Automatic control system for work machine and control method for work machine

Abstract

A work implement posture sensor detects a posture of a work implement. A controller identifies a passing point through which a bucket passes during revolution of a revolving body, based on a result of the detection by the work implement posture sensor, calculates a corrected passing point by adding a vertical offset, derived from shape data of the bucket, to the height position of the passing point, and controls the bucket so as to pass through the corrected passing point during the revolution.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an automatic control system for a work machine and a control method for the work machine.BACKGROUND ART

[0002] JP 2019-190234 A (Patent Document 1) describes a technique for changing a target revolution speed of a revolving body so that a bucket does not interfere with a loading target while the revolving body is revolving in automatic loading.CITATION LISTPatent LiteraturePatent Document 1: JP 2019-190234 ASUMMARY OF INVENTIONTechnical Problem

[0004] However, in the technique described in Patent Document 1, depending on the posture of a work implement having a work tool such as a bucket, the work tool may interfere with the loading target.

[0005] An object of the present disclosure is to provide an automatic control system for a work machine and a control method for the work machine, the work machine being able to reduce interference between a work tool and a loading target.Solution to Problem

[0006] An automatic control system for a work machine according to the present disclosure includes a revolving body, a work implement, a work implement posture sensor, and a controller. The revolving body revolves. The work implement is attached to the revolving body and has a work tool. The work implement posture sensor detects a posture of the work implement. The controller identifies a passing point through which the work tool passes when the revolving body revolves, based on a detection result of the work implement posture sensor, calculates a corrected passing point by adding a vertical offset, derived from shape data of the work tool, to the height position of the passing point, and performs a control such that the work tool passes through the corrected passing point during revolution.

[0007] A control method for a work machine according to the present disclosure is a method of controlling a work machine including a revolving body that revolves and a work implement attached to the revolving body and having a work tool, the method including the following steps.

[0008] Based on a detection result of a posture of the work implement, a passing point through which the work tool passes when the revolving body revolves is identified. A corrected passing point is calculated by adding a vertical offset, derived from shape data of the work tool, to the height position of the passing point. A control is performed such that the work tool passes through the corrected passing point during revolution.Advantageous Effects of Invention

[0009] According to the present disclosure, it is possible to obtain an automatic control system for a work machine and a control method for the work machine, the work machine being able to reduce interference between a work tool and a loading target.BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 is a diagram illustrating a configuration of a hydraulic excavator as an example of a work machine according to an embodiment of the present disclosure.

[0011] FIG. 2 is a diagram illustrating an operation flow of excavation and loading by a hydraulic excavator.

[0012] FIG. 3 is a perspective view illustrating a state in which a hydraulic excavator performs automatic loading.

[0013] FIG. 4 is a side view illustrating different postures of a bucket in the hydraulic excavator.

[0014] FIG. 5 is a block diagram illustrating an automatic control system for the hydraulic excavator of FIG. 1.

[0015] FIG. 6 is a side view of the bucket for explaining calibration of an interference avoidance point (passing point).

[0016] FIG. 7 is a flowchart illustrating a control method for a hydraulic excavator according to an embodiment of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0017] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0018] In the specification and the drawings, the same components or equivalent components are denoted by the same reference signs, and duplicated descriptions are not repeated. In the drawings, configurations may be omitted or simplified for convenience of description.

[0019] In the following description, “up”, “down”, “front”, “back”, “left”, and “right” are directions with reference to an operator seated on an operator seat 4S in a cab 4 illustrated in FIG. 1.

[0020] Configuration of Work Machine A configuration of a hydraulic excavator as an example of a work machine of the present disclosure will be described using FIG. 1.

[0021] FIG. 1 is a diagram schematically illustrating a configuration of a hydraulic excavator according to an embodiment of the present disclosure. As illustrated in FIG. 1, a hydraulic excavator 100 of the present embodiment includes a main body 1 and a work implement 2 that is operated by a hydraulic pressure. The main body 1 includes a revolving body 3 and a traveling body 5.

[0022] The traveling body 5 includes a pair of crawler belts 5Cr and a traveling motor 5M. The hydraulic excavator 100 can travel by the turn of the crawler belts 5Cr. The traveling motor 5M is provided as a driving source of the traveling body 5. The traveling motor 5M is a hydraulic motor operated by a hydraulic pressure. The traveling body 5 may include wheels (tires).

[0023] The revolving body 3 is disposed on the traveling body 5 and supported by the traveling body 5. The revolving body 3 can be revolved about a revolution axis RX with respect to the traveling body 5 by a revolving motor (not illustrated). The revolving motor is a hydraulic motor operated by a hydraulic pressure. The revolution axis RX is a virtual straight line serving as a revolution center of the revolving body 3. The traveling motor 5M or the revolving motor may be an electric motor.

[0024] The revolving body 3 includes a cab 4. An operator seat 4S on which an operator is seated is provided inside the cab 4. The operator (occupant) can be seated in the cab 4 to perform an operation of the work implement 2, a revolving operation of the revolving body 3 with respect to the traveling body 5, and a traveling operation of the hydraulic excavator 100 by the traveling body 5. The revolving body 3 includes an exterior cover 9. The exterior cover 9 covers a machine room. The hydraulic excavator 100 may be remotely operated.

[0025] The work implement 2 is supported by the revolving body 3. The work implement 2 includes a boom 6, an arm 7, and a bucket 8. The work implement 2 further includes a boom cylinder 10, an arm cylinder 11, and a bucket cylinder 12.

[0026] The boom 6 is pivotably connected to the main body 1. Specifically, a base end portion of the boom 6 is pivotably connected to the revolving body 3 with a boom foot pin 13 as a supporting point. The arm 7 is pivotably connected to the boom 6. Specifically, a base end portion of the arm 7 is pivotably connected to a leading end portion of the boom 6 with a boom top pin 14 as a supporting point. The bucket 8 is turnably connected to the arm 7. Specifically, a base end portion of the bucket 8 is pivotably connected to a leading end portion of the arm 7 with an arm top pin 15 as a supporting point. The bucket 8 may be another work tool such as a grapple. Since the overall length of a grapple varies depending on the open / close state of claws, the grapple may interfere with a loading target 200 due to a change in the state or posture of the grapple. The present disclosure can be applied to a work tool having a length varying depending on the state or posture as described above or, in other words, a work implement whose relative positional relationship with the loading target 200, which will be described below, varies.

[0027] One end of the boom cylinder 10 is connected to the revolving body 3, and the other end is connected to the boom 6. The boom 6 can be driven relative to the main body 1 by the boom cylinder 10. By this driving, the boom 6 is pivotable in an up-down direction with respect to the revolving body 3 with the boom foot pin 13 as a supporting point.

[0028] One end of the arm cylinder 11 is connected to the boom 6, and the other end is connected to the arm 7. The arm 7 can be driven relative to the boom 6 by the arm cylinder 11. By this driving, the arm 7 is pivotable in the up-down direction or a front-back direction with respect to the boom 6 with the boom top pin 14 as a supporting point.

[0029] One end of the bucket cylinder 12 is connected to the arm 7, and the other end is connected to a bucket link 17. The bucket 8 can be driven relative to the arm 7 by the bucket cylinder 12. By this driving, the bucket 8 is pivotable in the up-down direction with respect to the arm 7 with the arm top pin 15 as a supporting point.

[0030] Each of the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 is a hydraulic cylinder driven by a hydraulic pressure, but may be another actuator such as an electric cylinder.

[0031] The hydraulic excavator 100 further includes a work implement posture sensor 20 (FIG. 5), a position and orientation sensor 21, a tilt sensor 22 (FIG. 5), and a detection sensor 23. The work implement posture sensor 20 detects a posture of the work implement 2 and outputs a posture signal indicating the posture of the work implement 2. The work implement posture sensor 20 can detect a posture of each of the boom 6, the arm 7, and the bucket 8. The work implement posture sensor 20 includes sensors disposed at each of the boom 6, the arm 7, and the bucket 8. The work implement posture sensor 20 may be any one of or any combination of an inertial measurement unit (IMU), a stroke sensor, a potentiometer, an imaging device, and the like.

[0032] The position and orientation sensor 21 is, for example, a global navigation satellite systems (GNSS) receiver. The position and orientation sensor 21 includes two GNSS receivers 21a and 21b. The two GNSS receivers 21a and 21b are installed at different positions of the revolving body 3. Each of the GNSS receivers 21a and 21b receives a satellite positioning signal indicating a position of the revolving body 3 in the global coordinate system from a satellite. The position and orientation sensor 21 outputs the received satellite positioning signal indicating the position of the revolving body 3 in the global coordinate system. The controller 50 calculates, from the satellite positioning signal, the position of the revolving body 3 in the global coordinate system and the orientation in which the revolving body 3 faces.

[0033] The position and orientation sensor 21 may include a revolution angle sensor. The revolution angle sensor is fixed to the revolving body 3, for example. The revolution angle sensor detects a revolution angle of the revolving body 3 with respect to the traveling body 5 and outputs a revolution angle signal indicating the revolution angle of the revolving body 3. The revolution angle sensor can detect a revolution angle in a machine coordinate system (local coordinate system). The revolution angle sensor may be any one of or any combination thereof an IMU, a potentiometer, an imaging device, and the like. The machine coordinate system is an orthogonal coordinate system represented by an axis extending in the front-back direction, an axis extending in a left-right direction, and an axis extending in the up-down direction (the revolution axis RX) with the revolution center of the revolving body 3 as an origin.

[0034] The tilt sensor 22 measures an acceleration and an angular velocity (revolution speed) of the revolving body 3 and, based on a result of the measurement, detects a posture (e.g., a roll angle, a pitch angle, and a yaw angle) of the revolving body 3. The tilt sensor 22 is installed, for example, on a lower surface of the revolving body 3. The tilt sensor 22 is, for example, an IMU. The tilt sensor 22 outputs a tilt signal obtained by the measurement.

[0035] The detection sensor 23 detects a landform or an object around a work site of the hydraulic excavator 100. For example, the detection sensor 23 may be attached to the cab 4, or may be attached to the exterior cover 9, or may be attached to any other member. The detection sensor 23 outputs a detection signal detected.

[0036] The detection sensor 23 is, for example, a light detection and ranging (LiDAR) that acquires information on a target object by emitting laser light. The detection sensor 23 may be a radio detection and ranging (Radar) that acquires information on a target object by emitting radio waves. The Radar may be, for example, a millimeter wave radar that detects, with a reception antenna, a state in which radio waves in a millimeter wave band emitted from a transmission antenna is reflected by a surface of an object and returns. The detection sensor 23 may be a visual sensor including a camera. Note that the detection sensor 23 may have a function of detecting a posture of the work implement 2, similarly to the work implement posture sensor 20. For example, a posture of the work implement 2 may be detected by emitting laser light toward the work implement 2 by the LiDAR.

[0037] The hydraulic excavator 100 further includes an instruction unit 24 (FIG. 5) and an operation unit 25 (FIG. 5). Each of the instruction unit 24 and the operation unit 25 is disposed in the cab 4. The instruction unit 24 and the operation unit 25 are manually operated by the operator who is seated in the cab 4 and output an operation command by manual driving. The instruction unit 24 is a unit for designating a point through which the bucket 8 is to pass in an automatic loading control. The operation unit 25 is a unit for operating each of the operation, revolution, and traveling of the boom 6, the arm 7, and the bucket 8.

[0038] Operation Flow of Excavation and Loading and Automatic Loading Control Next, an operation flow of excavation and loading of the work machine and an automatic loading control will be described using FIGS. 2 to 4.

[0039] FIG. 2 is a diagram illustrating an operation flow of excavation and loading by the hydraulic excavator. FIG. 3 is a perspective view illustrating a state in which the hydraulic excavator performs automatic loading. FIG. 4 is a side view illustrating different postures of the bucket in the hydraulic excavator.

[0040] As illustrated in FIGS. 2 and 3, in excavation and loading by the hydraulic excavator 100, excavation is first performed (step SA). By the excavation, a load such as earth and sand is loaded in the bucket 8. After the excavation, the revolving body 3 revolves with the load loaded in the bucket 8 (step SB). This revolution is so-called loaded revolution. During the loaded revolution, the operation of the bucket 8 is controlled so as not to interfere with the loading target 200. The loading target 200 is, for example, a dump truck. The dump truck 200 includes a vessel 200A for loading a load in the bucket 8.

[0041] When the bucket 8 reaches a point at which the load in the bucket 8 is unloaded to the vessel 200A by the loaded revolution, the revolution of the revolving body 3 is stopped. Then, the load in the bucket 8 is discharged (unloaded) to the vessel 200A of the dump truck 200 (step SC). After unloading, the revolving body 3 performs return revolution to perform excavation again (step SD).

[0042] As illustrated in FIG. 3, in order to automate the loading operation, a point through which the bucket 8 passes during the loading operation needs to be identified. In this automation, the operation of the work implement 2 needs to be controlled so that the bucket 8 as a work tool does not interfere with the vessel 200A. As the point through which the bucket 8 passes during the loading operation, for example, at least a passing point (interference avoidance point) PIA, an unloading point P2, and a returning point (excavating point) P3 are identified.

[0043] The passing point PIA is a point at which the center of the arm top pin 15 in the left-right direction is positioned directly above a side edge SE of the loading target 200 (e.g., a side edge of the vessel 200A). The unloading point P2 is a point at which the center of the arm top pin 15 in the left-right direction is positioned directly above the loading target 200 (e.g., the vessel 200A). The returning point P3 is a point at which the center of the arm top pin 15 in the left-right direction is positioned directly above a point where excavation is to be performed. Here, in order to identify the passing point PIA, the unloading point P2, and the returning point P3, the points PIA, P2, and P3 are described as points at which the center of the arm top pin 15 in the left-right direction is positioned. However, each of the points PIA, P2, and P3 may be identified using another point. For example, the passing point PIA, the unloading point P2, and the returning point P3 may be identified using a point of a blade tip 8T of the bucket 8. Alternatively, for example, when the position of the loading target 200 is detected by an external sensor or the like and the instruction unit 24 is operated, the passing point PIA, the unloading point P2, and the returning point P3 may be identified using a point on the work implement 2 at which the relative distance between the work implement 2 and the loading target 200 is the closest.

[0044] Each of the passing point PIA, the unloading point P2, and the returning point P3 is identified, for example, by the operator operating the instruction unit 24 during the revolution of the revolving body 3. Specifically, the operator operates the instruction unit 24 when the operator visually determines that the center of the arm top pin 15 in the left-right direction is positioned directly above the side edge SE of the loading target 200 (for example, the side edge of the vessel 200A) during the revolution of the revolving body 3. The operator operates the instruction unit 24 when the operator visually determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a point at which the load in the bucket 8 is to be unloaded during the revolution of the revolving body 3. The operator operates the instruction unit 24 when the operator visually determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a point at which excavation is to be performed during the revolution of the revolving body 3.

[0045] The coordinates of the points PIA, P2, and P3 in the machine coordinate system are calculated based on the posture of the work implement 2 and the revolution angle of the revolving body 3 at a timing at which the operator operates the instruction unit 24. As a result, the points PIA, P2, and P3 are identified. Each of the points PIA, P2, and P3 is identified, for example, during return revolution after unloading. In the automatic loading control, the operation of the work implement 2 and the revolution of the revolving body 3 are controlled such that the center of the arm top pin 15 in the left-right direction moves from the returning point P3, passes through the passing point PIA, and reaches the unloading point P2.

[0046] The passing point PIA is identified such that the bucket 8 does not interfere with the loading target 200. However, depending on the posture of the bucket 8, the bucket 8 may interfere with the loading target 200. Specifically, as illustrated in FIG. 4, the bucket 8 is in a posture 8A of bucket dumping for unloading. The posture 8A is a posture in which the opening of the bucket 8 faces downward. There may be a case in which the return revolution is performed while maintaining the posture of bucket dumping and the passing point PIA is identified. In that case, since the bucket 8 is in the posture 8A, interference between the bucket 8 and the loading target 200 can be avoided. However, when the bucket 8 is in a loaded posture 8B, in which the load is loaded, during the loading operation, the bucket 8 may interfere with the loading target 200. The loaded posture 8B is a posture in which the opening of the bucket 8 faces upward. In addition, when the bucket 8 is in a posture 8C in which the blade tip 8T is positioned at the lower end of the bucket 8, the bucket 8 may interfere with the loading target 200. The posture 8C is a posture in which the opening of the bucket 8 faces the main body 1 of the hydraulic excavator 100.

[0047] Therefore, in the present disclosure, the passing point PIA is calibrated to a corrected passing points PIB and PIC (FIG. 6) so that the bucket 8 does not interfere with the loading target 200 regardless of the posture of the bucket 8 during the automatic loading control. An automatic control system for the work machine that calibrate the passing point PIA to the corrected passing points PIB and PIC (FIG. 6) and a control method for the work machine will be described.Automatic Control System for Work Machine

[0048] First, a configuration of an automatic control system according to the present embodiment will be described using FIG. 5.

[0049] FIG. 5 is a block diagram illustrating an automatic control system for the hydraulic excavator in the present disclosure. As illustrated in FIG. 5, the automatic control system includes a controller 50. The controller 50 includes a processor, a main memory, and a storage unit 53. The processor is, for example, a central processing unit (CPU). The main memory includes, for example, a non-volatile memory such as a read only memory (ROM) and a volatile memory such as a random access memory (RAM). The controller 50 reads a program stored in the storage unit 53, loads the program into the main memory, and executes predetermined processing in accordance with the program.

[0050] The controller 50 includes an instruction point identification unit 51, a corrected passing point calculation unit 52, a storage unit 53, and an EPC valve control unit 54.

[0051] The instruction point identification unit 51 acquires a posture signal output from the work implement posture sensor 20. The instruction point identification unit 51 acquires a satellite positioning signal and a revolution angle signal output from the position and orientation sensor 21. The instruction point identification unit 51 acquires a tilt signal output from the tilt sensor 22. The instruction point identification unit 51 acquires a detection signal output from the detection sensor 23. The instruction point identification unit 51 acquires an instruction signal output from the instruction unit 24.

[0052] The instruction point identification unit 51 identifies the coordinates of a point through which the bucket is to pass in the automatic loading control. Specifically, the instruction point identification unit 51 calculates the coordinates of the center position of the arm top pin 15 in the left-right direction at a timing at which an instruction signal is acquired from the instruction unit 24.

[0053] When the operator operates the instruction unit 24 for the purpose of acquiring the passing point PIA, the coordinates of the center position of the arm top pin 15 in the left-right direction at a timing at which the instruction unit 24 is operated are calculated by a passing point identification unit 51A as the coordinates of the passing point PIA. When the operator operates the instruction unit 24 for the purpose of acquiring the unloading point P2, the coordinates of the center position of the arm top pin 15 in the left-right direction at a timing at which the instruction unit 24 is operated are calculated by an unloading point identification unit 51B as the coordinates of the unloading point P2. When the operator operates the instruction unit 24 for the purpose of acquiring the returning point P3, the coordinates of the center position of the arm top pin 15 in the left-right direction at a timing at which the instruction unit 24 is operated are calculated by a returning point identification unit 51C as the coordinates of the returning point P3.

[0054] The coordinates of each of the points PIA, P2, and P3 are calculated based on a signal acquired from each of the work implement posture sensor 20, the position and orientation sensor 21, and the tilt sensor 22. At this time, the instruction point identification unit 51 may refer to dimensions and the like, stored in the storage unit 53, of each component of the work implement 2. The instruction point identification unit 51 outputs coordinate signals of the identified passing point PIA, unloading point P2, and returning point P3 to the corrected passing point calculation unit 52.

[0055] Although the passing point identification unit 51A, the unloading point identification unit 51B, and the returning point identification unit 51C are illustrated separately from each other in the drawing, the passing point identification unit 51A, the unloading point identification unit 51B, and the returning point identification unit 51C are not necessarily separated from each other and may be the same part. That is, the points PIA, P2, and P3 may be identified by the same part of the instruction point identification unit 51. The instruction point identification unit 51 may output the coordinate signals of the identified unloading point P2 and returning point P3, not to the corrected passing point calculation unit 52, but directly to the EPC valve control unit 54. The corrected passing point calculation unit 52 acquires the coordinate signal of the passing point PIA from the passing point identification unit 51A. The corrected passing point calculation unit 52 calibrates the acquired coordinates of the passing point PIA to a corrected passing point PIB or PIC.

[0056] The calibration of the coordinates of the passing point PIA is performed by adding a vertical offset, derived from the shape data of the bucket 8, to the height position of the passing point PIA to calculate the coordinates of the corrected passing point PIB or PIC.

[0057] FIG. 6 is a side view of the bucket for explaining the calibration of the passing point (interference avoidance point) PIA. As illustrated in FIG. 6, a height position HA of the passing point P1A is determined by the center position of the arm top pin 15 in the left-right direction. However, as described above, when the bucket 8 is in the loaded posture 8B or the posture 8C in which the blade tip 8T is positioned at the lower end during the loading operation, the bucket 8 may interfere with the loading target 200 (vessel 200A).

[0058] Therefore, the corrected passing point PIB is calculated by adding a vertical offset (h1+α) based on a height dimension h1 of the bucket 8 in the loaded posture 8B (loaded state), to the height position HA of the passing point PIA. The height dimension h1 of the bucket 8 may be the maximum height dimension of a distance from the opening of the bucket 8 to a back surface of the bucket 8 in a side view of the bucket 8. In addition, the corrected passing point PIC may be calculated by adding a vertical offset (h2+α) based on a maximum height dimension h2 of the bucket 8 in a side view, to the height position HA of the passing point PIA. The maximum height dimension h2 of the bucket 8 in a side view may be a dimension from the blade tip 8T of the bucket 8 to the center of a hole into which the arm top pin 15 is inserted.

[0059] Here, a is a margin for control. For example, when the bucket 8 is loaded with a large load, the sinking amount of the bucket 8 also increases, and thus a may be determined in consideration of the sinking amount.

[0060] As illustrated in FIG. 5, when calculating the corrected passing points PIB and PIC, the corrected passing point calculation unit 52 refers to the shape data of the bucket 8 stored in the storage unit 53, the margin a for control, and the like. The storage unit 53 stores dimensions of each component of the work implement 2, the margin a for control, and the like. The value of a corresponding to the margin for control may be set to any value using an input device 26.

[0061] Various types of information are input to the storage unit 53 from the input device 26. The input device 26 may be a touch panel, a keyboard, or the like. The input device 26 may be mounted on the hydraulic excavator 100, or may be located away from the hydraulic excavator 100 and connected to the controller 50 in a wired or wireless manner. In addition, the shape data of the bucket 8 (work tool), the margin a for control, and the like may be stored in advance in the storage unit 53, or may be transmitted from the outside to the storage unit 53 in a wireless manner by the input device 26.

[0062] The corrected passing point calculation unit 52 outputs signals indicating the respective coordinates of the calculated corrected passing points PIB and PIC, the unloading point P2, and the returning point P3 to the EPC valve control unit 54. The EPC valve control unit 54 controls an EPC valve 28, based on the acquired signals indicating the coordinates of the corrected passing points PIB and PIC, the unloading point P2, and the returning point P3.

[0063] The EPC valve 28 controls a hydraulic valve 30, based on a command current from the EPC valve control unit 54 of the controller 50. As a result, the supply of oil pumped up from an oil tank (not illustrated) by a hydraulic pump 27 to an actuator 29 is controlled via the hydraulic valve 30. The actuator 29 is, for example, a hydraulic actuator, such as the boom cylinder 10, the arm cylinder 11, the bucket cylinder 12, and the revolving motor.

[0064] The EPC valve 28 is controlled by the EPC valve control unit 54, whereby each of the hydraulic actuators is controlled such that the center of the arm top pin 15 in the left-right direction moves from the returning point P3, passes through the corrected passing point PIB or PIC, and reaches the unloading point P2 in the automatic loading control. As a result, the automatic loading control in which interference between the bucket 8 and the loading target 200 is prevented becomes available.

[0065] The EPC valve control unit 54 acquires an operation signal from the operation unit 25. The EPC valve control unit 54 may control the EPC valve 28, based on an operation command for manual driving output from the operation unit 25. Accordingly, the operation of the work implement 2 and the revolution of the revolving body 3 can be performed through manual driving by the operator. As a result, the operator can move the work implement to positions corresponding to the passing point PIA, the unloading point P2, and the returning point P3.

[0066] A series of excavation and loading operations illustrated in FIG. 2 may be fully automated based on the detection signal of the detection sensor 23. The detection sensor 23 detects a situation and an object around the hydraulic excavator 100, so that a relative positional relationship between the hydraulic excavator 100 and an excavating point or the loading target 200 can be detected. Thus, each of the passing point PIA, the unloading point P2, and the returning point P3 can also be automatically identified during automatic returning revolution SD (FIG. 2). In addition, the detection sensor 23 detects the landform around the hydraulic excavator 100 or the like, so that excavation SA (FIG. 2) can also be automatically performed. Accordingly, in combination with the automatic loading control, the series of excavation and loading operations can be fully automated.

[0067] Each of the controller 50, the instruction unit 24, the operation unit 25, and the input device 26 may be mounted on the hydraulic excavator 100, or may be disposed outside and away from the hydraulic excavator 100. When each of the controller 50, the instruction unit 24, the operation unit 25, and the input device 26 is disposed outside and away from the hydraulic excavator 100, each of the controller50, the instruction unit 24, the operation unit 25, and the input device 26 may be connected to the various sensors 20 to 23, the EPC valve 28, and the like in a wireless manner. The controller 50 may be stored in a server away from the hydraulic excavator 100. When the operation unit 25 is away from the hydraulic excavator 100, the operator may remotely operate the hydraulic excavator 100 without being seated in the cab 4 of the hydraulic excavator 100.Control Method for Work Machine

[0068] Next, a control method for a work machine according to the present embodiment will be described using FIGS. 5 and 7.

[0069] FIG. 7 is a flowchart illustrating a control method for a hydraulic excavator according to an embodiment of the present disclosure. As illustrated in FIGS. 5 and 7, the instruction point identification unit 51 of the controller 50 acquires a posture signal (work implement posture information) output from the work implement posture sensor 20 (step S1: FIG. 7). The instruction point identification unit 51 of the controller 50 acquires a satellite positioning signal and a revolution angle signal (revolution angle information) output from the position and orientation sensor 21 (step S2: FIG. 7). The instruction point identification unit 51 of the controller 50 acquires a tilt signal output from the tilt sensor 22. The instruction point identification unit 51 of the controller 50 acquires a detection signal output from the detection sensor 23. The instruction point identification unit 51 of the controller50 acquires an instruction signal output from the instruction unit 24.

[0070] The instruction point identification unit 51 of the controller 50 identifies the coordinates of a point through which the bucket 8 is to pass in the automatic loading control. Specifically, the instruction point identification unit 51 calculates the coordinates of the center position of the arm top pin 15 in the left-right direction at a timing at which an instruction signal is acquired from the instruction unit 24.

[0071] When the operator determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a side edge of the loading target 200 and operates the instruction unit 24 or when the detection sensor 23 determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a side edge of the loading target 200, the coordinates of the center position of the arm top pin 15 in the left-right direction at that timing are calculated by the passing point identification unit 51A as the coordinates of the passing point PIA. As a result, the passing point PIA is identified (step S3: FIG. 7).

[0072] When the operator determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a point at which a load is to be unloaded and operates the instruction unit 24 or when the detection sensor 23 determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a point at which a load is to be unloaded, the coordinates of the center position of the arm top pin 15 in the left-right direction at that timing are calculated by the unloading point identification unit 51B as the coordinates of the unloading point P2. As a result, the unloading point P2 is identified.

[0073] When the operator determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a point at which excavation is to be performed and operates the instruction unit 24 or when the detection sensor 23 determines that the center of the arm top pin 15 in the left-right direction is positioned directly above a point at which excavation is to be performed, the coordinates of the center position of the arm top pin 15 in the left-right direction at that timing are calculated by the returning point identification unit 51C as the coordinates of the returning point P3. As a result, the returning point P3 is identified.

[0074] The instruction point identification unit 51 outputs coordinate signals of the identified passing point PIA, unloading point P2, and returning point P3 to the corrected passing point calculation unit 52. The instruction point identification unit 51 may output the coordinate signals of the identified unloading point P2 and returning point P3, not to the corrected passing point calculation unit 52, but directly to the EPC valve control unit 54.

[0075] The corrected passing point calculation unit 52 acquires the coordinate signal of the passing point PIA from the passing point identification unit 51A and calibrates the acquired coordinates of the passing point PIA to the corrected passing point PIB or PIC. That is, the corrected passing point calculation unit 52 of the controller 50 calculates a corrected passing point obtained by correcting the passing point PIA (step S4: FIG. 7).

[0076] As described above using FIG. 6, the calibration of the coordinates of the passing point PIA is performed by adding a vertical offset, derived from the shape data of the bucket 8, to the height position of the passing point PIA to calculate the coordinates of the corrected passing point PIB or PIC.

[0077] The corrected passing point calculation unit 52 outputs signals indicating the respective coordinates of the calculated corrected passing points PIB or PIC, the unloading point P2, and the returning point P3 to the EPC valve control unit 54. The EPC valve control unit 54 controls the EPC valve 28, based on the acquired signals indicating the respective coordinates of the corrected passing points PIB or PIC, the unloading point P2, and the returning point P3.

[0078] The EPC valve 28 is controlled by the EPC valve control unit 54, whereby each of the hydraulic actuators is controlled such that the center of the arm top pin 15 in the left-right direction moves from the returning point P3, passes through the corrected passing point PIB or PIC, and reaches the unloading point P2 in the automatic loading control (step S5: FIG. 7). As a result, the automatic loading control in which interference between the bucket 8 and the loading target 200 is prevented becomes available.Effects

[0079] Next, the effects of the present embodiment will be described.

[0080] In the present embodiment, as illustrated in FIG. 6, the corrected passing point PIB or PIC is calculated by adding the vertical offset h1+α or h2+α, derived from the shape data of the bucket 8 (work tool), to the height position HA of the passing point PIA. Then, the operation of the work implement 2 is controlled so as to pass through the corrected passing point PIB or PIC during revolution. Accordingly, interference between the bucket 8 and the loading target 200 can be prevented even in the automatic loading control.

[0081] In the present embodiment, as illustrated in FIG. 6, the corrected passing point PIB is calculated by adding the vertical offset h1+α based on the height dimension h1 of the bucket 8 in the loaded state, to the height position HA of the passing point PIA. Accordingly, the automatic loading control is executed based on the corrected passing point PIB, and thus interference between the bucket 8 and the loading target 200 can be prevented even when the bucket 8 is in the loaded posture 8B in the automatic loading control.

[0082] In the present embodiment, as illustrated in FIG. 6, the corrected passing point PIC is calculated by adding the vertical offset h2+α based on the maximum height dimension h2 of the bucket 8 in a side view, to the height position HA of the passing point PIA. Accordingly, the automatic loading control is executed based on the corrected passing point PIC, and thus interference between the bucket 8 and the loading target 200 can be prevented even when the bucket 8 is in any posture in the automatic loading control.

[0083] In the present embodiment, as illustrated in FIG. 5, the automatic control system includes the operation unit 25 that outputs an operation command for manually driving the actuator 29, and the instruction unit 24 that designates the passing point PIA when the operation command is output to operate the work implement 2. Accordingly, the operator can operate the work implement 2 and the revolving body 3 by manual driving to identify the passing point PIA.

[0084] It should be understood that the embodiment disclosed herein is illustrative in all respects and is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.REFERENCE SIGNS LIST1 Main body; 2 Work implement; 3 Revolving body; 4 Cab; 4S Operator seat; 5 Traveling body; 5Cr Crawler belt; 5M Traveling motor; 6 Boom; 7 Arm; 8 Bucket; 8T Blade tip; 9 Exterior cover; 10 Boom cylinder; 11 Arm cylinder; 12 Bucket cylinder; 13 Boom foot pin; 14 Boom top pin; 15 Arm top pin; 17 Bucket link; 20 Work implement posture sensor; 21 Position and orientation sensor; 21a, 21b Receiver; 22 Tilt sensor; 23 Detection sensor; 24 Instruction unit; 25 Operation unit; 26 Input device; 27 Hydraulic pump; 28 EPC valve; 29 Actuator; 50 Controller; 51 Instruction point identification unit; 51A Passing point identification unit; 51B Unloading point identification unit; 51C Returning point identification unit; 52 Corrected passing point calculation unit; 53 Storage unit; 54 EPC valve control unit; 100 Hydraulic excavator; 200 Loading target (dump truck); 200A vessel; P1A Passing point; PIC, PIB Corrected passing point; P2 Unloading point; P3 Returning point; RX Revolution axis; SE Side edge.

Claims

1. An automatic control system for a work machine, comprising:a revolving body configured to revolve;a work implement attached to the revolving body and having a work tool;a work implement posture sensor configured to detect a posture of the work implement; anda controller configured to:identify a passing point through which the work tool passes during revolution of the revolving body, based on a result of the detection by the work implement posture sensor;calculate a corrected passing point by adding a vertical offset, derived from shape data of the work tool, to the height position of the passing point; andperform control such that the work tool passes through the corrected passing point during the revolution.

2. The automatic control system for a work machine according to claim 1, wherein the controller is configured to calculate the corrected passing point by adding a vertical offset, based on a height dimension of the work tool, to the height position of the passing point.

3. The automatic control system for a work machine according to claim 1, wherein the controller is configured to calculate the corrected passing point by adding a vertical offset, based on a maximum height dimension of the work tool in a side view, to the height position of the passing point.

4. The automatic control system for a work machine according to claim 1, further comprising:an actuator configured to drive the work implement;an operation unit configured to output an operation command for manually driving the actuator; andan instruction unit configured to designate the passing point when the operation command is output to operate the work implement.

5. A control method for a work machine,the work machine comprising:a revolving body configured to revolve; anda work implement attached to the revolving body and having a work tool,the control method comprising:identifying a passing point through which the work tool passes during revolution of the revolving body, based on a detection result of a posture of the work implement;calculating a corrected passing point by adding a vertical offset, derived from shape data of the work tool, to the height position of the passing point; andperforming control such that the work tool passes through the corrected passing point during the revolution.

6. The control method for a work machine according to claim 5, wherein, in the identifying, the passing point is identified based on a detection result of a posture of the work implement when an operation signal based on a manual operation is input.

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