Method, system and work machine for determining an orientation of a blade relative to a lift frame in a work machine

Abstract

To accurately detect a blade angle in a working machine.SOLUTION: The method includes obtaining a length of the pitch link, obtaining a blade tilt angle of the blade relative to the lift frame, obtaining a stroke length of the angling cylinder, and determining an estimate of a blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angling cylinder.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] SUMMARY The present disclosure relates to a method, system, and work machine for determining the attitude of a blade relative to a lift frame on a work machine. [Background technology]

[0002] In recent years, there has been a demand for work machines to accurately detect the attitude of the blade for purposes such as blade control. To this end, for example, in the work machine disclosed in Patent Document 1, sensors such as an IMU (Inertial Measurement Unit) are attached to the vehicle body, lift frame, and blade. The controller of the work machine determines the attitude of the blade based on the pitch angle, roll angle, and yaw angle of the vehicle body, lift frame, and blade, respectively, detected by these sensors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-51133 Summary of the Invention [Problem to be solved by the invention]

[0004] Some work machines have a blade supported relative to a lift frame so that it can move in pitch, tilt, and angle directions. The pitch direction is the direction in which the blade tilts forward and backward relative to the lift frame. The tilt direction is the direction in which the blade tilts relative to the lift frame so that one of the left and right ends of the blade is positioned differently in the up and down direction from the other. The angle direction is the direction in which the blade tilts relative to the lift frame so that one of the left and right ends of the blade is positioned differently in the up and down direction from the other.

[0005] In the above-described work machine, the blade can move in an angular direction relative to the lift frame. Therefore, in order to accurately detect the blade attitude, it is necessary to accurately detect the blade angle relative to the lift frame. The blade angle relative to the lift frame can be calculated from the blade yaw angle. However, sensors such as the above-described IMU have low detection accuracy for the blade yaw angle. Therefore, it is difficult to accurately detect the blade angle relative to the lift frame. An object of the present disclosure is to accurately detect the blade angle in a work machine. [Means for solving the problem]

[0006] A method according to a first aspect of the present disclosure is a computer-implemented method for determining a blade attitude relative to a lift frame of a work machine. The work machine includes a vehicle body, a lift frame, a blade, a pitch link, a tilt cylinder, and an angle cylinder. The lift frame is supported relative to the vehicle body so as to be movable in a vertical direction. The blade is supported relative to the lift frame so as to be movable in a pitch direction, a tilt direction, and an angle direction. The pitch link connects the blade to the lift frame so as to be movable in the pitch direction. The tilt cylinder is connected to the lift frame and the blade and moves the blade in the tilt direction. The angle cylinder is connected to the lift frame and the blade and moves the blade in the angle direction. The method according to this aspect includes obtaining a length of the pitch link, obtaining a blade tilt angle of the blade relative to the lift frame, obtaining a stroke length of the angle cylinder, and determining an estimated blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder.

[0007] A system according to a second aspect of the present disclosure is a system for determining the attitude of a blade relative to a lift frame of a work machine. The work machine includes a vehicle body, a lift frame, a blade, a pitch link, a tilt cylinder, and an angle cylinder. The lift frame is supported relative to the vehicle body so as to be movable in the vertical direction. The blade is supported relative to the lift frame so as to be movable in the pitch direction, tilt direction, and angle direction. The pitch link connects the blade to the lift frame so as to be movable in the pitch direction. The tilt cylinder is connected to the lift frame and the blade and moves the blade in the tilt direction. The angle cylinder is connected to the lift frame and the blade and moves the blade in the angle direction. The system according to this aspect includes an angle stroke sensor and a controller. The angle stroke sensor detects the stroke length of the angle cylinder. The controller obtains the length of the pitch link. The controller obtains the blade tilt angle of the blade relative to the lift frame. The controller obtains the stroke length of the angle cylinder. The controller determines an estimate of the blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder.

[0008] A work machine according to a third aspect of the present disclosure includes a vehicle body, a lift frame, a blade, a pitch link, a tilt cylinder, an angle cylinder, an angle stroke sensor, and a controller. The lift frame is supported on the vehicle body so as to be movable in the vertical direction. The blade is supported on the lift frame so as to be movable in the pitch direction, the tilt direction, and the angle direction. The pitch link connects the blade to the lift frame so as to be movable in the pitch direction. The tilt cylinder is connected to the lift frame and the blade and moves the blade in the tilt direction. The angle cylinder is connected to the lift frame and the blade and moves the blade in the angle direction. The angle stroke sensor detects the stroke length of the angle cylinder. The controller acquires the length of the pitch link. The controller acquires the blade tilt angle of the blade relative to the lift frame. The controller acquires the stroke length of the angle cylinder. The controller determines an estimated value of the blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder. [Effects of the Invention]

[0009] According to the present disclosure, an estimated value of the blade angle relative to the lift frame is determined by using the stroke length of the angle cylinder. The stroke length of the angle cylinder can be easily and accurately detected. Therefore, the estimated value of the blade angle can be determined accurately by using the stroke length of the angle cylinder. As a result, the blade angle can be detected accurately. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing a work machine according to an embodiment. [Figure 2] FIG. [Figure 3] FIG. 2 is a side view showing a part of the work machine. [Figure 4]FIG. [Figure 5] FIG. [Figure 6] 1 is a block diagram showing the configuration of a drive system and a control system of a work machine. [Figure 7] FIG. 2 is a top view of the work machine showing the lift frame site coordinate system and the blade site coordinate system. [Figure 8] FIG. 1 is a side view of the implement showing the lift frame site coordinate system, the blade site coordinate system, and the lift frame datum. [Figure 9] FIG. 1 is a front view of the implement showing the lift frame site coordinate system and the blade site coordinate system. [Figure 10] FIG. 10 is a diagram showing the blade pitch angle relative to the lift frame. [Figure 11] FIG. 10 is a diagram showing the blade angle based on the lift frame. [Figure 12] FIG. 10 is a diagram showing the blade tilt angle relative to the lift frame. [Figure 13] 10 is a flowchart showing a process for determining the attitude of a blade relative to a lift frame reference in a work machine. [Figure 14] FIG. 10 is a diagram showing an example of a map for calculating a blade angle based on a lift frame. [Figure 15] FIG. 10 is a diagram showing an example of a map for calculating a blade angle based on a lift frame. DETAILED DESCRIPTION OF THE INVENTION

[0011] A work machine according to an embodiment will now 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 comprises a vehicle body 11 and a work implement 12. The vehicle body 11 includes a driver's cab 13, a power compartment 14, and a traveling device 15. The power compartment 14 is located in front of the driver's cab 13. The traveling device 15 is provided below the vehicle body 11. The traveling device 15 includes a pair of left and right tracks 16A, 16B.

[0012] The work implement 12 is attached to the vehicle body 11. The work implement 12 includes a lift frame 17, a blade 18, a lift cylinder 19, angle cylinders 20A and 20B, a tilt cylinder 21, and a pitch link 22. The lift cylinder 19, the angle cylinders 20A and 20B, and the tilt cylinder 21 are hydraulic cylinders.

[0013] The lift frame 17 is supported on the vehicle body 11 so as to be movable up and down around a lift axis A1. The lift axis A1 extends in the left-right direction of the vehicle body 11. The blade 18 is disposed in front of the vehicle body 11. The blade 18 is supported by the lift frame 17. The blade 18 moves up and down as the lift cylinder 19 extends and retracts.

[0014] Fig. 2 is a perspective view showing a portion of the work machine 12. Fig. 3 is a side view showing a portion of the work machine 12. As shown in Figs. 2 and 3, the blade 18 is supported by the lift frame 17 via a ball joint 23. As shown in Fig. 3, the blade 18 is supported so as to be movable in the pitch direction relative to the lift frame 17. The pitch direction is the direction in which the blade 18 rotates around a pitch axis A2. The pitch axis A2 passes through the center C1 of the ball joint 23 and extends in the left-right direction of the lift frame 17.

[0015] The pitch link 22 is connected to the blade 18 and the lift frame 17. The pitch link 22 connects the blade 18 to the lift frame 17 so that the blade 18 can move in the pitch direction. As shown in FIG. 2 , the pitch link 22 includes a cylinder 24, a first shaft 25, and a second shaft 26. The first shaft 25 includes a first connection portion 27. The first shaft 25 is rotatably connected to the lift frame 17 at the first connection portion 27. The second shaft 26 includes a second connection portion 28. The second shaft 26 is rotatably connected to the blade 18 at the second connection portion 28.

[0016] The first shaft 25 and the second shaft 26 are threadedly engaged with the cylinder 24 within the cylinder 24. The length L1 of the pitch link 22 shown in FIG. 3 is changed by manually rotating the first shaft 25 and the second shaft 26 relative to the cylinder 24. Changing the length L1 of the pitch link 22 causes the blade 18 to move in the pitch direction. However, when the work machine 1 is in use, the length L1 of the pitch link 22 is fixed.

[0017] FIG. 4 is a top view showing a portion of the work machine 12. As shown in FIG. 4, the blade 18 is supported on the lift frame 17 so as to be movable in an angle direction. The angle direction is the direction in which the blade 18 rotates around an angle axis A3 on the lift frame 17. As shown in FIG. 3, the angle axis A3 extends through the center C1 of the ball joint 23 and the support point 29 of the tilt cylinder 21 on the lift frame 17. The angle cylinders 20A and 20B are connected to the lift frame 17 and the blade 18. The extension and contraction of the angle cylinders 20A and 20B causes the blade 18 to move in the angle direction.

[0018] Figure 5 is a front view of the work machine 1. As shown in Figure 5, the blade 18 is supported relative to the lift frame 17 so as to be movable in a tilt direction. The tilt direction is the direction in which the blade 18 rotates around a tilt axis A4 at the ball joint 23. The tilt axis A4 passes through the center C1 of the ball joint 23 and extends in the front-to-rear direction of the lift frame 17. The tilt cylinder 21 is connected to the lift frame 17 and the blade 18. The extension and contraction of the tilt cylinder 21 causes the blade 18 to move in the tilt direction.

[0019] FIG. 6 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. 6, the drive system 2 includes a drive source 30, a hydraulic pump 31, and a power transmission device 32. The drive source 30 includes, for example, an internal combustion engine. The drive source 30 may also include an electric motor. The hydraulic pump 31 is driven by the drive source 30 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 31 is supplied to the lift cylinder 19, the angle cylinders 20A and 20B, and the tilt cylinder 21. Although FIG. 6 shows one hydraulic pump 31, multiple hydraulic pumps may be provided.

[0020] The power transmission device 32 transmits the driving force of the drive source 30 to the traveling device 15. The power transmission device 32 may be, for example, an HST (Hydro Static Transmission). Alternatively, the power transmission device 32 may be, for example, a torque converter or a transmission having multiple speed change gears.

[0021] The control system 3 includes a controller 33 and a control valve 34. The controller 33 is programmed to control the work machine 1 based on the acquired data. The controller 33 includes a memory device 35 and a processor 36. The processor 36 includes, for example, a CPU. The memory device 35 includes, for example, a memory and an auxiliary memory device. The memory device 35 may be, for example, a RAM or a ROM. The memory device 35 may be, for example, a semiconductor memory or a hard disk. The memory device 35 stores computer instructions that are executable by the processor 36 and that are used to control the work machine 1.

[0022] The control valve 34 is controlled by a command signal from the controller 33. The control valve 34 is arranged between the hydraulic cylinders, such as the lift cylinder 19, the angle cylinders 20A and 20B, and the tilt cylinder 21, and the hydraulic pump 31. The control valve 34 controls the flow rate of hydraulic oil supplied from the hydraulic pump 31 to the lift cylinder 19, the angle cylinders 20A and 20B, and the tilt cylinder 21. The control valve 34 may be a pressure proportional control valve. Alternatively, the control valve 34 may be an electromagnetic proportional control valve.

[0023] The control system 3 includes an operating device 37. The operating device 37 includes, for example, an operating lever. The operating device 37 can be operated by an operator to operate the traveling device 15 and the work implement 12. The controller 33 controls the drive source 30 and the power transmission device 32 in accordance with the operation of the operating device 37 so as to cause the work machine 1 to travel. The controller 33 controls the control valve 34 in accordance with the operation of the operating device 37 so as to operate the work implement 12. As a result, the work implement 12 operates.

[0024] The control system 3 includes an input device 38 and a display 39. The input device 38 includes, for example, a touch panel. However, the input device 38 may include other devices such as switches. The operator can use the input device 38 to configure control settings for the work machine 1. The display 39 displays information related to the work machine 1.

[0025] The control system 3 includes a frame IMU (Inertial Measurement Unit) 41, a blade IMU 42, and angle stroke sensors 43A and 43B. The frame IMU 41 is attached to the lift frame 17. The frame IMU 41 detects the attitude of the lift frame 17. The frame IMU 41 detects the frame pitch angle and frame roll angle of the lift frame 17 in the site coordinate system.

[0026] As shown in Figures 8 and 9, the frame IMU 41 has an x1-axis, a y1-axis, and a z1-axis. The x1-axis extends in the front-to-rear direction of the lift frame 17. The y1-axis extends in the left-to-right direction of the lift frame 17. The z1-axis extends in the up-and-down direction of the lift frame 17. The site coordinate system of the lift frame 17 has an x'-axis, a y'-axis, and a z'-axis. The x'-axis extends in the direction of the x1-axis projected onto a horizontal plane. The y'-axis extends in the direction of the y1-axis projected onto a horizontal plane. The z'-axis extends in the direction of gravity. As shown in Figure 8, the frame pitch angle θ1 of the lift frame 17 in the site coordinate system is the angle of the x1-axis of the frame IMU 41 relative to the x'-axis. As shown in Figure 9, the frame roll angle θ2 of the lift frame 17 in the site coordinate system is the angle of the y1-axis of the frame IMU 41 relative to the y'-axis.

[0027] The blade IMU 42 has an x2 axis, a y2 axis, and a z2 axis. The x2 axis extends in the fore-and-aft direction of the blade 18. The y2 axis extends in the left-right direction of the blade 18. The z2 axis extends in the up-and-down direction of the blade 18. The on-site coordinate system of the blade 18 has an x″ axis, a y″ axis, and a z″ axis. The x″ axis extends in the direction of the x2 axis projected onto a horizontal plane. The y″ axis extends in the direction of the y2 axis projected onto a horizontal plane. The z″ axis extends in the direction of gravity. As shown in FIG. 8, the blade pitch angle θ3 of the blade 18 in the on-site coordinate system is the angle of the x2 axis of the blade IMU 42 with respect to the x″ axis. As shown in FIG. 9, the blade roll angle θ4 of the blade 18 in the on-site coordinate system is the angle of the y2 axis of the blade IMU 42 with respect to the y″ axis.

[0028] The angle stroke sensors 43A and 43B are attached to the angle cylinders 20A and 20B, respectively. The angle stroke sensor 43A detects the stroke length B1 of the angle cylinder 20A shown in Fig. 4. The angle stroke sensor 43B detects the stroke length B2 of the angle cylinder 20B shown in Fig. 4. For example, the angle stroke sensors 43A and 43B are position sensors that detect the positions of the pistons relative to the cylinder tubes of the angle cylinders 20A and 20B, thereby detecting the stroke lengths B1 and B2 of the angle cylinders 20A and 20B.

[0029] Next, a process for determining the attitude of the blade 18 relative to the lift frame reference in the work machine 1 will be described. The lift frame reference is a coordinate system fixed to the lift frame 17. As shown in FIG. 8, the lift frame reference has an x-axis, a y-axis, and a z-axis. The x-axis extends in the front-to-rear direction of the lift frame 17. More specifically, the x-axis, in a side view of the vehicle, has the lift axis A1 as its origin and extends so as to pass through the center C1 of the ball joint 23. The y-axis extends in the left-to-right direction of the lift frame 17, parallel to the lift axis A1. The z-axis extends perpendicular to the y-axis and x-axis.

[0030] The attitude of the blade 18 relative to the lift frame includes the blade pitch angle, blade tilt angle, and blade angle of the blade 18 relative to the lift frame. For example, as shown in Fig. 10, the blade pitch angle θp relative to the lift frame is the angle between the angle axis A3 and a straight line D1 connecting the second connecting portion 28 of the pitch link 22 and the center C1 of the ball joint 23. As shown in Fig. 11, the blade angle angle θa relative to the lift frame is the angle between a direction D2 parallel to the left-right direction of the lift frame 17 around the angle axis A3 and a direction D3 parallel to the cutting edge of the blade 18.

[0031] 12, the blade tilt angle θt relative to the lift frame is the angle between a direction D4 parallel to the left-right direction of the lift frame 17 around the tilt axis A4 and a direction D5 parallel to the cutting edge of the blade 18. However, the blade pitch angle θp, blade tilt angle θt, and blade angle θa of the blade 18 relative to the lift frame may be any angle as long as they are defined relative to the lift frame 17, and are not limited to the above angles and may be changed.

[0032] FIG. 13 is a flowchart showing a process for determining the attitude of the blade 18 relative to the lift frame in the work machine 1. As shown in FIG. 13, in step S1, the controller 33 acquires the frame pitch angle θ1 and the frame roll angle θ2 in the site coordinate system. The controller 33 acquires the frame pitch angle θ1 and the frame roll angle θ2 in the site coordinate system detected by the frame IMU 41. The frame yaw angle is set to 0 degrees. In other words, the lift frame 17 moves up and down relative to the vehicle body 11 but does not move left and right, so the x' axis of the lift frame 17 in the site coordinate system coincides with the traveling direction of the vehicle body 11.

[0033] In step S2, the controller 33 acquires the blade pitch angle θp relative to the lift frame. The controller 33 repeatedly calculates the attitude of the blade 18 relative to the lift frame at a predetermined cycle. The controller 33 acquires the value of the blade pitch angle at the time of the previous calculation as the blade pitch angle θp relative to the lift frame. If there is no value at the time of the previous calculation, the controller 33 sets the blade pitch angle θp relative to the lift frame to 0 degrees.

[0034] In step S3, the controller 33 acquires the blade tilt angle θt relative to the lift frame. The controller 33 acquires the value of the blade tilt angle at the time of the previous calculation as the blade tilt angle θt relative to the lift frame. If there is no value at the time of the previous calculation, the controller 33 sets the blade tilt angle θt relative to the lift frame to 0 degrees.

[0035] In step S4, the controller 33 acquires the stroke lengths B1 and B2 of the angle cylinders 20A and 20B detected by the angle stroke sensors 43A and 43B. In step S5, the controller 33 acquires the length L1 of the pitch link 22. The length L1 of the pitch link 22 is measured manually, for example, and input to the controller 33 via the input device 38. In step S6, the controller 33 acquires the blade pitch angle θ3 and the blade roll angle θ4 in the on-site coordinate system detected by the blade IMU 42.

[0036] In step S7, the controller 33 determines an estimated value of the blade angle θa relative to the lift frame. The controller 33 calculates the estimated value of the blade angle θa relative to the lift frame based on the blade tilt angle θt relative to the lift frame, the stroke lengths B1 and B2 of the angle cylinders 20A and 20B, and the length L1 of the pitch link 22.

[0037] The blade angle angle θa, blade pitch angle θp, and blade tilt angle θt are correlated. For example, even if the length L1 of the pitch link 22 is the same, if the blade angle angle θa changes, the blade pitch angle θp will change. The controller 33 stores a map that defines the relationship between the length L1 of the pitch link 22, the blade tilt angle θt relative to the lift frame, the stroke length B1 of the angle cylinder 20A, and the blade angle angle θa relative to the lift frame.

[0038] 14 and 15 are diagrams showing examples of maps for calculating the angle angle θa relative to the lift frame. In FIG. 14, a solid line M1 indicates the relationship between the blade tilt angle θt and the blade angle θa relative to the lift frame when the length L1 of the pitch link 22 is a predetermined first value and the stroke length B1 of the angle cylinder 20A is a predetermined first stroke length. A dashed line M2 indicates the relationship between the blade tilt angle θt and the blade angle θa relative to the lift frame when the length of the pitch link 22 is a first value and the stroke length B1 of the angle cylinder 20A is a second stroke length different from the first stroke length. In FIG. 15, a solid line M3 indicates the relationship between the blade pitch angle θp and the blade angle θa relative to the lift frame when the length of the pitch link 22 is a first value. A dashed line M4 indicates the relationship between the blade pitch angle θp and the blade angle θa relative to the lift frame when the length of the pitch link 22 is a second value different from the first value.

[0039] The map is obtained in advance by computer simulation and stored in the controller 33. For example, the map is created by using a 3D model of the work machine 1 to calculate the blade tilt angle θt relative to the lift frame, the stroke lengths B1 and B2 of the angle cylinders 20A and 20B, and the length L1 of the pitch link 22, and calculating the blade angle θa relative to the lift frame when these are changed.

[0040] In step S8, the controller 33 determines the relative yaw angle θ5 of the blade 18 in the site coordinate system. The relative yaw angle θ5 of the blade 18 in the site coordinate system is the angle of the x" axis in the site coordinate system of the blade 18 relative to the x' axis in the site coordinate system of the lift frame 17, as shown in FIG. 7. The controller 33 calculates the relative yaw angle θ5 of the blade 18 in the site coordinate system based on the frame pitch angle θ1 and frame roll angle θ2 in the site work system and the estimated values ​​of the blade pitch angle θp, blade tilt angle θt, and blade angle angle θa relative to the lift frame. As a result, in step S9, the controller 33 obtains the blade pitch angle θ3, blade roll angle θ4, and relative yaw angle θ5 of the blade 18 in the site coordinate system.

[0041] In step S10, the controller 33 determines the attitude of the blade 18 relative to the lift frame based on the relative angle between the angle of the lift frame 17 in the site coordinate system and the angle of the blade 18 in the site coordinate system. That is, in step S10, the controller 33 determines the blade pitch angle θp, blade tilt angle θt, and blade angle angle θa relative to the lift frame. The controller 33 calculates the blade pitch angle θp, blade tilt angle θt, and blade angle angle θa relative to the lift frame based on the frame pitch angle θ1, frame roll angle θ2, and frame yaw angle of the lift frame 17 in the site coordinate system, and the blade pitch angle θ3, blade roll angle θ4, and relative yaw angle θ5 of the blade 18 in the site coordinate system.

[0042] According to the control system for the work machine 1 according to the present embodiment described above, the stroke lengths B1 and B2 of the angle cylinders 20A and 20B are used to determine an estimated value of the blade angle angle θa of the blade 18 relative to the lift frame. While it is difficult for the blade IMU 42 to accurately detect the relative yaw angle θ5 of the blade 18 in the site coordinate system, it is possible to easily and accurately detect the stroke lengths B1 and B2 of the angle cylinders 20A and 20B. Therefore, by using the stroke lengths B1 and B2 of the angle cylinders 20A and 20B, it is possible to accurately determine an estimated value of the blade angle angle θa. This makes it possible to accurately detect the blade angle angle θa relative to the lift frame.

[0043] 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.

[0044] The work machine 1 is not limited to a bulldozer, and may be other vehicles such as a wheel loader or motor grader. The work machine 1 may be remotely operable. In that case, the operation device 37, input device 38, and display 39 may be located outside the work machine 1. The work machine 1 may have multiple controllers that are separate from one another. The processing by the controller 33 described above may be distributed and executed by multiple controllers.

[0045] The structure of the pitch link 22 is not limited to that of the above embodiment and may be modified. For example, the pitch link 22 may be a hydraulic cylinder. In this case, the length L1 of the pitch link 22 may be obtained by detecting the stroke length of the hydraulic cylinder.

[0046] The controller 33 may automatically control the blade 18 using the blade pitch angle θp, blade tilt angle θt, and blade angle angle θa relative to the lift frame. For example, the controller 33 may store a target trajectory of the blade 18 and control the work implement 12 so that the blade 18 moves according to the target trajectory based on the blade pitch angle θp, blade tilt angle θt, and blade angle angle θa relative to the lift frame. Alternatively, the controller 33 may cause the display 39 to display the current position of the blade 18 using the blade pitch angle θp, blade tilt angle θt, and blade angle angle θa relative to the lift frame. [Industrial Applicability]

[0047] According to the present disclosure, the blade angle can be detected with high accuracy in a work machine. [Explanation of symbols]

[0048] 11: Body, 17: Lift frame, 18: Blade, 22: Pitch link, 21: Tilt cylinder, 20A, 20B: Angle cylinder, 41: Frame IMU, 42: Blade IMU

Claims

1. a lift frame supported on the vehicle body so as to be movable in a vertical direction relative to the vehicle body; a blade supported on the lift frame so as to be movable in a pitch direction, a tilt direction, and an angle direction; a pitch link connecting the blade to the lift frame so as to be movable in the pitch direction; a tilt cylinder connected to the lift frame and the blade and moving the blade in the tilt direction; and an angle cylinder connected to the lift frame and the blade and moving the blade in the angle direction, the method being executed by a computer to determine the attitude of the blade relative to the lift frame, obtaining the length of the pitch link; Obtaining a blade tilt angle of the blade relative to the lift frame; Obtaining a stroke length of the angle cylinder; determining an estimate of a blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder; A method for providing

2. Obtaining a map defining a relationship between the length of the pitch link, the blade tilt angle, the stroke length of the angle cylinder, and the blade angle; and determining an estimate of the blade angle relative to the lift frame reference based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder by referring to the map. The method of claim 1.

3. the work machine further includes a frame IMU attached to the lift frame; Using the frame IMU, obtain a frame pitch angle of the lift frame in a site coordinate system and a frame roll angle of the lift frame in the site coordinate system; Obtaining a blade pitch angle of the blade relative to the lift frame; calculating a relative yaw angle of the blade with respect to the lift frame in the site coordinate system based on the frame pitch angle and the frame roll angle of the lift frame in the site coordinate system and the estimated values ​​of the blade pitch angle, the blade tilt angle, and the blade angle angle with respect to the lift frame; The method of claim 1 , comprising:

4. the work machine further includes a blade IMU attached to the blade; Using the blade IMU, obtain a blade pitch angle of the blade in the site coordinate system and a blade roll angle of the blade in the site coordinate system; Calculating the blade pitch angle, the blade tilt angle, and the blade angle angle based on the lift frame reference based on the frame pitch angle and the frame roll angle in the site coordinate system, and the blade pitch angle, the blade roll angle, and the relative yaw angle in the site coordinate system; The method of claim 3 comprising:

5. a lift frame supported on the vehicle body so as to be movable in a vertical direction; a blade supported on the lift frame so as to be movable in a pitch direction, a tilt direction, and an angle direction; a pitch link connecting the blade to the lift frame so as to be movable in the pitch direction; a tilt cylinder connected to the lift frame and the blade to move the blade in the tilt direction; and an angle cylinder connected to the lift frame and the blade to move the blade in the angle direction, an angle stroke sensor that detects the stroke length of the angle cylinder; A controller; Equipped with The controller Obtaining the length of the pitch link; obtaining a blade tilt angle of the blade relative to the lift frame; Obtaining the stroke length of the angle cylinder; determining an estimate of a blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder; system.

6. The controller a map that defines the relationship between the length of the pitch link, the blade tilt angle, the stroke length of the angle cylinder, and the blade angle is stored; determining an estimate of the blade angle relative to the lift frame reference based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder, by referring to the map; The system of claim 5.

7. the work machine further includes a frame IMU attached to the lift frame; The controller using the frame IMU to obtain a frame pitch angle of the lift frame in a site coordinate system and a frame roll angle of the lift frame in the site coordinate system; obtaining a blade pitch angle of the blade relative to the lift frame; calculating a relative yaw angle of the blade with respect to the lift frame based on estimated values ​​of a frame pitch angle and a frame roll angle of the lift frame in the site coordinate system and the blade pitch angle, the blade tilt angle, and the blade angle angle with respect to the lift frame; The system of claim 5.

8. the work machine further includes a blade IMU attached to the blade; The controller using the blade IMU to obtain a blade pitch angle of the blade in the site coordinate system and a blade roll angle of the blade in the site coordinate system; calculating the blade pitch angle, the blade tilt angle, and the blade angle angle based on the lift frame reference based on the frame pitch angle and the frame roll angle in the on-site coordinate system, and the blade pitch angle, the blade roll angle, and the relative yaw angle in the on-site coordinate system; The system of claim 7.

9. The car body and a lift frame supported on the vehicle body so as to be movable in the vertical direction; a blade supported on the lift frame so as to be movable in a pitch direction, a tilt direction, and an angle direction; a pitch link connecting the blade to the lift frame so as to be movable in the pitch direction; a tilt cylinder connected to the lift frame and the blade to move the blade in the tilt direction; an angle cylinder connected to the lift frame and the blade for moving the blade in the angle direction; an angle stroke sensor that detects the stroke length of the angle cylinder; A controller; Equipped with The controller Obtaining the length of the pitch link; obtaining a blade tilt angle of the blade relative to the lift frame; Obtaining the stroke length of the angle cylinder; determining an estimate of a blade angle of the blade relative to the lift frame based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder; Work machinery.

10. The controller a map that defines the relationship between the length of the pitch link, the blade tilt angle, the stroke length of the angle cylinder, and the blade angle is stored; determining an estimate of the blade angle relative to the lift frame reference based on the length of the pitch link, the blade tilt angle, and the stroke length of the angle cylinder, by referring to the map; 10. The work machine according to claim 9.

11. a frame IMU attached to the lift frame; The controller using the frame IMU to obtain a frame pitch angle of the lift frame in a site coordinate system and a frame roll angle of the lift frame in the site coordinate system; obtaining a blade pitch angle of the blade relative to the lift frame; calculating a relative yaw angle of the blade with respect to the lift frame in the site coordinate system based on the frame pitch angle and the frame roll angle in the site coordinate system and the estimated values ​​of the blade pitch angle, the blade tilt angle, and the blade angle angle with respect to the lift frame; 10. The work machine according to claim 9.

12. a blade IMU attached to the blade; The controller using the blade IMU to obtain a blade pitch angle of the blade in the site coordinate system and a blade roll angle of the blade in the site coordinate system; calculating the blade pitch angle, the blade tilt angle, and the blade angle angle based on the lift frame reference based on the frame pitch angle and the frame roll angle in the on-site coordinate system, and the blade pitch angle, the blade roll angle, and the relative yaw angle in the on-site coordinate system; 12. A work machine according to claim 11.

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