A work machine and a method for controlling a work machine.

Abstract

To provide a working machine capable of reducing slip generated while minimizing the decline in work efficiency.SOLUTION: A blade is supported rotatably on a pitch axis with respect to the car body. The pitch actuator drives the blade to perform a pitch motion on the pitch axis. The controller determines whether or not any slip is generated in the running gear. When determining that a slip is generated, the controller controls the blade to perform a pitch motion in the backward direction.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a work machine and a method for controlling a work machine. [Background technology]

[0002] Some construction machines are equipped with a blade and use the blade to perform work such as excavation. For example, the construction machine of Patent Document 1 performs excavation work by having a controller move the blade according to a design surface. The controller also determines whether a slip has occurred in the travel gear of the construction machine. When the controller determines that a slip has occurred, it raises the design surface. The controller raises the blade according to the design surface. This reduces the load on the blade, allowing the construction machine to escape from the slip. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-197425 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a slip occurs during excavation work, the above-mentioned work machine raises the blade by performing a lifting operation. This allows the work machine to escape from the slip, but reduces the amount of soil excavated by the blade. In that case, the excavation work efficiency decreases. An object of the present invention is to prevent the occurrence of slips in the work machine and to prevent a decrease in work efficiency. [Means for solving the problem]

[0005] A work machine according to one aspect of the present invention includes a vehicle body, a blade, a pitch actuator, and a controller. The vehicle body includes a traveling device. The blade is supported on the vehicle body so as to be rotatable about a pitch axis. The pitch actuator pitches the blade about the pitch axis. The controller determines whether slippage is occurring in the traveling device while the blade is working. When the controller determines that slippage is occurring, it pitches the blade in a rearward tilt direction.

[0006] A method according to another aspect of the present invention is a method for controlling a work machine. The work machine includes a vehicle body, a blade, and a pitch actuator. The vehicle body includes a traveling device. The blade is supported on the vehicle body so as to be rotatable about a pitch axis. The pitch actuator pitches the blade about the pitch axis. The method according to this aspect includes determining whether slippage is occurring in the traveling device while the blade is working, and pitching the blade in a rearward tilt direction when it is determined that slippage is occurring. Effect of the Invention

[0007] According to the present invention, when it is determined that a slip has occurred, the blade pitches in a rearward direction. This reduces the resistance to the blade, allowing the work machine to escape from the slip. In addition, because the work machine is allowed to escape from the slip by pitching rather than by lifting the blade, the lifting of the blade is suppressed. This prevents a decrease in work efficiency. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing a work machine according to an embodiment. [Diagram 2] 2 is a block diagram showing the configuration of a drive system and a control system of the work machine. FIG. [Diagram 3] FIG. 13 is a diagram showing a lifting operation of the blade. [Figure 4] FIG. 4 illustrates the pitch movement of the blade. [Diagram 5] 3 is a flowchart showing automatic control of the work machine according to the first embodiment. [Figure 6] FIG. 2 is a diagram showing an example of a current terrain and a target terrain. [Figure 7] 5 is a flowchart showing a control process for suppressing the occurrence of slippage. [Figure 8] FIG. 13 is a diagram showing the pitch movement of the blade when slipping occurs. [Figure 9] FIG. 13 illustrates the lift motion of the blade when the blade has not yet come out of slip after pitch motion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a work machine according to an embodiment will be described with reference to the drawings. Fig. 1 is a side view showing a work machine 1 according to an embodiment. The work machine 1 according to this embodiment is a bulldozer. The work machine 1 includes a vehicle body 11 and a work implement 12.

[0010] The vehicle body 11 includes a cab 13, an engine compartment 14, and a traveling device 15. A driver's seat (not shown) is disposed in the cab 13. The engine compartment 14 is disposed in front of the cab 13. The traveling device 15 is provided on the lower part of the vehicle body 11. The traveling device 15 includes a pair of left and right tracks 16. Note that only the left track 16 is shown in FIG. 1. The work machine 1 travels as the tracks 16 rotate.

[0011] The work machine 12 is attached to the vehicle body 11. The work machine 12 has a lift frame 17, a blade 18, a lift actuator 19, and a pitch actuator 20. The lift frame 17 is supported on the vehicle body 11 so as to be rotatable about a lift axis X1. The lift axis X1 extends in the lateral direction of the vehicle body 11. The lift frame 17 rotates about the lift axis X1 to perform a lift operation up and down. The lift frame 17 may be attached to the traveling device 15. The lift frame 17 may be disposed inside the traveling device 15, or outside the traveling device 15.

[0012] The blade 18 is disposed in front of the vehicle body 11. The blade 18 is supported to be rotatable about a pitch axis X2 relative to the lift frame 17. The pitch axis X2 extends in the lateral direction of the vehicle body 11. The blade 18 pitches back and forth by rotating about the pitch axis X2. The blade 18 moves up and down in association with the up and down movement of the lift frame 17.

[0013] The lift actuator 19 is connected to the vehicle body 11 and the lift frame 17. The lift actuator 19 is a hydraulic cylinder. When the lift actuator 19 expands and contracts, the lift frame 17 is lifted up and down. When the lift actuator 19 contracts, the blade 18 rises. When the lift actuator 19 expands, the blade 18 descends. The lift actuator 19 may be attached to the blade 18.

[0014] The pitch actuator 20 is connected to the lift frame 17 and the blade 18. The pitch actuator 20 is a hydraulic cylinder. The pitch actuator 20 extends and retracts, causing the blade 18 to pitch forward and backward. The blade 18 pitches about the pitch axis X2, causing a part of the blade 18, for example the upper end, to move forward and backward. The blade 18 tilts forward when the pitch actuator 20 extends. The blade 18 tilts backward when the pitch actuator 20 contracts.

[0015] Fig. 2 is a block diagram showing the configuration of the drive system 2 and control system 3 of the work machine 1. As shown in Fig. 2, the drive system 2 includes an engine 22, a hydraulic pump 23, and a power transmission device 24. The hydraulic pump 23 is driven by the engine 22 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 23 is supplied to the lift actuator 19 and the pitch actuator 20. Note that, although one hydraulic pump is shown in Fig. 2, multiple hydraulic pumps may be provided.

[0016] The power transmission device 24 transmits the driving force of the engine 22 to the traveling device 15. The power transmission device 24 may be, for example, a hydrostatic transmission (HST). Alternatively, the power transmission device 24 may be, for example, a torque converter or a transmission having a plurality of speed change gears.

[0017] The control system 3 includes a controller 26 and a control valve 27. The controller 26 is programmed to control the work machine 1 based on the acquired data. The controller 26 includes a memory device 28 and a processor 29. The processor 29 includes, for example, a CPU. The memory device 28 includes, for example, a memory and an auxiliary memory device. The memory device 28 may be, for example, a RAM or a ROM. The memory device 28 may be, for example, a semiconductor memory or a hard disk. The memory device 28 is an example of a non-transitory computer-readable recording medium. The memory device 28 stores computer instructions that are executable by the processor 29 and for controlling the work machine 1.

[0018] The control valve 27 is a proportional control valve, and is controlled by a command signal from the controller 26. The control valve 27 is disposed between the hydraulic actuators, such as the lift actuator 19 and the pitch actuator 20, and the hydraulic pump 23. The control valve 27 controls the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the lift actuator 19. The control valve 27 controls the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the pitch actuator 20. The control valve 27 may be a pressure proportional control valve. Alternatively, the control valve 27 may be an electromagnetic proportional control valve.

[0019] The control system 3 includes an operation device 31 and an input device 32. The operation device 31 includes, for example, a lever. Alternatively, the operation device 31 may include a pedal or a switch. An operator can manually operate the traveling of the work machine 1 and the operation of the work implement 12 using the operation device 31. The operation device 31 outputs an operation signal that indicates the operation of the operation device 31. The controller 26 receives the operation signal from the operation device 31.

[0020] The operating device 31 is capable of operating the lift operation of the blade 18. In particular, the operating device 31 is capable of operating the raising and lowering operations of the blade 18. When the operator performs a raising operation on the operating device 31, the controller 26 controls the lift actuator 19 so that the blade 18 rises. When the operator performs a lowering operation on the operating device 31, the controller 26 controls the lift actuator 19 so that the blade 18 descends.

[0021] Fig. 3 is a schematic diagram showing the lifting operation of the work machine 1. In Fig. 3, P0 indicates the current position of the cutting edge of the blade 18. P1 indicates the highest position of the cutting edge of the blade 18. P2 indicates the lowest position of the cutting edge of the blade 18. The work machine 1 can perform a lifting operation of the blade 18 between the highest position P1 and the lowest position P2.

[0022] The operating device 31 is capable of controlling the pitch movement of the blade 18. In particular, the operating device 31 is capable of tilting the blade 18 forward and backward. When the operator tilts the operating device 31 forward, the controller 26 controls the pitch actuator 20 so that the blade 18 tilts forward. When the operator tilts the operating device 31 backward, the controller 26 controls the pitch actuator 20 so that the blade 18 tilts backward.

[0023] 4A to 4C are diagrams showing the pitch angle of the blade 18. As shown in FIG. 4A to FIG. 4C, the pitch angle θ0-θ2 of the blade 18 is the angle between the cutting edge of the blade 18 and the ground contact surface G1 of the crawler belt 16. FIG. 4B shows the pitch angle θ0 of the blade 18 in a standard state (hereinafter referred to as the "standard pitch angle"). FIG. 4A shows the pitch angle θ1 of the blade 18 tilted further forward than the standard state. FIG. 4C shows the pitch angle θ2 of the blade 18 tilted further backward than the standard state. The more the blade 18 tilts forward, the larger the pitch angle. The more the blade 18 tilts backward, the smaller the pitch angle. That is, θ1>θ0>θ2.

[0024] The operating device 31 may be a hydraulic pilot type device. For example, the operating device 31 may output pilot oil pressure according to the operation of the operating device 31. The lift actuator 19 or the pitch actuator 20 may be controlled by controlling the control valve 27 by the pilot oil pressure from the operating device 31. The controller 26 may receive a signal indicating the pilot oil pressure as an operation signal.

[0025] The input device 32 includes, for example, a touch panel. However, the input device 32 may include other devices such as a switch. An operator can use the input device 32 to set a control mode for the pitch angle of the blades 18 by the controller 26. The control modes include a manual mode and an automatic control. In the manual mode, the operator can manually change the pitch angle of the blades 18 using the operation device 31. The automatic control of the pitch angle will be described in detail later.

[0026] As shown in FIG. 2, the control system 3 is equipped with a sensor 33 that detects the current position of the cutting edge of the blade 18 (hereinafter referred to as "cutting edge position P0"). The sensor 33 includes a vehicle body sensor 34, a frame sensor 35, a blade sensor 36, and a position sensor 37. The vehicle body sensor 34 is attached to the vehicle body 11. The vehicle body sensor 34 detects the attitude of the vehicle body 11. The frame sensor 35 is attached to the lift frame 17. The frame sensor 35 detects the attitude of the lift frame 17. The blade sensor 36 is attached to the blade 18. The blade sensor 36 detects the attitude of the blade 18. The position sensor 37 detects the current position of the vehicle body 11.

[0027] The vehicle body sensor 34, the frame sensor 35, and the blade sensor 36 are each an IMU (Inertial Measurement Unit). However, the frame sensor 35 and the blade sensor 36 are not limited to an IMU, and may be other sensors such as an angle sensor or a cylinder stroke sensor.

[0028] The vehicle body sensor 34 detects the front-to-rear angle of the vehicle body 11 with respect to the horizontal (vehicle body pitch angle). The frame sensor 35 detects the rotation angle of the lift frame 17. The blade sensor 36 detects the pitch angle of the blade 18. The vehicle body sensor 34, the frame sensor 35, and the blade sensor 36 each output a detection signal indicating the detected angle.

[0029] The position sensor 37 is, for example, a position sensor of a Global Navigation Satellite System (GNSS) such as a Global Positioning System (GPS). The position sensor 37 includes, for example, a GNSS receiver and an antenna. The position sensor 37 detects the current position of the position sensor 37. The position sensor 37 is arranged on the vehicle body 11. Therefore, the position sensor 37 detects the current position of the vehicle body 11. The current position of the vehicle body 11 is indicated in global coordinates based on the earth. However, the current position of the vehicle body 11 may also be indicated in local coordinates based on the work site where the work machine 1 performs work. The controller 26 acquires a detection signal indicating the current position of the vehicle body 11 from the position sensor 37.

[0030] The controller 26 receives detection signals from the vehicle body sensor 34, the frame sensor 35, the blade sensor 36, and the position sensor 37. The controller 26 stores machine dimension data indicating the dimensions and positional relationship between the vehicle body 11, the lift frame 17, and the blade 18. The controller 26 calculates the cutting edge position P0 of the blade 18 based on the angles detected by the vehicle body sensor 34, the frame sensor 35, and the blade sensor 36, the current position of the vehicle body 11 detected by the position sensor 37, and the machine dimension data.

[0031] The work machine 1 is equipped with a speed sensor 38. The speed sensor 38 detects the operating speed of the traveling device 15. The speed sensor 38 outputs a detection signal indicating the operating speed of the traveling device 15. The controller 26 acquires the detection signal indicating the operating speed of the traveling device 15 from the speed sensor 38. For example, the speed sensor 38 detects the rotational speed of the output shaft of the power transmission device 24. The controller 26 calculates the operating speed of the crawler 16 from the rotational speed of the output shaft of the power transmission device 24. Alternatively, the speed sensor 38 may detect the rotational speed of another rotating element of the power transmission device 24. Alternatively, the speed sensor 38 may detect the rotational speed of a rotating element of the traveling device 15, such as a sprocket. Alternatively, the speed sensor 38 may detect the engine rotational speed.

[0032] The controller 26 automatically controls the work machine 1. The following describes the automatic control of the work machine 1 executed by the controller 26. Figure 5 is a flowchart showing the automatic control process.

[0033] 5, in step S101, the controller 26 acquires the current position of the work machine 1. Here, the controller 26 acquires the cutting edge position P0 of the blade 18 described above as the current position of the work machine 1.

[0034] In step S102, the controller 26 acquires current terrain data. The current terrain data indicates the current terrain 50 of the work target. Fig. 6 is a diagram showing an example of the current terrain 50. The current terrain data includes coordinates and altitudes of multiple points on the current terrain 50 located in the traveling direction of the work machine 1. The controller 26 may acquire the current terrain data from an external computer. The controller 26 may acquire updated current terrain data based on the trajectory of the bottom surface of the track 16.

[0035] In step S103, the controller 26 acquires target terrain data. The target terrain data indicates the target terrain 60 relative to the current terrain 50. The target terrain data includes coordinates and altitudes of a plurality of points on the target terrain 60 located in the traveling direction of the work machine 1. As shown in Fig. 6, at least a portion of the target terrain 60 is displaced in the vertical direction relative to the current terrain 50. At least a portion of the target terrain 60 is located below the current terrain 50.

[0036] The controller 26 may determine the target terrain 60 based on the current terrain 50. For example, the controller 26 may determine the target terrain 60 by displacing the current terrain 50 downward. The controller 26 may determine a trajectory extending at a predetermined angle from a predetermined start position of the work as the target terrain 60. The controller 26 may determine the target terrain 60 based on the capacity or load of the blade 18. The controller 26 may determine the target terrain 60 based on the volume of soil held by the blade 18. Alternatively, the controller 26 may obtain target terrain data from an external computer.

[0037] In step S104, the controller 26 controls the work machine 12 in accordance with the target terrain 60. The controller 26 controls the lift actuator 19 so that the cutting edge of the blade 18 moves in accordance with the target terrain 60. As a result, the blade 18 is lifted up and down so that the cutting edge of the blade 18 moves along the target terrain 60 while the work machine 1 moves forward. As a result, the current terrain 50 is excavated by the blade 18. Note that the forward movement of the work machine 1 may be manually performed by the operator operating the operation device 31. Alternatively, the forward movement of the work machine 1 may be performed by automatic control by the controller 26.

[0038] In the work machine 1 according to this embodiment, the controller 26 monitors the occurrence of slippage of the traveling gear 15 while automatically controlling the height of the blade 18 in accordance with the target terrain 60. When slippage occurs, the controller 26 executes automatic control of the pitch angle of the blade 18 to suppress the slippage. Figure 7 is a flowchart showing the control process for suppressing slippage.

[0039] As shown in FIG. 7, in step S201, the controller 26 performs a first slip determination. In the first slip determination, the controller 26 determines that slippage of the crawler 16 is occurring when a first slip condition is satisfied. The first slip condition is that the slip ratio is smaller than a first threshold value. The slip ratio is the ratio of the actual vehicle speed to the theoretical vehicle speed of the vehicle body 11. The controller 26 calculates the theoretical vehicle speed of the vehicle body 11 based on the operating speed of the traveling device 15. The controller 26 calculates the actual vehicle speed of the vehicle body 11 based on the position of the vehicle body 11. That is, the first slip condition is expressed by the following formula (1). Rs=Va / Vt <Th1 Rs is the slip ratio. Va is the actual vehicle speed. Vt is the theoretical vehicle speed. Th1 is the first threshold value.

[0040] The first slip condition may include a condition in which the theoretical vehicle speed is not increasing. When the controller 26 determines in step S201 that slippage is occurring, the process proceeds to step S202.

[0041] In step S202, the controller 26 pitches the blade 18 in a rearward direction as shown in Fig. 8. For example, the controller 26 reduces the pitch angle of the blade 18 by a predetermined angle. The predetermined angle may be a constant value. Alternatively, the predetermined angle may be an angle according to a parameter such as a slip ratio or a load received by the blade 18.

[0042] In step S203, the controller 26 determines whether the traveling apparatus 15 has escaped from a slip. The controller 26 determines that the traveling apparatus 15 has escaped from a slip when a first slip escaping condition is satisfied. The first slip escaping condition is that the slip ratio is equal to or greater than a first threshold value. The controller 26 determines that the traveling apparatus 15 has escaped from a slip when the first slip escaping condition is satisfied.

[0043] When the controller 26 determines in step S203 that the traveling gear 15 has escaped from the slip, the controller 26 returns the pitch angle to the standard state in step S208, and then continues to control the blade 18 to follow the above-mentioned target terrain 60. When the controller 26 determines in step S203 that the traveling gear 15 has not escaped from the slip, the process proceeds to step S204.

[0044] In step S204, the controller 26 performs a second slip determination. In the second slip determination, the controller 26 determines whether or not slippage of the traveling device 15 occurs when a second slip condition is satisfied. The second slip condition is that the theoretical vehicle speed is greater than a second threshold value. When the controller 26 determines that slippage occurs, the process proceeds to step S205.

[0045] In step S205, the controller 26 raises the target terrain 60 as shown in FIG. 9. This causes the controller 26 to raise the blade 18. The controller 26 may raise the blade 18 while continuing the pitch motion of the blade 18. In step S206, the controller 26 determines whether the traveling device 15 has escaped from the slip. Here, the controller 26 determines that the traveling device 15 has escaped from the slip when a second slip escape condition is satisfied. The second slip escape condition is that the theoretical vehicle speed is equal to or less than a second threshold value. When the controller 26 determines in step S206 that the traveling device 15 has not escaped from the slip, the process returns to step S205. Therefore, the controller 26 continues to raise the target terrain 60.

[0046] When the controller 26 determines in step S206 that the traveling device 15 has escaped from the slip, the process proceeds to step S207. In step S207, the controller 26 resets the target terrain 60. The controller 26 resets the target terrain 60' when it is determined that the traveling device 15 has escaped from the slip as a new target terrain 60. Then, the controller 26 continues to control the blade 18 according to the reset target terrain 60. Furthermore, in step S208, the controller 26 returns the pitch angle to the standard state.

[0047] In the work machine 1 according to the present embodiment described above, when it is determined that a slip has occurred, the blade 18 pitches in a rearward direction. This reduces the excavation resistance to the blade 18, allowing the traveling gear 15 to escape from the slip. In addition, because the traveling gear 15 is escaped from the slip by pitching rather than lifting the blade 18, the lifting of the blade 18 is suppressed. This suppresses a decrease in work efficiency.

[0048] 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.

[0049] The work machine 1 is not limited to a bulldozer, but may be another vehicle such as a wheel loader or a motor grader. The controller 26 may have a plurality of controllers separate from each other. Some of the plurality of controllers may be disposed outside the work machine 1. That is, the work machine 1 may be remotely controllable. The processing by the controller 26 is not limited to that in the above embodiment, and may be modified. Some of the automatic control processing described above may be omitted. Alternatively, some of the processing described above may be modified.

[0050] The lift actuator 19 and the pitch actuator 20 are not limited to hydraulic cylinders. The lift actuator 19 and the pitch actuator 20 may be other actuators such as electric motors. The position sensor 37 is not limited to being disposed in the vehicle body 11, and may be disposed in other parts of the work machine 1. For example, the position sensor 37 may be disposed in the blade 18.

[0051] The control process for suppressing slippage is not limited to the above process and may be modified. For example, the process for determining the occurrence of a slippage and the process for determining whether the slippage has been overcome are not limited to the above process and may be modified. When it is determined that a slippage is occurring, the controller 26 may directly raise the blade 18 without depending on the rise of the target terrain 60.

[0052] The theoretical vehicle speed may be calculated from the change per unit time in the position of the vehicle body 11 acquired by the position sensor 37. Alternatively, the theoretical vehicle speed may be calculated from an integrated value of the acceleration of the vehicle body 11 acquired by the vehicle body sensor 34. Alternatively, the theoretical vehicle speed may be calculated from the change per unit time in the position of an external object acquired from the vehicle body 11 by a positioning means such as a radar. [Industrial Applicability]

[0053] According to the present invention, it is possible to suppress the occurrence of slippage in a work machine and to suppress a decrease in work efficiency. [Explanation of symbols]

[0054] 11 Body 17 Lift frame 18 Blades 19 Lift actuator 20 Pitch Actuator 26 Controller 37 Position Sensor 38 Speed ​​Sensor 50 Current Topography 60 Target terrain

Claims

1. A vehicle body including a running gear; A blade supported rotatably about a pitch axis relative to the vehicle body; a pitch actuator that pitches the blade about the pitch axis; a controller that determines whether a first slip has occurred in the traveling device while working with the blade based on a first slip condition, and when it is determined that the first slip has occurred, pitches the blade in a rearward direction, and determines whether the traveling device has escaped from the first slip, and when it is determined that the traveling device has not escaped from the first slip, determines whether a second slip has occurred in the traveling device while working with the blade based on a second slip condition different from the first slip condition, and when it is determined that the second slip has occurred, raises the blade; A work machine comprising:

2. a lift frame supported rotatably about a lift shaft relative to the vehicle body; a lift actuator that lifts the lift frame up and down around the lift shaft; Equipped with The blade is supported on the vehicle body via the lift frame, The controller: Obtain current terrain data that indicates the current terrain that is the subject of the work; acquiring target terrain data indicating a target terrain at least a portion of which is located below the current terrain; performing the work by controlling the lift actuator so that the cutting edge of the blade moves according to the target topography; 2. The work machine of claim 1.

3. a position sensor for detecting a position of the vehicle body; A speed sensor for detecting an operating speed of the traveling device; Further equipped with The controller: Calculating an actual vehicle speed of the work machine based on the position of the vehicle body; Calculating a theoretical vehicle speed of the work machine based on the operating speed of the traveling device; determining whether the first slip is occurring in the traveling device based on the actual vehicle speed and the theoretical vehicle speed; 2. The work machine of claim 1.

4. A method for controlling a work machine including a vehicle body including a traveling device, a blade supported rotatably about a pitch axis relative to the vehicle body, and a pitch actuator that pitches the blade about the pitch axis, the method comprising: determining whether a first slip is occurring in the traveling device while the blade is working based on a first slip condition; pitching the blade in a rearward direction when it is determined that the first slip has occurred; determining whether the traveling device has escaped from the first slip; when it is determined that the traveling device has not escaped from the first slip, determining whether a second slip is occurring in the traveling device during work by the blade based on a second slip condition different from the first slip condition; raising the blade when it is determined that the second slip has occurred; A method for providing the above.

5. The work machine includes: a lift frame supported rotatably about a lift shaft relative to the vehicle body; a lift actuator that lifts the lift frame up and down around the lift shaft; Equipped with The blade is supported on the vehicle body via the lift frame, Acquiring current terrain data indicating the current terrain that is the target of work; acquiring target terrain data indicative of a target terrain at least a portion of which is located below the current terrain; performing the work by controlling the lift actuator so that the cutting edge of the blade moves according to the target topography; The method of claim 4 further comprising:

6. Obtaining a position of the vehicle body; Obtaining an operating speed of the traveling device; Calculating an actual vehicle speed of the work machine based on the position of the vehicle body; Calculating a theoretical vehicle speed of the work machine based on an operating speed of the traveling device; determining whether the first slip is occurring in the traveling device based on the actual vehicle speed and the theoretical vehicle speed; The method of claim 4 further comprising:

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