrated in FIG. 8 indicates a case where the operation of the arm 5 and the boom 4 is controlled together with the swing operation of the upper structure 3 in the above-described embodiment so that the bucket 6 is controlled to maintain substantially the same height.

The automatic control unit 55 according to the present modification controls a close operation of the arm 5 together with a swing operation of the upper structure 3. Thus, as indicated by an arrow 1802 illustrated in FIG. 8, the bucket 6 is lowered in accordance with the close operation of the arm 5. In the present modification, when the automatic control unit 55 performs this control, slope shaping can be performed without controlling the boom 4. Thus, the control load can be reduced. In the present modification, it is possible to minimize the stop of the swing operation at the stage of contacting the slope and to operate the excavator 100 in accordance with the operation performed by the operator. Therefore, the operability can be improved.

Second Embodiment

In the above embodiment, the case where slope shaping work is performed with the excavator 100 in which the operator is present has been described. However, the above embodiment is not limited to the method of performing the slope shaping work when the operator is present in the excavator 100. For example, when the excavator 100 performs the slope shaping work in accordance with remote control, substantially the same processing as in the above embodiment may be performed. Therefore, in a second embodiment, a case where the remote control of the excavator 100 is performed will be described.

An overview of a remote operation system SYS according to the second embodiment will be described with reference to FIG. 9. FIG. 9 is a schematic view illustrating an example of the remote operation system SYS according to the second embodiment.

As illustrated in FIG. 9, the remote operation system SYS according to the second embodiment includes an excavator 100 and a remote operation room RC.

The excavator 100 and the remote operation room RC are connected through a communication line NT so that data can be transmitted and received.

The excavator 100 enables radio communication by using a communication device T1. The excavator 100 can transmit and receive data to and from equipment (e.g., the remote control room RC) connected to the communication line NT.

The excavator 100 can transmit information on a work site to the remote operation room RC. Accordingly, the remote operation room RC can confirm the work site with the information from the excavator 100. In the present embodiment, a device for measuring the work site is not limited to the excavator 100, but may be a different device such as a drone flying over the work site, a fixed-point camera, or a personally owned imaging device.

For example, the excavator 100 is provided with an imaging device S6. The excavator 100 transmits, to the remote operation room RC, a captured image indicating the result of imaging the work site by the imaging device S6.

The remote operation system SYS may include one or more excavators 100. Thus, the remote operation system SYS can provide information on the work site to the remote operation room RC through the excavators 100.

Configuration Example of Remote Operation Room

The remote operation room RC includes a communication device T2, a remote controller R30, an operating device R26, an operation sensor R29, and a display device D1. The remote operation room RC is also provided with an operation seat DS for an operator OP who remotely operates the excavator 100 to sit.

The communication device T2 controls communication with the communication device T1 attached to the excavator 100.

The remote controller R30 is a computing device that executes various calculations. In the present embodiment, the remote controller R30 is formed by a microcomputer including a central processing unit (CPU) and a memory. Various functions of the remote controller R30 are implemented by the CPU executing a program stored in the memory.

The display device D1 displays a screen based on the information transmitted from the excavator 100 so that the operator OP in the remote operation room RC can visually confirm the surroundings of the excavator 100. With the display device D1, the operator OP can confirm a state of the work site including the surroundings of the excavator 100 even though the operator OP is in the remote operation room RC.

The operating device R26 is provided with the operation sensor R29 for detecting an operation detail of the operating device R26. The operation sensor R29 is, for example, a tilt sensor for detecting a tilt angle of the control lever, an angle sensor for detecting an oscillation angle of the control lever about an oscillation axis, or the like. The operation sensor R29 may be formed of a different sensor such as a pressure sensor, a current sensor, a voltage sensor, or a distance sensor. The operation sensor R29 outputs the detected information on the operation detail of the operating device R26 to the remote controller R30. The remote controller R30 generates an operation signal based on the received information and transmits the generated operation signal to the excavator 100. The operation sensor R29 may generate an operation signal. In this case, the operation sensor R29 may output the operation signal to the communication device T2 without passing through the remote controller R30. Accordingly, the remote operation of the excavator 100 can be realized from the remote operation room RC.

The communication device T1 of the excavator 100 receives the operation signal from the communication device T2 of the remote controller R30.

A machine guidance unit 50 in a controller 30 of the excavator 100 performs substantially the same control as in the above-described embodiment or modifications based on a received control signal.

That is, while receiving an operation signal indicating that the MC switch is pressed from the communication device T2, the machine guidance unit 50 controls a swing operation of an upper structure 3 when further receiving an operation signal indicating a swing of the upper structure 3. A determination unit 54 of the machine guidance unit 50 determines whether or not a working portion of a bucket 6 is in contact with a target construction surface. When the determination unit 54 determines that the working portion is in contact with the target construction surface, an automatic control unit 55 controls at least one of the boom 4, the arm 5, or the bucket 6 so that the working portion follows the target construction surface. A control method is substantially the same as that described in the above-described embodiment and modifications, and description thereof is omitted.

In the present embodiment, when remote operation is performed only based on the screen displayed on the display device D1, it is sometimes difficult for the operator to control the working portion of the bucket 6 to follow the target construction surface. Thus, in the present embodiment, slope shaping can be performed by the machine guidance unit 50 controlling at least one of the boom 4, the arm 5, or the bucket 6 in substantially the same manner as in the above-described embodiment. Therefore, the operation load can be reduced.

Effects

The swing operation is stopped in the related art when the bucket 6 is about to come into contact with the slope due to the swing operation. However, in the above-described embodiments and modifications, slope shaping work can be performed by a swing operation. Thus, the work can be performed in accordance with the operation performed by the operator, thereby improving the work efficiency.

In the above-described embodiments and modifications, slope shaping work is performed with the end edge of the back surface of the bucket 6 together with the swing operation. Since the back surface of the bucket 6 is often longer in the traveling direction (e.g., the left end edge or the right end edge) than in the width direction, the region in which the work can be performed is larger than that in the related art, thereby improving the work speed.

Although the embodiments of the excavator, the remote operation system, and the control method according to the present invention have been described above, the present invention is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. They also naturally fall within the technical scope of the present invention.