System and method for controlling work machine

Abstract

A system according to the present disclosure controls a work machine. The work machine includes: a traveling body including a crawler; and a work implement. The system comprises a sensor and a controller. The sensor detects the posture of the work machine. The controller determines, on the basis of the posture of the work machine, whether the front part of the crawler is lifted from the ground. When the controller determines that the front part of the crawler is lifted from the ground, the controller controls the work implement so as to suppress the lifting of the crawler.

Description

System and method for controlling a work machine

[0001] The present disclosure relates to a system and method for controlling a work machine.

[0002] Some work machines detect the slip of the crawler and execute slip control to suppress the slip when the crawler is slipping. For example, in the work machine of Patent Document 1, the controller calculates the ratio of the actual vehicle speed to the theoretical vehicle speed of the work machine as the slip ratio. The controller determines that the crawler is slipping when the slip ratio is smaller than the threshold value. When the controller determines that the crawler is slipping, the controller operates the blade in the backward tilt direction. Thereby, the slip is suppressed.

[0003] Japanese Unexamined Patent Application Publication No. 2023-6408

[0004] Although the crawler of the work machine is not slipping, the front part of the crawler may be lifted off the ground. In such a case, in the work machine described above, since the crawler is not slipping, the slip control is not executed. Therefore, the work machine performs operations such as excavation or earth moving with the front part of the crawler lifted off the ground. In this case, the vibration of the work machine increases and the riding comfort deteriorates. An object of the present disclosure is to suppress an increase in vibration of the work machine due to the front part of the crawler being lifted off the ground.

[0005] A system according to one aspect of the present disclosure is a system for controlling a work machine. The work machine includes a traveling body including crawlers and a work implement. The system includes a sensor and a controller. The sensor detects the attitude of the work machine. The controller determines whether the front part of the crawler is lifted off the ground based on the attitude of the work machine. When the controller determines that the front part of the crawler is lifted off the ground, the controller controls the work implement so as to suppress the lifting of the crawler.

[0006] Another aspect of the present disclosure relates to a method for controlling a work machine. The work machine includes a running body including tracks and a work implement. The method comprises detecting the posture of the work machine, determining whether the front of the tracks is lifted off the ground based on the posture of the work machine, and, if it is determined that the front of the tracks is lifted off the ground, controlling the work implement to suppress the lifting of the tracks.

[0007] According to this disclosure, the increase in vibration of the work machine caused by the front of the track being lifted can be suppressed.

[0008] This is a side view showing a work machine according to an embodiment. This is a side view of a work machine showing the operation of the work machine. This is a block diagram showing the configuration of the drive system and control system of the work machine. This is a flowchart showing the processing of automatic control of the work machine. This is a diagram showing an example of the current terrain and the target terrain. This is a flowchart showing the processing of front lift suppression control. This is a side view of a work machine showing the wheelie angle of the track. This is a side view of a work machine showing the first height and second height of the track. This is a side view showing a work machine when it is going over the toe of a slope. This is a side view showing a work machine when it is going over a step. This is a side view showing a work machine when it is going over an inclined surface. This is a side view of a work machine showing the velocity vector when the work machine is moving in reverse.

[0009] The following description of the work machine according to the embodiment will be made with reference to the drawings. Figure 1 is a side view showing the work machine 1 according to the embodiment. The work machine 1 according to this embodiment is a bulldozer. The work machine 1 comprises a vehicle body 11 and a work machine 12.

[0010] The vehicle body 11 includes a driver's cab 13, a power source room 14, and a running body 15. The driver's cab 13 has a driver's seat (not shown). The running body 15 is located at the bottom of the vehicle body 11. The running body 15 includes a pair of left and right tracks 16, an idler 42, and a sprocket 41.

[0011] The track 16 is wrapped around the sprocket 41 and the idler 42. Note that only the left track 16 is shown in Figure 1. The idler 42 is located in front of the sprocket 41. The front part of the track 16 is wrapped around the idler 42. The rear part of the track 16 is wrapped around the sprocket 41. When the sprocket 41 is rotated, the track 16 rotates, causing the work machine 1 to move.

[0012] The work implement 12 is attached to the vehicle body 11. The work implement 12 is positioned in front of the traveling body 15. The work implement 12 has a lift frame 17, a blade 18, a lift actuator 19, and a pitch link 20. The lift frame 17 is supported so as to be rotatable around the lift axis X1 relative to the vehicle body 11. The lift axis X1 extends laterally from the vehicle body 11. As shown by the dashed line in Figure 2, the lift frame 17 moves up and down by rotating around the lift axis X1. The blade 18 moves up and down in conjunction with the up and down movement of the lift frame 17.

[0013] The blade 18 is positioned at the front of the vehicle body 11. The blade 18 is supported on the lift frame 17 so as to be rotatable around the pitch axis X2. The pitch axis X2 extends laterally from the vehicle body 11. As shown by the dashed line in Figure 2, the blade 18 tilts forward and backward by rotating around the pitch axis X2.

[0014] The lift actuator 19 is connected to the vehicle body 11 and the lift frame 17. The lift actuator 19 is a hydraulic cylinder. As the lift actuator 19 extends and retracts, the lift frame 17 moves up and down. The lift actuator 19 may also be attached to the blade 18. The pitch link 20 is connected to the lift frame 17 and the blade 18. The pitch link 20 may be a controllable actuator, such as a hydraulic cylinder. Alternatively, the pitch link 20 may be a manually extendable member, such as one with a screw-type structure. As the pitch link 20 extends and retracts, the blade 18 tilts back and forth.

[0015] Figure 3 is a block diagram showing the configuration of the drive system 2 and control system 3 of the work machine 1. As shown in Figure 2, the drive system 2 includes a power source 22, a hydraulic pump 23, and a power transmission device 24. The power source 22 includes, for example, an internal combustion engine. Alternatively, the power source 22 may include an electric motor. The hydraulic pump 23 is driven by the power source 22 and discharges hydraulic fluid. The hydraulic fluid discharged from the hydraulic pump 23 is supplied to the lift actuator 19 and the pitch link 20. Although one hydraulic pump is shown in Figure 2, multiple hydraulic pumps may be provided.

[0016] The power transmission device 24 transmits the driving force of the power source 22 to the vehicle body 15. The power transmission device 24 may be, for example, an HST (Hydro Static Transmission). Alternatively, the power transmission device 24 may be, for example, a torque converter or a transmission having multiple gears.

[0017] The control system 3 comprises a controller 26 and a control valve 27. The controller 26 is programmed to control the work machine 1 based on acquired data. The controller 26 includes a storage device 28 and a processor 29. The processor 29 includes, for example, a CPU. The storage device 28 includes, for example, memory and auxiliary storage device. The storage device 28 may be, for example, RAM or ROM. The storage device 28 may be semiconductor memory or a hard disk. The storage device 28 is an example of a non-transitory computer-readable recording medium. The storage device 28 is executable by the processor 29 and records computer commands 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 positioned between the hydraulic actuators, such as the lift actuator 19 and the pitch link 20, and the hydraulic pump 23. The control valve 27 controls the flow rate of hydraulic fluid supplied from the hydraulic pump 23 to the lift actuator 19. The control valve 27 also controls the flow rate of hydraulic fluid supplied from the hydraulic pump 23 to the pitch link 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 operating device 31 and an input device 32. The operating device 31 may include, for example, a lever. Alternatively, the operating device 31 may include a pedal or a switch. The operator can use the operating device 31 to manually control the movement of the work machine 1 and the operation of the work machine 12. The operating device 31 outputs an operation signal indicating the operation of the operating device 31. The controller 26 receives the operation signal from the operating device 31.

[0020] The input device 32 includes, for example, a touch panel. However, the input device 32 may also include other devices such as switches. The operator can use the input device 32 to set the automatic control of the work machine 12 by the controller 26.

[0021] The control system 3 includes a vehicle body sensor 34, a frame sensor 35, a blade sensor 36, and a position sensor 37, as shown in Figure 1. 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.

[0022] The vehicle body sensor 34, the frame sensor 35, and the blade sensor 36 are all IMUs (Inertial Measurement Units). However, the frame sensor 35 and the blade sensor 36 are not limited to IMUs; they may be other sensors such as angle sensors or cylinder stroke sensors.

[0023] The vehicle body sensor 34 detects the pitch angle and roll angle of the vehicle body 11. The frame sensor 35 detects the pitch angle and roll angle of the lift frame 17. The blade sensor 36 detects the pitch angle and roll angle of the blade 18. The vehicle body sensor 34, frame sensor 35, and blade sensor 36 each output a detection signal indicating the detected angle. The controller 26 receives the detection signals from the vehicle body sensor 34, frame sensor 35, and blade sensor 36.

[0024] The position sensor 37 detects the current position of the vehicle body 11. The position sensor 37 is a GNSS (Global Navigation Satellite System) position sensor, such as a GPS (Global Positioning System). The position sensor 37 includes, for example, a GNSS receiver and an antenna. The position sensor 37 detects its own current position. The position sensor 37 is located on the vehicle body 11. The current position of the vehicle body 11 is indicated in global coordinates relative to the Earth. However, the current position of the vehicle body 11 may be indicated in local coordinates relative to the work site where the work machine 1 performs its work.

[0025] The controller 26 obtains a detection signal from the position sensor 37 indicating the current position of the vehicle body 11. Based on the current position of the vehicle body 11 detected by the position sensor 37, the controller 26 detects the vehicle speed. Alternatively, the controller may detect the vehicle speed based on a detection signal from the power transmission device 24 or a sensor that detects the driving speed of the vehicle body 15.

[0026] The controller 26 automatically controls the work machine 1. The automatic control of the work machine 1 performed by the controller 26 will be described below. Figure 4 is a flowchart showing the process of automatic control of the work machine 1.

[0027] As shown in Figure 4, in step S101, the controller 26 acquires position data. The controller 26 acquires the current position of the vehicle body 11 detected by the position sensor 37 as position data. In step S102, the controller 26 acquires posture data. The controller 26 acquires the angles detected by the vehicle body sensor 34, the frame sensor 35, and the blade sensor 36 as posture data indicating the posture of the work machine 1.

[0028] In step S103, the controller 26 obtains the cutting edge position of the blade 18. The controller 26 stores mechanical dimension data that shows the dimensions and positional relationship between the vehicle body 11, the lift frame 17, and the blade 18. Based on the attitude data, position data, and mechanical dimension data, the controller 26 calculates the cutting edge position P0 of the blade 18.

[0029] In step S104, the controller 26 acquires current terrain data. The current terrain data represents the current terrain 50 of the work area. Figure 5 shows an example of the current terrain 50. The current terrain data includes the coordinates and altitudes of multiple points on the current terrain 50 located in the direction of travel of the work machine 1. The controller 26 may acquire initial data of the current terrain data from, for example, an external computer. The controller 26 may update the current terrain data based on the movement trajectory of the cutting edge position P0 or the movement trajectory of the track 16.

[0030] In step S105, the controller 26 acquires target terrain data. The target terrain data shows the target terrain 60 relative to the current terrain 50. The target terrain data includes the coordinates and altitudes of several points on the target terrain 60 located in the direction of travel of the work machine 1. As shown in Figure 5, at least a portion of the target terrain 60 is displaced vertically with respect to the current terrain 50. At least a portion of the target terrain 60 is located below the current terrain 50.

[0031] 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 the target terrain 60 as a trajectory extending at a predetermined angle from a predetermined starting position of the work. 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 amount of soil held by the blade 18. Alternatively, the controller 26 may acquire target terrain data from an external computer.

[0032] In step S106, the controller 26 controls the work machine 12 according to the target terrain 60. The controller 26 controls the lift actuator 19 so that the cutting edge of the blade 18 moves according to the target terrain 60. As a result, the blade 18 moves up and down so that the cutting edge of the blade 18 moves along the target terrain 60 as the work machine 1 moves forward. As a result, the current terrain 50 is excavated by the blade 18. Note that the forward and reverse movement of the work machine 1 may be performed manually by the operator using the control device 31. Alternatively, the forward and reverse movement of the work machine 1 may be performed by automatic control by the controller 26.

[0033] In the work machine 1 according to this embodiment, the controller 26 monitors the lifting of the front of the track 16 (hereinafter referred to as front lift) while performing automatic control of the height of the blade 18 according to the target terrain 60. If front lift of the track 16 occurs, the controller 26 performs automatic control of the work machine 12 to suppress front lift of the track 16 (hereinafter referred to as front lift suppression control). Figure 6 is a flowchart of the front lift suppression control process. The following description shows the process when the work machine 1 is moving forward.

[0034] As shown in Figure 6, in step S201, the controller 26 obtains the position of the sprocket contact point P1 of the track 16. As shown in Figure 7, the sprocket contact point P1 is a point on the bottom surface of the track 16 located directly below the sprocket 41. The controller 26 calculates the position of the sprocket contact point P1 based on the attitude data, position data, and mechanical dimension data.

[0035] In step S202, the controller 26 obtains the position of the idler contact point P2 of the track 16. As shown in Figure 8, the idler contact point P2 is a point on the bottom surface of the track 16 located directly below the idler 42. The controller 26 calculates the position of the idler contact point P2 based on the attitude data, position data, and mechanical dimension data.

[0036] In step S203, the controller 26 obtains the position of the track center P3. As shown in Figure 8, the track center P3 is the point located in the center in the longitudinal direction on the bottom surface of the track 16. The controller 26 calculates the position of the track center P3 based on the attitude data, position data, and mechanical dimension data.

[0037] In step S204, the controller 26 obtains the wheelie angle θ1. The wheelie angle θ1 represents the inclination angle of the vehicle body 11 in the longitudinal direction relative to the direction of travel of the work machine 1. As shown in Figure 7, the controller 26 obtains the velocity vector Vt of the track 16 at the sprocket contact point P1 in the vehicle body coordinate system X-Y-Z. The vehicle body coordinate system X-Y-Z is a coordinate system based on the vehicle body 11 and is fixed to the vehicle body 11. The X axis of the vehicle body coordinate system X-Y-Z extends in the longitudinal direction of the vehicle body 11. The Y axis of the vehicle body coordinate system X-Y-Z extends in the left-right direction of the vehicle body 11. The Z axis of the vehicle body coordinate system X-Y-Z extends in the up-down direction of the vehicle body 11.

[0038] The controller 26 calculates the wheelie angle θ1 of the track 16 at the sprocket contact point P1 in the vehicle coordinate system X-Y-Z based on the following equation (1): In equation (1), Vx is the X-axis component of the velocity vector Vt. Vz is the Z-axis component of the velocity vector Vt. θ1 = atan(Vz / Vx) ... (1)

[0039] In step S205, the controller 26 obtains the first height H1 from the ground GL of the front of the track 16. As shown in Figure 8, the first height H1 is the height of the idler contact point P2 from the ground GL. The controller 26 calculates the first height H1 based on the position of the idler contact point P2 and the position of the ground GL. The position of the ground GL is the position of the current terrain 50 as described above. The controller 26 obtains the movement trajectory of the blade tip position P0 as the position of the ground GL.

[0040] In step S206, the controller 26 obtains the second height H2 of the track center P3 from the ground GL. The controller 26 calculates the second height H2 based on the position of the track center P3 and the position of the ground GL.

[0041] The controller 26 determines whether the front of the track 16 is lifted by processing in steps S207 to S209. Specifically, in step S207, the controller 26 determines whether the wheelie angle θ1 is greater than the angle threshold θth. The wheelie angle θ1 used here to determine whether the front is lifted may be the wheelie angle θ1 described above, smoothed with a first-order time-constant lag filter. If the wheelie angle θ1 is greater than the angle threshold θth, the process proceeds to step S208.

[0042] In step S208, the controller 26 determines whether the first height H1 is greater than the first threshold Hth1. As shown in Figure 9, when the work machine 1 goes over the toe of the slope 90, the front of the track 16 does not lift, but the wheelie angle θ1 may be greater than the angle threshold θth. Alternatively, as shown in Figure 10, when the work machine 1 goes over the step 91, the front of the track 16 does not lift, but the wheelie angle θ1 may be greater than the angle threshold θth. Even in such cases, the occurrence of front lift of the track 16 can be accurately determined by determining whether the first height H1 of the idler contact point P2 is greater than the first threshold Hth1. If the first height H1 is greater than the first threshold Hth1, the process proceeds to step S209.

[0043] In step S209, the controller 26 determines whether the second height H2 is greater than the second threshold value Hth2. As shown in FIG. 11, when the working machine 1 crosses the inclined surface 92, the front lift of the crawler 16 does not occur, but there are cases where the Willie angle θ1 becomes greater than the angle threshold value θth and the first height H1 becomes greater than the first threshold value Hth1. Even in such a case, by determining whether the second height H2 of the center portion P3 of the crawler is greater than the second threshold value Hth2, it is possible to accurately determine the occurrence of the front lift of the crawler 16. If the second height H2 is greater than the second threshold value Hth2, the process proceeds to step S210.

[0044] In step S210, the controller 26 executes front lift suppression control. In the front lift suppression control, the controller 26 controls the working machine 1 to contract the lift actuator 19 and raise the blade 18. Alternatively, in the front lift suppression control, the controller 26 may control the working machine 1 to contract the pitch link 20 and tilt the blade 18 backward. Thereby, the front lift of the crawler 16 is suppressed.

[0045] Note that, at the start of the work by the working machine 1, the controller 26 may invalidate the front lift determination processes of steps S207 to S209 until the center portion P3 of the crawler reaches the initial position of the cutting edge position P0. After the center portion P3 of the crawler reaches the initial position of the cutting edge position P0, the controller 26 may validate the front lift determination processes of steps S207 to S209. Thereby, it is possible to suppress the misdetection of the front lift of the crawler 16 when the idler contact point P2 or the center portion P3 of the crawler passes on the ground GL that is not excavated by the blade 18.

[0046] When the working machine 1 moves backward, in step S204, as shown in FIG. 12, the controller 26 calculates the idler angle θ1 using the velocity vector Vt' obtained by reversing the velocity vector Vt of the crawler 16 at the sprocket contact point P1 in the vehicle body coordinate system X - Y - Z. Also, when the working machine 1 moves backward, in steps S205 and S206, the controller 26 acquires the movement locus of the sprocket contact point P1 as the position of the ground GL and acquires the first height H1 and the second height H2. However, immediately after the start of backward movement, there is no movement locus of the sprocket contact point P1. Therefore, the controller 26 regards the straight line indicating the bottom surface of the crawler 16 at the start of backward movement as the movement locus of the virtual sprocket contact point P1 and acquires the first height H1 and the second height H2. Other processes during backward movement are the same as the processes during forward movement described above.

[0047] In the working machine 1 according to the present embodiment described above, the front float of the crawler 16 is determined based on the posture of the working machine 1. When it is determined that the front float of the crawler 16 has occurred, the working machine 12 is controlled to suppress the front float of the crawler 16. Thereby, an increase in vibration of the working machine 1 due to the front float of the crawler 16 is suppressed.

[0048] As described above, an embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0049] The working machine 1 is not limited to a bulldozer and may be other vehicles such as a wheel loader or a motor grader. The controller 26 may have a plurality of controllers that are separate from each other. A part of the plurality of controllers may be arranged outside the working machine 1. That is, the working machine 1 may be controllable remotely.

[0050] The processing by the controller 26 is not limited to that of the above embodiment and may be changed. A part of the automatic control processing described above may be omitted. Alternatively, a part of the processing described above may be changed. The front float suppression control processing is not limited to automatic control and may be executed during manual operation of the working machine 1.

[0051] The process for suppressing front lift is not limited to the process described above and may be modified. For example, in the embodiment described above, the controller 26 determines front lift of the track 16 based on the wheelie angle θ1, the first height H1 of the track 16, and the second height H2 of the track 16. However, the controller 26 may determine front lift of the track 16 based on a part of the wheelie angle θ1, the first height H1 of the track 16, and the second height H2 of the track 16. Alternatively, front lift of the track 16 may be determined by directly measuring the position of the ground GL and the idler 42 using sensors such as a camera, laser, or radar.

[0052] According to this disclosure, the increase in vibration of the work machine caused by the front of the track being lifted can be suppressed.

[0053] 1: Work machine, 12: Work machine, 15: Vehicle, 16: Track, 26: Controller, 34: Vehicle sensor, 35: Frame sensor, 36: Blade sensor, 37: Position sensor, 41: Sprocket, 42: Idler, θ1: Wheelie angle, H1: First height, H2: Second height

Claims

1. A system for controlling a work machine including a tracked vehicle and a work implement, comprising: a sensor for detecting the posture of the work implement; and a controller, wherein the controller determines, based on the posture of the work machine, whether the front of the track is lifted off the ground, and if it determines that the front of the track is lifted off the ground, controls the work implement to suppress the lifting of the track.

2. The system according to claim 1, wherein the controller obtains the wheelie angle of the track based on the posture of the work machine, and determines whether the front of the track is lifted off the ground based on the wheelie angle of the track.

3. The system according to claim 2, wherein the vehicle body includes a sprocket around which the track is wound, and the controller obtains a velocity vector of the track directly below the sprocket and calculates the wheelie angle of the track based on the velocity vector of the track.

4. The system according to claim 1, wherein the controller obtains a first height from the ground to the front of the track and determines, based on the first height, whether the front of the track is lifted off the ground.

5. The system according to claim 4, wherein the running body includes an idler around which the front portion of the track is wound, and the controller obtains the first height based on the position of the idler.

6. The system according to claim 4, wherein the controller obtains a second height from the ground of the central part of the track in the longitudinal direction, and determines whether the front part of the track is lifted off the ground based on the first height and the second height.

7. The system according to claim 6, wherein the controller obtains the wheelie angle of the track based on the posture of the work machine, and determines whether the front of the track is lifted off the ground based on the wheelie angle of the track, the first height, and the second height.

8. The system according to claim 4, wherein the work machine is positioned in front of the track, the controller acquires the movement trajectory of the work machine, and when the work machine is moving forward, acquires the height of the front of the track from the movement trajectory of the work machine as the first height.

9. The system according to claim 8, wherein the controller enables the determination of whether the front part of the track is lifted off the ground after the central part of the track in the front-rear direction has reached the initial position of the cutting edge of the work machine when work by the work machine is started.

10. The system according to claim 4, wherein the controller acquires the movement trajectory of the rear of the track, and when the work machine is moving in reverse, acquires the height of the front of the track from the movement trajectory of the rear of the track as the first height.

11. A method for controlling a work machine including a tracked vehicle and a work implement, comprising: detecting the posture of the work implement; determining, based on the posture of the work implement, whether the front part of the track is lifted off the ground; and, if it is determined that the front part of the track is lifted off the ground, controlling the work implement to suppress the lifting of the track.

12. The method according to claim 11, comprising: obtaining the wheelie angle of the track based on the posture of the work machine; and determining whether the front part of the track is lifted off the ground based on the wheelie angle of the track.

13. The method according to claim 12, wherein the running body includes a sprocket around which the track is wound, and further comprises obtaining the velocity vector of the track directly below the sprocket, and calculating the wheelie angle of the track based on the velocity vector of the track.

14. The method according to claim 11, comprising: obtaining a first height of the front of the track from the ground; and determining, based on the first height, whether the front of the track is lifted off the ground.

15. The method according to claim 14, wherein the running body includes an idler around which the front portion of the track is wound, and the first height is obtained based on the position of the idler.

16. The method according to claim 14, comprising: obtaining a second height from the ground of the central part of the track in the longitudinal direction; and determining whether the front part of the track is lifted off the ground based on the first height and the second height.

17. The method according to claim 16, comprising: obtaining the wheelie angle of the track based on the posture of the work machine; and determining whether the front part of the track is lifted off the ground based on the wheelie angle of the track, the first height, and the second height.

18. The method according to claim 14, wherein the work machine is positioned in front of the track, and the method comprises acquiring the movement trajectory of the work machine, and, when the work machine is moving forward, acquiring the height of the front of the track from the movement trajectory of the work machine as the first height.

19. The method according to claim 18, further comprising: when starting work by the work machine, the determination of whether the front part of the track is lifted off the ground after the central part of the track in the front-rear direction has reached the initial position of the cutting edge of the work machine; 20. The method according to claim 14, comprising: obtaining the movement trajectory of the rear of the track; and, when the work machine is moving in reverse, obtaining the height of the front of the track from the movement trajectory of the rear of the track as the first height.

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