Control device, control method, and work machine

Abstract

To provide a control device, a control method, and a work machine capable of improving work efficiency in excavation work.SOLUTION: The control device includes: An apparatus for controlling a work implement including a boom rotatably coupled to a main body of a work machine including the work implement, an arm rotatably coupled to the boom, and a bucket rotatably coupled to the arm, the apparatus controlling an operation of the boom in accordance with operations of the bucket and the arm such that a direction of a vector of a force generated at a tip portion of a blade included in the bucket is a normal direction of a straight line connecting a coupling portion between the arm and the boom and the tip portion during excavation work.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a control device, a control method, and a work machine. [Background technology]

[0002] Patent Document 1 describes a control device that can automatically release range limiting control of a work machine. Patent Document 1 also describes that, in response to the operation of one of multiple control levers, the direction of the velocity vector of the bucket tip is controlled so that it is perpendicular to a line connecting the boom, arm, or bucket pivot point and the bucket tip (paragraph 0027 of Patent Document 1). However, Patent Document 1 does not specifically describe the simultaneous operation of multiple control levers. Patent Document 2 also describes a work machine that generates a target trajectory for the work machine according to an excavation curve ratio, which is expressed as the ratio of excavation depth to excavation length, and automatically operates the work machine according to the target trajectory. The work machine described in Patent Document 2 determines the target position and target attitude of the bucket based on the target trajectory and the current position of the bucket cutting edge, and controls the boom, arm, and bucket based on the determined target position and target attitude of the bucket. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4455465 [Patent Document 2] Patent No. 7088792 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, it is known that in excavation work, a skilled operator can perform the work efficiently by operating the boom, arm, and bucket in coordination. However, the control device of Patent Document 1 cannot operate the boom, arm, and bucket in coordination, which poses a problem that excavation work may not be performed efficiently. Furthermore, the work machine of Patent Document 2 controls the work equipment using position and attitude as targets, which poses a problem that excavation work may not be performed efficiently depending on, for example, the hardness and weight of the material to be excavated.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a control device, a control method, and a work machine that can improve work efficiency in excavation work. [Means for solving the problem]

[0006] One aspect of the present disclosure is a device for controlling a work machine having a working implement, the work machine having a boom rotatably connected to a main body of the work machine, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm, wherein the control device controls the movement of the boom in accordance with the movement of the bucket and the arm so that, during excavation work, the direction of the vector of the force generated at the tip of the blade of the bucket is normal to the line connecting the connection between the arm and the boom and the tip.

[0007] Another aspect of the present disclosure is a method for controlling a work machine having a boom rotatably connected to a main body of the work machine equipped with the work implement, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm, the method controlling the movement of the boom in accordance with the movement of the bucket and the arm so that, during excavation work, the direction of the vector of the force generated at the tip of the blade of the bucket is normal to the line connecting the connection between the arm and the boom and the tip.

[0008] Another aspect of the present disclosure is a work machine comprising: a main body, a boom rotatably connected to the main body, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm; and a control device that controls the operation of the boom in accordance with the operation of the bucket and the arm so that, during excavation work, the direction of the vector of the force generated at the tip of the blade of the bucket is normal to the line connecting the connection between the arm and the boom and the tip. [Effects of the Invention]

[0009] The control device, control method, and work machine disclosed herein can improve the work efficiency in excavation work. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side view showing a hydraulic excavator, which is a work machine according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a system diagram according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a diagram illustrating an example of a flow of an excavation operation according to an embodiment of the present disclosure. [Figure 4] FIG. 10 illustrates an example of cutting edge force direction control according to an embodiment of the present disclosure. [Figure 5] FIG. 10 illustrates an example of cutting edge force direction control according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a diagram illustrating a coordinate system and the like of a work machine according to an embodiment of the present disclosure. [Figure 7] FIG. 10 is a schematic diagram for explaining an example of weight correction for a work machine according to an embodiment of the present disclosure. [Figure 8] FIG. 1 is a functional block diagram according to an embodiment of the present disclosure. [Figure 9] 11 is a flowchart illustrating an example of operation of the control device according to the embodiment of the present disclosure, together with FIG. 10 . [Figure 10] 10 is a flowchart illustrating an example of operation of the control device according to the embodiment of the present disclosure, together with FIG. 9 . [Figure 11]FIG. 10 is a schematic diagram for explaining an example of the operation of the control device according to the embodiment of the present disclosure. [Figure 12] FIG. 1 is a functional block diagram according to an embodiment of the present disclosure. [Figure 13] FIG. 10 is a diagram illustrating a change in boom cylinder force over time according to an embodiment of the present disclosure. [Figure 14] FIG. 10 is a diagram illustrating an example of a correction angle value according to an embodiment of the present disclosure. [Figure 15] 17 is a flowchart illustrating another example of operation of the control device according to the embodiment of the present disclosure, together with FIG. 16. [Figure 16] 16 is a flowchart illustrating another example of operation of the control device according to the embodiment of the present disclosure, in conjunction with FIG. 15 . DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

[0012] FIG. 1 is a side view showing a hydraulic excavator 1, which is a work machine according to an embodiment. The hydraulic excavator 1 has a vehicle body 1B as a main body and a work implement 2. The vehicle body 1B has an upper rotating body 3, which is a rotating body, and a traveling device 5, which is a traveling body. The upper rotating body 3 accommodates devices such as an engine, which is a power generating device, and a hydraulic pump inside an engine room 3EG. In the embodiment, the hydraulic excavator 1 uses an internal combustion engine, such as a diesel engine, as the engine, which is the power generating device, but the power generating device is not limited to an internal combustion engine. The power generating device of the hydraulic excavator 1 may be, for example, a so-called hybrid device that combines an internal combustion engine, a generator motor, and a power storage device. Alternatively, the power generating device of the hydraulic excavator 1 may not have an internal combustion engine, but may instead combine a power storage device and a generator motor.

[0013] The upper rotating body 3 has a driver's seat 4. The driver's seat 4 is installed on the other end side of the upper rotating body 3. In other words, the driver's seat 4 is installed on the opposite side to the side where the engine room 3EG is located. The driver's seat 4 is provided with operating devices 50 such as a plurality of levers, pedals, switches, etc.

[0014] The traveling device 5 is mounted on the upper rotating body 3. The traveling device 5 has tracks 5a (tracks 5b on the back side of the page). The traveling device 5 is driven by one or both of hydraulic motors 5c provided on the left and right sides. The tracks 5a, 5b of the traveling device 5 rotate to cause the hydraulic excavator 1 to travel. The work implement 2 is attached in front of the driver's seat 4 of the upper rotating body 3.

[0015] The hydraulic excavator 1 may be provided with tires instead of the tracks 5a, 5b, and may be provided with a traveling device that can transmit the driving force of the engine to the tires via a transmission to travel. An example of such a hydraulic excavator 1 is a wheeled hydraulic excavator.

[0016] The side of the upper rotating body 3 where the work implement 2 and the driver's seat 4 are located is the front, and the side where the engine room 3EG is located is the rear. The left side as you face the front is the left of the upper rotating body 3, and the right side as you face the front is the right of the upper rotating body 3. The left-right direction of the upper rotating body 3 is also called the width direction. With respect to the hydraulic excavator 1 or the vehicle body 1B, the traveling gear 5 side is the bottom relative to the upper rotating body 3, and the upper rotating body 3 side is the top relative to the traveling gear 5.

[0017] The work implement 2 has a boom 6, an arm 7, and a bucket 8, which is a work implement, a boom cylinder 10, an arm cylinder 11, and a bucket cylinder 12. The base end of the boom 6 is rotatably connected to the front of the vehicle body 1B via a boom pin 13. The base end of the arm 7 is rotatably connected to the tip of the boom 6 via an arm pin 14. The bucket 8 is rotatably connected to the tip of the arm 7 via a bucket pin 15. The bucket 8 rotates around the bucket pin 15. The bucket 8 has multiple blades 8B attached to the side opposite the bucket pin 15. Blade tips 8T are the tips (tip portions) of the blades 8B. The arm pin 14 is a connection between the arm 7 and the boom 6 according to the present disclosure. Furthermore, hereinafter, the boom 6, arm 7, and bucket 8 will be collectively referred to as work implement elements. The boom cylinder 10, arm cylinder 11, bucket cylinder 12, etc. are one configuration example of an "actuator" according to the present disclosure.

[0018] Bucket 8 does not have to have multiple blades 8B. In other words, it may not have blades 8B as shown in Fig. 1, and the cutting edge may be formed in a straight shape from a steel plate. Work implement 2 may be equipped with, for example, a flat-blade bucket with a single blade.

[0019] The boom cylinder 10, arm cylinder 11, and bucket cylinder 12 shown in Fig. 1 are hydraulic cylinders each driven by the pressure of hydraulic oil discharged from a hydraulic pump. The boom cylinder 10 drives the boom 6 to raise and lower it. The arm cylinder 11 drives the arm 7 to rotate it about an arm pin 14. The bucket cylinder 12 drives the bucket 8 to rotate it about a bucket pin 15.

[0020] In this embodiment, the boom pin 13 corresponds to the boom foot (or the boom foot position), the arm pin 14 corresponds to the boom top (or the boom top position) and the arm foot (or the arm foot position), and the bucket pin 15 corresponds to the bucket foot (or the bucket foot position) and the arm top (or the arm top position).

[0021] Figure 2 is a system diagram of a work machine 1 according to an embodiment of the present disclosure. The work machine 1 shown in Figure 2 is equipped with a control device 30, a boom cylinder head pressure sensor 41, a boom cylinder bottom pressure sensor 42, a boom cylinder stroke sensor 43, an arm cylinder head pressure sensor 44, an arm cylinder bottom pressure sensor 45, an arm cylinder stroke sensor 46, a bucket cylinder head pressure sensor 47, a bucket cylinder bottom pressure sensor 48, a bucket cylinder stroke sensor 49, an operation device 50, a vehicle body tilt angle sensor 51, and an input device 52. The work machine 1 shown in Figure 2 also is equipped with an arm shaft hydraulic valve 61, a bucket shaft hydraulic valve 62, and a boom shaft hydraulic valve 63.

[0022] The control device 30 can be configured using a computer such as a microcontroller and peripheral circuits, for example, and includes a work machine control unit 31 as a functional block configured by a combination of hardware such as a computer and peripheral circuits, and software such as a program executed by the computer. The work machine control unit 31 also includes a cutting edge force direction control unit 32. The control device 30 is a device that controls the work machine 2, which has a boom 6 rotatably connected to the vehicle body 1B (main body) of the work machine 1 equipped with the work implement 2, an arm 7 rotatably connected to the boom 6, and a bucket 8 rotatably connected to the arm 7. The work machine control unit 31 also includes one or more other control units, such as a control unit for implementing automatic operation of the work implement 2, upper revolving body 3, traveling device 5, etc., and a control unit for controlling the work implement 2, upper revolving body 3, traveling device 5, etc. in accordance with the operation of the operation device 50, etc.

[0023] The cutting edge force direction control unit 32 controls the direction of the cutting edge force in the excavation mode (excavation operation) during excavation work. FIG. 3 shows an example of the basic flow of excavation work. In excavation work, first, the bucket 8 is moved to the excavation start position (step S1). Next, excavation (also referred to as the excavation mode) is performed (step S2). Next, excavation is completed and the bucket 8 is raised (step S3). Next, swing and the bucket 8 is raised (step S4). Swinging while the bucket 8 is raised (or while holding the excavated material) is also called hoist swing. Next, the excavated material, such as earth and sand, is discharged (ejected) at the discharge position (step S5). Next, swing and the bucket 8 is lowered (step S6). Swinging while the bucket 8 is lowered is also called down swing. If excavation is still to be continued, the work from step S1 onwards is repeated. Note that all or part of the operations in steps S1 to S6 may be performed automatically in an unmanned state, for example, or may be performed manually by an operator while on board the work machine 1 or from a remote location, or may be performed semi-automatically with some parts automated. The cutting edge force direction control unit 32 of this embodiment performs cutting edge force direction control for the excavation (excavation mode) in step S2. Note that the start and end conditions for the excavation mode can be determined, for example, by a notification from a control function that performs automatic operation in the case of automatic operation, or by the operation of a predetermined operation button or the like in the case of manual operation.

[0024] An overview of cutting edge force direction control in this embodiment will be described with reference to FIG. 4. FIG. 4 schematically illustrates a state in which the work machine 2 is excavating an excavation object 70. During excavation work, if the arm 7 and bucket 8 are considered to be rigid bodies at each instant of excavation, in order for this rigid body to efficiently push the soil around the arm foot fulcrum (arm pin 14), it is preferable that the direction of the cutting edge force vector F_hsk be perpendicular to the line L1 connecting the arm foot (arm pin 14) and the cutting edge 8T. The cutting edge force vector F_hsk is a force generated at the tip (cutting edge 8T) of the blade 8B of the bucket 8. The magnitude of the cutting edge force vector F_hsk is determined by the object being excavated (the hardness and weight of the soil). Therefore, intentional control is generally not possible. However, the direction of the cutting edge force vector F_hsk can be controlled.

[0025] The cutting edge force vector F_hsk is determined by the work implement attitude, boom shaft torque (shaft torque of the boom 6's rotation shaft (boom pin 13)) Trq_bm, arm shaft torque (shaft torque of the arm 7's rotation shaft (arm pin 14)) Trq_am, and bucket shaft torque (shaft torque of the bucket 8's rotation shaft (bucket pin 15)) Trq_bkt. In this case, once the direction of the cutting edge force vector F_hsk is determined, the target boom shaft torque, which is the target value of the boom shaft torque Trq_bm, can be back-calculated from the work implement attitude, arm shaft torque Trq_am, and bucket shaft torque Trq_bkt. The work implement attitude is geometrically calculated based on the angles (rotation angles) of each work implement element, etc.

[0026] Cutting edge force direction control unit 32 controls the movement of boom 6 in accordance with the movement of bucket 8 and arm 7 so that the direction of the force vector (cutting edge force vector F_hsk) generated at the tip (cutting edge 8T) of blade 8B of bucket 8 during excavation work is approximately normal (substantially vertical) to line L1 connecting the connecting part (arm pin 14) between arm 7 and boom 6 and the tip (cutting edge 8T). At this time, cutting edge force direction control unit 32 feedback-controls the cylinder force to control the movement of boom 6, as will be described later, so that a target torque determined based on the attitude of work implement 2, the axial torque of the pivot shaft of arm 7, and the axial torque of the pivot shaft of bucket 8 becomes a target cylinder force that drives boom 6. Alternatively, the cutting edge force direction control unit 32 may control the operation of the boom 6 by feedback-controlling the axial torque Trq_bm of the rotation shaft of the boom 6 so that the target torque is determined based on the attitude of the work implement 2, the axial torque Trq_am of the rotation shaft of the arm 7, and the axial torque Trq_bkt of the rotation shaft of the bucket 8. The cutting edge force direction control unit 32 may correct the approximately normal direction using a predetermined correction value, as described below. The predetermined correction value may be changeable, for example, in response to an instruction from an operator. The cutting edge force direction control unit 32 may set the target cylinder force or target torque to a corrected value based on the weight of each element of the work implement 2 and the tilt angle of the vehicle body 1B (main body), as described below.

[0027] 5 is a diagram illustrating an example of cutting edge force direction control according to an embodiment of the present disclosure. Fig. 5 shows an example of changes in the posture of the work machine 2 at time intervals of Δt from the beginning of excavation in the upper left, and changes in the line L1 and the cutting edge force vector F_hsk.

[0028] Returning to FIG. 2 , the boom cylinder head pressure sensor 41 measures the head pressure of the hydraulic pressure supplied to the boom cylinder 10 and outputs the measurement result to the control device 30. The boom cylinder bottom pressure sensor 42 measures the bottom pressure of the hydraulic pressure supplied to the boom cylinder 10 and outputs the measurement result to the control device 30. The boom cylinder stroke sensor 43 measures the cylinder length of the boom cylinder 10 and outputs the measurement result to the control device 30. The arm cylinder head pressure sensor 44 measures the head pressure of the hydraulic pressure supplied to the arm cylinder 11 and outputs the measurement result to the control device 30. The arm cylinder bottom pressure sensor 45 measures the bottom pressure of the hydraulic pressure supplied to the arm cylinder 11 and outputs the measurement result to the control device 30. The arm cylinder stroke sensor 46 measures the cylinder length of the arm cylinder 11 and outputs the measurement result to the control device 30. The bucket cylinder head pressure sensor 47 measures the head pressure of the hydraulic pressure supplied to the bucket cylinder 12 and outputs the measurement result to the control device 30. A bucket cylinder bottom pressure sensor 48 measures the bottom pressure of the hydraulic pressure supplied to the bucket cylinder 12 and outputs the measurement result to the control device 30. A bucket cylinder stroke sensor 49 measures the cylinder length of the bucket cylinder 12 and outputs the measurement result to the control device 30. A vehicle body inclination angle sensor 51 measures the inclination angle of the vehicle main body 1B (main body portion) and outputs the measurement result to the control device 30. The input device 52 includes a touch panel, a dial, etc., and is used to input predetermined correction values ​​and the like (such as a cutting edge force target direction correction value k_rev, which will be described later) in response to an operation by the operator and outputs the input result to the control device 30.

[0029] The arm shaft hydraulic valve 61 includes a plurality of control valves, relief valves, etc., and adjusts the hydraulic pressure supplied to the arm cylinder 11 based on the arm shaft valve command value output by the control device 30. The bucket shaft hydraulic valve 62 adjusts the hydraulic pressure supplied to the bucket cylinder 12 based on the bucket shaft valve command value output by the control device 30. The boom shaft hydraulic valve 63 adjusts the hydraulic pressure supplied to the boom cylinder 10 based on the boom shaft valve command value output by the control device 30.

[0030] During excavation work shown in FIG. 3 , for example, the work machine control unit 31 automatically generates and outputs an arm shaft valve command value and a bucket shaft valve command value in steps S1 to S6, or generates and outputs an arm shaft valve command value and a bucket shaft valve command value in response to an operator's operation on the control device 50. In addition, the work machine control unit 31 automatically generates and outputs a boom shaft valve command value in step S1 and steps S3 to S6, or generates and outputs a boom shaft valve command value in response to an operator's operation on the control device 50. In the excavation mode of step S2, the cutting edge force direction control unit 32 automatically generates and outputs a boom shaft valve command value. In addition, the work machine control unit 31 can generate and output control signals (not shown) to the upper rotating body 3 and the traveling unit 5 automatically, or in response to an operator's instruction.

[0031] Next, an example of the operation of the control device 30 will be described. First, with reference to Fig. 6 and Fig. 7, the work machine coordinate system used in this embodiment and some of the variables used in the processing will be described. Fig. 6 is a diagram showing the coordinate system of the work machine according to the embodiment of the present disclosure. Fig. 7 is a schematic diagram for explaining an example of self-weight correction of the work machine according to the embodiment of the present disclosure.

[0032] The work implement coordinate system shown in FIG. 6 has the boom foot (boom pin 13) as its origin, the vertical direction relative to the vehicle body 1B as the Y-axis, the fore-and-aft direction of the work implement 2 as the X-axis, and the direction perpendicular to the paper surface as the rotation axis (Z-axis). FIG. 6 shows the boom cylinder length l_cyl_bm, arm cylinder length l_cyl_am, bucket cylinder length l_cyl_bkt, boom angle (with respect to the vehicle body) θ_bm, arm angle (with respect to the boom axis) θ_am, bucket angle (with respect to the arm axis) θ_bkt, boom cylinder moment length l_mt_bm, arm cylinder moment length l_mt_am, bucket cylinder moment length l_mt_bkt, boom axis length l_bm which is the line connecting the boom foot and the boom top, arm axis length l_am which is the line connecting the arm foot and the arm top, and bucket axis length l_bkt which is the line connecting the bucket foot and the cutting edge 8T (bucket top). Note that the clockwise direction is positive. The boom angle θ_bm, the arm angle θ_am, and the bucket angle θ_bkt are also referred to as shaft angles.

[0033] 7 shows the center of gravity CG1 of the boom 6, the center of gravity CG2 of the arm 7, the center of gravity CG3 of the bucket 8, the distance l_G_bm between the boom center of gravity and the boom foot, the distance l_G_am between the center of gravity of the arm and the arm foot, the distance l_G_bkt between the center of gravity of the bucket and the bucket foot, the gravity W_bm acting on the boom 6, the gravity W_am acting on the arm 7, the gravity W_bkt acting on the bucket 8, the angle θ_G_bm between the line connecting the boom center of gravity and the boom foot and the line connecting the boom top and the boom foot, the angle θ_G_am between the line connecting the arm center of gravity and the arm foot and the line connecting the arm top and the arm foot, and the angle θ_G_bkt between the line connecting the bucket center of gravity and the bucket foot and the line connecting the bucket top and the bucket foot. FIG. 7 also shows the vehicle body inclination θ_vcl.

[0034] 8 schematically shows input and output signals of cutting edge force direction control unit 32 and the flow of signal processing from input signals to output signals. In the example shown in Fig. 8, vehicle body inclination θ_vcl, cutting edge force target direction correction value k_rev, boom cylinder length l_cyl_bm, arm cylinder length l_cyl_am, bucket cylinder length l_cyl_bkt, boom cylinder bottom pressure P_bm_btm, boom cylinder head pressure P_bm_hd, arm cylinder bottom pressure P_am_btm, arm cylinder head pressure P_am_hd, bucket cylinder bottom pressure P_bkt_btm, and bucket cylinder head pressure P_bkt_hd are used as input signals, and a boom axis valve command value Odr_vlv_bm is calculated as an output signal. The arm axis valve command value Odr_vlv_am and bucket axis valve command value Odr_vlv_bkt, which are enclosed by dashed line blocks, are calculated by a component within work machine control unit 31 other than cutting edge force direction control unit 32, for example. The cutting edge force target direction correction value k_rev is input, for example, by the input device 52 (or further stored in a predetermined storage area).

[0035] Next, an example of the operation of the cutting edge force direction control unit 32 will be described with reference to the flowcharts shown in Figures 9 and 10. The flow shown in Figure 9 and the flow shown in Figure 10 are connected to each other by the same connectors C1 and C2.

[0036] 9 is started when the excavation mode is started, and each step is repeatedly executed at a predetermined cycle until the excavation mode is ended. In the process shown in FIG. 9, cutting edge force direction control unit 32 first acquires the following data (step S101). The data acquired in step S101 is cutting edge force target direction correction value k_rev, cylinder length sensor data for each axis (boom cylinder length l_cyl_bm, arm cylinder length l_cyl_am, and bucket cylinder length l_cyl_bkt), vehicle body inclination angle sensor data (vehicle body inclination θ_vcl), and hydraulic pressure sensor data for each axis cylinder (boom cylinder bottom pressure P_bm_btm, boom cylinder head pressure P_bm_hd, arm cylinder bottom pressure P_am_btm, arm cylinder head pressure P_am_hd, bucket cylinder bottom pressure P_bkt_btm, and bucket cylinder head pressure P_bkt_hd).

[0037] Next, the cutting edge force direction control unit 32 calculates the shaft angle of each work machine element and the coordinates of each point of the work machine from the cylinder length of each shaft (step S102). In step S102, for example, the x-coordinate bm_top_x and y-coordinate bm_top_y of the boom top, the x-coordinate am_top_x and y-coordinate am_top_y of the arm top, and the x-coordinate bkt_top_x and y-coordinate bkt_top_y of the bucket top are calculated using equations (1) to (6), for example.

[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0044] Next, the cutting edge force direction control unit 32 calculates the moment lengths (moment length l_mt_bm of the boom cylinder, moment length l_mt_am of the arm cylinder, and moment length l_mt_bkt of the bucket cylinder) when converting the cylinder force into axial torque (step S103).

[0045] Next, the cutting edge force direction control unit 32 calculates the target direction of the cutting edge force (cutting edge force target direction k_mok) from the cutting edge force target direction correction value k_rev, the boom top coordinates (bm_top_x and bm_top_y), and the bucket cutting edge coordinates (bkt_top_x and bkt_top_y) shown in Fig. 11 (equation (7)) (step S104). At that time, the cutting edge force direction control unit 32 calculates the boom top → bucket cutting edge inclination k_weqp (equation (8)).

[0046]

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[0047]

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[0048] Next, the cutting edge force direction control unit 32 calculates the influence of the weight of each work equipment element on each cylinder from the shaft angle of each work equipment element, the coordinates of each point of the work equipment, the vehicle body tilt angle, and the moment length when converting the cylinder force to shaft torque (step S105). In step S105, the weight holding boom cylinder force F_hld_bm, weight holding arm cylinder force F_hld_am, weight holding bucket cylinder force F_hld_bkt, etc. are calculated using, for example, equations (9) to (17).

[0049]

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[0050]

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[0054]

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[0055]

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[0058] Here, x_G_bm is the horizontal distance of the boom center of gravity. x_G_am is the horizontal distance of the arm center of gravity (based on the arm foot). x_G_bkt is the horizontal distance of the bucket center of gravity (based on the bucket foot). l_G_bm is the distance between the boom center of gravity and the boom foot. l_G_am is the distance between the arm center of gravity and the arm foot. l_G_bkt is the distance between the bucket center of gravity and the bucket foot. hld_bm_top_x is the horizontal distance of the boom top for holding force calculation. hld_am_top_x is the horizontal distance of the arm top for holding force calculation (based on the boom foot). hld_local_am_top_x is the horizontal distance of the arm top for holding force calculation (based on the arm foot). Wt_bkt is the bucket mass. Wt_am is the arm mass. Wt_bm is the boom mass.

[0059] Next, the cutting edge force direction control unit 32 calculates each axis cylinder force corrected for its own weight from the hydraulic pressure sensor data of each axis cylinder and the influence of the weight of each work machine element on each cylinder (step S106). In step S106, the boom cylinder force (including its own weight correction) F_cyl_bm, the arm cylinder force (including its own weight correction) F_cyl_am, and the bucket cylinder force (including its own weight correction) F_cyl_bkt are calculated using, for example, equations (18) to (20).

[0060]

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[0061]

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[0063] Here, A_bm_btm is the pressure receiving area on the bottom side of the boom cylinder. A_bm_hd is the pressure receiving area on the head side of the boom cylinder. A_am_btm is the pressure receiving area on the bottom side of the arm cylinder. A_am_hd is the pressure receiving area on the head side of the arm cylinder. A_bkt_btm is the pressure receiving area on the bottom side of the bucket cylinder. A_bkt_hd is the pressure receiving area on the head side of the bucket cylinder. Also, the cylinder force is positive when it pushes in the extension direction.

[0064] Next, the cutting edge force direction control unit 32 calculates the arm shaft torque Trq_am and the bucket shaft torque Trq_bkt using equations (21) and (22) from the cylinder force corrected for the moment length and the weight when converting the cylinder force into shaft torque at the arm shaft and bucket shaft (step S107).

[0065]

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[0067] Next, the cutting edge force direction control unit 32 calculates the Jacobian matrix J from the shaft angles of each work machine element (step S108), calculates the inverse Jacobian matrix J-1 from the Jacobian matrix J (step S109), and calculates the boom axis target torque from the cutting edge force target direction, arm axis torque, bucket axis torque, and inverse Jacobian matrix (step S110).

[0068] If the x-coordinate of the cutting edge 8T (equivalent to bkt_top_x in equation (5)) is expressed by equation (23), the y-coordinate of the cutting edge 8T (equivalent to bkt_top_y in equation (6)) is expressed by equation (24), and the angle θz of the cutting edge 8T is expressed by equation (25), the relationship between the time differential values ​​of x, y, and θz and the time differential values ​​of the boom angle θ_bm, arm angle θ_am, and bucket angle θ_bkt can be expressed by equation (26) using the Jacobian matrix J. Note that the components J11 to J33 of the Jacobian matrix J are expressed by equation (27). Note that the angle θz is an angle relative to the X-axis.

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[0074] Here, when equation (28), derived from the principle of virtual work, is transformed using equation (26), equation (29) is obtained. Note that M_hsk_z is the moment around the Z axis. Furthermore, when equation (29) is transformed using the inverse matrix J-1 (equation (31)) of the Jacobian matrix shown in equation (26), equation (30) is obtained.

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[0079] Using each axial torque and the inverse Jacobian matrix, the x and y components of the cutting edge force vector F_hsk can be calculated using equations (32) and (33), and the cutting edge force target direction k_mok can be calculated using equation (34).

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[0083] Furthermore, from equations (32) to (34), the boom shaft desired torque Trq_mok_bm is calculated by equation (35).

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[0085] In step S110, the cutting edge force direction control unit 32 calculates the boom shaft target torque Trq_mok_bm using equations (35) and k_mok in equation (7).

[0086] Next, cutting edge force direction control unit 32 calculates boom cylinder target force F_cyl_bm_mok using equation (36) from the moment length when converting the cylinder force related to the boom axis into axial torque (step S111). Next, cutting edge force direction control unit 32 calculates boom axis valve command value Odr_vlv_bm from the boom axis cylinder force F_cyl_bm corrected for its own weight and the boom cylinder target force F_cyl_bm_mok (step S112).

[0087]

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[0088] FIG. 12 shows an example of a control block for calculating the boom axis valve command value Odr_vlv_bm from the boom cylinder target force F_cyl_bm_mok and the boom axis cylinder force F_cyl_bm corrected for its own weight in step S112. A subtractor 81 calculates the boom cylinder deviation ΔF_cyl_bm by subtracting the boom axis cylinder force F_cyl_bm corrected for its own weight from the boom cylinder target force F_cyl_bm_mok. A proportional actuator 82 multiplies the boom cylinder deviation ΔF_cyl_bm by a predetermined coefficient Kp and outputs the result. An integral actuator 83 time-integrates the boom cylinder deviation ΔF_cyl_bm, multiplies it by a predetermined coefficient Ki, and outputs the result. An adder 84 adds the output of the proportional actuator 82 and the output of the integral actuator 83 to calculate the boom axis valve command value Odr_vlv_bm.

[0089] Next, cutting edge force direction control unit 32 outputs a boom axis valve command value Odr_vlv_bm, a predetermined arm axis valve command value Odr_vlv_am, and a bucket axis valve command value Odr_vlv_bk (step S113).

[0090] Next, the cutting edge force direction control unit 32 determines whether the excavation mode has ended (whether the termination condition has been met) (step S114). If the excavation mode has not ended (step S114: N), the cutting edge force direction control unit 32 executes the processing from step S101 again, and if the termination condition has been met (step S114: Y), the cutting edge force direction control unit 32 ends the excavation mode and transitions to another work mode (step S115).

[0091] As described above, the control device 30 of this embodiment is a device that controls the work machine 1 having the boom 6 rotatably connected to the vehicle body 1B (main body) of the work machine 1 equipped with the work implement 2, the arm 7 rotatably connected to the boom 6, and the bucket 8 rotatably connected to the arm 7. During excavation work, the control device 30 controls the movement of the boom 6 in accordance with the movement of the bucket 8 and the arm 7 so that the direction of the force vector (cutting edge force vector F_hsk) generated at the cutting edge 8T (tip) of the blade 8B of the bucket 8 is approximately normal to the line L1 connecting the connecting portion (arm pin 14) between the arm 7 and the boom 6 and the cutting edge 8T (tip). With this configuration, the boom, arm, and bucket can be operated in coordination, allowing excavation work to be performed efficiently. In other words, the control device 30 of this embodiment can improve the work efficiency in excavation work.

[0092] Furthermore, the control device 30 of this embodiment controls the operation of the boom 6 by controlling the cylinder force so that the target torque, which is determined based on the attitude of the work implement 2, the axial torque of the rotation shaft of the arm 7, and the axial torque of the rotation shaft of the bucket 8, becomes a target cylinder force that drives the boom 6. With this configuration, the axial torque of the boom can be controlled to the target torque by feedback control of the cylinder force.

[0093] Furthermore, the control device 30 of this embodiment corrects the approximately normal direction using a changeable predetermined correction value (cutting edge force target direction correction value k_rev). With this configuration, the direction of the cutting edge force vector F_hsk can be corrected to suit, for example, the preference of the operator.

[0094] Furthermore, in the control device 30 of this embodiment, the target cylinder force is a value corrected based on the weight of the work implement 2 and the tilt angle of the vehicle body 1B (main body). With this configuration, the direction of the cutting edge force vector F_hsk can be controlled with high precision.

[0095] FIG. 13 shows the verification results of this embodiment. The horizontal axis represents time, and the vertical axis represents the boom cylinder force [kg]. The dashed line represents the change in cylinder force during excavation when the cutting edge force target direction correction value k_rev is set to 0 degrees (when the cutting edge force vector F_hsk is set to the normal direction (vertical)). The solid line represents the change in cylinder force during excavation when the cutting edge force target direction correction value k_rev is set to 10 degrees (when the cutting edge force vector F_hsk is set at a shallower angle of 10 degrees from the normal direction (vertical)). It can be seen that excavation efficiency is higher when the cutting edge force vector F_hsk is set to the normal direction. However, in the example shown in FIG. 13, when the cutting edge force vector F_hsk is set to the normal direction, a cylinder force that exceeds the force SP corresponding to the set pressure of the relief valve is generated.

[0096] Therefore, in the modified example of this embodiment shown in Figs. 14 to 16, the target direction (i.e., the approximately normal direction) of the cutting edge force vector F_hsk is corrected in accordance with the load on the actuator that rotates the boom. Fig. 14 shows an example of the relationship between the cutting edge force target direction inclination correction angle value k_rev_deg and the boom cylinder hydraulic pressure. The cutting edge force target direction inclination correction angle value k_rev_deg is a correction value added to the cutting edge force target direction correction value k_rev. Up to a threshold value (F_α), the cutting edge force target direction inclination correction angle value k_rev_deg is "0". Above the threshold value (F_α), The absolute value increases with a constant slope up to the minimum value k_rev_deg_min.

[0097] Figures 15 and 16 show an example of operation of a modified example. The flow shown in Figure 15 and the flow shown in Figure 16 are connected to each other by the same connectors C11 and C12. Steps S3A and S3B are added to the processes shown in Figures 9 and 10 in the processes shown in Figures 15 and 16. In step S3A, it is determined whether the boom lowering force is equal to or greater than a specified value. If it is equal to or greater than the specified value, a cutting edge force target direction inclination correction angle value k_rev_deg corresponding to the boom lowering force is added to the cutting edge force target correction value k_rev by referring to the map shown in Figure 14, for example (step S3B).

[0098] In this embodiment, the approximately normal direction, which is the cutting edge force target direction k_mok, is corrected according to the load on the actuator (boom cylinder 10) that rotates the boom 6. This configuration makes it possible to avoid, for example, the relief valve from operating.

[0099] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to the above-described embodiments and includes design modifications and the like within the scope of the present invention. Furthermore, a part or all of the programs executed by a computer, such as the control device 30, in the above-described embodiments can be distributed via a computer-readable recording medium or a communication line. For example, in the above-described embodiment, the movement of the boom 6 is controlled so that the direction of the force vector (cutting edge vector F_hsk) generated at the tip of the blade of the bucket 8 (cutting edge 8T) is approximately normal to the line L1 connecting the connecting portion (arm pin 14) between the arm 7 and the boom 6 and the tip of the bucket 8 (cutting edge 8T). In this case, "approximately normal direction" refers to, for example, a predetermined angle range including the normal direction (90 degrees). Here, the predetermined angle range refers to, for example, the range of errors resulting from calculation accuracy and detection accuracy of each sensor, or the range of offsets in cases where offsetting the target value by a predetermined value from 90 degrees improves control performance. Therefore, if the term "normal direction" is understood to mean a direction having a certain angle range based on 90 degrees in automatic control that targets the "normal direction," then in this disclosure "approximately normal direction" can be read as "normal direction" with the "approximately" omitted.

[0100] [Note] The control device 30 described in the embodiment can be understood as follows.

[0101] (1) A control device according to a first aspect of the present disclosure is a device for controlling a work machine having a working implement, the work machine having a boom rotatably connected to a main body of the work machine, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm, and controls the movement of the boom in accordance with the movement of the bucket and the arm so that, during excavation work, the direction of the vector of the force generated at the tip of the blade of the bucket is normal to the line connecting the connection between the arm and the boom and the tip.

[0102] (2) A control device according to a second aspect of the present disclosure is a control device according to (1), which controls the operation of the boom by controlling the cylinder force so that the target torque determined based on the attitude of the work implement, the axial torque of the pivot shaft of the arm, and the axial torque of the pivot shaft of the bucket becomes a target cylinder force converted into a cylinder force that drives the boom.

[0103] (3) A control device according to a third aspect of the present disclosure is the control device according to (1) or (2), in which the normal direction is corrected using a correction value.

[0104] (4) A control device according to a fourth aspect of the present disclosure is the control device according to any one of (1) to (3), wherein the correction value is changeable.

[0105] (5) A control device according to a fifth aspect of the present disclosure is a control device according to (1) to (4), wherein the target cylinder force is a value corrected based on the weight of the work machine and the inclination angle of the main body.

[0106] (6) A control device according to a sixth aspect of the present disclosure is the control device of any one of (1) to (5), wherein the normal direction is corrected in accordance with a load on an actuator that rotates the boom. [Explanation of symbols]

[0107] 1 work machine, 1B vehicle body, 2 work equipment, 6 boom, 7 arm, 8 bucket, 8B blade, 8T cutting edge, 14 arm pin, 30 control device, 31 work machine control unit, 32 cutting edge force direction control unit

Claims

1. A device for controlling a work machine having a work implement, the work machine having a boom rotatably connected to a main body of the work machine, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm, During excavation work, the movement of the boom is controlled in accordance with the movement of the bucket and the arm so that the direction of the vector of the force generated at the tip of the blade of the bucket is normal to the line connecting the connecting part of the arm and the boom and the tip. Control device.

2. The boom operation is controlled by converting a target torque determined based on the attitude of the work implement, the axial torque of the pivot shaft of the arm, and the axial torque of the pivot shaft of the bucket into a cylinder force for driving the boom, and controlling the cylinder force to achieve the target cylinder force. The control device according to claim 1 .

3. The normal direction is corrected using a correction value. The control device according to claim 2 .

4. The correction value is variable The control device according to claim 3 .

5. The target cylinder force is a value corrected based on the weight of the work machine and the tilt angle of the main body. The control device according to claim 4.

6. The normal direction is corrected according to the load of an actuator that rotates the boom. The control device according to claim 5 .

7. A method for controlling a work machine having a work implement, the work implement having a boom rotatably connected to a main body of the work machine, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm, comprising: During excavation work, the movement of the boom is controlled in accordance with the movement of the bucket and the arm so that the direction of the vector of the force generated at the tip of the blade of the bucket is normal to the line connecting the connecting part of the arm and the boom and the tip. Control method.

8. a main body; a work machine having a boom rotatably connected to the main body, an arm rotatably connected to the boom, and a bucket rotatably connected to the arm; a control device that controls the movement of the boom in accordance with the movement of the bucket and the arm so that the direction of a vector of a force generated at the tip of the blade of the bucket during excavation work is normal to a line connecting the connection between the arm and the boom and the tip; A work machine comprising:

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