Work machine monitoring method, computer-readable medium, and work machine monitoring system

Abstract

The present invention makes it possible to ascertain a load applied to a work unit. This work machine monitoring method comprises: a step (S2) for acquiring a posture of a work unit of a work machine; a step (S3) for acquiring a load applied to the work unit; and a step (S5) for outputting the load applied to the work unit for each posture of the work unit from the acquired load applied to the work unit and the posture of the work unit when the load is acquired.

Description

Monitoring Method for Working Machine, Computer-Readable Medium, and Monitoring System for Working Machine

[0001] The present disclosure relates to a monitoring method for a working machine, a computer-readable medium, and a monitoring system for a working machine.

[0002] The working machine described in Japanese Patent Application Laid-Open No. 2023-146974 (Patent Document 1) divides the stroke range of a boom cylinder into a plurality of stroke sections. By calculating the operating time of the boom cylinder in each of the plurality of stroke sections, it is described that a local deterioration risk for each stroke section is calculated.

[0003] Japanese Patent Application Laid-Open No. 2023-146974

[0004] If the load applied to the working machine of the working machine can be grasped, countermeasures can be taken before a malfunction occurs.

[0005] In the present disclosure, a technique that enables grasping of the load applied to the working machine is proposed.

[0006] The monitoring method for a working machine according to an aspect of the present disclosure includes the following steps. The first step is to acquire the posture of the working machine of the working machine. The second step is to acquire the load applied to the working machine. The third step is to output the load applied to the working machine for each posture of the working machine based on the acquired load applied to the working machine and the posture of the working machine when the load was acquired.

[0007] A computer-readable medium according to an aspect of the present disclosure stores instructions for executing processing. The above processing includes acquiring the posture of the working machine of the working machine, acquiring the load applied to the working machine, and outputting the load applied to the working machine for each posture of the working machine based on the acquired load applied to the working machine and the posture of the working machine when the load was acquired.

[0008] A monitoring system for a work machine relating to a certain aspect of this disclosure comprises a work machine having a work implement and a controller for controlling the work machine. The controller is configured to acquire the posture of the work implement, acquire the load applied to the work implement, and output the load applied to the work implement for each posture of the work implement based on the acquired load applied to the work implement and the posture of the work implement at the time the load was acquired.

[0009] According to this disclosure, it will be possible to understand the load applied to the work equipment.

[0010] This is an external view of the work machine. This is a diagram showing the configuration of the hydraulic circuit. This is a diagram showing the range of motion of the arm top pin. This is a block diagram showing the schematic configuration of the work machine monitoring system. This is a flowchart showing the processing flow in the work machine monitoring method. This is a chart showing the time course of the work machine's posture and hydraulic fluid pressure. This is a diagram showing the posture of the work machine when the hydraulic fluid pressure was acquired. This is a map showing the first example of the load frequency distribution for each posture of the work machine. This is a map showing the second example of the load frequency distribution for each posture of the work machine. This is a map showing the third example of the load frequency distribution for each posture of the work machine. This is a map showing the fourth example of the load frequency distribution for each posture of the work machine. This is a bubble chart in a specific range of pump pressure. This is a chart showing the time course of the work machine's posture and arm acceleration. This is a diagram showing the posture of the work machine when the peak value of acceleration was acquired. This is a map showing the fifth example of the load frequency distribution for each posture of the work machine. This is a map showing the sixth example of the load frequency distribution for each posture of the work machine. This is a map showing the seventh example of the load frequency distribution for each posture of the work machine. This is a map showing the eighth example of the load frequency distribution for each posture of the work machine. This is a bubble chart showing a specific range of accelerations.

[0011] The embodiments 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 of them will not be repeated. In the drawings, some configurations may be omitted or simplified for the sake of explanation. It is also intended from the outset that any configuration may be extracted from the embodiments and combined in any way.

[0012] <Configuration of the work machine> Figure 1 is an external view of a hydraulic excavator 100 as an example of a work machine based on the embodiment.

[0013] As shown in Figure 1, the hydraulic excavator 100 has a main body 1 and a hydraulically operated work implement 2. The main body 1 has a slewing body 3 and a traveling body 5. The traveling body 5 has a pair of tracks 5Cr and a traveling motor 5M. The traveling motor 5M is provided as the drive source for the traveling body 5. The traveling motor 5M is a hydraulic motor that is operated by hydraulics. The traveling body 5 can travel on the ground by the rotation of the tracks 5Cr.

[0014] The slewing body 3 is positioned on and supported by the traveling body 5. The slewing body 3 is mounted on the traveling body 5 so as to be able to rotate relative to the traveling body 5 about a pivot axis RX. The slewing body 3 is attached to the traveling body 5 via a slewing circle section. The slewing body 3 is made able to rotate relative to the traveling body 5 by transmitting driving force from the slewing motor to the slewing circle section and causing it to rotate. The slewing motor may be a hydraulic motor or an electric motor.

[0015] The slewing body 3 has a cab 4. The operator of the hydraulic excavator 100 sits in this cab 4 and operates the hydraulic excavator 100. The cab 4 is provided with a driver's seat 4S where the operator sits. The operator can operate the hydraulic excavator 100 from inside the cab 4. From inside the cab 4, the operator can operate the work implement 2, rotate the slewing body 3 relative to the vehicle 5, and move the hydraulic excavator 100 using the vehicle 5. In this disclosure, the hydraulic excavator 100 is operated from inside the cab 4, but it may also be remotely controlled by wireless from a location away from the hydraulic excavator 100.

[0016] In this embodiment, the positional relationships of each part of the slewing body 3 of the hydraulic excavator 100 will be described with reference to an operator seated in the driver's seat 4S inside the cab 4. The front-rear direction refers to the front-rear direction of the operator seated in the driver's seat 4S. The direction directly facing the operator seated in the driver's seat 4S is the front direction, and the direction behind the operator seated in the driver's seat 4S is the rear direction. The left-right direction refers to the left-right direction of the operator seated in the driver's seat 4S. The right and left sides are the right and left directions, respectively, when the operator seated in the driver's seat 4S is facing directly forward. The up-down direction refers to the up-down direction of the operator seated in the driver's seat 4S. The lower side is towards the operator's feet, and the upper side is towards their head.

[0017] In the forward and backward directions, the side from which the work implement 2 protrudes from the rotating body 3 is the forward direction, and the opposite direction is the backward direction. Looking in the forward direction, the right and left sides are the right and left directions, respectively. In the up and down directions, the side with the ground is the down side, and the side with the sky is the up side.

[0018] The slewing body 3 has an engine room 9 in which the engine is housed, and a counterweight located at the rear of the slewing body 3. The engine room 9 houses the engine that generates the driving force, a hydraulic pump that receives the driving force generated by the engine and supplies hydraulic fluid to the hydraulic actuator, and the like.

[0019] The work machine 2 is mounted on and supported by the slewing body 3. The work machine 2 has a boom 6, an arm 7, and a bucket 8. The bucket 8 has multiple blades. The tip of the bucket 8 is called the blade tip 8a. The bucket 8 does not have to have blades. The tip of the bucket 8 may be formed from a straight steel plate. The bucket 8 is an example of an attachment that can be attached to the tip of the work machine 2. Depending on the type of work, the attachment can be changed to a breaker, grapple, or lifting magnet, etc.

[0020] The base end of the boom 6 is connected to the slewing body 3 via the boom foot pin 13. The base end of the arm 7 is connected to the tip of the boom 6 via the boom top pin 14. The bucket 8 is connected to the tip of the arm 7 via the arm top pin 15. The boom foot pin 13, boom top pin 14, and arm top pin 15 extend approximately in the left-right direction.

[0021] The work machine 2 includes a boom cylinder 10, an arm cylinder 11, and a bucket cylinder 12. Each of the boom cylinder 10, arm cylinder 11, and bucket cylinder 12 is a hydraulic cylinder driven by hydraulic fluid.

[0022] The boom cylinder 10 drives the boom 6. The boom 6 can rotate relative to the slewing body 3 around the boom foot pin 13 by the extension and retraction of the boom cylinder 10. The arm cylinder 11 drives the arm 7. The arm 7 can rotate relative to the boom 6 around the boom top pin 14 by the extension and retraction of the arm cylinder 11. The bucket cylinder 12 drives the bucket 8. The bucket 8 can rotate relative to the arm 7 around the arm top pin 15 by the extension and retraction of the bucket cylinder 12.

[0023] The hydraulic excavator 100 is equipped with a controller 50. The controller 50 controls the operation of the hydraulic excavator 100.

[0024] Figure 2 shows the configuration of the hydraulic circuit, which is the drive circuit for the hydraulic cylinder. The operating device that receives input from the operator includes a left work implement lever 17 and a right work implement lever 18. The left work implement lever 17 and the right work implement lever 18 are located inside the cab 4. The left work implement lever 17 and the right work implement lever 18 are operated by the operator sitting in the cab 4 for the operation of the work implement 2 and the slewing body 3. The left work implement lever 17 and the right work implement lever 18 are, for example, electrically operated levers.

[0025] The left work implement lever 17 is located to the left of the driver's seat 4S. The operator seated in the driver's seat 4S operates the left work implement lever 17 with their left hand. The left work implement lever 17 receives input from the operator regarding the rotation direction of the slewing body 3 and the vertical movement of the arm 7.

[0026] The right work implement lever 18 is located to the right of the driver's seat 4S. The operator seated in the driver's seat 4S operates the right work implement lever 18 with their right hand. The right work implement lever 18 receives input from the operator regarding the vertical movement of the boom 6 and the vertical movement of the bucket 8. The operator's operating direction and amount for the left work implement lever 17 and the right work implement lever 18 are output to the controller 50 as operating signals, which are electrical signals.

[0027] The controller 50 determines the operation of the left work implement lever 17 and the right work implement lever 18 based on the input operation signals. Based on the operation signals, the controller 50 outputs a command signal (command current) to the main valve (directional control valve) 22.

[0028] The hydraulic pump 24 is driven by the rotational driving force transmitted from an engine (not shown). The oil discharged from the hydraulic pump 24 is supplied to the main valve 22 as hydraulic fluid. The pressure sensor 25 detects the pressure of the hydraulic fluid discharged by the hydraulic pump 24. The hydraulic fluid pressure detected by the pressure sensor 25 is output as an electrical signal to the controller 50.

[0029] The main valve 22 is a spool-type valve that switches the direction of hydraulic fluid flow by moving a rod-shaped spool. The spool moves axially due to the action of a solenoid based on a command current output from the controller 50.

[0030] Based on the command current, the spool of the main valve 22 moves axially, thereby controlling the flow rate and direction (supply and discharge) of the hydraulic fluid supplied from the hydraulic pump 24 to the hydraulic actuator 21 through the main valve 22. By controlling the supply and discharge of hydraulic fluid to the hydraulic actuator 21, the operation of the work machine 2, the rotation of the slewing body 3, and the travel operation of the traveling body 5 are controlled. The hydraulic actuator 21 includes the boom cylinder 10, arm cylinder 11, bucket cylinder 12, and travel motor 5M shown in Figure 1, as well as a slewing motor.

[0031] A display device 23 is connected to the controller 50. The display device 23 displays various information acquired by the controller 50. The contents of the display device 23 may include, for example, the frequency distribution of the load applied to the work machine 2 for each posture of the work machine 2, which is created by the controller 50. Details of this frequency distribution will be described later.

[0032] Figure 3 shows the range of motion 72 of the arm top pin 15. Figure 3 schematically shows the hydraulic excavator 100 as viewed from the right. The area enclosed by the range of motion boundary 71 shown in Figure 3 represents the range of motion 72 of the arm top pin 15. The boom 6 rotates relative to the slewing body 3 in the vertical direction. The arm 7 rotates relative to the boom 6 in the digging direction (the direction in which the arm top pin 15 approaches the main body 1) and the dumping direction (the direction in which the arm top pin 15 moves away from the main body).

[0033] The movable range boundary 71 includes the trajectory of the arm top pin 15 when the arm 7 is moved by the maximum angle in both the excavation direction and the dumping direction with the boom 6 in its highest position. The movable range boundary 71 also includes the trajectory of the arm top pin 15 when the boom 6 is moved from the position with the boom 6 in its highest position and the arm 7 moved to its lowest position while maintaining the relative position of the arm 7 with respect to the boom 6 until the boom 6 is lowered to its lowest position.

[0034] The movable range boundary 71 includes the trajectory of the arm top pin 15 when the arm 7 is moved by the maximum angle in both the excavation direction and the dumping direction with the boom 6 in its lowest position. The movable range boundary 71 also includes the trajectory of the arm top pin 15 when the boom 6 is moved from the lowest position with the boom 6 and the arm 7 moved most in the excavation direction, while maintaining the relative position of the arm 7 with respect to the boom 6, until the boom 6 is raised to its highest position.

[0035] Let x be the unit distance in the front-rear direction. The position of the boom foot pin 13 in the front-rear direction is defined as the zero position. The +x, +2x, +3x, ... shown in Figure 3 represent the position at a unit distance x minutes forward from the zero position, a position at twice the unit distance x forward from the zero position, a position at three times the unit distance x forward from the zero position, ...

[0036] Let z be the unit distance in the vertical direction. The position of the ground in contact with the vehicle 5 in the vertical direction is defined as the zero position. +z, +2z, +3z, ... shown in Figure 3 represent the position a unit distance z above the zero position, a position twice the unit distance z above the zero position, a position three times the unit distance z above the zero position, ... respectively. -z, -2z, -3z, ... shown in Figure 3 represent the position a unit distance z below the zero position, a position twice the unit distance z below the zero position, a position three times the unit distance z below the zero position, ... respectively.

[0037] <System Configuration> Figure 4 is a block diagram showing the schematic configuration of the monitoring system for the work machine. As explained with reference to Figure 2, the operating devices (left work machine lever 17, right work machine lever 18) output operating signals to the controller 50. The pressure sensor 25 outputs an electrical signal indicating the hydraulic fluid pressure to the controller 50. The hydraulic fluid pressure corresponds to an example of a sensor value related to the load applied to the work machine 2.

[0038] The boom IMU (Inertial Measurement Unit) 27 is attached to the boom 6. The boom IMU 27 detects the acceleration of the boom 6 in the front-rear direction, left-right direction, and up-down direction, and the angular velocity of the boom 6 around the front-rear direction, left-right direction, and up-down direction. The boom IMU 27 outputs the detection results of the acceleration and angular velocity of the boom 6 to the controller 50 as electrical signals.

[0039] The arm IMU 28 is attached to the arm 7. The arm IMU 28 detects the acceleration of the arm 7 in the front-rear direction, left-right direction, and up-down direction, and the angular velocity of the arm 7 around the front-rear direction, left-right direction, and up-down direction. The arm IMU 28 outputs the detection results of the acceleration and angular velocity of the arm 7 to the controller 50 as electrical signals.

[0040] The boom IMU 27 and the arm IMU 28 constitute an acceleration sensor that acquires the acceleration of the working machine 2 (boom 6, arm 7). The acceleration of the arm 7 corresponds to an example of a sensor value related to the load applied to the working machine 2.

[0041] From the detection value of the boom IMU 27, the angle of the boom 6 with respect to the revolving body 3 (boom angle) is acquired. From the detection value of the arm IMU 28, the angle of the arm 7 with respect to the boom 6 (arm angle) is acquired. The boom IMU 27 and the arm IMU 28 constitute an angle sensor that detects information for acquiring the angles of the working machine 2 (boom 6, arm 7).

[0042] The angle sensor may be a rotation angle sensor attached around the boom foot pin 13 and the boom top pin 14. The rotation angle sensor may be a potentiometer or a rotary encoder. The angle sensor may be a cylinder stroke sensor that detects the displacement amount of the cylinder rod with respect to the cylinder in the boom cylinder 10 and the arm cylinder 11.

[0043] The position of the boom top pin 14 is calculated from the dimensions of the boom 6 and the boom angle. The position of the arm top pin 15 is calculated from the position of the boom top pin 14, the dimensions of the arm 7, and the arm angle. The boom IMU 27 and the arm IMU 28 (angle sensors) constitute attitude sensors that detect information for calculating the attitude of the work machine 2 (boom 6, arm 7). The boom angle detected by the boom IMU 27 and the arm angle detected by the arm IMU 28 constitute sensor values regarding the attitude of the work machine 2. The position of the arm top pin 15 corresponds to an example of information indicating the position of the attachment at the tip of the work machine 2.

[0044] The controller 50 has a processor. The processor is, for example, a CPU (Central Processing Unit). The controller 50 has a storage unit 59. The storage unit 59 stores various programs and data. The storage unit 59 includes a main memory and a storage. The main memory includes a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The processor reads out the program stored in the storage and expands it in the main memory, and executes predetermined processing according to the program. The program and data may be stored in an external storage device provided separately from the controller 50 and distributed to the controller 50 via a network.

[0045] The program includes a program for causing a computer to execute processing related to a method for monitoring a work machine, which will be described later. The processing described with reference to the flowchart shown in FIG. 5 and FIGS. 6 to 19, which will be described later, is realized by causing a computer to execute the program. The program is stored using various types of computer-readable media and can be supplied to a computer. The computer-readable media stores instructions for executing processing.

[0046] Computer-readable media may include non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic storage media, optical storage media, magneto-optical storage media, and semiconductor memory. Magnetic storage media include, for example, flexible disks, magnetic tapes, and hard disk drives. Optical storage media include, for example, CDs (Compact Discs), DVDs (Digital Versatile Discs), and BDs (Blu-ray® Discs). Magneto-optical storage media include, for example, magneto-optical disks. Semiconductor memory includes, for example, mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, RAMs, and SSDs (Solid State Drives).

[0047] Computer-readable media may include transient computer-readable media. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transitive computer-readable media can supply programs to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.

[0048] The controller 50 and each of the left work lever 17 and right work lever 18 may be mounted on the hydraulic excavator 100 or may be located separately outside the hydraulic excavator 100. If a system is constructed in which the controller 50 is located separately outside the hydraulic excavator 100, the controller 50 may be wirelessly connected to the boom IMU 27, arm IMU 28, pressure sensor 25, etc. Because the left work lever 17 and right work lever 18 are located separately from the hydraulic excavator 100, the operator may operate the hydraulic excavator 100 remotely without boarding the cab 4 of the hydraulic excavator 100.

[0049] The controller 50 may be stored in a server (external controller) located away from the hydraulic excavator 100. Some or all of the processing related to the monitoring method of the work machine, which will be described later, may be executed on the server. Detection values ​​from sensors such as the boom IMU 27, arm IMU 28, and pressure sensor 25 may be transmitted to the server. The server may calculate the posture of the work machine 2 from the detection values ​​of the angle sensor. The load applied to the work machine 2 and the posture of the work machine 2 when that load was detected may be associated and stored in the server. The server may create a frequency distribution of the load applied to the work machine 2 for each posture of the work machine 2.

[0050] The controller 50 also includes a work machine motion detection unit 51, a posture sensor value acquisition unit 52, a posture calculation unit 53, a load sensor value acquisition unit 54, an acceleration peak value acquisition unit 55, a frequency distribution creation unit 56, and an output unit 57.

[0051] <Method for Monitoring Work Machinery: First Embodiment> Figure 5 is a flowchart showing the processing flow in the method for monitoring work machinery. The method for monitoring work machinery and the monitoring system will be described in detail with reference to Figures 4, 5 and subsequent figures as appropriate.

[0052] In step S1, the implement operation detection unit 51 of the controller 50 determines whether or not the implement 2 is operating. The implement operation detection unit 51 can determine whether or not the implement 2 is operating based on the operation signals input from the operating devices (left implement lever 17, right implement lever 18). Specifically, if the controller 50 receives operation signals indicating the operation of the left implement lever 17 for the up and down movement of the arm 7, and / or the operation of the right implement lever 18 for the up and down movement of the boom 6, the implement operation detection unit 51 can determine that the implement 2 is operating.

[0053] The implement operation detection unit 51 may determine the operation of the implement 2 based on information other than the operation signal. The speed of the boom 6 can be calculated using the acceleration of the boom 6 input from the boom IMU 27, and the implement operation detection unit 51 may determine that the implement 2 is operating if the speed of the boom 6 is not zero. The speed of the arm 7 can be calculated using the acceleration of the arm 7 input from the arm IMU 28, and the implement operation detection unit 51 may determine that the implement 2 is operating if the speed of the arm 7 is not zero. If the controller 50 outputs a command current to move the spool of the main valve 22, as explained with reference to Figure 2, the implement operation detection unit 51 may determine that the implement 2 is operating.

[0054] If it is determined that the work implement 2 is not operating (NO in the determination in step S1), the determination in step S1 is repeated. When the work implement 2 is not operating, sensor values ​​related to the posture of the work implement 2 are not acquired, and sensor values ​​related to the load on the work implement 2 are not acquired.

[0055] If it is determined that the work machine 2 is operating (YES in the determination in step S1), the process proceeds to step S2. In step S2, the controller 50 acquires the posture of the work machine 2. The posture sensor value acquisition unit 52 acquires sensor values ​​related to the posture of the work machine 2. Specifically, the posture sensor value acquisition unit 52 acquires the boom angle and arm angle from the detected values ​​of the angle sensors (boom IMU 27, arm IMU 28).

[0056] The dimensions of the boom 6 and the arms 7 are stored in the memory unit 59. The attitude calculation unit 53 reads the dimensions of the boom 6 and arms 7 from the memory unit 59. The attitude calculation unit 53 calculates the position of the boom top pin 14 from the dimensions of the boom 6 and the boom angle. The attitude calculation unit 53 calculates the position of the arm top pin 15 from the position of the boom top pin 14, the dimensions of the arms 7, and the arm angle.

[0057] The attitude calculation unit 53 obtains the X and Z coordinates of the position of the arm top pin 15. Referring also to Figure 3, the X coordinate indicates the distance the arm top pin 15 moves forward from the zero position, with the position of the boom foot pin 13 in the longitudinal direction being the zero position. The Z coordinate indicates the distance the arm top pin 15 moves vertically from the zero position, with the position of the ground that the vehicle 5 is in contact with in the vertical direction being the zero position. When the position of the arm top pin 15 is above the zero position, the Z coordinate is a positive value. When the position of the arm top pin 15 is below the zero position, the Z coordinate is a negative value.

[0058] In step S3, the load sensor value acquisition unit 54 of the controller 50 acquires sensor values ​​related to the load applied to the work machine 2. The sensor value related to the load applied to the work machine 2 is, for example, the pressure of the hydraulic fluid detected by the pressure sensor 25.

[0059] Figure 6 is a chart showing the posture of the work machine 2 and the pressure of the hydraulic fluid over time. In Figure 6, the horizontal axis of the three graphs arranged vertically all represents time. The vertical axis of the top graph is the angle of the boom 6 and arm 7. The vertical axis of the middle graph is the X and Z coordinates of the arm top pin 15. The vertical axis of the bottom graph is the pressure of the hydraulic fluid discharged from the hydraulic pump 24 (Figure 2).

[0060] In the example shown in Figure 6, the load sensor value acquisition unit 54 acquires the hydraulic fluid pressure detected by the pressure sensor 25 10 times at equal time intervals from time t1 to time t10. In Figure 6, the 10 dashed lines extending vertically indicate the times when the load sensor value acquisition unit 54 acquires the hydraulic fluid pressure.

[0061] Figure 7 shows the posture of the work machine 2 when the hydraulic fluid pressure is acquired. The time intervals from time t1 to time t2, from time t2 to time t3, ..., from time t9 to time t10 are all equal. The load sensor value acquisition unit 54 acquires the hydraulic fluid pressure at time t1, time t2, ..., time t10. The "pump pressure" shown in Figures 6 and 7 indicates the sensor value of the hydraulic fluid pressure detected by the pressure sensor 25.

[0062] The "arm angle" shown in Figures 6 and 7 represents the sensor value of the arm angle detected by the arm IMU 28. The "boom angle" shown in Figures 6 and 7 represents the sensor value of the boom angle detected by the boom IMU 27. The "arm top X coordinate" shown in Figures 6 and 7 represents the X coordinate of the position of the arm top pin 15, calculated based on the arm angle and boom angle. The unit distance x is the unit distance in the front-rear direction. The "arm top Z coordinate" shown in Figures 6 and 7 represents the Z coordinate of the position of the arm top pin 15, calculated based on the arm angle and boom angle. The unit distance z is the unit distance in the up-down direction.

[0063] The table shown in Figure 7 is stored in the storage unit 59. In step S4 shown in Figure 5, the controller 50 stores in the storage unit 59 the sensor value of the hydraulic fluid pressure (load on the work machine 2) acquired by the load sensor value acquisition unit 54 and the posture of the work machine 2 when the hydraulic fluid pressure was detected, in association with each other.

[0064] In step S5 shown in Figure 5, the frequency distribution creation unit 56 of the controller 50 creates a frequency distribution of the load applied to the work machine 2 for each posture of the work machine 2.

[0065] Figure 8 is a map showing a first example of the frequency distribution of load for each posture of the work machine 2. Of the 10 pump pressures shown in Figure 7, the 7 pump pressures acquired at times t1 to t3 and t5 to t8 are in the range of 0 to 10 MPa. The frequency distribution generation unit 56 plots the X and Z coordinates of the arm top pin 15 at the time these 7 pump pressures were acquired on the map shown in Figure 8.

[0066] At time t1, the X-coordinate of the arm top pin 15 is 5.3x and the Z-coordinate is 0.6z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 8 for X coordinates 5x to 6x and Z coordinates 0 to +z. At time t2, the X-coordinate of the arm top pin 15 is 4.2x and the Z-coordinate is 0.8z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 8 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time t3, the X-coordinate of the arm top pin 15 is 4.1x and the Z-coordinate is 0.8z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 8 for X coordinates 4x to 5x and Z coordinates 0 to +z.

[0067] At time t5, the X-coordinate of the arm top pin 15 is 5.0x and the Z-coordinate is 0.5z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 8 for X coordinates 5x to 6x and Z coordinates 0 to +z. At time t6, the X-coordinate of the arm top pin 15 is 6.2x and the Z-coordinate is 0.6z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 8 for X coordinates 6x to 7x and Z coordinates 0 to +z. At time t7, the X-coordinate of the arm top pin 15 is 7.3x and the Z-coordinate is 0.6z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 8 for X coordinates 7x to 8x and Z coordinates 0 to +z. At time t8, the X-coordinate of the arm top pin 15 is 8.0x and the Z-coordinate is 0.4z. The frequency distribution generation unit 56 adds 1 to the number of data points in the X coordinates 7x to 8x and Z coordinates 0 to +z shown in Figure 8.

[0068] In this way, by plotting the positions of the seven arm top pins 15 acquired at times t1 to t3 and t5 to t8, when the pump pressure is in the range of 0 to 10 MPa, the frequency distribution creation unit 56 creates the frequency distribution shown in Figure 8.

[0069] Figure 9 is a map showing a second example of the frequency distribution of load for each posture of the work machine 2. Of the 10 pump pressures shown in Figure 7, the three pump pressures acquired at times t4 and t9-t10 are in the range of 10-20 MPa. The frequency distribution generation unit 56 plots the X and Z coordinates of the arm top pin 15 at the time these three pump pressures were acquired on the map shown in Figure 9.

[0070] At time t4, the X-coordinate of the arm top pin 15 is 4.3x and the Z-coordinate is 0.6z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 9 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time t9, the X-coordinate of the arm top pin 15 is 8.3x and the Z-coordinate is 0.2z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 9 for X coordinates 8x to 9x and Z coordinates 0 to +z. At time t10, the X-coordinate of the arm top pin 15 is 8.3x and the Z-coordinate is 0.1z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 9 for X coordinates 8x to 9x and Z coordinates 0 to +z.

[0071] In this way, by plotting the positions of the three arm top pins 15 acquired at times t4 and t9-t10, when the pump pressure is in the range of 10-20 MPa, the frequency distribution creation unit 56 creates the frequency distribution shown in Figure 9.

[0072] Figures 6-9 illustrate an example of plotting 10 data points representing the posture of the work machine 2, acquired at times t1, t2, ..., t10, on separate maps for each magnitude of the hydraulic fluid pressure. As time progresses and data accumulates, the number of data points plotted on the map increases. Figure 10 is a map showing a third example of the frequency distribution of load for each posture of the work machine 2. Figure 11 is a map showing a fourth example of the frequency distribution of load for each posture of the work machine 2. Figure 10 shows the frequency distribution for each posture of the work machine 2 over time when the pump pressure is in the range of 0 to 10 MPa. Figure 11 shows the frequency distribution for each posture of the work machine 2 over time when the pump pressure is in the range of 33 MPa or higher.

[0073] The frequency distribution generation unit 56 of the controller 50 creates a bubble chart to visualize each map. The bubble chart represents the number of data points for each posture of the work machine 2 when the load applied to the work machine 2 is within a specific range, using the size of the circles. Figure 12 is a bubble chart for a specific range of pump pressures. Figure 12 shows a bubble chart that visualizes the map shown in Figure 11.

[0074] In the map shown in Figure 11, the number of data points is 1 or more for each of the five positions of the work implement 2. The first position of the work implement 2 is when the X coordinate of the arm top pin 15 is 7x to 8x and the Z coordinate is 0 to +z. The second position of the work implement 2 is when the X coordinate is 8x to 9x and the Z coordinate is 0 to +z. The third position of the work implement 2 is when the X coordinate is 4x to 5x and the Z coordinate is -3z to -2z. The fourth position of the work implement 2 is when the X coordinate is 5x to 6x and the Z coordinate is -3z to -2z. The fifth position of the work implement 2 is when the X coordinate is 6x to 7x and the Z coordinate is -3z to -2z. The first position has the most data points, and the fifth position has the fewest data points.

[0075] Figure 12 displays circles of a size corresponding to the number of data points at the X and Z coordinate positions for each posture. The largest circle is displayed at the position where the X coordinate of the arm top pin 15 is 7x to 8x and the Z coordinate is 0 to +z, corresponding to the posture of the first work implement 2. The smallest circle is displayed at the position where the X coordinate is 6x to 7x and the Z coordinate is -3z to -2z, corresponding to the fifth posture. No circle is displayed for postures of work implement 2 where the number of data points is zero in the map shown in Figure 11.

[0076] In step S6 shown in Figure 5, the output unit 57 of the controller 50 outputs the created bubble chart. Specifically, the output unit 57 outputs a signal to the display device 23 that causes the bubble chart shown in Figure 12 to be displayed. The display device 23, upon receiving this signal, displays the bubble chart.

[0077] By looking at the display device 23 showing the bubble chart shown in Figure 12, it is easy to recognize the posture of the work implement 2 when the pump pressure is 33 MPa or higher and the load on the work implement 2 is relatively large. For example, when the hydraulic excavator 100 is excavating the ground, it can be determined that the load on the work implement 2 is large at the moment the bucket 8 contacts the ground. Also, for example, if the load on the work implement 2 increases as the depth to which the bucket 8 digs into the ground increases during excavation, it can be determined that the operator of the hydraulic excavator 100 may feel that the driving force of the work implement 2 is insufficient during excavation.

[0078] <Method for monitoring work machinery: Second embodiment> In the explanation using Figures 6 to 12, in step S3 shown in Figure 5, the load sensor value acquisition unit 54 of the controller 50 acquires the hydraulic fluid pressure detected by the pressure sensor 25. The sensor value related to the load on the work machine 2 acquired by the load sensor value acquisition unit 54 is not limited to the hydraulic fluid pressure. The sensor value related to the load on the work machine 2 may also be the acceleration of the arm 7 detected by the arm IMU 28.

[0079] Figure 13 is a chart showing the time course of the posture of the work machine 2 and the acceleration of the arm 7. Similar to Figure 6, the horizontal axis of the three graphs arranged vertically in Figure 13 all represents time. The vertical axis of the top graph is the angle of the boom 6 and arm 7. The vertical axis of the middle graph is the X and Z coordinates of the arm top pin 15. The vertical axis of the bottom graph is the acceleration of the arm 7 detected by the arm IMU 28.

[0080] In the example shown in Figure 13, the load sensor value acquisition unit 54 acquires the acceleration of arm 7 detected by arm IMU 28. The acceleration peak value acquisition unit 55 shown in Figure 4 observes the time change of the acceleration of arm 7. The acceleration peak value acquisition unit 55 acquires the maximum value as the peak value of the acceleration of arm 7 when the acceleration of arm 7, which had been increasing over time, reaches a maximum value and then begins to decrease, and continues to decrease for a certain period of time or decreases by a certain amount.

[0081] In Figure 13, the nine dashed lines extending vertically indicate the time at which the load sensor value acquisition unit 54 acquires the peak value of the acceleration of the arm 7. In the example shown in Figure 13, there are nine peak values ​​for the acceleration of the arm 7 between time tp1 and time tp9, and the load sensor value acquisition unit 54 acquires these nine peak values.

[0082] Figure 14 shows the posture of the work machine 2 when the peak acceleration value is acquired. The load sensor value acquisition unit 54 acquires the peak acceleration value of the arm 7 at times tp1, tp2, ..., tp9. The "IMU acceleration" shown in Figures 13 and 14 indicates the sensor value of the acceleration of the arm 7 detected by the arm IMU 28.

[0083] The "arm angle" shown in Figures 13 and 14 represents the sensor value of the arm angle detected by the arm IMU 28. The "boom angle" shown in Figures 13 and 14 represents the sensor value of the boom angle detected by the boom IMU 27. The "arm top X coordinate" shown in Figures 13 and 14 represents the X coordinate of the position of the arm top pin 15, calculated based on the arm angle and boom angle. The unit distance x is the unit distance in the front-rear direction. The "arm top Z coordinate" shown in Figures 13 and 14 represents the Z coordinate of the position of the arm top pin 15, calculated based on the arm angle and boom angle. The unit distance z is the unit distance in the up-down direction.

[0084] The table shown in Figure 14 is stored in the storage unit 59. In step S4 shown in Figure 5, the controller 50 stores in the storage unit 59 the sensor value of the acceleration of the arm 7 (load applied to the work machine 2) acquired by the load sensor value acquisition unit 54, and the posture of the work machine 2 when the peak value of the acceleration of the arm 7 was detected, in association with each other.

[0085] In step S5 shown in Figure 5, the frequency distribution creation unit 56 of the controller 50 creates a frequency distribution of the load applied to the work machine 2 for each posture of the work machine 2.

[0086] Figure 15 is a map showing a fifth example of the frequency distribution of load for each posture of the work machine 2. Of the nine IMU accelerations shown in Figure 14, the nine IMU accelerations acquired at times tp1 to tp9 are between 0 and 20 m / s². ２ It is within this range. The frequency distribution generation unit 56 plots the X and Z coordinates of the arm top pin 15 when the IMU accelerations of these nine points are acquired on the map shown in Figure 15.

[0087] At time tp1, the X-coordinate of the arm top pin 15 is 4.1x and the Z-coordinate is 0.8z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time tp2, the X-coordinate of the arm top pin 15 is 4.1x and the Z-coordinate is 0.8z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time tp3, the X-coordinate of the arm top pin 15 is 4.1x and the Z-coordinate is 0.8z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z.

[0088] At time tp4, the X-coordinate of the arm top pin 15 is 4.1x and the Z-coordinate is 0.8z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time tp5, the X-coordinate of the arm top pin 15 is 4.4x and the Z-coordinate is 0.6z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time tp6, the X-coordinate of the arm top pin 15 is 4.7x and the Z-coordinate is 0.5z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z.

[0089] At time tp7, the X-coordinate of the arm top pin 15 is 5.0x and the Z-coordinate is 0.5z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 4x to 5x and Z coordinates 0 to +z. At time tp8, the X-coordinate of the arm top pin 15 is 8.2x and the Z-coordinate is 0.4z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 8x to 9x and Z coordinates 0 to +z. At time tp9, the X-coordinate of the arm top pin 15 is 8.3x and the Z-coordinate is 0.0z. The frequency distribution generation unit 56 adds 1 to the number of data points shown in Figure 15 for X coordinates 8x to 9x and Z coordinates 0 to +z.

[0090] Thus, the IMU accelerations acquired between time tp1 and tp9 were between 0 and 20 m / s². ２ By plotting the positions of the nine arm top pins 15 within the specified range on a map, the frequency distribution creation unit 56 creates the frequency distribution shown in Figure 15.

[0091] Figure 16 is a map showing a sixth example of the frequency distribution of load for each posture of the work machine 2. The IMU acceleration shown in Figure 14 is 20–40 m / s². ２ It does not include IMU acceleration within the specified range. There is no data to plot on the map shown in Figure 16 based on the IMU acceleration shown in Figure 14. Therefore, in the frequency distribution shown in Figure 16, the number of data points is zero for the X and Z coordinates of all arm top pins 15.

[0092] Figures 13-16 illustrate an example of plotting nine data points representing the posture of the work machine 2, acquired at times tp1, tp2, ..., tp9, on separate maps for each magnitude of the hydraulic fluid pressure. As time progresses and data accumulates, the number of data points plotted on the map increases. Figure 17 is a map showing a seventh example of the frequency distribution of load for each posture of the work machine 2. Figure 18 is a map showing an eighth example of the frequency distribution of load for each posture of the work machine 2. Figure 17 shows the IMU acceleration over time, ranging from 0 to 20 m / s². ２ The frequency distribution for each posture of the work machine 2 within the specified range is shown. Figure 18 shows the IMU acceleration at 80 m / s² over time. ２ The frequency distribution for each posture of the work machine 2 within the above range is shown.

[0093] The frequency distribution creation unit 56 of the controller 50 creates a bubble chart to visualize each map. The bubble chart represents the number of data points for each posture of the work machine 2 when the load applied to the work machine 2 is within a specific range, using the size of the circles. Figure 19 is a bubble chart for a specific acceleration range. Figure 19 shows a bubble chart that visualizes the map shown in Figure 18.

[0094] In the map shown in Figure 18, the number of data points is 1 or more for each of the five positions of the work implement 2. The first position of the work implement 2 is when the X coordinate of the arm top pin 15 is 4x to 5x and the Z coordinate is 0 to +z. The second position of the work implement 2 is when the X coordinate is 5x to 6x and the Z coordinate is 0 to +z. The third position of the work implement 2 is when the X coordinate is 6x to 7x and the Z coordinate is 0 to +z. The fourth position of the work implement 2 is when the X coordinate is 7x to 8x and the Z coordinate is 0 to +z. The fifth position of the work implement 2 is when the X coordinate is 8x to 9x and the Z coordinate is 0 to +z. Of the first to fifth positions of the work implement 2, the third position has the most data points, while the first and fifth positions have the fewest data points.

[0095] Figure 19 shows circles of a size corresponding to the number of data points at the X and Z coordinate positions of the postures of the first to fifth work implements 2. For the posture of the third work implement 2, the circle is relatively large at the position where the X coordinate of the arm top pin 15 is 6x to 7x and the Z coordinate is 0 to +z. For the posture of the first work implement 2, the circle is relatively small at the position where the X coordinate is 4x to 5x and the Z coordinate is 0 to +z, and for the posture of the fifth work implement 2, the circle is relatively small at the position where the X coordinate is 8x to 9x and the Z coordinate is 0 to +z. No circle is displayed for the posture of work implement 2 where the number of data points is zero in the map shown in Figure 18.

[0096] Even in the positions of the sixth to eighth work implements 2, which are not shown in Figure 18, the number of data points is 1 or more. The sixth position of the sixth work implement 2 is when the X coordinate of the arm top pin 15 is 5x to 6x and the Z coordinate is +7z to +8z. The seventh position of the seventh work implement 2 is when the X coordinate is 6x to 7x and the Z coordinate is +7z to +8z. The eighth position of the eighth work implement 2 is when the X coordinate is 6x to 7x and the Z coordinate is +6z to +7z. Of the positions of the sixth to eighth work implements 2, the seventh position has the most data points.

[0097] Figure 19 shows circles of a size corresponding to the number of data points at the X and Z coordinate positions of the postures of the 6th to 8th work implements 2. The size of the circles is relatively larger at the position where the X coordinate of the arm top pin 15 is 6x to 7x and the Z coordinate is +7z to +8z, corresponding to the posture of the 7th work implement 2.

[0098] In step S6 shown in Figure 5, the output unit 57 of the controller 50 outputs the created bubble chart. Specifically, the output unit 57 outputs a signal to the display device 23 that causes the bubble chart shown in Figure 19 to be displayed. The display device 23, upon receiving this signal, displays the bubble chart.

[0099] By viewing the display device 23 showing the bubble chart shown in Figure 19, the IMU acceleration is 80 m / s². ２ As described above, when the load on the work implement 2 is relatively large, it is easy to recognize what position the work implement 2 is in. For example, when the hydraulic excavator 100 is digging the ground, it can be determined that the load on the work implement 2 is large at the moment the bucket 8 contacts the ground. Also, for example, if the load on the work implement 2 is large when the Z coordinate of the arm top pin 15 is large, it can be determined that upward excavation is being performed, where the boom 6 and arm 7 are swung up to excavate terrain that is high above the ground.

[0100] In this way, the series of processes in the method for monitoring the work machine is completed ("End" in Figure 5).

[0101] <Function and Effects> The characteristic configuration and effects of this embodiment are summarized below.

[0102] As shown in Figure 5, the memory unit 59 shown in Figure 4 stores the load applied to the work implement 2 and the position of the work implement 2 at the time the load was acquired, associating them together. As shown in Figures 5 and 12 and 19, the output unit 57 shown in Figure 4 outputs the load applied to the work implement 2 for each position of the work implement 2. The load applied to the work implement 2 is visualized for each load magnitude and for each position of the work implement 2.

[0103] By observing the output load, designers of the work equipment 2 can determine whether there is a history of heavy loads being placed on it. Based on the cumulative time that heavy loads were placed on work equipment 2, the lifespan of work equipment 2 can be predicted. Therefore, it becomes possible to suggest recommended operating methods and maintenance suggestions to the work equipment user before problems such as cracks in the sheet metal actually occur in work equipment 2. Early detection of potential problems in work equipment 2 becomes possible, and by taking countermeasures before problems actually occur, problems can be prevented, thus avoiding work equipment downtime and reducing repair costs.

[0104] Furthermore, by examining the load on the work implement 2 for each position, designers of work implements 2 can understand how much load is placed on it in each position. For example, a designer can understand the position of work implement 2 when it is under heavy load. If a designer finds that work implement 2 is frequently subjected to heavy loads, such as upward excavation, they can determine that it is desirable to design work implement 2 to be able to withstand frequent heavy loads without malfunction. If a designer finds that the driving force of work implement 2 is insufficient during excavation work, they can consider whether to increase the driving force. This allows for design feedback to be provided to the next development model that corresponds to the actual usage of the work implement, enabling efficient revision of design standards.

[0105] The output unit 57 shown in Figure 4 may output the frequency distribution of the load applied to the work implement 2 for each posture of the work implement 2. For example, a designer of the work implement can visually grasp the history of the load applied to the work implement 2 for each posture of the work implement 2 by looking at the frequency distribution of the load for each posture of the work implement 2, as shown in Figures 12 and 19.

[0106] As shown in Figure 4, the boom angle detected by the boom IMU 27 and the arm angle detected by the arm IMU 28 constitute an example of sensor values ​​related to the posture of the work machine 2. The posture sensor value acquisition unit 52 shown in Figure 4 may acquire the boom angle and arm angle from the detected values ​​of the angle sensors (boom IMU 27, arm IMU 28). As shown in Figures 7 and 14, the posture calculation unit 53 shown in Figure 4 can accurately calculate the posture of the work machine 2 from the acquired sensor values ​​and the preset specification values ​​of the work machine 2, such as the dimensions of the work machine 2.

[0107] The load sensor value acquisition unit 54 shown in Figure 4 may acquire sensor values ​​related to the load applied to the work machine 2. As shown in Figures 6-7 and 13-14, the acquired sensor values ​​can be associated with the posture of the work machine 2 at the time the sensor values ​​were acquired. As shown in Figures 12 and 19, by outputting the load applied to the work machine 2 for each magnitude of the acquired sensor value and for each posture of the work machine 2, it becomes possible to quickly address malfunctions of the work machine 2 and easily improve its design.

[0108] As shown in Figure 4, the acceleration of arm 7 detected by arm IMU 28 constitutes an example of a sensor value related to the load on the work machine 2. The load sensor value acquisition unit 54 shown in Figure 4 may acquire the acceleration of arm 7 from the value detected by arm IMU 28. As shown in Figures 13 to 14, the acquired acceleration of arm 7 can be associated with the posture of the work machine 2 at the time the acceleration was acquired. As shown in Figure 19, it becomes possible to output the load on the work machine 2 for each acquired acceleration of arm 7 and for each posture of the work machine 2.

[0109] As shown in Figure 13, the load sensor value acquisition unit 54 shown in Figure 4 may acquire the peak value of the acceleration of the arm 7. The peak value of the acceleration of the arm 7 is an example of the dynamic load applied to the work machine 2. As shown in Figures 13 to 14, the magnitude of the dynamic load applied to the work machine 2 can be associated with the posture of the work machine 2 when that dynamic load was acquired. As shown in Figure 19, it becomes possible to output the load applied to the work machine 2 for each magnitude of the dynamic load applied to the work machine 2 and for each posture of the work machine 2.

[0110] As shown in Figure 4, the hydraulic fluid pressure detected by the pressure sensor 25 constitutes an example of a sensor value related to the load on the work machine 2. The load sensor value acquisition unit 54 shown in Figure 4 may acquire the hydraulic fluid pressure from the value detected by the pressure sensor 25. As shown in Figures 6-7, the acquired hydraulic fluid pressure can be associated with the posture of the work machine 2 at the time the pressure was acquired. As shown in Figure 12, it becomes possible to output the load on the work machine 2 for each acquired hydraulic fluid pressure and for each posture of the work machine 2.

[0111] As shown in Figures 6-7, the load sensor value acquisition unit 54 may acquire the hydraulic fluid pressure at equal time intervals. The hydraulic fluid pressure acquired at equal time intervals is an example of the static load applied to the work implement 2. As shown in Figures 6-7, the magnitude of the static load applied to the work implement 2 can be associated with the posture of the work implement 2 when the static load was acquired. As shown in Figure 12, it becomes possible to output the load applied to the work implement 2 for each magnitude of the static load applied to the work implement 2 and for each posture of the work implement 2.

[0112] The output unit 57 shown in Figure 4 may output the frequency distribution of the load for each posture of the work implement 2, according to the magnitude of the load applied to the work implement 2. For example, a designer of the work implement can visually understand under what posture the work implement 2 is subjected to a large load by looking at the frequency distribution of the load for each posture of the work implement 2 when the load applied to the work implement 2 is large, as shown in Figures 12 and 19.

[0113] As shown in Figure 4, the output unit 57 may display the load on the work implement 2 for each orientation of the work implement 2 on the display device 23. By looking at the display device 23, the designer of the work implement can reliably visually grasp the load on the work implement 2 for each orientation of the work implement 2.

[0114] As shown in Figure 1, the arm top pin 15 is the connection point between the arm 7 and the bucket 8, so the position of the arm top pin 15 corresponds to an example of information indicating the position of the attachment at the tip of the work machine 2, as also shown in Figure 3. The attitude sensor value acquisition unit 52 shown in Figure 4 acquires the boom angle and arm angle, and the attitude calculation unit 53 can accurately calculate the position of the arm top pin 15 using the acquired boom angle and arm angle, as shown in Figures 7 and 14.

[0115] In this embodiment, the output unit 57 displays the load on the work machine 2 for each position of the work machine 2 on the display device 23, but the manner in which the output unit 57 outputs the load is not limited to this. The load on the work machine 2 for each position of the work machine 2 may be printed so that the operator can visually confirm the printed material. The output unit 57 may also transmit the load on the work machine 2 to an external computer configured separately from the work machine, and display the load on an external monitor. The external computer may be located in a remote location away from the work machine. The external computer may be a portable device. The external computer may be a portable device that the operator can carry and use, such as a laptop computer, tablet computer, or smartphone.

[0116] In this embodiment, a pressure sensor 25 for detecting the pressure of the hydraulic fluid is provided in the path of the hydraulic fluid discharged by the hydraulic pump 24. If the hydraulic excavator 100 is equipped with multiple hydraulic pumps, the average value of the sensor values ​​of the pressure sensors provided on the outlet side of each hydraulic pump may be used as the hydraulic fluid pressure. The hydraulic fluid pressure is not limited to the discharge pressure of the hydraulic pump. A pressure sensor may also be provided in the path of the hydraulic fluid connecting the hydraulic cylinders (arm cylinder 11, boom cylinder 10) that drive the work machine 2 and the main valve 22 to detect the pressure of the hydraulic fluid supplied to and discharged from the oil chamber of the hydraulic cylinder.

[0117] In this embodiment, the attitude sensor value acquisition unit 52 acquires sensor values ​​related to the attitude of the work machine 2, and the attitude calculation unit 53 calculates the position of the arm top pin 15 from the acquired sensor values, but this is not the only example. For example, it is also possible to attach a high-performance GNSS (Global Navigation Satellite System) receiver to the arm top pin 15 and directly acquire the detection result of the GNSS receiver as the position of the arm top pin 15.

[0118] In this embodiment, the position of the arm top pin 15 is acquired as information indicating the position of the attachment at the tip of the work implement 2. However, the position of the bucket 8, typically the position of the cutting edge 8a, may also be acquired as information indicating the position of the attachment. If an attachment other than the bucket 8 is attached to the tip of the work implement 2, any position on the attachment, or the position of the arm top pin 15, may be used as information indicating the position of the attachment. By acquiring a position near the tip of the work implement 2 as information indicating the position of the attachment, the amount of information that can be acquired can be increased.

[0119] In the embodiments, a hydraulic excavator 100 was described as an example of a work machine, but the concept of this disclosure may be applied not only to the hydraulic excavator 100 but also to other types of work machines such as wheel loaders.

[0120] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.

[0121] 1 Main body, 2 Work implement, 3 Slewing body, 5 Traveling body, 6 Boom, 7 Arm, 8 Bucket, 13 Boom foot pin, 14 Boom top pin, 15 Arm top pin, 17 Left work implement lever, 18 Right work implement lever, 21 Hydraulic actuator, 22 Main valve, 23 Display device, 24 Hydraulic pump, 25 Pressure sensor, 27 Boom IMU, 28 Arm IMU, 50 Controller, 51 Work implement motion detection unit, 52 Posture sensor value acquisition unit, 53 Posture calculation unit, 54 Load sensor value acquisition unit, 55 Acceleration peak value acquisition unit, 56 Frequency distribution creation unit, 57 Output unit, 59 Memory unit, 71 Movable range boundary, 72 Movable range, 100 Hydraulic excavator.

Claims

1. A method for monitoring a work machine, comprising: acquiring the posture of the work machine; acquiring the load applied to the work machine; and outputting the load for each posture from the acquired load and the posture at the time the load was acquired.

2. The method for monitoring a work machine according to claim 1, wherein outputting the load includes outputting the frequency distribution of the load for each posture.

3. The method for monitoring a work machine according to claim 1, wherein acquiring the posture includes acquiring sensor values ​​related to the posture and calculating the posture from the acquired sensor values, and acquiring the load includes acquiring sensor values ​​related to the load.

4. The method for monitoring a work machine according to claim 3, wherein obtaining sensor values ​​related to the load includes obtaining the acceleration of the work machine.

5. The method for monitoring a work machine according to claim 4, wherein obtaining the acceleration includes obtaining the peak value of the acceleration.

6. The method for monitoring a work machine according to claim 3, wherein obtaining sensor values ​​relating to the load includes obtaining the pressure of the hydraulic fluid supplied to the hydraulic cylinder that drives the work machine.

7. The method for monitoring a work machine according to claim 6, wherein obtaining the pressure includes obtaining the pressure at equal time intervals.

8. The method for monitoring a work machine according to claim 2, wherein outputting the frequency distribution includes outputting the frequency distribution for each magnitude of the load.

9. The method for monitoring a work machine according to claim 1, wherein outputting the load includes displaying the load on a display device.

10. The method for monitoring a work machine according to claim 1, wherein acquiring the posture includes acquiring information indicating the position of the attachment at the tip of the work machine.

11. A computer-readable medium for storing instructions for executing a process, wherein the process includes: acquiring the posture of a work machine; acquiring the load applied to the work machine; and outputting the load for each posture from the acquired load and the posture at the time the load was acquired.

12. The computer-readable medium according to claim 11, wherein outputting the load includes outputting the frequency distribution of the load for each posture.

13. The computer-readable medium according to claim 11, wherein acquiring the posture includes acquiring sensor values ​​related to the posture and calculating the posture from the acquired sensor values, and acquiring the load includes acquiring sensor values ​​related to the load.

14. The computer-readable medium according to claim 13, wherein acquiring sensor values ​​relating to the load includes acquiring the acceleration of the work machine.

15. The computer-readable medium according to claim 13, wherein acquiring sensor values ​​relating to the load includes acquiring the pressure of the hydraulic fluid supplied to the hydraulic cylinder driving the work machine.

16. A monitoring system for a work machine comprising a work machine having a work implement and a controller for controlling the work machine, wherein the controller is configured to acquire the posture of the work machine, acquire the load applied to the work machine, and output the load for each posture based on the acquired load and the posture at the time the load was acquired.

17. The monitoring system for a work machine according to claim 16, wherein the controller outputs the frequency distribution of the load for each posture.

18. The monitoring system for a work machine according to claim 16, wherein the controller acquires sensor values ​​relating to the posture and calculates the posture from the acquired sensor values ​​to acquire the posture, and the controller acquires sensor values ​​relating to the load to acquire the load.

19. The monitoring system for a work machine according to claim 18, wherein the controller obtains sensor values ​​related to the load by obtaining the acceleration of the work machine.

20. The monitoring system for a work machine according to claim 18, wherein the controller obtains sensor values ​​related to the load by obtaining the pressure of the hydraulic fluid supplied to the hydraulic cylinder that drives the work machine.

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