System and method for controlling work machine

Abstract

Provided is a system for controlling a work machine, the work machine including a vehicle body and a work implement. The work implement is attached to the vehicle body. The system comprises a controller. The controller acquires a design line extending on the terrain to be subjected to construction. The controller determines a line obtained by linearly extending the design line as a target line. The controller executes, while the work machine is traveling, travel alignment control for automatically steering the work machine so that a travel reference point included in the vehicle body is aligned with the target line.

Description

System and method for controlling a work machine

[0001] TECHNICAL FIELD The present disclosure relates to systems and methods for controlling a work machine.

[0002] Some work machines are equipped with a vehicle body and a working implement. The work implement includes, for example, a bucket and performs work such as excavation. Such work machines are sometimes used to dig a long linear trench. The operator of the work machine operates the work machine to form a trench by excavating the terrain along a design line that indicates the position where the trench will be formed. In this case, the operator moves the work machine so that the position of a predetermined reference point on the vehicle body is aligned with the design line. The operator excavates the terrain on the design line using the work implement. The operator then reverses the work machine along the design line. By repeating this process of excavating and reversing, a long linear trench is constructed on the terrain.

[0003] In the above work, it is necessary to align the position of the reference point of the vehicle body with the design line with high precision. As a technology for supporting such alignment, for example, Patent Document 1 discloses a display system that displays a screen showing the reference point of the vehicle body, the reference point of the work machine, and the design line on a display.

[0004] International Publication No. WO2017 / 010563

[0005] The above-described technology allows the operator to easily grasp the positional relationship between the vehicle body reference point and the design line from the screen displayed on the display. However, in order to align the position of the vehicle body reference point with the design line, the work machine needs to be precisely steered each time the work machine is driven, which places a heavy burden on the operator. An object of the present disclosure is to facilitate the operation of aligning the vehicle body in a work machine.

[0006] One aspect of the present disclosure is a system for controlling a work machine. The work machine includes a vehicle body and a work implement. The work implement is attached to the vehicle body. The system includes a controller. The controller acquires a design line extending on a terrain to be worked on. The controller determines a line that is a linear extension of the design line as a target line. The controller executes travel alignment control to automatically steer the work machine while the work machine is traveling so that a travel reference point included on the vehicle body is aligned with the target line.

[0007] Another aspect of the present disclosure is a method for controlling a work machine. The work machine includes a vehicle body and a work implement. The work implement is attached to the vehicle body. The method includes acquiring a design line extending on a terrain to be worked on, determining a target line that is a linear extension of the design line, and executing travel alignment control that automatically steers the work machine while the work machine is traveling so that a travel reference point included on the vehicle body is aligned with the target line.

[0008] According to the present disclosure, the working machine is automatically steered by the traveling alignment control so that the traveling reference point of the vehicle body is aligned with the target line, thereby facilitating the operation for aligning the vehicle body.

[0009] Furthermore, in the present disclosure, the work machine is automatically steered not along the design line but along a target line that is a linear extension of the design line. If the work machine is automatically steered along the design line, the work machine may deviate from the design line if the design line includes both straight and curved portions. For example, if the work machine is located at the front of the vehicle body, when the work machine moves in reverse and the travel reference point moves from the straight portion to the curved portion, the orientation of the vehicle body changes, and the orientation of the work machine also changes. This causes the work machine to deviate from the straight portion. However, in the present disclosure, the work machine is automatically steered not along the design line but along a target line that is a linear extension of the design line. This prevents the work machine from deviating from the design line.

[0010] FIG. 1 is a side view of a work machine. FIG. 2 is a block diagram showing the configuration of a work machine and its control system. FIG. 3 is a flowchart showing the processing of traveling alignment control. FIG. 4 is a diagram showing an example of a guide screen. FIG. 5 is an enlarged view of an icon showing the work machine displayed on the guide screen. FIG. 6 is a diagram showing an example of a guide screen in traveling alignment control. FIG. 7 is a diagram showing an example of a guide screen showing a control execution area. FIG. 8 is a diagram showing an example of a guide screen in a state where the traveling reference point matches the target line. FIG. 9 is a diagram showing an example of a guide screen while automatic steering is stopped. FIG. 10 is a flowchart showing the processing of turning alignment control. FIG. 11 is a diagram showing an example of a guide screen in turning alignment control. FIG. 12 is a diagram showing an example of a guide screen in a state where the working reference point matches the target line. FIG. 13 is a diagram showing an example of a guide screen showing a control stop area. FIG. 14 is a top view showing the operation of a work machine according to a comparative example.

[0011] A work machine according to an embodiment will now be described with reference to the drawings. Figure 1 is a side view of a work machine 1. In this embodiment, the work machine 1 is an excavator such as a hydraulic excavator or an electric excavator.

[0012] As shown in Figure 1, the work machine 1 includes a vehicle body 2 and a work implement 3. The vehicle body 2 includes a revolving unit 4 and a running unit 5. The work implement 3 is attached to the revolving unit 4. The revolving unit 4 is connected to the running unit 5 so that it can rotate. The revolving unit 4 can rotate around a rotation center C1. A cab 6 is disposed on the revolving unit 4. The running unit 5 includes tracks 7. Note that Figure 1 shows only one of the left and right tracks 7. The work machine 1 moves when the tracks 7 are driven.

[0013] The work implement 3 is attached to the rotating unit 4 so as to be movable up and down. The work implement 3 includes a boom 11, an arm 12, and a bucket 13. The boom 11 is rotatably attached to the rotating unit 4. The arm 12 is rotatably attached to the boom 11. The bucket 13 is rotatably attached to the arm 12.

[0014] The work implement 3 includes a boom cylinder 14, an arm cylinder 15, and a bucket cylinder 16. The boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16 are, for example, hydraulic cylinders. The boom cylinder 14 operates the boom 11. The arm cylinder 15 operates the arm 12. The bucket cylinder 16 operates the bucket 13.

[0015] Figure 2 is a block diagram showing the configuration of the work machine 1 and its control system. As shown in Figure 2, the work machine 1 includes a drive source 21, a hydraulic pump 22, a power transmission device 23, and a controller 24. The drive source 21 is controlled by a command signal from the controller 24. The drive source 21 is, for example, an internal combustion engine. Alternatively, the drive source 21 may include a drive source such as an electric motor or a hydrogen engine. The hydraulic pump 22 is driven by the drive source 21 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 22 is supplied to the boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16.

[0016] The work machine 1 includes a swing motor 25. The swing motor 25 is, for example, a hydraulic motor. The swing motor 25 is driven by hydraulic oil from the hydraulic pump 22. Alternatively, the swing motor 25 may be an electric motor. The swing motor 25 swings the swing body 4. Note that although one hydraulic pump is shown in FIG. 2, multiple hydraulic pumps may be provided.

[0017] The hydraulic pump 22 is a variable displacement pump. A pump control device 26 is connected to the hydraulic pump 22. The pump control device 26 controls the tilt angle of the hydraulic pump 22. The pump control device 26 includes, for example, a solenoid valve, and is controlled by a command signal from the controller 24. The controller 24 controls the displacement of the hydraulic pump 22 by controlling the pump control device 26.

[0018] The work machine 1 includes a control valve 27. The hydraulic pump 22, the cylinders 14-16, and the swing motor 25 are connected by a hydraulic circuit via the control valve 27. The control valve 27 is controlled by a command signal from the controller 24. The control valve 27 controls the flow rate of hydraulic oil supplied from the hydraulic pump 22 to the cylinders 14-16 and the swing motor 25. The controller 24 controls the operation of the work machine 3 by controlling the control valve 27. The controller 24 controls the swing of the swing body 4 by controlling the control valve 27. It should be noted that the cylinders 14-16 are not limited to hydraulic cylinders, and may be mechanical cylinders driven by an electric motor.

[0019] The power transmission device 23 transmits the driving force of the drive source 21 to the traveling body 5. The crawler 7 is driven by the driving force from the power transmission device 23 to travel the work machine 1. The power transmission device 23 may be, for example, a torque converter or a transmission having a plurality of speed change gears. Alternatively, the power transmission device 23 may be another type of transmission such as an HST (Hydro Static Transmission) or an HMT (Hydraulic Mechanical Transmission).

[0020] The controller 24 includes a processor 31 such as a CPU, and a storage device 32. The processor 31 performs processing for controlling the work machine 1. The storage device 32 includes memory such as RAM or ROM, and an auxiliary storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). The storage device 32 stores data and programs for controlling the work machine 1.

[0021] The control system includes an operation device 33, an input device 34, and a display 35. The operation device 33, the input device 34, and the display 35 are arranged in the cab 6. The operation device 33 can be operated by an operator. The operation device 33 includes a travel operation device 33A, a steering operation device 33B, a swing operation device 33C, and a work implement operation device 33D.

[0022] The travel operation device 33A can be operated by an operator to manually control the forward and reverse travel of the work machine 1. The travel operation device 33A includes, for example, a switch. However, the travel operation device 33A may include other members such as a lever. The travel operation device 33A can be operated from a neutral position N1 in a forward direction A1 and a reverse direction B1. The travel operation device 33A outputs an operation signal to the controller 24 in response to operation by the operator.

[0023] The steering operation device 33B can be operated by an operator to manually operate the steering of the work machine 1. The steering operation device 33B includes, for example, a switch. However, the steering operation device 33B may include other members such as a lever. The steering operation device 33B can be operated from the neutral position N2 in a right steering direction A2 and a left steering direction B2. The steering operation device 33B outputs an operation signal to the controller 24 in accordance with the operation by the operator.

[0024] The swing operation device 33C can be operated by an operator to manually operate the swing of the swing body 4. The swing operation device 33C includes, for example, a lever. However, the swing operation device 33C may include other members such as a switch. The swing operation device 33C can be operated from a neutral position N3 in a right swing direction A3 and a left swing direction B3. The swing operation device 33C outputs an operation signal to the controller 24 in accordance with the operation of the operator.

[0025] The work machine operating device 33D can be operated by an operator to manually operate the work machine 3. The work machine operating device 33D includes, for example, a lever. However, the work machine operating device 33D may include other components such as a switch. For example, the work machine operating device 33D can be operated in a raising direction A4 and a lowering direction B4 from a neutral position N4. The swing operating device 33C outputs an operating signal to the controller 24 in response to the operator's operation. Note that each of the operating devices 33A-33D may be configured using common components.

[0026] The controller 24 controls the drive source 21 and the power transmission device 23 to cause the work machine 1 to travel in response to operation of the travel operation device 33A by the operator. As a result, the work machine 1 moves forward or backward in response to operation of the travel operation device 33A. The controller 24 controls the drive source 21 and the power transmission device 23 to steer the work machine 1 to the left or right in response to operation of the steering operation device 33B by the operator. For example, the controller 24 steers the work machine 1 to the left or right by using the speed difference between the left and right tracks 7. As a result, the work machine 1 is steered to the left or right in response to operation of the travel operation device 33A.

[0027] The controller 24 controls the control valve 27 in response to the operation of the swing operation device 33C by the operator so as to swing the swing body 4 relative to the traveling body 5. As a result, the swing body 4 swings clockwise or counterclockwise in response to the operation of the swing operation device 33C. The controller 24 controls the control valve 27 in response to the operation of the work machine operation device 33D by the operator so as to operate the work machine 3. As a result, the work machine 3 moves up and down in response to the operation of the work machine operation device 33D.

[0028] The input device 34 can be operated by an operator. The input device 34 is a touch screen. However, the input device 34 may also include hardware keys. The operator operates the input device 34 to input various settings related to the work machine 1. The input device 34 outputs an input signal in response to an operation by the operator. The display 35 is, for example, an LCD, an OELD, or another type of display. The display 35 displays a screen in response to a display signal from the controller 24.

[0029] The control system includes a position sensor 36, an attitude sensor 37, and a work machine sensor 38. The position sensor 36 detects the position and orientation of the work machine 1. The position sensor 36 includes, for example, a sensor using a Global Navigation Satellite System (GNSS). In detail, the position sensor 36 detects the position and orientation of the revolving unit 4. The position sensor 36 outputs position data indicating the position and orientation of the revolving unit 4.

[0030] The attitude sensor 37 is attached to the revolving unit 4. The attitude sensor 37 detects the attitude of the revolving unit 4. The attitude of the revolving unit 4 includes, for example, a yaw angle, a pitch angle, and a roll angle of the revolving unit 4. The attitude sensor 37 is, for example, an IMU (Inertial Measurement Unit). The attitude sensor 37 outputs first attitude data indicating the attitude of the revolving unit 4.

[0031] The work implement sensor 38 detects the attitude of the work implement 3. The attitude of the work implement 3 includes a boom angle, an arm angle, and a bucket angle. The boom angle is the angle of the boom 11 relative to the revolving unit 4. The arm angle is the angle of the arm 12 relative to the boom 11. The bucket angle is the angle of the bucket 13 relative to the arm 12. The work implement sensor 38 outputs second attitude data indicating the boom angle, the arm angle, and the bucket angle. The work implement sensor 38 may, for example, detect the stroke length of each of the cylinders 14-16, and the controller 24 may calculate the boom angle, the arm angle, and the bucket angle from the stroke length of each of the cylinders 14-16. Alternatively, the work implement sensor 38 may be an angle sensor that directly detects the boom angle, the arm angle, and the bucket angle.

[0032] The controller 24 receives an operation signal from the operation device 33. The controller 24 receives an input signal from the input device 34. The controller 24 outputs a display signal to the display 35. The controller 24 receives position data from the position sensor 36. The controller 24 receives first attitude data from the attitude sensor 37. The controller 24 receives second attitude data from the work implement sensor 38.

[0033] The controller 24 calculates the position and orientation of the work machine 1 from the position data, first attitude data, and second attitude data. For example, the controller 24 calculates the position and orientation of the running body 5 and the position and orientation of the revolving body 4 based on the position data and the first attitude data. The controller 24 calculates the position and orientation of the work implement 3 based on the position data, first attitude data, and second attitude data. Note that the position and orientation of the work implement 3 may be detected directly by a position sensor attached to the work implement 3. The position of the work machine 1 is indicated by planar coordinates and altitude at the work site. The orientation of the work machine 1 is indicated by east-west, north-south azimuth coordinates.

[0034] Next, automatic control of the work machine 1 will be described. The controller 24 executes automatic control of the work machine 1 based on the position and orientation of the work machine 1. In this embodiment, the work machine 1 performs work to form a long trench at the work site by excavating the terrain along a design line extending on the terrain to be worked on. In this process, the automatic control assists manual operation by the operator. The design line is set, for example, based on a construction plan. Alternatively, the design line may be set based on a survey of the terrain at the work site.

[0035] The automatic controls include travel alignment control and swing alignment control. In travel alignment control, the controller 24 automatically controls the steering of the work machine 1 when the work machine 1 is traveling so that the travel direction of the work machine 1 aligns with the direction in which the design line extends. In swing alignment control, the controller 24 automatically stops the rotating body 4 when the work machine 1 is performing excavation work so that the bucket 13 aligns with the position of the design line. The operator can enable or disable each of the travel alignment control and swing alignment control by operating the input device 34.

[0036] 3 is a flowchart showing the process of the traveling alignment control. As shown in FIG. 3, in step S101, the controller 24 acquires a design line. The position of the design line is stored in the storage device 32. For example, the controller 24 acquires data indicating the position of the design line from an external computer. Alternatively, the controller 24 may acquire the position of the design line via the input device 34.

[0037] As shown in Figure 4, the controller 24 displays a guide screen 40 on the display 35, which shows the positional relationship between a design line 41 and the work machine 1. The guide screen 40 shows the work machine 1 and the design line 41 in a top view. The work machine 1 is shown by an icon having the shape of the work machine 1 in a top view. The controller 24 displays the work machine 1 and the design line 41 on the guide screen 40 in accordance with the actual position and orientation of the work machine 1.

[0038] The guide screen 40 also includes assist images 51-53. The assist images 51-53 indicate the position or orientation of a specific portion of the work machine 1. Fig. 5 is an enlarged view of the icon indicating the work machine 1 and the assist images 51-53. As shown in Fig. 5, the assist images include a work assist image 51, a driving assist image 52, and an orientation assist image 53.

[0039] The work assist image 51 indicates the position of a work reference point P1 included in the work implement 3. The work reference point P1 is, for example, the center in the left-right direction of the cutting edge of the bucket 13. Alternatively, the work reference point P1 may be the left end or right end of the cutting edge of the bucket 13. The work reference point P1 may be selectable from the left end, center, or right end of the bucket 13 using the input device 34. The work assist image 51 has a crosshair shape. The intersection of the crosshairs on the work assist image 51 indicates the position of the work reference point P1.

[0040] The driving assist image 52 indicates the positions of the turning center C1 and a driving reference point P2 included in the vehicle body 2. The driving assist image 52 has a shape that combines crosshairs and an arc. The intersection of the crosshairs on the driving assist image 52 indicates the position of the turning center C1. The driving reference point P2 is a position that is offset from the turning center C1 in the left-right direction of the traveling body 5. The vertex of the arc of the crosshairs on the driving assist image 52 indicates the driving reference point P2.

[0041] The traveling reference point P2 is indicated by the point of contact between the work machine plane PL1 and an arc centered at the turning center C1. The work machine plane PL1 is a plane that includes the trajectory of the work reference point P1 when the work machine 3 moves up and down. In a top view of the work machine 1, the work machine plane PL1 is indicated by a straight line that passes through the work reference point P1 and extends in the fore-and-aft direction of the work machine 1 when the work machine 3 is arranged along the fore-and-aft direction of the traveling body 5.

[0042] The orientation assist image 53 indicates the orientation of the traveling object 5. The orientation assist image 53 indicates the direction of the crawler 7. The orientation assist image 53 is shown in the shape of a triangle, for example.

[0043] In step S102, the controller 24 determines whether the traveling alignment control is enabled. For example, when the traveling alignment control is set to on and the operator touches the design line 41 on the guide screen 40, the controller 24 determines that the traveling alignment control is enabled. The traveling alignment control is turned on or off by, for example, the input device 34. If the traveling alignment control is enabled, the process proceeds to step S103.

[0044] In step S103, the controller 24 determines the target line 42. The controller 24 determines a line that is a linear extension of the design line 41 as the target line 42. As shown in Fig. 6 , the controller 24 displays the target line 42 on the guide screen 40. When the design line 41 includes a straight line portion 41A and a curved line portion 41B and the straight line portion 41A is touched, the controller 24 determines a line that is an extension of the straight line portion 41A as the target line 42.

[0045] As shown in Figure 6, the controller 24 displays the target line 42 on the guide screen 40 in a different format from the design line 41 shown in Figure 4. For example, the controller 24 displays the target line 42 on the guide screen 40 in a different color from the design line 41. The controller 24 also displays a control icon IC1 on the guide screen 40, indicating that travel alignment control has started. The operator operates the travel operation device 33A to move the work machine 1 forward or backward so that the work machine 1 approaches the target line 42.

[0046] In step S104, the controller 24 determines whether the driving reference point P2 is located within the control execution region 43. The control execution region 43 is a region extending from the target line 42 to a position that is separated by an allowable width in both directions to the left and right of the target line 42. The allowable width can be set, for example, by the input device 34. If the driving reference point P2 is located within the control execution region 43, the controller 24 displays the control execution region 43 on the guide screen 40, as shown in FIG. 7. The control execution region 43 is separated by two straight lines L1 and L2 that extend parallel to the target line 42 and are separated by two straight lines L1 and L2 from the target line 42 in both directions to the left and right.

[0047] If the traveling reference point P2 is located outside the control execution area 43, the controller 24 does not perform automatic steering, but steers the work machine 1 in accordance with manual operation by the steering operation device 33B. Also, as shown in Figure 6, if the traveling reference point P2 is located outside the control execution area 43, the controller 24 does not display the control execution area 43 on the guide screen 40.

[0048] If the traveling reference point P2 is located within the control execution area 43, the processing proceeds to step S105. In step S105, the controller 24 executes traveling alignment control. As shown in Figures 7 and 8, while the work machine 1 is traveling, the controller 24 automatically steers the work machine 1 so that the traveling reference point P2 is along the target line 42. In other words, the controller 24 automatically steers the work machine 1 so that the arc of the traveling assist image 52 is tangent to the target line 42 at the traveling reference point P2. As a result, the controller 24 travels the work machine 1 in accordance with manual operation by the traveling operation device 33A, and automatically steers the work machine 1 so that the traveling reference point P2 is along the target line 42.

[0049] As shown in Figure 8, when the driving reference point P2 coincides with the target line 42, the controller 24 displays the driving assist image 52 in a manner different from when the driving reference point P2 does not coincide with the target line 42.

[0050] Furthermore, even if the traveling reference point P2 is located within the control execution region 43, if a manual operation is performed using the steering operation device 33B, the controller 24 prioritizes the manual operation using the steering operation device 33B over the traveling alignment control. In other words, even if the traveling reference point P2 is located within the control execution region 43, if a manual operation is performed using the steering operation device 33B, the controller 24 stops the traveling alignment control and steers the work machine 1 in accordance with the manual operation using the steering operation device 33B.

[0051] 7 and 8, while travel alignment control is being executed, the controller 24 displays the control icon IC1 in a different manner than when travel alignment control is stopped. For example, while travel alignment control is being executed, the controller 24 displays the control icon IC1 in a different color than when travel alignment control is stopped. As shown in Fig. 9, even if the travel reference point P2 is located within the control execution area 43, while travel alignment control is stopped, the controller 24 does not display the control execution area 43 on the display 35. Note that even when the operator is not operating the travel operation device 33A and the work machine 1 is stopped from traveling, the controller 24 displays the control icon IC1 in the same manner as when travel alignment control is stopped.

[0052] When the driving operation by the driving operation device 33A ends, the controller 24 stops the driving alignment control. However, because the driving alignment control is still active, when the driving operation by the driving operation device 33A is resumed, the controller 24 continues to execute the driving alignment control.

[0053] Next, the turning alignment control will be described. Fig. 10 is a flowchart showing the processing of the turning alignment control. As shown in Fig. 10, in step S201, the controller 24 acquires the design line 41. The controller 24 acquires the design line 41 in the same manner as in the running alignment control described above.

[0054] In step S202, the controller 24 determines whether the swing alignment control is enabled. For example, when the swing alignment control is set to on and the operator touches the design line 41 on the guide screen 40, the controller 24 determines that the swing alignment control is enabled. The swing alignment control is turned on or off by, for example, the input device 34. If the swing alignment control is enabled, the process proceeds to step S203.

[0055] In step S203, the controller 24 determines the target line 42. The controller 24 determines the target line 42 in the same manner as in the processing of the traveling alignment control. FIG. 11 is a diagram showing the guide screen 40 during the turning alignment control. As in the traveling alignment control, the controller 24 displays the target line 42 on the guide screen 40 in a manner different from that of the design line 41. For example, the controller 24 displays the target line 42 on the guide screen 40 in a color different from that of the design line 41. In addition, the controller 24 displays a control icon IC2 on the guide screen 40, which indicates that the turning alignment control has started.

[0056] After the target line 42 is determined, the operator operates the swing operation device 33C to swing the swing unit 4. In FIG. 11 , the working reference point P1 is located at a position outside the target line 42, for example, at the soil unloading position. The operator operates the swing operation device 33C to swing the swing unit 4 so that the working reference point P1 approaches the target line 42.

[0057] In step S204, the controller 24 determines whether the rotation operation amount of the rotating unit 4 is greater than the target rotation speed. If the rotation speed corresponding to the operation of the rotation operation device 33C of the rotating unit 4 is greater than the target rotation speed, the controller 24 determines that the rotation operation amount of the rotating unit 4 is greater than the target rotation speed. If the rotation operation amount of the rotating unit 4 is greater than the target rotation speed, the processing proceeds to step S205.

[0058] In step S205, the controller 24 decelerates the rotating body 4. The controller 24 decelerates the rotating body 4 until the working reference point P1 reaches the target line 42, and automatically stops the rotation of the rotating body 4 when it reaches the target line 42. As a result, as shown in FIG. 12 , the rotating body 4 stops with the working reference point P1 aligned with the target line 42. In this state, the operator can excavate the terrain on the target line 42 by operating the work machine operation device 33D. Note that in step S204, if the rotation operation amount of the rotating body 4 is equal to or less than the target rotation speed, the rotating body 4 does not decelerate or automatically stop, but continues to rotate in response to the operation of the swing operation device 33C.

[0059] When the task reference point P1 is aligned with the target line 42, the controller 24 displays the task assist image 51 in a different manner than when the task reference point P1 is deviated from the target line 42. For example, when the task reference point P1 is aligned with the target line 42, the controller 24 displays the task assist image 51 in a different color than when the task reference point P1 is deviated from the target line 42.

[0060] Furthermore, while the revolving unit 4 is automatically stopped, the controller 24 displays the control icon IC2 in a different manner than when the revolving unit 4 is not automatically stopped. For example, while the revolving unit 4 is automatically stopped, the controller 24 displays the control icon IC2 in a different color than when the revolving unit 4 is not automatically stopped.

[0061] After the rotating unit 4 has automatically stopped, when the operator returns the swing operation device 33C to the neutral position, the controller 24 displays a control invalid area 44 on the guide screen 40, as shown in FIG. 13 . The control invalid area 44 is an area extending from the target line 42 to a position that is separated by an allowable width to the left and right of the target line 42. The allowable width can be set, for example, by the input device 34. The control invalid area 44 is separated from the target line 42 to the left and right, and is indicated by two straight lines L3 and L4 that extend in a direction parallel to the target line 42. Furthermore, after the operator returns the swing operation device 33C to the neutral position, the controller 24 swings the rotating unit 4 in accordance with the operation of the swing operation device 33C.

[0062] In step S206, the controller 24 determines whether the working reference point P1 is located within the control invalid area 44. If the working reference point P1 is located within the control invalid area 44, in step S207, the controller 24 disables the automatic stop of the rotating unit 4. That is, even if the operator manually rotates the rotating unit 4 after the automatic stop of the rotating unit 4 and the working reference point P1 reaches the target line 42, the controller 24 does not automatically stop the rotating unit 4 if the working reference point P1 is located within the control invalid area 44. This allows the operator to easily excavate the terrain near the target line 42 by manually rotating the working reference point P1 within the control invalid area 44.

[0063] When the operator manually rotates the rotating unit 4, causing the work reference point P1 to move outside the control invalid area 44, the controller 24 erases the control invalid area 44 from the guide screen 40, as shown in FIG. 11 . For example, after the operator excavates the terrain on the target line 42 with the work implement 3, the operator rotates the rotating unit 4 and dumps earth and sand from the bucket 13 to a position outside the target line 42. This erases the control invalid area 44 from the guide screen 40.

[0064] Furthermore, when the working reference point P1 moves out of the control invalid area 44, the controller 24 re-enables the automatic stopping of the rotating unit 4. As a result, as described above, if the rotation speed of the rotating unit 4 is slower than the rotation operation, the rotation of the rotating unit 4 is decelerated, and when the working reference point P1 reaches the target line 42, the controller 24 automatically stops the rotating unit 4. By repeating such operations of the work machine 1, a groove is formed in the terrain on the target line 42.

[0065] Next, the operator reverses the work machine 1. At this time, the work machine 1 is automatically steered by the above-mentioned traveling alignment control so that the traveling reference point P2 moves along the target line 42. Then, excavation and earth removal are repeated again by rotating the rotating body 4, thereby forming a trench in the terrain on the target line 42. By repeating such operations of the work machine 1, a long trench is formed in the terrain along the target line 42.

[0066] As with the traveling alignment control, the turning alignment control may also be terminated when a control termination operation is performed.

[0067] In the work machine 1 according to the present embodiment described above, the work machine 1 is automatically steered by the traveling alignment control so that the traveling reference point P2 of the vehicle body 2 is aligned with the target line 42. This makes it easier to perform operations for aligning the vehicle body 2.

[0068] Furthermore, the work machine 1 is automatically steered not along the design line 41, but along a target line 42 that is a linear extension of the design line 41. If the work machine 1 is automatically steered along the design line 41, the work implement 3 may deviate from the design line 41 if the design line 41 includes a straight portion 41A and a curved portion 41B as described above.

[0069] For example, Fig. 14 is a top view showing the operation of a work machine according to a comparative example. In the comparative example shown in Fig. 14, traveling alignment control is performed using the design line 41 itself as the target line. As shown in Fig. 14, when the work machine 1 moves backward and the traveling reference point P2 moves from the straight portion 41A to the curved portion 41B, the orientation of the vehicle body 2 changes, and the orientation of the work implement 3 also changes. As a result, the working reference point P1 of the work implement 3 deviates from the straight portion 41A. However, with the work machine 1 according to this embodiment, the work machine 1 is automatically steered so that it follows not the design line 41, but a target line 42 that is a linear extension of the design line 41. This prevents the work implement 3 from deviating from the design line 41.

[0070] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0071] The work machine 1 may be equipped with wheels instead of tracks 7. The work machine 1 may be remotely operable. The operation device 33, input device 34, and display 35 may be located outside the work machine 1. Part of the automatic control processing described above may be executed by a controller external to the work machine 1. The automatic control processing may be distributed and executed among multiple controllers.

[0072] The work performed by the work machine 1 under automatic control is not limited to the work of forming a trench, and may be other work. For example, automatic control may be applied to the work of filling a trench with earth and sand. The automatic control process is not limited to that of the above embodiment, and may be modified. For example, the start of travel alignment control or turning alignment control is not limited to touching the design line 41, and may be another operation. Turning alignment control may be omitted.

[0073] The guide screen 40 is not limited to that of the above embodiment and may be modified. For example, the task assist image 51 is not limited to crosshairs and may be other shapes such as dots. The driving assist image 52 is not limited to crosshairs and arcs and may be other shapes such as dots. The orientation assist image 53 is not limited to triangles and may be other shapes such as arrows. The "different aspects" of the display of the guide screen 40 described above are not limited to different colors and may be different shapes. The shape of the control invalid area 44 is not limited to that of the above embodiment and may be modified. For example, the control invalid area 44 may have a trapezoidal or fan-shaped shape.

[0074] (Supplementary Note 1) A system for controlling a work machine including a vehicle body and a work implement attached to the vehicle body, comprising a controller, wherein the controller acquires a design line extending on a terrain to be worked on, determines a line that is a linear extension of the design line as a target line, and executes driving alignment control to automatically steer the work machine while the work machine is traveling so that a driving reference point included on the vehicle body is aligned with the target line.

[0075] (Supplementary Note 2) The system according to Supplementary Note 1, further comprising a display, wherein the controller causes the display to display the work machine, the target line, and the traveling reference point.

[0076] (Supplementary Note 3) The system described in Supplementary Note 1 or Supplementary Note 1, further comprising a steering operation device operable by an operator to manually operate the steering of the work machine, wherein the controller steers the work machine in accordance with manual operation using the steering operation device when the driving reference point is located outside a predetermined area, and automatically steers the work machine when the driving reference point is located within the predetermined area.

[0077] (Supplementary Note 4) The system according to Supplementary Note 3, wherein, when the driving reference point is located within a predetermined area and manual operation is performed using the steering operation device, the controller prioritizes the manual operation using the steering operation device.

[0078] (Supplementary Note 5) The system described in Supplementary Note 3 or Supplementary Note 4 further comprises a travel operation device operable by an operator to manually operate the forward and / or reverse travel of the work machine, and when the travel reference point is located within a predetermined area, the controller causes the work machine to travel in accordance with manual operation using the travel operation device, and automatically steers the work machine so that the travel reference point is aligned with the target line.

[0079] (Supplementary Note 6) The system according to any one of Supplementary Notes 3 to 5, further comprising a display, wherein the controller causes the display to display the work machine, the target line, the traveling reference point, and the predetermined area. (Supplementary Note 7) The system according to any one of Supplementary Notes 3 to 6, wherein the predetermined area is a range up to a position away from the target line by an allowable width.

[0080] (Supplementary Note 8) The system described in any of Supplementary Notes 1 to 7, wherein the vehicle body includes a rotating body that can rotate around a rotation center, the driving reference point is, in a top view of the work machine, a point of contact between a work machine plane and an arc centered on the rotation center, the work machine plane passes through a work reference point included in the work machine and extends in the fore-and-aft direction of the work machine when the work machine is arranged along the fore-and-aft direction of the work machine, in a top view of the work machine, and the controller, in the driving alignment control, automatically steers the work machine so that the arc is tangent to the target line at the driving reference point.

[0081] (Supplementary Note 9) A method for controlling a work machine including a vehicle body and a work implement attached to the vehicle body, the method comprising: obtaining a design line extending on a terrain to be worked on; determining a line that is a linear extension of the design line as a target line; and executing driving alignment control to automatically steer the work machine while the work machine is traveling so that a driving reference point included in the vehicle body is aligned with the target line.

[0082] (Supplementary Note 10) The method according to Supplementary Note 9, further comprising displaying the work machine, the target line, and the traveling reference point on a display.

[0083] (Supplementary Note 11) A method according to Supplementary Note 9 or Supplementary Note 10, comprising: receiving an operation signal from a steering operation device operable by an operator to manually operate the steering of the work machine; steering the work machine in accordance with manual operation by the steering operation device when the traveling reference point is located outside a predetermined area; and automatically steering the work machine when the traveling reference point is located within a predetermined area.

[0084] (Supplementary Note 12) The method according to Supplementary Note 11, further comprising, when the driving reference point is located within a predetermined area and manual operation is performed using the steering operation device, prioritizing the manual operation using the steering operation device.

[0085] (Supplementary Note 13) A method according to Supplementary Note 11 or Supplementary Note 12, comprising: receiving an operation signal from a travel operation device operable by an operator to manually operate forward and / or reverse travel of the work machine; and when the travel reference point is located within a predetermined area, traveling the work machine in accordance with manual operation by the travel operation device, and automatically steering the work machine so that the travel reference point is along the target line.

[0086] (Supplementary Note 14) The method according to any one of Supplementary Note 11 to Supplementary Note 13, further comprising displaying the work machine, the target line, the traveling reference point, and the predetermined area on a display.

[0087] (Supplementary Note 15) The system according to any one of Supplementary Note 11 to Supplementary Note 14, wherein the predetermined area is a range up to a position separated from the target line by an allowable width.

[0088] (Supplementary Note 16) The method according to any one of Supplementary Notes 9 to 15, wherein the vehicle body includes a rotating body that can rotate around a rotation center, the traveling reference point is, in a top view of the work machine, a point of contact between a work machine plane and an arc centered on the rotation center, the work machine plane passes through a work reference point included in the work machine and extends in the fore-and-aft direction of the work machine when the work machine is arranged along the fore-and-aft direction of the work machine, in a top view of the work machine, and the traveling alignment control comprises automatically steering the work machine so that the arc becomes tangent to the target line at the traveling reference point.

[0089] To facilitate an operation for aligning a body of a work machine.

[0090] 1: Work machine 3: Work implement 4: Swing body 24: Controller 33A: Travel operation device 33B: Steering operation device 35: Display 41: Design line 42: Target line C1: Swing center P2: Travel reference point PL1: Work implement plane

Claims

1. A system for controlling a work machine including a vehicle body and a work implement attached to the vehicle body, comprising a controller, wherein the controller obtains a design line extending on a terrain to be worked on, determines a target line as a linear extension of the design line, and executes driving alignment control to automatically steer the work machine while the work machine is traveling so that a driving reference point included on the vehicle body is aligned with the target line.

2. The system according to claim 1, further comprising a display, wherein said controller causes said work machine, said target line, and said traveling reference point to be displayed on said display.

3. The system described in claim 1, further comprising a steering operation device that can be operated by an operator to manually operate the steering of the work machine, wherein the controller steers the work machine in response to manual operation by the steering operation device when the driving reference point is located outside a predetermined area, and automatically steers the work machine when the driving reference point is located within the predetermined area.

4. The system according to claim 3, wherein, when the driving reference point is located within a predetermined area and manual operation is performed using the steering operation device, the controller prioritizes the manual operation using the steering operation device.

5. The system according to claim 3, further comprising a travel operation device operable by an operator to manually operate the forward and / or reverse travel of the work machine, wherein when the travel reference point is located within a specified area, the controller travels the work machine in response to manual operation using the travel operation device, and automatically steers the work machine so that the travel reference point is aligned with the target line.

6. The system according to claim 3, further comprising a display, wherein the controller causes the work machine, the target line, the traveling reference point, and the predetermined area to be displayed on the display.

7. The system according to claim 3, wherein the predetermined area is a range up to a position away from the target line by a tolerance width.

8. The system described in claim 1, wherein the vehicle body includes a rotating body capable of rotating around a rotation center, the driving reference point is, in a top view of the work machine, a tangent point between a work machine plane and an arc centered on the rotation center, the work machine plane passes through a work reference point included in the work machine and extends in the fore-and-aft direction of the work machine with the work machine arranged along the fore-and-aft direction of the work machine in a top view of the work machine, and the controller, in the driving alignment control, automatically steers the work machine so that the arc is tangent to the target line at the driving reference point.

9. A method for controlling a work machine including a vehicle body and a work implement attached to the vehicle body, comprising: acquiring a design line extending on a terrain to be worked on; determining a target line as a linear extension of the design line; and executing driving alignment control to automatically steer the work machine while the work machine is traveling so that a driving reference point included on the vehicle body is aligned with the target line.

10. The method according to claim 9, further comprising displaying the work machine, the target line, and the driving reference point on a display.

11. A method according to claim 9, comprising: receiving an operation signal from a steering operation device operable by an operator to manually operate the steering of the work machine; steering the work machine in response to manual operation by the steering operation device when the driving reference point is located outside a predetermined area; and automatically steering the work machine when the driving reference point is located within a predetermined area.

12. The method according to claim 11, further comprising, when the driving reference point is located within a predetermined area and manual operation is performed using the steering operation device, giving priority to manual operation using the steering operation device.

13. The method according to claim 11, comprising: receiving an operation signal from a travel operation device operable by an operator to manually operate the forward and / or reverse travel of the work machine, and when the travel reference point is located within a predetermined area, traveling the work machine in response to manual operation by the travel operation device, and automatically steering the work machine so that the travel reference point is along the target line.

14. The method according to claim 11, further comprising displaying the work machine, the target line, the traveling reference point, and the predetermined area on a display.

15. The system according to claim 11, wherein the predetermined area is a range up to a position away from the target line by a tolerance width.

16. The method according to claim 9, wherein the vehicle body includes a rotating body capable of rotating around a rotating center, the driving reference point is, in a top view of the work machine, a tangent point between a work machine plane and an arc centered on the rotating center, the work machine plane passes through a work reference point included in the work machine and extends in the fore-and-aft direction of the work machine when the work machine is arranged along the fore-and-aft direction of the work machine in a top view of the work machine, and the driving alignment control includes automatically steering the work machine so that the arc is tangent to the target line at the driving reference point.

Images