Pay load calculation system of work machine and pay load calculation method of work machine

Abstract

To provide a pay load calculation system of a work machine and a pay load calculation method of a work machine which can easily calculate a center of gravity of a bucket after replacement.SOLUTION: A controller 10 calculates a coordinate of a center of gravity BG of a bucket 43, using a gravity center angle θG of the bucket 43 in a just below state in which the center of gravity BG of the bucket 43 is located just below an arm top pin 49, a bucket ground angle θdig in an excavation attitude of the bucket 43, a pay load value Wdig and a torque Tdig of a boom cylinder 44, a bucket ground angle θdump in a dump attitude of the bucket 43, and a pay load value Wdump and a torque Tdump of the boom cylinder 44.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a system for calculating a payload of a work machine and a method for calculating a payload of a work machine. [Background technology]

[0002] When calculating the payload of a work machine such as a hydraulic excavator, the position of the center of gravity of the bucket is required. When the bucket is replaced, the position of the center of gravity of the bucket may change. Therefore, in order to calculate the payload, it is necessary to obtain the position of the center of gravity of the replaced bucket.

[0003] Obtaining the center of gravity position of the replaced bucket is described, for example, in Japanese Patent Application Laid-Open No. 2021-152275 (Patent Document 1). In Patent Document 1, the bucket is rotated to find the bucket rotation angle γ at which the arm length Lw of the moment due to the force on the center of gravity position caused by the bucket's own weight is maximized, thereby determining the center of gravity position of the bucket. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-152275 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is no description of how to calculate the payload in Patent Document 1. Furthermore, in Patent Document 1, it is necessary to find the rotation angle γ at which the length Lw is maximized, which makes calculation of the center of gravity position complicated.

[0006] An object of the present disclosure is to provide a work machine payload calculation system and a work machine payload calculation method that can easily calculate the center of gravity position of a replaced bucket. [Means for solving the problem]

[0007] A work machine payload calculation system according to the present disclosure includes a work implement and a controller. The work implement has a boom, an arm rotatably attached to the boom, a bucket rotatably attached to the arm via an arm top pin, and a boom cylinder that drives the boom. The controller calculates the coordinates of the bucket's center of gravity using the bucket's center of gravity angle in a directly down state in which the bucket's center of gravity is located directly below the arm top pin, a first bucket ground angle in the bucket's digging position, a first payload value, and a first torque of the boom cylinder, and a second bucket ground angle in the bucket's dump position, a second payload value, and a second torque of the boom cylinder.

[0008] The method for calculating the payload of a work machine according to the present disclosure is a method for calculating the payload of a work machine including a work implement having a boom, an arm rotatably attached to the boom, a bucket rotatably attached to the arm by an arm top pin, and a boom cylinder that drives the boom. The method for calculating the payload of a work machine according to the present disclosure has the following steps.

[0009] The bucket center of gravity angle is calculated when the bucket's center of gravity is directly below the arm top pin. When the bucket is in the digging position, the first bucket ground angle, first payload value, and first torque of the boom cylinder are calculated. When the bucket is in the dump position, the second bucket ground angle, second payload value, and second torque of the boom cylinder are calculated. The coordinates of the bucket's center of gravity position are calculated using the center of gravity angle, first bucket ground angle, first payload value, first torque, second bucket ground angle, second payload value, and second torque. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to realize a work machine payload calculation system and a work machine payload calculation method that can easily calculate the center of gravity position of a replaced bucket. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view showing a configuration of a hydraulic excavator as an example of a work machine in one embodiment. [Figure 2] 2 is a block diagram showing a schematic configuration of a payload calculation system for a work machine shown in FIG. 1. FIG. [Figure 3] FIG. 2 is a schematic diagram of a work machine for explaining moment balance. [Figure 4] FIG. 4 is a flowchart illustrating how to calculate the center of gravity position of a bucket in a method for calculating the payload of a work machine according to one embodiment. [Figure 5] FIG. 10 is a side view showing a state in which the center of gravity of the bucket is positioned directly below the arm top pin in order to calculate the position of the center of gravity of the bucket. [Figure 6] FIG. 10 is a side view showing the excavation posture of the bucket for calculating the position of the center of gravity of the bucket. [Figure 7] FIG. 4 is a side view showing the dump posture of the bucket for calculating the position of the center of gravity of the bucket. [Figure 8] 10A and 10B are diagrams illustrating the relationship between a change in bucket attitude and a payload. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present disclosure will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. In the drawings, configurations may be omitted or simplified for the sake of convenience. It is also intended from the outset that any configurations may be extracted from the embodiments and arbitrarily combined.

[0013] In the following description, the terms "up," "down," "front," "rear," "left," and "right" refer to directions relative to the operator seated in the driver's seat in the driver's cab 31.

[0014] <Work machine configuration>

[0015] Fig. 1 is a side view showing a schematic configuration of a hydraulic excavator as an example of a work machine in one embodiment. As shown in Fig. 1, the hydraulic excavator 50 in this embodiment is a large hydraulic excavator. The hydraulic excavator 50 is, for example, a mining hydraulic excavator used in mines. The hydraulic excavator 50 mainly includes a traveling body 35, a rotating body 30, and a work implement 40.

[0016] The hydraulic excavator 50 is capable of traveling by means of the running body 35. The rotating body 30 is installed so as to be able to rotate freely relative to the running body 35. The rotating body 30 has a cab 31. The interior space of the cab 31 is provided with a driver's seat for an operator, various control levers 17, 18 (Fig. 2), control switches, etc. for the operator to operate.

[0017] The work implement 40 is supported on the front side of the revolving unit 30. The work implement 40 has, for example, a boom 41, an arm 42, a bucket 43, etc. The base end of the boom 41 is rotatably connected to the revolving unit 30 by a boom foot pin 47. The base end of the arm 42 is rotatably connected to the tip of the boom 41 by a boom top pin 48. The bucket 43 is rotatably connected to the tip of the arm 42 by an arm top pin 49.

[0018] The work implement 40 further has a boom cylinder 44, an arm cylinder 45, and a bucket cylinder 46. The boom 41 can be driven relative to the revolving unit 30 by extension and retraction of the boom cylinder 44. The arm 42 can be driven relative to the boom 41 by extension and retraction of the arm cylinder 45. The bucket 43 can be driven relative to the arm 42 by extension and retraction of the bucket cylinder 46. The boom cylinder 44, the arm cylinder 45, and the bucket cylinder 46 are hydraulic cylinders that operate using hydraulic oil, for example.

[0019] <Overview of the work machine system>

[0020] Fig. 2 is a block diagram showing a schematic configuration of a system including the work machine shown in Fig. 1. The system in this embodiment is a payload calculation system for calculating the weight of a load in a bucket 43. 2, the system in this embodiment includes a hydraulic excavator 50 (FIG. 1) as an example of a work machine, and a controller 10. The controller 10 may be mounted on the hydraulic excavator 50, or may be installed in a remote location away from the hydraulic excavator 50.

[0021] The bucket IMU (Inertial Measurement Unit) 11 is attached to, for example, a bucket link (wrist link) that connects the bucket cylinder 46 and the bucket 43. The bucket IMU 11 detects the acceleration of the bucket 43 in the front-to-back, left-to-right, and up-to-down directions, as well as the angular velocity of the bucket 43 around the front-to-back, left-to-right, and up-to-down directions. The angle of the bucket 43 with respect to the arm 42 (bucket angle A3; see FIG. 3 ) is calculated from the detection values ​​of the bucket IMU 11. The bucket IMU 11 corresponds to a bucket angle sensor that detects information for calculating the rotation angle of the bucket 43 around the arm top pin 49.

[0022] The bucket angle sensor may be attached around the arm top pin 49. The bucket angle sensor may be a potentiometer or a rotary encoder. The bucket angle sensor may also calculate the rotation angle of the bucket 43 from a detection value of a bucket cylinder stroke sensor that detects the amount of displacement of the cylinder rod in the bucket cylinder 46 relative to the cylinder.

[0023] The arm IMU 12 is attached to the arm 42. The arm IMU 12 detects the acceleration of the arm 42 in the front-rear, left-right, and up-down directions, and the angular velocity of the arm 42 around the front-rear, left-right, and up-down directions. The angle of the arm 42 with respect to the boom 41 (arm angle A2; see Figure 3) is calculated from the detection values ​​of the arm IMU 12. The arm IMU 12 corresponds to an arm angle sensor that detects information for calculating the rotation angle of the arm 42 around the boom top pin 48.

[0024] The arm angle sensor may be attached around the boom top pin 48. The arm angle sensor may be a potentiometer or a rotary encoder. The arm angle sensor may also be a sensor that calculates the rotation angle of the arm 42 from the detection value of an arm cylinder stroke sensor that detects the amount of displacement of the cylinder rod relative to the cylinder in the arm cylinder 45.

[0025] The boom IMU 13 is attached to the boom 41. The boom IMU 13 detects the acceleration of the boom 41 in the forward / backward, left / right, and up / down directions, and the angular velocity of the boom 41 around the forward / backward, left / right, and up / down directions. The angle of the boom 41 with respect to the revolving structure 30 (boom angle A1; see FIG. 3 ) is calculated from the detected values ​​of the boom IMU 13. The boom IMU 13 corresponds to a boom angle sensor that detects information for calculating the rotation angle of the boom 41 around the boom foot pin 47.

[0026] The boom angle sensor may be attached around the boom foot pin 47. The boom angle sensor may be a potentiometer or a rotary encoder. The boom angle sensor may also calculate the rotation angle of the boom 41 from the detection value of a boom cylinder stroke sensor that detects the amount of displacement of the cylinder rod relative to the cylinder in the boom cylinder 44. The bucket angle sensor, arm angle sensor, and boom angle sensor correspond to angle sensors that detect information for calculating the rotation angle of the work implement 40.

[0027] The rotating unit IMU 14 is attached to the rotating unit 30. The rotating unit IMU 14 measures the acceleration of the rotating unit 30 in the forward / backward, left / right, and up / down directions, and the angular velocity of the rotating unit 30 around the forward / backward, left / right, and up / down directions.

[0028] Boom cylinder bottom pressure sensor 15 is attached to the bottom side of boom cylinder 44 and detects the pressure (bottom pressure) of the hydraulic oil in the cylinder bottom-side oil chamber of boom cylinder 44. Boom cylinder head pressure sensor 16 is attached to the head side of boom cylinder 44 and detects the pressure (head pressure) of the hydraulic oil in the cylinder head-side oil chamber of boom cylinder 44.

[0029] The left working implement lever 17 and the right working implement lever 18 are disposed inside the operator's cab 31. The left working implement lever 17 and the right working implement lever 18 are operated by an operator sitting in the operator's cab 31. The left working implement lever 17 and the right working implement lever 18 are operated to operate the working implement 40 and the rotating body 30. The left working implement lever 17 and the right working implement lever 18 are, for example, electric operating levers. The left working implement lever 17 and the right working implement lever 18 may also be pilot hydraulic operating levers.

[0030] The left working implement lever 17 is located to the left of the driver's seat. An operator seated in the driver's seat grips the left working implement lever 17 with his left hand and operates the left working implement lever 17. The left working implement lever 17 operates, for example, the arm 42 and the rotating structure 30. The left working implement lever 17 receives input from the operator regarding the rotation direction of the rotating structure 30 and the up and down movement of the arm 42. Operation of the left working implement lever 17 in the left and right directions corresponds to the rotation of the rotating structure 30, and left and right rotation operations of the rotating structure 30 are performed in response to the left and right direction operation. Operation of the left working implement lever 17 in the front and rear directions corresponds to the movement of the arm 42, and upward and downward movement of the arm 42 is performed in response to the front and rear direction operation.

[0031] The right work implement lever 18 is located to the right of the driver's seat. An operator sitting in the driver's seat grips the right work implement lever 18 with his right hand and operates the right work implement lever 18. The right work implement lever 18 operates, for example, the boom 41 and the bucket 43. The right work implement lever 18 receives input from the operator regarding the up and down movement of the boom 41 and the up and down movement of the bucket 43. Operation of the right work implement lever 18 in the forward and backward directions corresponds to the movement of the boom 41, and the boom 41 is raised and lowered in response to the forward and backward operation. Operation of the right work implement lever 18 in the left and right directions corresponds to the movement of the bucket 43, and the bucket 43 is moved downward and upward in response to the left and right operation.

[0032] The above-described operation patterns of the left working implement lever 17 and the right working implement lever 18 are merely examples and are not intended to be limiting. The forward / backward and left / right operation of the left working implement lever 17 and the right working implement lever 18 may correspond to actions different from those described above.

[0033] Detection signals from the IMUs 11 to 14 and the pressure sensors 15, 16 are input to the controller 10. Detection signals indicating the amounts of operation of the work equipment levers 17, 18 are input to the controller 10.

[0034] The controller 10 includes a processor, a main memory, and a storage. The processor is, for example, a CPU (Central Processing Unit). The main memory includes, for example, a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The controller 10 reads a program stored in the storage, loads it into the main memory, and executes predetermined processing in accordance with the program. The program may also be distributed to the controller 10 via a network.

[0035] The controller 10 and the work implement levers 17, 18 may each be mounted on the hydraulic excavator 50, or may be disposed remotely outside the hydraulic excavator 50. When the controller 10 and the work implement levers 17, 18 are disposed remotely outside the hydraulic excavator 50, the controller 10 and the work implement levers 17, 18 may each be wirelessly connected to the IMUs 11 to 14, the pressure sensors 15, 16, etc. The controller 10 may be stored in a server remote from the hydraulic excavator 50. Furthermore, since the work implement levers 17, 18 are disposed remotely from the hydraulic excavator 50, an operator may operate the hydraulic excavator 50 remotely without being inside the operator's cab 51 of the hydraulic excavator 50.

[0036] <Calculating the weight of the load in bucket 43>

[0037] A method for calculating the weight of a load carried by the work implement 40 will now be described. FIG. 3 is a schematic diagram of the work implement for explaining moment balance. As shown in FIG. 3, in this embodiment, the weight value W of the current load in the bucket 43 is detected from the balance of each moment around the boom foot pin 47. Here, the balance of each moment around the boom foot pin 47 is expressed by the following equation (1).

number

[0038] In equation (1), Mboomcyl is the moment around the boom foot pin 47 generated by the pressure of the hydraulic oil supplied to the boom cylinder 44. Mboom is the moment around the boom foot pin 47 due to the weight of the boom 41. Marm is the moment around the boom foot pin 47 due to the weight of the arm 42. Mbucket is the moment around the boom foot pin 47 due to the weight of the bucket 43. W is the weight of the current load in the bucket 43. L is the horizontal distance from the boom foot pin 47 to the center of gravity 0 of the load in the bucket 43. Here, the center of gravity of the load when a rated load is loaded in the bucket 43 is stored in the memory unit 10a of the controller 10 as the center of gravity C4 of the load. W×L is the moment around the boom foot pin 47 due to the load in the bucket 43.

[0039] Mboomcyl is calculated from the load on the boom cylinder 44 (head pressure and bottom pressure; that is, the pressure of the hydraulic oil supplied to the boom cylinder 44). The head pressure of the boom cylinder 44 is detected by the boom cylinder head pressure sensor 16. The bottom pressure of the boom cylinder 44 is detected by the boom cylinder bottom pressure sensor 15. Based on the head pressure and bottom pressure of the boom cylinder 44, the controller 10 calculates the moment Mboomcyl about the boom foot pin 47 generated by the load on the boom cylinder 44.

[0040] Mboom is calculated by multiplying the distance r1 between the center of gravity C1 of the boom 41 and the boom foot pin 47 by the weight M1 of the boom 41 (r1 × M1). The position of the center of gravity C1 of the boom 41 is calculated from the boom angle A1, etc. The weight M1 of the boom 41, etc. are stored in the memory unit 10a of the controller 10.

[0041] Marm is calculated as the product (r2 × M2) of the distance r2 between the center of gravity C2 of the arm 42 and the boom foot pin 47 and the weight M2 of the arm 42. The position of the center of gravity C2 of the arm 42 is calculated from the arm angle A2, etc. The weight M2 of the arm 42, etc. are stored in the memory unit 10a of the controller 10.

[0042] Mbucket is calculated by multiplying the distance r3 between the center of gravity C3 of the bucket 43 and the boom foot pin 47 by the weight M3 of the bucket 43 (r3 × M3). The position of the center of gravity C3 of the bucket 43 is calculated from the bucket angle A3 and the like. The weight M3 of the bucket 43 and the like are stored in the memory unit 10a of the controller 10.

[0043] In calculating the current weight value W in the bucket 43, the controller 10 calculates the boom angle A1, arm angle A2, and bucket angle A3 based on the respective detection values ​​of the bucket IMU 11, arm IMU 12, and boom IMU 13. Based on these boom angle A1, arm angle A2, and bucket angle A3, the controller 10 calculates the respective positions of the centers of gravity C1, C2, C3, and C4. The controller 10 calculates the respective distances r1, r2, and r3 between the centers of gravity C1, C2, and C3 and the boom foot pin 47.

[0044] The controller 10 reads out the weight M1 of the boom 41 from the memory unit 10a, and calculates the product of the distance r1 and the weight M1 as the moment Mboom of the boom 41 about the boom foot pin 47. The controller 10 reads out the weight M2 of the arm 42 from the memory unit 10a, and calculates the product of the distance r2 and the weight M2 as the moment Marm of the arm 42 about the boom foot pin 47. The controller 10 reads out the weight M3 of the bucket 43 from the memory unit 10a, and calculates the product of the distance r3 and the weight M3 as the moment Mbucket of the bucket 43 about the boom foot pin 47.

[0045] Controller 10 reads the length of boom 41, the length of arm 42, and the center of gravity C4 of the load in bucket 43 at the rated load from memory unit 10a. Controller 10 calculates the horizontal distance L from boom foot pin 47 to the center of gravity C4 of the load based on the boom angle A1, arm angle A2, and bucket angle A3 calculated above, the lengths of boom 41 and arm 42, and the center of gravity C4 of the load.

[0046] The controller 10 substitutes the moments Mboomcyl, Mboom, Marm, Mbucket and distance L calculated above into the above equation (1). In this way, the controller 10 calculates the weight value W of the load currently loaded in the bucket 43. The weight value W of the load in the bucket 43 is calculated based on the load on the boom cylinder 44 and the attitude of the work implement 40.

[0047] However, the bucket 43 may be replaced with another bucket having a different shape, etc. In this case, the shape data, center of gravity position data, etc. of the other bucket may not be stored in the memory unit 10a of the controller 10. In such a case, it may not be possible to calculate the weight value W based on equation (1), or even if the weight value W can be calculated, it may not be possible to calculate an accurate weight value W. In particular, in a large work machine 50, the bucket 43 is also large, so the center of gravity position of the bucket 43 may shift significantly, resulting in a large error in the weight value W. Therefore, in this embodiment, it is possible to accurately calculate the weight value W even when the bucket 43 is replaced with one for which the shape data, center of gravity position data, etc. are not stored in the memory unit 10a of the controller 10.

[0048] <How to calculate the payload of a work machine>

[0049] Next, a method for calculating the payload of a work machine that can accurately calculate the weight value W (hereinafter also referred to as "payload value") as described above will be described with reference to FIGS.

[0050] Fig. 4 is a flow diagram for calculating the position of the center of gravity of a bucket in a method for calculating the payload of a work machine in one embodiment. Fig. 5 is a side view showing a state in which the center of gravity of the bucket is positioned directly below the arm top pin in order to calculate the position of the center of gravity of the bucket. Fig. 6 is a side view showing the digging position of the bucket in order to calculate the position of the center of gravity of the bucket. Fig. 7 is a side view showing the dump position of the bucket in order to calculate the position of the center of gravity of the bucket. Fig. 8 is a diagram showing the relationship between changes in bucket position and payload.

[0051] 4, in step S1, an operation is started to calculate the center of gravity position of the bucket 43. This operation is started by the operator operating, for example, a switch for starting center of gravity position calculation. When this operation is started, the work machine 50 enters a center of gravity position calculation mode.

[0052] In step S2, the boom 41 and arm 42 of the work implement 40 are positioned at predetermined positions. For example, the boom cylinder 44 and arm cylinder 45 are positioned so that they each reach their cylinder ends so that the work implement 40 does not naturally descend. Specifically, the boom cylinder 44 reaches its extension stroke end, and the tip of the boom 41 is raised to its maximum extent. Furthermore, the arm cylinder 45 reaches its extension stroke end, and the tip of the arm 42 is rotated to its maximum extent in the excavation direction. This operation of the work implement 40 is performed by the operator operating at least one of the left work implement lever 17 and the right work implement lever 18.

[0053] In step S3, as shown in Fig. 5, the center of gravity BG of the bucket 43 is positioned directly below the arm top pin 49 in a side view of the work implement 40. Here, "the center of gravity BG of the bucket 43 is positioned directly below the arm top pin 49" means that the center of gravity BG of the bucket 43 is positioned directly below the vertical center of rotation 49C of the arm top pin 49 in a side view of the work implement 40. Hereinafter, the state in which the center of gravity BG of the bucket 43 is positioned directly below the arm top pin 49 in a side view of the work implement 40 is also referred to as the "directly below state."

[0054] The direct-down state is determined as follows: First, the bucket 43 is rotated several times between the excavation side and the dump side relative to the arm 42 while it is empty, and the payload during each rotation is measured. This results in a curve showing the relationship between the change in attitude of the bucket 43 and the payload, as shown in Figure 8.

[0055] In Figure 8, if the position of the center of gravity BG of the bucket 43 is accurately known, the payload will be constant at zero (0) between the full dump state and the full digging state. The full dump state is a state in which the bucket 43 has rotated to the dump side to the maximum extent, and the full digging state is a state in which the bucket 43 has rotated to the digging side to the maximum extent. On the other hand, if the position of the center of gravity BG of the bucket 43 deviates from that of the bucket 43 before replacement due to, for example, replacing the bucket 43, the payload will vary depending on the rotation angle of the bucket 43, as shown by the curve indicated by the solid line in Figure 8. The attitude (rotation angle) of the bucket 43 that is the inflection point on the curve shown in Figure 8 is considered to be the directly below state.

[0056] Furthermore, when a valve connected to the oil chamber of bucket cylinder 46 is fully opened so that no load is applied to bucket cylinder 46 and bucket 43 can freely rotate about arm top pin 49 relative to arm 42, bucket 43 may be positioned so as to be stationary relative to arm 42 in the directly down state.

[0057] As shown in Figure 5, in a side view of the work implement 40, the direction from the rotation center 49C of the arm top pin 49 toward the cutting edge 43a of the bucket 43 is defined as the bucket coordinate Z. In addition, in a side view of the work implement 40, the direction that passes through the rotation center 49C of the arm top pin 49 and is perpendicular to the bucket coordinate Z is defined as the bucket coordinate X. In addition, the angle formed by the horizontal line that passes through the rotation center 49C of the arm top pin 49 and the bucket coordinate Z (the line segment connecting the rotation center 49C of the arm top pin 49 and the cutting edge 43a of the bucket 43) is defined as the bucket ground angle θ. In addition, the angle formed by the line segment connecting the rotation center 49C of the arm top pin 49 and the center of gravity BG of the bucket 43 and the bucket coordinate Z is defined as the bucket center of gravity angle θ. G It is said that.

[0058] In step S4 of FIG. 4, the center of gravity angle θ of the bucket 43 in the direct downward state G is calculated by the controller 10. The center of gravity angle θ GIn calculating the angle θ of the center of gravity of the bucket 43, first, the ground angle θ0 of the bucket 43 in the direct hit state is calculated by the controller 10. The controller 10 calculates the ground angle θ0 of the bucket 43 in the direct hit state based on the detection value of the bucket IMU 11. The controller 10 calculates the ground angle θ0 of the bucket 43 in the direct hit state using the following equation (2) from the calculated ground angle θ0 of the bucket 43. G Calculate.

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[0059] In step S5, as shown in Fig. 6, bucket 43 is rotated relative to arm 42 so as to assume an excavation posture. In this excavation posture, bucket 43 is in a state where it has rotated to the maximum extent toward the excavation side relative to arm 42 (full excavation state). In this excavation posture, bucket cylinder 46 has reached the stroke end on the extension side and is fully extended.

[0060] In step S6, the ground angle θ of the bucket 43 in the excavation posture is dig (first bucket ground angle) is calculated by the controller 10. The controller 10 calculates the ground angle θ of the bucket 43 in the excavation posture based on the detection value of the bucket IMU 11. dig Calculate.

[0061] The controller 10 calculates the length l from the rotation center 49C of the arm top pin 49 to the center of gravity BG of the bucket 43. G The horizontal length l of dig The following equation (4) is generated by substituting equation (2) into equation (3) below.

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[0062] Here, the boom cylinder torque when the bucket 43 is in the excavation position is T dig(first torque). The payload value when the bucket 43 is in the excavation posture is W dig The horizontal distance from the arm top pin 49 (the rotation center of the bucket 43) to the boom foot pin 47 (the rotation center of the boom 41) is defined as L. dig , W dig The relationship between L and L is expressed by the following equation (5) based on the balance equation (1). dig By substituting equation (4) into equation (5), the right side of equation (5) is obtained. In equation (5), the distance (Ll) from the center of gravity BG of the bucket 43 to the center of rotation of the boom 41 is dig ) to generate torque T dig is calculated, and the payload value W dig is calculated.

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[0063] In step S7, as shown in Fig. 7, the bucket 43 is rotated to a dump position relative to the arm 42. In this dump position, the bucket 43 is in a state where it has rotated to the maximum extent toward the dump side relative to the arm 42 (full dump state). In this dump position, the bucket cylinder 46 has reached the stroke end on the retraction side and is retracted to the maximum extent.

[0064] In step S8, the ground angle θ of the bucket 43 in the dump posture is dump (second bucket ground angle) is calculated by the controller 10. The controller 10 calculates the ground angle θ of the bucket 43 in the dump posture based on the detection value of the bucket IMU 11. dump Calculate.

[0065] The controller 10 calculates the length l from the rotation center 49C of the arm top pin 49 to the center of gravity BG of the bucket 43. G The horizontal length l of dump The following equation (7) is generated by substituting equation (2) into equation (6) below.

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[0066] Here, the boom cylinder torque when the bucket 43 is in the dump position is T dump (second torque). The payload value when the bucket 43 is in the dump position is W dump (second payload value). T dump , W dump The relationship between and L is expressed by the following equation (8) based on the balance equation (1). dump By substituting equation (7) into equation (8), the right side of equation (8) is obtained. In equation (8), the distance (L+l) from the center of gravity BG of the bucket 43 to the center of rotation of the boom 41 is dump ) to generate torque T dump is calculated, and the payload value W dump is calculated.

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[0067] By deleting L from the equations (5) and (8) obtained above, the following equation (9) is obtained.

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[0068] In step S9, the controller 10 determines whether or not the operation of the work implement 40 has been completed. If the controller 10 determines that the operation has not been completed, the steps from step S2 onwards are repeated. On the other hand, if the controller 10 determines that the operation has been completed, the controller 10 calculates the position of the center of gravity BG of the bucket 43 in step S10.

[0069] The coordinates G(Z, X) of the center of gravity BG of the bucket 43 are expressed by the following equations (10) and (11) based on equation (2).

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[0070] In each of equations (10) and (11), l in equation (9) G By substituting the above, the following equations (12) and (13) are obtained.

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[0071] As a result, the center of gravity angle θ of the bucket 43 in the direct downward state G and the bucket ground angle θ in the excavation position dig , payload value W dig and torque T dig and the bucket ground angle θ in the dump position dump , payload value W dump and torque T dump The coordinates G(Z,X) of the center of gravity BG of the bucket 43 are calculated using the above.

[0072] In step S11, the position of the center of gravity BG of the bucket 43 calculated by the controller 10 is stored. The position of the center of gravity BG of the bucket 43 may be stored in the storage unit 10a of the controller 10, or may be stored in a storage unit separate from the controller 10.

[0073] After the coordinate G(Z,X) of the center of gravity BG of the bucket 43 is calculated as described above, the weight value W can be calculated with high accuracy by using the coordinate G(Z,X) and equation (1) to calculate the weight value W.

[0074] In the above embodiment, an example has been described in which the work machine is a hydraulic excavator 50, but the work machine is not limited to the hydraulic excavator 50 and may be another type of work machine that has a work implement capable of transporting a load and a hydraulic cylinder for operating the work implement. For example, the work machine may be a crane, a loading shovel, a tire-powered excavator, a wheel loader, a skid steer loader, etc.

[0075] In addition, in the above embodiment, the posture of the bucket 43 is changed in the order of the direct below state (steps S3, S4), the excavation posture (steps S5, S6), and the dump posture (steps S7, S8), but the present disclosure is not limited to this order, and the postures may be changed in any order.

[0076] Furthermore, in the above embodiment, the state in which the bucket cylinder 46 reaches the extension stroke end is the digging posture of the bucket 43, and the state in which the bucket cylinder 46 reaches the retraction stroke end is the dump posture of the bucket 43. However, as in a loading shovel, the state in which the bucket cylinder 46 reaches the extension stroke end may be the dump posture of the bucket 43, and the state in which the bucket cylinder 46 reaches the retraction stroke end may be the digging posture of the bucket 43.

[0077] <Action and effect>

[0078] Next, the operation and effects of this embodiment will be described.

[0079] In this embodiment, as shown in FIGS. 5 to 7, the controller 10 controls the bucket center of gravity angle θ G and the bucket ground angle θ in the excavation position dig , payload value W dig and the torque T of the boom cylinder 44 dig and the bucket ground angle θ in the dump position dump , payload value W dump and the torque T of the boom cylinder 44 dumpand calculate the coordinate G(Z,X) of the center of gravity BG of the bucket 43. As a result, even if the bucket 43 is replaced and the center of gravity position of the replaced bucket 43 is not stored in the work machine 50, it becomes possible to accurately calculate the center of gravity position of the replaced bucket 43. Therefore, it becomes possible to easily and accurately calculate the position of the center of gravity BG of the replaced bucket 43, and even if the bucket 43 is replaced with one for which center of gravity position data and the like are not stored, it is possible to accurately calculate the payload.

[0080] According to this embodiment, as shown in FIGS. 5 to 7, the controller 10 calculates the bucket center-of-gravity angle θ in the direct-down state based on the rotation angle of the bucket 43 detected by an angle sensor (for example, the boom IMU 13). G and the bucket ground angle θ in the excavation position dig and the bucket ground angle θ in the dump position dump This makes it possible to calculate the position of the center of gravity BG of the replaced bucket 43 as described above.

[0081] 5 to 7, the calculated coordinates G(Z,X) of the center of gravity BG of the bucket 43 are stored. This eliminates the need to calculate the center of gravity BG when replacing the bucket 43 with one whose position of the center of gravity BG has been stored.

[0082] According to this embodiment, as shown in FIGS. 6 and 7, the controller 10 uses the distance from the center of gravity BG of the bucket 43 to the boom foot pin 47 to calculate the torque T dig and T dump Calculate the payload value W dig and W dump This makes it possible to calculate the position of the center of gravity BG of the replaced bucket 43 as described above.

[0083] According to this embodiment, as shown in FIG. 6, the controller 10 determines the state in which the bucket cylinder 46 reaches the stroke end on the extension side as the excavation posture of the bucket 43 and sets the bucket ground angle θ digAs a result, the bucket 43 is prevented from descending naturally, and the bucket ground angle θ dig It becomes possible to detect

[0084] According to this embodiment, as shown in FIG. 7, the controller 10 determines the state in which the bucket cylinder 46 reaches the stroke end on the contraction side as the dump posture of the bucket 43, and sets the bucket ground angle θ dump As a result, the bucket 43 is prevented from descending naturally, and the bucket ground angle θ dump It becomes possible to detect

[0085] <Additional Notes>

[0086] The above description includes the following additional features.

[0087] (Appendix 1) a work machine having a boom, an arm rotatably attached to the boom, a bucket rotatably attached to the arm by an arm top pin, and a boom cylinder that drives the boom; and a controller that calculates coordinates of the center of gravity of the bucket using a center of gravity angle of the bucket in a direct down state in which the center of gravity of the bucket is located directly below the arm top pin, a first bucket ground angle, a first payload value, and a first torque of the boom cylinder when the bucket is in an excavation attitude, and a second bucket ground angle, a second payload value, and a second torque of the boom cylinder when the bucket is in a dump attitude.

[0088] (Appendix 2) further comprising an angle sensor; 2. The work machine payload calculation system according to claim 1, wherein the controller calculates the center of gravity angle, the first bucket ground angle, and the second bucket ground angle based on the rotation angle of the bucket calculated from the detection value of the angle sensor.

[0089] (Appendix 3) 3. The payload calculation system for a work machine according to claim 1 or 2, wherein the calculated coordinates of the center of gravity of the bucket are stored.

[0090] (Appendix 4) 4. The payload calculation system for a work machine according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the controller determines the first torque and the second torque using a distance from the center of gravity of the bucket to a center of rotation of the boom, and calculates the first payload value and the second payload value.

[0091] (Appendix 5) The work machine further includes a bucket cylinder that extends and retracts to rotate the bucket relative to the arm, 5. The payload calculation system for a work machine according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the controller calculates the first bucket ground angle by considering a state in which the bucket cylinder has reached one of an extension and a retraction stroke end as the digging posture of the bucket.

[0092] (Appendix 6) The payload calculation system for a work machine described in Appendix 5, wherein the controller calculates the second bucket ground angle by considering a state in which the bucket cylinder has reached the other of an extension and a retraction stroke end as the dump posture of the bucket.

[0093] (Appendix 7) A method for calculating a payload of a work machine including a work implement having a boom, an arm rotatably attached to the boom, a bucket rotatably attached to the arm by an arm top pin, and a boom cylinder that drives the boom, calculating a center of gravity angle of the bucket in a directly down state where the center of gravity of the bucket is positioned directly under the arm top pin; calculating a first bucket ground angle, a first payload value, and a first torque of the boom cylinder at an excavation attitude of the bucket; calculating a second bucket ground angle, a second payload value, and a second torque of the boom cylinder in a dump attitude of the bucket; calculating coordinates of the center of gravity of the bucket using the center of gravity angle, the first bucket ground angle, the first payload value, the first torque, the second bucket ground angle, the second payload value, and the second torque.

[0094] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0095] 10 controller, 10a memory unit, 11 bucket IMU, 12 arm IMU, 13 boom IMU, 14 rotating body IMU, 15 boom cylinder bottom pressure sensor, 16 boom cylinder head pressure sensor, 17 left work implement lever, 18 right work implement lever, 30 rotating body, 31 operator's cab, 35 running body, 40 work implement, 41 boom, 42 arm, 43 bucket, 43a cutting edge, 44 boom cylinder, 45 arm cylinder, 46 bucket cylinder, 47 boom foot pin, 48 boom top pin, 49 arm top pin, 49C rotation center, 50 work machine.

Claims

1. a work machine having a boom, an arm rotatably attached to the boom, a bucket rotatably attached to the arm by an arm top pin, and a boom cylinder that drives the boom; a controller that calculates coordinates of the center of gravity of the bucket using a center of gravity angle of the bucket in a direct down state in which the center of gravity of the bucket is located directly below the arm top pin, a first bucket ground angle, a first payload value, and a first torque of the boom cylinder when the bucket is in an excavation attitude, and a second bucket ground angle, a second payload value, and a second torque of the boom cylinder when the bucket is in a dump attitude.

2. further comprising an angle sensor; 2. The payload calculation system for a work machine according to claim 1, wherein the controller calculates the center of gravity angle, the first bucket ground angle, and the second bucket ground angle based on the rotation angle of the bucket calculated from the detection value of the angle sensor.

3. The payload calculation system for a work machine according to claim 1 , wherein the calculated coordinates of the center of gravity of the bucket are stored.

4. 2. The payload calculation system for a work machine according to claim 1, wherein the controller determines the first torque and the second torque using a distance from the center of gravity of the bucket to a center of rotation of the boom, and calculates the first payload value and the second payload value.

5. The work machine further includes a bucket cylinder that extends and retracts to rotate the bucket relative to the arm, 2. The payload calculation system for a work machine according to claim 1, wherein the controller calculates the first bucket ground angle by considering a state in which the bucket cylinder has reached one of an extension and a retraction stroke end as the digging attitude of the bucket.

6. 6. The payload calculation system for a work machine according to claim 5, wherein the controller calculates the second bucket ground angle by considering a state in which the bucket cylinder has reached the other of its extension and retraction stroke ends as the dump posture of the bucket.

7. A method for calculating a payload of a work machine including a work implement having a boom, an arm rotatably attached to the boom, a bucket rotatably attached to the arm by an arm top pin, and a boom cylinder that drives the boom, calculating a center of gravity angle of the bucket in a directly down state where the center of gravity of the bucket is positioned directly under the arm top pin; calculating a first bucket ground angle, a first payload value, and a first torque of the boom cylinder at an excavation attitude of the bucket; calculating a second bucket ground angle, a second payload value, and a second torque of the boom cylinder in a dump attitude of the bucket; calculating a coordinate of the center of gravity of the bucket using the center of gravity angle, the first bucket ground angle, the first payload value, the first torque, the second bucket ground angle, the second payload value, and the second torque.

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