Working machinery

Abstract

Improve the accuracy of weight calculation. [Solution] A work machine according to one embodiment comprises a lower traveling body, an upper rotating body mounted on the lower traveling body so as to be rotatable, an attachment having a boom, an arm, and an end attachment, a posture sensor that acquires the posture of the attachment, a sensor that acquires information for deriving torque related to the boom, a control device that calculates the torque generated by the load loaded on the attachment based on the torque related to the boom derived from the information, an inertial torque calculated based on posture information acquired by the posture sensor, a speed-dependent torque calculated based on a torque acquired by the posture sensor and pre-associated with posture information, and a no-load torque calculated based on the posture and the weight of the attachment acquired by the posture sensor, and calculates the weight of the load based on the torque generated by the load and the posture.

Description

Technical Field

[0001] The present invention relates to a working machine.

Background Art

[0002] Conventionally, work has been performed by a working machine to load a loaded material onto a dump truck or the like. In order to perform such work efficiently, calculation of the weight of the loaded material has been required. Therefore, a technique for calculating the weight of the loaded material carried by the working machine has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the excavating machine described in Patent Document 1, the weight of the loaded material is calculated in consideration of the speed of the attachment. However, when calculating the weight of the loaded material, it is necessary to consider various factors. For example, due to factors such as inertia, an error may occur in the calculation of the weight of the loaded material.

[0005] In view of the above, it is realized to improve the calculation accuracy of the weight of the loaded material loaded on the attachment.

Means for Solving the Problems

[0006] A working machine according to one aspect of the present invention comprises a lower traveling body, an upper rotating body mounted on the lower traveling body so as to be rotatable, an attachment having a boom, an arm, and an end attachment, a posture sensor for acquiring the posture of the attachment, a sensor for acquiring information for deriving torque related to the boom, and a control device that calculates the torque generated by the load loaded on the attachment based on the torque related to the boom derived from the information, an inertial torque calculated based on the posture information acquired by the posture sensor, a speed-dependent torque calculated based on the torque acquired by the posture sensor and pre-associated with the posture information, and a no-load torque calculated based on the posture and the weight of the attachment acquired by the posture sensor, and calculates the weight of the load based on the torque generated by the load and the posture. [Effects of the Invention]

[0007] According to one aspect of the present invention, the accuracy of calculating the weight of the load placed on the attachment is improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view showing a work machine according to the first embodiment. [Figure 2] This figure shows an example of the configuration of the drive control system for a work machine according to the first embodiment. [Figure 3] This is a conceptual diagram illustrating the measurement of the weight of a load in a work machine according to the first embodiment. [Figure 4] This figure illustrates the configuration of the speed-dependent torque setting unit according to the first embodiment. [Figure 5] This flowchart shows the processing procedure for updating the speed-dependent torque storage unit in the speed-dependent torque setting unit according to the first embodiment. [Figure 6] This figure illustrates the table structure of the speed-dependent torque storage unit according to the first embodiment. [Figure 7]This figure illustrates the configuration of the weight calculation unit according to the first embodiment. [Figure 8] This figure shows the correspondence between the angular velocity of the boom and the speed-dependent torque generated at that angular velocity, as stored in the speed-dependent torque memory unit according to the first embodiment. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are illustrative and do not limit the invention. Not all features and combinations thereof in the embodiments of this disclosure are necessarily essential to the invention. In each drawing, the same or corresponding components are denoted by the same or corresponding reference numerals, and redundant descriptions may be omitted.

[0010] The working machine 100 according to the embodiment of this disclosure is a shovel. The working machine 100 may be a machine other than a shovel, such as a crane. In the illustrated example, the shovel as the working machine 100 is an excavator equipped with a bucket 6 as an end attachment, but it may be an applied machine such as a forestry machine equipped with an end attachment other than the bucket 6. Furthermore, it may be a crawler crane equipped with a lower traveling body, an upper rotating body, and an attachment provided on the upper rotating body.

[0011] (First embodiment) First, an overview of the work machine 100 according to this embodiment will be described with reference to Figure 1. Figure 1 is a side view of the work machine 100 as a work machine according to the first embodiment.

[0012] In Figure 1, +X represents one direction of the X-axis in the three-dimensional Cartesian coordinate system, and (not shown) -X represents the other direction of the X-axis. +Y represents one direction of the Y-axis in the three-dimensional Cartesian coordinate system, and (not shown) -Y represents the other direction of the Y-axis. +Z represents one direction of the Z-axis in the three-dimensional Cartesian coordinate system, and (not shown) -Z represents the other direction of the Z-axis. In Figure 1, the +X side of the work machine 100 corresponds to the front side of the work machine 100, and the -X side of the work machine 100 corresponds to the rear side of the work machine 100. Also, the +Y side of the work machine 100 corresponds to the left side of the work machine 100, and the -Y side of the work machine 100 corresponds to the right side of the work machine 100. Furthermore, the +Z side of the work machine 100 corresponds to the top side of the work machine 100, and the -Z side of the work machine 100 corresponds to the bottom side of the work machine 100. The same applies to other figures.

[0013] The work machine 100 comprises a lower traveling body 1, an upper rotating body 3 mounted on the lower traveling body 1 so as to be rotatable via a slewing mechanism 2, an attachment AT for performing various tasks, and a driver's cab 10. The driver's cab 10 is also called a cabin or cab. The front side of the work machine 100 (upper rotating body 3) corresponds to the side on which the attachment AT is attached to the upper rotating body 3 when the work machine 100 is viewed from directly above along the slewing axis of the upper rotating body 3. The left, right, and rear sides of the work machine 100 (upper rotating body 3) correspond to the left, right, and rear sides as seen from the perspective of an operator seated in the driver's seat inside the driver's cab 10, respectively.

[0014] The lower travel body 1 includes, for example, a pair of left and right crawlers 1C. Specifically, the crawlers 1C include a left crawler and a right crawler. The left crawler is driven by a left travel hydraulic motor 2ML (see Figure 2), and the right crawler is driven by a right travel hydraulic motor 2MR (see Figure 2). The left travel hydraulic motor 2ML is a travel drive unit that drives the left crawler, which is the driven part, and can rotate the left crawler. The right travel hydraulic motor 2MR is a travel drive unit that drives the right crawler, which is the driven part, and can rotate the right crawler. Note that the travel drive units may also be electric motors.

[0015] At the center of the front part of the upper swing body 3, a boom 4 is rotatably attached. At the tip of the boom 4, an arm 5 is rotatably attached. At the tip of the arm 5, a bucket 6 is rotatably attached. In the illustrated example, the boom 4, the arm 5, and the bucket 6 constitute an excavation attachment which is an example of an attachment AT. The boom 4, the arm 5, and the bucket 6 are respectively driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9.

[0016] The bucket 6 is an example of a working tool (end attachment). The bucket 6 is used, for example, in excavation work or the like. At the tip of the arm 5, depending on the work content or the like, another working tool may be attached instead of the bucket 6. The other working tool may be, for example, other types of buckets such as a large bucket, a slope bucket, a dredging bucket, etc. Also, the other working tool may be a working tool of a type other than a bucket such as a stirrer, a breaker, a grapple, or a lifting magnet. The excavation attachment may be provided with a bucket tilt mechanism.

[0017] The swing hydraulic motor 2A, the left travel hydraulic motor 2ML, the right travel hydraulic motor 2MR, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 are hydraulic actuators driven by hydraulic oil discharged from a hydraulic pump.

[0018] Note that all or part of the driven parts such as the lower travel body 1, the upper swing body 3, the boom 4, the arm 5, and the bucket 6 of the working machine 100 may be electrically driven. That is, the working machine 100 may be a hybrid excavator or an electric excavator in which all or part of the driven parts are driven by electric actuators.

[0019] The imaging device S6 is provided on the upper swing body 3, images the periphery of the working machine 100, and acquires image information representing the periphery of the working machine 100. In the illustrated example, the imaging device S6 includes a front camera S6F, a left camera S6L, a right camera S6R, and a rear camera S6B.

[0020] The front camera S6F is a camera that captures images in front of the work machine 100 and is mounted on the outside of the operator's cab 10, such as on the roof of the operator's cab 10 or the side of the boom 4. The left camera S6L is a camera that captures images to the left of the work machine 100, the right camera S6R is a camera that captures images to the right of the work machine 100, and the rear camera S6B is a camera that captures images behind the work machine 100. Specifically, the front camera S6F, left camera S6L, right camera S6R, and rear camera S6B are all monocular wide-angle cameras equipped with an image sensor such as a CCD or CMOS, and the information of the captured images is taken up by the controller 30. Alternatively, the images captured by the imaging device S6 may be output to the display device D1 (see Figure 2).

[0021] In the illustrated example, the front camera S6F is mounted on the roof of the driver's cab 10, the left camera S6L is mounted on the upper left end of the upper surface of the upper rotating body 3, the right camera S6R is mounted on the upper right end of the upper surface of the upper rotating body 3, and the rear camera S6B is mounted on the upper rear end of the upper surface of the upper rotating body 3.

[0022] The imaging device S6 may constitute an object detection device that detects objects in the vicinity of the work machine 100. The object detection device may consist of devices other than a camera. For example, the object detection device may be a LiDAR. A LiDAR is, for example, a device capable of measuring the distance between a point cloud of 1 million or more points within the monitoring range and the LiDAR (laser source). Alternatively, the object detection device may be other devices capable of measuring the distance to an object, such as a stereo camera, a depth image camera, or a millimeter-wave radar. When a millimeter-wave radar or the like is used as the object detection device, the object detection device may determine the distance and direction of the object by transmitting a large number of signals (such as laser light) toward the object and receiving the reflected signals. Alternatively, the object detection device may be a combination of two or more types of devices. For example, the object detection device may be a combination of an imaging device and a LiDAR, or a combination of an imaging device and a millimeter-wave radar, or a combination of an imaging device and a stereo camera.

[0023] The controller 30 is an example of a control device and is composed of a computer including, for example, a CPU, a volatile memory device, a non-volatile memory device, and various input / output interfaces. The controller 30 implements various functions, for example, by reading a program from the non-volatile memory device, loading it into the volatile memory device, and having the CPU execute it. In the illustrated example, the controller 30 is configured to implement various functions and control the work machine 100. These functions include, for example, a machine guidance function that guides the operator in manually operating the work machine 100. The functions may also include a contact avoidance function that automatically or autonomously operates or stops the work machine 100 to avoid contact between the work machine 100 and objects within the monitoring range around the work machine 100.

[0024] The boom angle sensor S1 detects the rotation angle of the boom 4. In this embodiment, the boom angle sensor S1 is an acceleration sensor that can detect the rotation angle of the boom 4 relative to the upper slewing body 3 (hereinafter referred to as "boom angle") which changes per unit time. The boom angle sensor S1 can detect the angular velocity of the boom 4, which indicates the change in boom angle, and the angular acceleration of the boom 4, which indicates the rate of said change. The boom angle is, for example, at its minimum when the boom 4 is at its lowest position, and increases as the boom 4 is raised.

[0025] The arm angle sensor S2 detects the rotation angle of the arm 5. In this embodiment, the arm angle sensor S2 is an acceleration sensor and can detect the rotation angle of the arm 5 relative to the boom 4 (hereinafter referred to as "arm angle"). The arm angle sensor S2 can detect the angular velocity of the arm 5, which indicates the change in the arm angle, and the angular acceleration of the arm 5, which indicates the rate of change. The arm angle is, for example, at its minimum when the arm 5 is closed to its shortest extent, and increases as the arm 5 is opened.

[0026] The bucket angle sensor S3 detects the rotation angle of the bucket 6. In this embodiment, the bucket angle sensor S3 is an acceleration sensor and can detect the rotation angle of the bucket 6 relative to the arm 5 (hereinafter referred to as "bucket angle"). The bucket angle sensor S3 can detect the angular velocity of the bucket 6, which indicates the change in bucket angle, and the angular acceleration of the bucket 6, which indicates the rate of change. The bucket angle is, for example, at its minimum when the bucket 6 is fully closed, and increases as the bucket 6 is opened.

[0027] The boom angle sensor S1, arm angle sensor S2, and bucket angle sensor S3 can be any sensor capable of acquiring the attitude of the attachment (an example of an attitude sensor), and may be an IMU (Inertial Measurement Unit), a 6-axis sensor, a potentiometer using a variable resistor, a stroke sensor for detecting the stroke amount of the corresponding hydraulic cylinder, a rotary encoder for detecting the rotation angle around a connecting pin, a gyro sensor, or a combination of an acceleration sensor and a gyro sensor, respectively. In this embodiment, an example of acquiring boom angle, arm angle, and bucket angle as attitude information is described, but the attitude information is not limited to boom angle, arm angle, and bucket angle, and may be at least one of the boom angle, arm angle, and bucket angle, or it may be image information of the attitude of the attachment's AT that is visually captured.

[0028] The detection signals corresponding to the boom angle from the boom angle sensor S1, the detection signals corresponding to the arm angle from the arm angle sensor S2, and the detection signals corresponding to the bucket angle from the bucket angle sensor S3 are input to the controller 30. The detection signals may include angular velocity in addition to angle.

[0029] The machine tilt sensor S4 detects the tilt state of the machine (lower traveling body 1 or upper rotating body 3) relative to the horizontal plane. The machine tilt sensor S4 is, for example, attached to the upper rotating body 3 and detects the tilt angle of the work machine 100 (i.e., the upper rotating body 3) around two axes: the longitudinal direction and the lateral direction. The machine tilt sensor S4 may be, for example, an acceleration sensor, a 6-axis sensor, or an IMU. The detection signal corresponding to the tilt angle from the machine tilt sensor S4 is input to the controller 30.

[0030] The rotation sensor S5 outputs information regarding the rotation of the upper rotating body 3. The rotation sensor S5 detects, for example, the rotational angular velocity and rotational angular acceleration of the upper rotating body 3 relative to the lower traveling body 1. The rotation sensor S5 may also detect the rotation angle. The rotation sensor S5 may be, for example, a gyro sensor, a resolver, or a rotary encoder. The detection signals corresponding to the rotation angle, rotational angular velocity, and rotational angular acceleration of the upper rotating body 3 detected by the rotation sensor S5 are input to the controller 30.

[0031] The boom cylinder 7 is equipped with a boom rod pressure sensor S7R and a boom bottom pressure sensor S7B. The arm cylinder 8 is equipped with an arm rod pressure sensor S8R and an arm bottom pressure sensor S8B. The bucket cylinder 9 is equipped with a bucket rod pressure sensor S9R and a bucket bottom pressure sensor S9B. The boom rod pressure sensor S7R, boom bottom pressure sensor S7B, arm rod pressure sensor S8R, arm bottom pressure sensor S8B, bucket rod pressure sensor S9R, and bucket bottom pressure sensor S9B are collectively referred to as "cylinder pressure sensors".

[0032] The boom rod pressure sensor S7R detects the pressure in the rod-side oil chamber of the boom cylinder 7 (hereinafter referred to as "boom rod pressure"), and the boom bottom pressure sensor S7B detects the pressure in the bottom-side oil chamber of the boom cylinder 7 (hereinafter referred to as "boom bottom pressure"). The arm rod pressure sensor S8R detects the pressure in the rod-side oil chamber of the arm cylinder 8 (hereinafter referred to as "arm rod pressure"), and the arm bottom pressure sensor S8B detects the pressure in the bottom-side oil chamber of the arm cylinder 8 (hereinafter referred to as "arm bottom pressure"). The bucket rod pressure sensor S9R detects the pressure in the rod-side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket rod pressure"), and the bucket bottom pressure sensor S9B detects the pressure in the bottom-side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket bottom pressure").

[0033] In this embodiment, the boom rod pressure sensor S7R and the boom bottom pressure sensor S7B are used as sensors to acquire cylinder pressure (an example of information) for deriving torque related to boom 4. However, this embodiment does not limit the sensors for acquiring information for deriving torque related to boom 4 to the boom rod pressure sensor S7R and the boom bottom pressure sensor S7B. For example, an angular acceleration sensor (or angular velocity sensor) provided around the boom foot pin, or a strain gauge for detecting force generated on boom 4 may be used.

[0034] The positioning device PS measures the position of the upper rotating body 3. The positioning device PS is, for example, a GNSS (Global Navigation Satellite System) compass and detects the position and orientation of the upper rotating body 3. The detection signals corresponding to the position and orientation of the upper rotating body 3 are received by the controller 30. The function of detecting the orientation of the upper rotating body 3 may be realized by an orientation sensor attached to the upper rotating body 3. In this embodiment, the positioning device PS measures the current position of the work machine 100 in a globally identifiable reference coordinate system.

[0035] A reference coordinate system is, for example, the World Geodetic System, which can determine a location on Earth. The World Geodetic System is a three-dimensional orthogonal XYZ coordinate system with its origin at the Earth's center of mass, the X-axis pointing in the direction of the intersection of the Greenwich Meridian and the equator, the Y-axis pointing in the direction of 90 degrees east longitude, and the Z-axis pointing in the direction of the North Pole.

[0036] The operator's cab 10 is a compartment where the operator sits and is located on the front left side of the upper rotating body 3. However, the operator's cab 10 may be omitted if the work machine 100 is remotely controlled or if the work machine 100 operates by fully automatic operation.

[0037] The communication device T1 communicates with external devices through a communication network including a mobile communication network, a satellite communication network, or the Internet. The communication device T1 is, for example, a mobile communication module compatible with mobile communication standards such as LTE (Long Term Evolution), 4G (4th Generation), or 5G (5th Generation), a communication module compatible with short-range wireless communication standards such as Wi-Fi (registered trademark) or Bluetooth (registered trademark), or a satellite communication module for connecting to a satellite communication network.

[0038] The work machine 100 operates actuators in response to the operation of the operator seated in the cab 10, driving the driven parts such as the lower traveling body 1, the upper slewing body 3, the boom 4, the arm 5, and the bucket 6.

[0039] Alternatively, the work machine 100 may be configured to be remotely controlled from outside the work machine 100. When the work machine 100 is remotely controlled, the inside of the operator's cab 10 may be unoccupied.

[0040] Furthermore, the work machine 100 may automatically operate the actuators regardless of the operator's actions. This enables the work machine 100 to automatically operate at least a portion of the driven parts, such as the lower traveling body 1, the upper slewing body 3, the boom 4, the arm 5, and the bucket 6, that is, to achieve a so-called "machine control function".

[0041] Figure 2 is a schematic diagram showing an example of the configuration of the work machine 100. In Figure 2, the mechanical power transmission system, hydraulic fluid line, pilot line, and electrical control system are indicated by double lines, thick solid lines, thick dashed lines, and dotted lines, respectively.

[0042] The drive system of the work machine 100 includes an engine 11, a regulator 13, a main pump 14, and a control valve unit 17. The hydraulic drive system of the work machine 100 also includes hydraulic actuators such as a slewing hydraulic motor 2A, a left travel hydraulic motor 2ML, a right travel hydraulic motor 2MR, a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9.

[0043] The engine 11 is an example of a power source for the work machine 100, and is mounted, for example, at the rear of the upper rotating body 3. The power source for the work machine 100 may also be a combination of a battery or fuel cell and an electric motor. Specifically, the engine 11 rotates at a constant speed at a preset target rotational speed under direct or indirect control by the controller 30, driving the main pump 14 and the pilot pump 15. The engine 11 is, for example, a diesel engine that uses light oil as fuel. The engine 11 may also be a gasoline engine or a hydrogen engine, etc.

[0044] The regulator 13 controls the discharge rate of the main pump 14. For example, the regulator 13 controls the discharge rate of the main pump 14 by adjusting the angle (tilt angle) of the swash plate of the main pump 14 in response to a control command from the controller 30.

[0045] The main pump 14, for example, is mounted at the rear of the upper rotating body 3, similar to the engine 11, and supplies hydraulic fluid to the control valve unit 17 through the hydraulic fluid line. In the illustrated example, the main pump 14 is a variable displacement hydraulic pump.

[0046] The control valve unit 17 is one of the hydraulic control devices that control the hydraulic system in the work machine 100. In the illustrated example, the control valve unit 17 includes control valves 171 to 176. The control valve unit 17 is configured to selectively supply hydraulic fluid discharged by the main pump 14 to one or more hydraulic actuators through the control valves 171 to 176. The control valves 171 to 176 control the flow rate of hydraulic fluid flowing from the main pump 14 to the hydraulic actuators, and the flow rate of hydraulic fluid flowing from the hydraulic actuators to the hydraulic fluid tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left-travel hydraulic motor 2ML, a right-travel hydraulic motor 2MR, and a slewing hydraulic motor 2A. Specifically, control valve 171 corresponds to the left-travel hydraulic motor 2ML, control valve 172 corresponds to the right-travel hydraulic motor 2MR, and control valve 173 corresponds to the slewing hydraulic motor 2A. Furthermore, control valve 174 corresponds to bucket cylinder 9, control valve 175 corresponds to boom cylinder 7, and control valve 176 corresponds to arm cylinder 8.

[0047] The pilot pump 15 is an example of a pilot pressure generating device and is configured to supply hydraulic fluid to a hydraulic control device via a pilot line. In the illustrated example, the pilot pump 15 is a fixed-displacement hydraulic pump. However, the pilot pressure generating device may be implemented by the main pump 14. That is, the main pump 14 may have the function of supplying hydraulic fluid to the control valve unit 17 via a hydraulic fluid line, as well as the function of supplying hydraulic fluid to various hydraulic control devices via a pilot line. In this case, the pilot pump 15 may be omitted.

[0048] The discharge pressure sensor 28 is configured to detect the discharge pressure of the main pump 14. In the example shown in the figure, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0049] The operating device 26 is a device used by the operator to operate the actuator. The operating device 26 includes, for example, an operating lever and an operating pedal. The actuator may be a hydraulic actuator or an electric actuator.

[0050] The operation sensor 29 is configured to detect the operator's actions using the operation device 26. In this embodiment, the operation sensor 29 detects the operating direction and amount of the operation device 26 corresponding to each actuator and outputs the detected values ​​to the controller 30. In the illustrated example, the controller 30 can control the opening area of ​​the proportional valve 31 according to the output of the operation sensor 29. The controller 30 then supplies the hydraulic fluid discharged by the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17. The pressure of the hydraulic fluid supplied to each pilot port (pilot pressure) is, in principle, the pressure corresponding to the operating direction and amount of the operation device 26 corresponding to each hydraulic actuator. Thus, the operation device 26 is configured to supply the hydraulic fluid discharged by the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17.

[0051] The proportional valve 31, which functions as a control valve for machine control, is located in the pipeline connecting the pilot pump 15 and the pilot port of the control valve in the control valve unit 17, and is configured to change the flow area of ​​the pipeline. In the illustrated example, the proportional valve 31 operates in response to control commands output by the controller 30. Therefore, the controller 30 can adjust the pilot pressure acting on the pilot port of the control valve by the proportional valve 31, independently of the operation of the operating device 26 by the operator.

[0052] This configuration allows the controller 30 to operate the hydraulic actuator corresponding to a specific operating device 26 even when no operation is being performed on that particular operating device 26.

[0053] Furthermore, as shown in Figure 2, the control system of the work machine 100 includes a controller 30, an auxiliary storage device ST, a display device D1, an input device D2, and a communication device T1, etc.

[0054] The display device D1 is located in a place easily visible to a seated operator in the driver's cab 10 and displays various information images under the control of the controller 30. In the illustrated example, the display device D1 is located to the right front of the driver's seat and is connected to the controller 30 via a dedicated line. The display device D1 displays various image information. The display device D1 includes a display screen that displays information such as the working conditions or operating status of the work machine 100. The operator seated in the driver's seat can perform work on the work machine 100 while checking the various information displayed on the display device D1. The display device D1 may also be provided with an input device D2.

[0055] The input device D2 is located within reach of the operator seated in the driver's seat and receives various operation inputs from the operator, outputting signals corresponding to the operation inputs to the controller 30. The input device D2 includes a touch panel mounted on the display of the display device D1 which displays various information images, a knob switch provided at the tip of one or more of the operation levers included in the operation device 26, or a button switch, lever, toggle switch, or rotary dial installed around the display device D1. Signals corresponding to the content of operations on the input device D2 are received by the controller 30.

[0056] The controller 30 is configured to output control commands to the regulator 13 as needed, thereby changing the discharge rate of the main pump 14.

[0057] Furthermore, the controller 30 may be configured to perform control related to a machine guidance function that guides the manual operation of the work machine 100 by the operator through the operating device 26. Alternatively, the controller 30 may be configured to perform control related to a machine control function that automatically assists the manual operation of the work machine 100 by the operator through the operating device 26.

[0058] Furthermore, some of the functions of controller 30 may be implemented by other controllers (control devices). In other words, the functions of controller 30 may be implemented in a manner distributed among multiple controllers. For example, machine guidance functions and machine control functions may be implemented by dedicated controllers (control devices).

[0059] The auxiliary storage device ST is a read-write, non-volatile storage medium.

[0060] [Explanation regarding weight measurement] Next, the measurement of the weight of the load in the work machine 100 will be explained. Figure 3 is a conceptual diagram illustrating the measurement of the weight of the load in the work machine 100 according to this embodiment.

[0061] The example shown in Figure 3 illustrates the measurement of the weight of a load being attracted by a lifting magnet 6A. While Figure 3 shows an example where a lifting magnet 6A is provided as the end attachment, the end attachment is not limited to the lifting magnet 6A; any end attachment capable of carrying a load is acceptable. The end attachment may consist of, for example, a material handling device or a grapple, in addition to the lifting magnet 6A or bucket 6.

[0062] As shown in Figure 3, when the boom 4 is raised, a torque (hereinafter referred to as boom link torque) is generated with the center of the boom 4's link mechanism 4A (corresponding to, for example, the boom foot pin) as the axis of rotation. The difference Δτ between the boom link torque τ after the load is attracted to the lifting magnet 6A and the boom link torque τ0 before the load is attracted to the lifting magnet 6A corresponds to the boom link torque generated by the load.

[0063] Generally, the controller can calculate the weight of the load by dividing the difference Δτ of the boom link torque by the distance L between the center of the link mechanism 4A (e.g., the boom foot pin) and the center of gravity 6B of the load.

[0064] Incidentally, during the operation of boom 4, the torque generated around the center of boom 4's link mechanism 4A (e.g., boom foot pin) as the axis of rotation includes torque due to various factors in addition to the torque generated by the load. For this reason, it is difficult to accurately calculate the weight of the load unless the torque due to these various factors is removed from the boom link torque calculated based on the boom rod pressure sensor S7R and boom bottom pressure sensor S7B.

[0065] Therefore, the controller 30 according to this embodiment removes torques due to various factors from the boom link torque generated with the center of the boom 4's link mechanism 4A (for example, the boom foot pin) as the axis of rotation during the boom 4's operation, and calculates the weight of the load based on the torque after the removal of these factors. Next, the torque generated during the operation of the boom 4 will be explained.

[0066] In this embodiment, the torques generated during the operation of the boom 4 include no-load torque, speed-dependent torque, acceleration-dependent inertia torque, and rotation-dependent torque. This embodiment shows examples of torques generated during the operation of the boom 4, and other torques may also be considered.

[0067] The no-load torque is the torque generated by the respective weights of the boom 4, arm 5, and end attachment (e.g., lifting magnet 6A).

[0068] The no-load torque is determined from the positional relationship between the center of gravity of each component of the attachment and the center of the link mechanism 4A of the boom 4 (e.g., the boom foot pin) when the attachment is in any given position, and from the weight of each component of the attachment. Any method can be used to determine the center of gravity of each component. For example, the controller 30 may have information indicating the center of gravity in advance, or it may determine the center of gravity using calibration or the like. The method for calculating the no-load torque is not limited to the method described above, and can be calculated based on the posture acquired by posture sensors such as the boom angle sensor S1, arm angle sensor S2, and bucket angle sensor S3 (for example, the positional relationship between the center of gravity and the center of the link mechanism 4A of the boom 4 (e.g., the boom foot pin)) and the weight of the attachment.

[0069] In this embodiment, a no-load torque storage unit ST1, described later, is provided in advance. The no-load torque storage unit ST1 stores information corresponding to the orientation of the attachment and the sum of the torques due to the weight of the attachment in association with each other. The information corresponding to the orientation of the attachment may be, for example, the boom angle, the arm angle, and the angle of the end attachment (for example, the bucket angle or the angle of the lifting magnet). The information corresponding to the orientation of the attachment is not limited to the boom angle, the arm angle, and the angle of the end attachment (for example, the bucket angle or the angle of the lifting magnet), but may be any information that can identify the positional relationship between the center of gravity of each component of the attachment and the boom foot pin. Note that a no-load torque storage unit ST1 may be provided for each type of end attachment.

[0070] In the work machine 100 according to this embodiment, the speed-dependent torque is the torque generated depending on the magnitude of the angular velocity of the boom cylinder 7.

[0071] The speed-dependent torque corresponds to the angular velocity of the boom cylinder 7; in other words, the speed-dependent torque can be determined from the angular velocity of the boom cylinder 7. Therefore, in this embodiment, a speed-dependent torque storage unit ST3 is provided. The speed-dependent torque storage unit ST3 stores the angular velocity of the boom cylinder 7 and the speed-dependent torque in association. In this way, the speed-dependent torque according to this embodiment is pre-associated with attitude information (e.g., angular velocity) acquired by the attitude sensor.

[0072] Speed-dependent torque is a torque generated by, for example, friction, and also changes due to pipe losses and the degree of wear of each component, resulting in low reproducibility among multiple work machines 100.

[0073] Therefore, the controller 30 according to this embodiment performs a calibration operation to derive a correspondence between the angular velocity of the boom cylinder 7 and the velocity-dependent torque, and updates the velocity-dependent torque storage unit ST3 according to the results of the calibration operation.

[0074] In the work machine 100 according to this embodiment, the acceleration-dependent inertial torque is a torque based on the inertial force generated by the acceleration or deceleration of at least one of the boom 4 and arm 5 movements.

[0075] In this embodiment, parameters for calculating acceleration-dependent inertial torque are stored in advance. When the angular acceleration of the boom 4 and arm 5 is detected, the controller 30 calculates the acceleration-dependent inertial torque from the detected angular acceleration and the pre-stored parameters.

[0076] In this embodiment, the inertial torque parameter storage unit ST2 stores in advance parameters for calculating acceleration-dependent inertial torque. The parameters stored in advance can be any parameters necessary for calculating acceleration-dependent inertial torque based on angular acceleration, and well-known parameters may be used. This embodiment is merely one example of an inertial torque calculation method, and any method that calculates inertial torque based on attitude information (e.g., angular acceleration) acquired by attitude sensors such as the boom angle sensor S1, arm angle sensor S2, and bucket angle sensor S3 may be used.

[0077] The rotation-dependent torque is the torque generated by the centrifugal force perpendicular to the rotation axis of the attachments due to the rotational movement of the work machine 100 according to this embodiment. The rotation-dependent torque is calculated from the product of the centrifugal force and the distance from the boom foot to the center of gravity of each attachment. The centrifugal force is calculated from the rotational angular velocity, the horizontal distance from the rotation center to the center of gravity of each attachment, and the weight of each attachment.

[0078] As mentioned above, the speed-dependent torque among the torques generated during the operation of boom 4 is determined according to the results of the calibration work.

[0079] Traditionally, a calibration process was performed to generate a table that correlated the angular velocity of raising the boom 4 with the velocity-dependent torque. By referring to this table and using the velocity-dependent torque corresponding to the angular velocity of raising the boom 4, the weight of the load was calculated by correcting the boom link torque.

[0080] However, with conventional methods, when the angular velocity of raising boom 4 is high, the correction amount for the velocity-dependent torque associated with that angular velocity tends to be excessive, which reduces the accuracy of weight calculation.

[0081] This is thought to be because the velocity-dependent torque measured by conventional calibration procedures includes not only the velocity-dependent torque but also the acceleration-dependent inertial torque. In other words, in conventional work machines, when the boom is raised to calculate the weight of the load, if the angular velocity of the boom is large, a correction is made to remove the acceleration-dependent inertial torque when removing the velocity-dependent torque from the boom link torque. When a correction to remove the acceleration-dependent inertial torque is then applied to the boom link torque that has already been corrected in this way, the correction to remove the inertial torque is performed redundantly, resulting in a problem of reduced accuracy in weight calculation.

[0082] Therefore, in this embodiment, when performing the calibration work and registering the speed-dependent torque in the speed-dependent torque memory unit ST3 in association with the angular velocity, control is performed to remove the acceleration-dependent inertial torque from the speed-dependent torque.

[0083] <Block configuration of the controller for the work machine> Returning to Figure 2, the functional elements of the controller 30 and auxiliary storage device ST of the work machine 100 according to this embodiment will be described. In this embodiment, the controller 30 has a speed-dependent torque setting unit 301 and a weight calculation unit 302 as functional elements. The controller 30 (an example of a control unit) according to this embodiment is configured to control the entire work machine 100. The auxiliary storage device ST includes a no-load torque storage unit ST1, an inertia torque parameter storage unit ST2, and a speed-dependent torque storage unit ST3.

[0084] The no-load torque storage unit ST1 stores information indicating the orientation of the attachment and the sum of the torques due to the weight of the attachment (for example, boom 4, arm 5, and end attachment) in association with each other. In this embodiment, the boom angle, arm angle, and end attachment angle (bucket angle or lifting magnet angle) are used as information indicating the orientation of the attachment. In other words, the no-load torque storage unit ST1 stores the orientation of the work machine 100, indicated by the boom angle, arm angle, and end attachment angle (bucket angle or lifting magnet angle), in association with the sum of the torques generated by the weight of the attachment in that orientation. Then, when the weight calculation unit 302 calculates the weight of the load, it refers to the no-load torque due to the weight of the attachment and can remove the no-load torque from the boom link torque, thereby improving the accuracy of calculating the weight of the load.

[0085] The inertial torque parameter storage unit ST2 stores parameters for calculating acceleration-dependent inertial torque. These parameters include, for example, the inertia of the boom 4, the inertia of the arm 5, the distance between the pins of the boom 4, the distance between the pins of the arm 5, the weight of the boom 4, and the weight of the arm 5. For the attachment's inertia, a parameter obtained simply from the attachment's length, weight, and coefficient may be used. The controller 30 can calculate the inertial torque based on the inertial force generated by acceleration or deceleration from the parameters stored in the inertial torque parameter storage unit ST2 and the angular acceleration and angular velocity detected by the boom angle sensor S1, arm angle sensor S2, bucket angle sensor S3, and swing sensor S5. In other words, when the weight calculation unit 302 calculates the weight of the load, it refers to the inertial torque parameter storage unit ST2, calculates the inertial torque based on the inertial force from the detection results of the boom angle sensor S1, arm angle sensor S2, bucket angle sensor S3, and slewing sensor S5, and removes this inertial torque from the boom link torque, thereby improving the accuracy of weight calculation.

[0086] The speed-dependent torque storage unit ST3 stores the angular velocity of the boom cylinder 7 and the speed-dependent torque generated at that angular velocity in association with each other. The speed-dependent torque storage unit ST3 is updated by the processing of the speed-dependent torque setting unit 301, which will be described later.

[0087] Next, the configuration of the controller 30 will be described. The speed-dependent torque setting unit 301 calculates the speed-dependent torque by subtracting the no-load torque corresponding to the attitude of the attachment and the inertial torque corresponding to the rate of change in attitude from the torque derived from the boom rod pressure and boom bottom pressure acquired by the boom rod pressure sensor S7R and boom bottom pressure sensor S7B while the attachment is operating without any load. The speed-dependent torque and the angular velocity of the boom 4 acquired by the boom angle sensor S1 (an example of the rate of change in attitude) are associated and stored in the speed-dependent torque storage unit ST3.

[0088] Furthermore, in this embodiment, the speed-dependent torque setting unit 301 rotates the boom 4 at each of several angular velocities when performing the lifting operation of the boom 4 without any load as part of the calibration work. Then, while the boom 4 is being lifted at each of the several angular velocities, the speed-dependent torque setting unit 301 calculates the speed-dependent torque by removing the no-load torque and the inertia torque from the torque derived from the boom rod pressure and boom bottom pressure acquired by the boom rod pressure sensor S7R and boom bottom pressure sensor S7B, and stores the speed-dependent torque and the angular velocity in the speed-dependent torque storage unit ST3.

[0089] Figure 4 is a diagram illustrating the configuration of the speed-dependent torque setting unit 301 according to this embodiment. As shown in Figure 4, it comprises a no-load torque calculation unit 1401, an inertia torque calculation unit 1402, a boom cylinder thrust calculation unit 1403, a gain multiplier 1404, a first arithmetic unit 1405, a second arithmetic unit 1406, and an averaging processing unit 1407.

[0090] The no-load torque calculation unit 1401 calculates the no-load torque based on the angles of the boom 4, arm 5, and end attachment (e.g., bucket 6 or lifting magnet 6A) detected by the angle sensors S1, S2, and S3, and the information stored in the no-load torque storage unit ST1.

[0091] The inertial torque calculation unit 1402 calculates the inertial torque based on the inertial force generated around the pin of the boom 4 due to acceleration or deceleration, based on the angular acceleration and angular velocity of the boom 4, arm 5, and end attachment (e.g., bucket 6 or lifting magnet 6A) detected by angle sensors S1, S2, and S3, and parameters stored in the inertial torque parameter storage unit ST2. The method for calculating the inertial torque is assumed to be a well-known method and will not be explained further.

[0092] The boom cylinder thrust calculation unit 1403 calculates the thrust by the boom cylinder 7 based on the measured values ​​of the boom cylinder pressure (boom rod pressure and boom bottom pressure) obtained by the boom rod pressure sensor S7R and boom bottom pressure sensor S7B, and the pressure-receiving area of ​​the boom cylinder 7. The thrust calculation method is a well-known method and will not be explained further. In this embodiment, the boom rod pressure sensor S7R and boom bottom pressure sensor S7B are also referred to as boom cylinder pressure sensors S7R and S7B.

[0093] The gain multiplier 1404 calculates the torque generated around the center of the link mechanism 4A of the boom 4 (hereinafter referred to as boom link torque) by multiplying the thrust from the boom cylinder 7 by a predetermined link gain. The link gain is a value determined according to the embodiment.

[0094] The first arithmetic unit 1405 calculates the total torque by adding the inertial torque calculated by the inertial torque calculation unit 1402 to the no-load torque calculated by the no-load torque calculation unit 1401.

[0095] The second calculator 1406 calculates the speed-dependent torque by subtracting the sum of torques calculated by the first calculator 1405 from the boom link torque calculated by the boom cylinder thrust calculation unit 1403.

[0096] In other words, in this embodiment, the second arithmetic unit 1406 can calculate the velocity-dependent torque from which the inertial torque has been removed by subtracting the sum of the no-load torque and the inertial torque from the boom link torque calculated by the boom cylinder thrust calculation unit 1403.

[0097] The averaging processing unit 1407 calculates the average value of the speed-dependent torque corresponding to the angular velocity of the boom 4 based on the angular velocity of the boom 4 from the boom angle sensor S1, which is included in the angle sensors S1, S2, and S3, and the speed-dependent torque calculated by the second arithmetic unit 1406. The averaging processing unit 1407 then updates the speed-dependent torque storage unit ST3 with the average value of the speed-dependent torque corresponding to the angular velocity. For each of the multiple angular velocities, the averaging processing unit 1407 updates the speed-dependent torque storage unit ST3 with the average value of the speed-dependent torque at that angular velocity.

[0098] The processing procedure performed by the speed-dependent torque setting unit 301 according to this embodiment will now be described. Figure 5 is a flowchart showing the processing procedure for updating the speed-dependent torque storage unit ST3 in the speed-dependent torque setting unit 301 according to this embodiment. During the calibration work shown below, the working machine 100 will not rotate, and there will be no load in the end attachment (e.g., bucket 6).

[0099] First, the speed-dependent torque setting unit 301 determines whether or not it has received a start operation for the calibration process via the input device D2 (S1501). If it determines that it has not received a start operation (S1501: NO), it terminates the process.

[0100] When the speed-dependent torque setting unit 301 determines that it has received a calibration start operation via the input device D2 (S1501: YES), the speed-dependent torque setting unit 301 sets the engine speed corresponding to the number of boom raising operations (S1502). In this embodiment, the boom is raised 10 times, but the number of boom raising operations can be determined according to the embodiment. The speed-dependent torque setting unit 301 has engine speeds set for each of the 1st to 10th boom raising operations. When transitioning from S1501, the speed-dependent torque setting unit 301 sets the engine speed corresponding to the 1st boom raising operation.

[0101] The controller 30 starts raising the boom 4 according to the operation received by the operating device 26 (S1503).

[0102] The speed-dependent torque setting unit 301 determines whether the conditions for measurement are met (S1504). If it is determined that the conditions for measurement are not met (S1504: NO), the process of 1504 is repeated after a predetermined time. The conditions for measurement are, for example, that the pilot pressure during the raising operation of the boom 4 is within a predetermined range, the angle of the boom 4 is within a predetermined range, and the angular acceleration of the boom 4 is within a predetermined range, but appropriate conditions can be determined according to the embodiment.

[0103] On the other hand, if the speed-dependent torque setting unit 301 determines that the conditions for measurement have been met (S1504: YES), it acquires detection results from the boom cylinder pressure sensors S7R and S7B, and the angle sensors S1, S2, and S3 (S1505). When the acquisition of detection results is complete, the speed-dependent torque setting unit 301 may display a screen on the display device D1 prompting the user to stop raising the boom so as not to operate it to the stroke end.

[0104] Then, each component of the speed-dependent torque setting unit 301 (no-load torque calculation unit 1401, inertia torque calculation unit 1402, boom cylinder thrust calculation unit 1403, gain multiplier 1404, first arithmetic unit 1405, and second arithmetic unit 1406) performs the above-described processing using the detection results to calculate the speed-dependent torque (S1506).

[0105] The averaging unit 1407 averages the calculated speed-dependent torque to derive a speed-dependent torque corresponding to the angular velocity of the boom 4 input from the boom angle sensor S1 (S1507).

[0106] The averaging unit 1407 updates the speed-dependent torque storage unit ST3 with the speed-dependent torque corresponding to the angular velocity of boom 4 (S1508).

[0107] After the boom raising operation is completed, the controller 30 lowers the boom 4 according to the operation received by the operating device 26 (S1509).

[0108] The speed-dependent torque setting unit 301 determines whether the boom-raising operation has been performed a predetermined number of times (for example, 10 times) (S1510). If it is determined that the boom-raising operation has not been performed a predetermined number of times (S1510: NO), the process returns to S1502, and the engine speed corresponding to the number of boom-raising operations is set.

[0109] On the other hand, the speed-dependent torque setting unit 301 terminates processing when it determines that the boom raising operation has been performed a predetermined number of times (for example, 10 times) (S1510: YES).

[0110] In this embodiment, the speed-dependent torque setting unit 301 stores the angular velocity and the speed-dependent torque generated at that angular velocity in the speed-dependent torque storage unit ST3 in association with each other using the processing procedure described above. The weight calculation unit 302 then uses this speed-dependent torque when calculating the weight of the load, thereby suppressing overcorrection based on the inertial torque generated by the angular velocity and improving the accuracy of weight calculation. Furthermore, by updating the speed-dependent torque storage unit ST3 in the calibration process described above, the speed-dependent torque that takes into account the wear rate of each component of the current work machine 100 is registered in the speed-dependent torque storage unit ST3, thereby improving the accuracy of weight calculation.

[0111] In this embodiment, the speed-dependent torque setting unit 301 sets the rotational speed of the engine 11 for each number of times the boom 4 is raised, and operates the boom 4 at each of the multiple angular velocities. While the boom 4 is being raised at each of the multiple angular velocities, the speed-dependent torque setting unit 301 calculates the speed-dependent torque by removing the no-load torque and the inertia torque from the torque detected by the boom cylinder pressure sensors S7R and S7B, and stores the calculated speed-dependent torque in association with the corresponding angular velocity in the speed-dependent torque storage unit ST3. Therefore, when the weight calculation unit 302 measures the weight, it can correct the measurement using the speed-dependent torque corresponding to any of the multiple angular velocities, thereby improving the accuracy of the weight calculation.

[0112] As described above, the speed-dependent torque setting unit 301 in this embodiment, upon receiving a calibration start operation, controls the boom 4 to perform lifting and lowering operations each time the rotational speed of the engine 11 (an example of a drive source) is changed, while no load is loaded onto the end attachment (e.g., bucket 6). While the boom 4 is being lifted, the speed-dependent torque setting unit 301 calculates the speed-dependent torque, with inertial torque removed, according to the measurement results from various sensors, and updates the speed-dependent torque storage unit ST3 with the calculated speed-dependent torque. In this embodiment, by performing the lifting operation of the boom 4 each time the engine rotational speed is changed, the speed-dependent torque storage unit ST3 can be updated by associating the angular velocity of the boom 4 with the speed-dependent torque for each angular velocity of the boom 4 corresponding to the engine rotational speed. Therefore, the controller 30 can perform torque correction suitable for the angular velocity of the boom 4 by referring to the speed-dependent torque storage unit ST3, thereby improving the accuracy of calculating the weight of the load.

[0113] Figure 6 illustrates the table structure of the speed-dependent torque storage unit ST3 according to this embodiment. As shown in Figure 6, the speed-dependent torque storage unit ST3 stores the angular velocity of the boom 4 and the speed-dependent torque corresponding to that angular velocity. In other words, the controller 30 can recognize the speed-dependent torque generated by the angular velocity of the boom 4 by referring to the speed-dependent torque storage unit ST3.

[0114] Returning to Figure 2, the weight calculation unit 302 calculates the torque generated by the load based on the torque derived from the boom rod pressure and boom bottom pressure acquired by the boom rod pressure sensor S7R and boom bottom pressure sensor S7B, the inertial torque corresponding to the rate of change in boom angle detected by the boom angle sensor S1, the speed-dependent torque associated with the angular velocity of boom 4 detected by the boom angle sensor S1 and the speed-dependent torque storage unit ST3, and the no-load torque associated with the attitude of the attachment acquired by the angle sensors S1, S2, and S3 and the no-load torque storage unit ST1. Based on the calculated torque and the attitude of the attachment, the weight of the load is calculated.

[0115] Figure 7 is a diagram illustrating the configuration of the weight calculation unit 302 according to this embodiment. As shown in Figure 4, it comprises a no-load torque calculation unit 1701, an inertia torque calculation unit 1702, a velocity-dependent torque calculation unit 1703, a centrifugal force torque calculation unit 1704, a boom cylinder thrust calculation unit 1705, a gain multiplier 1706, a first arithmetic unit 1707, a second arithmetic unit 1708, a third arithmetic unit 1709, a fourth arithmetic unit 1710, a distance calculation unit 1711, and a fifth arithmetic unit 1712.

[0116] The no-load torque calculation unit 1701 calculates the no-load torque based on the angles of the boom 4, arm 5, and end attachment (e.g., bucket 6 or lifting magnet 6A) detected by the angle sensors S1, S2, and S3, and the information stored in the no-load torque storage unit ST1.

[0117] The inertial torque calculation unit 1702 calculates the inertial torque based on the inertial force generated around the pin of the boom 4 due to acceleration or deceleration, based on the angular acceleration and angular velocity of the boom 4, arm 5, and end attachment (e.g., bucket 6 or lifting magnet 6A) detected by the angle sensors S1, S2, and S3, and the parameters stored in the inertial torque parameter storage unit ST2.

[0118] The speed-dependent torque calculation unit 1703 calculates the speed-dependent torque generated by the angular velocity of the boom 4 based on the angular velocity of the boom 4 detected by the boom angle sensor S1 and the speed-dependent torque storage unit ST3.

[0119] The centrifugal torque calculation unit 1704 calculates the torque generated by centrifugal force (hereinafter referred to as centrifugal torque) based on the rotational angular velocity detected by the rotation sensor S5, the weight of each attachment, and the center of gravity position of each attachment detected by the angle sensors S1, S2, and S3.

[0120] The boom cylinder thrust calculation unit 1705 calculates the thrust from the boom cylinder 7 based on the boom rod pressure and boom bottom pressure obtained by the boom rod pressure sensor S7R and boom bottom pressure sensor S7B, and the pressure-receiving area of ​​the boom cylinder 7.

[0121] The gain multiplier 1706 calculates the torque generated by the boom 4's link mechanism 4A (hereinafter referred to as boom link torque) based on the boom 4's link mechanism 4A by multiplying the thrust from the boom cylinder 7 by a predetermined link gain.

[0122] The first arithmetic unit 1707 adds the velocity-dependent torque generated by the angular velocity of the boom 4, calculated by the velocity-dependent torque calculation unit 1703, to the centrifugal torque calculated by the centrifugal torque calculation unit 1704, and calculates a first total torque value.

[0123] The second arithmetic unit 1708 adds the inertial torque calculated by the inertial torque calculation unit 1402 to the first total torque to calculate the second total torque.

[0124] The third arithmetic unit 1709 adds the no-load torque calculated by the no-load torque calculation unit 1401 to the second total torque to calculate the third total torque.

[0125] The fourth arithmetic unit 1710 calculates the torque generated by the load by subtracting the third sum of torques calculated by the third arithmetic unit 1709 from the boom link torque calculated by the boom cylinder thrust calculation unit 1403.

[0126] The distance calculation unit 1711 calculates the distance from the center of the link mechanism 4A (e.g., the boom foot pin) to the center of gravity of the load, based on the angles of the boom 4, arm 5, and end attachment (e.g., the lifting magnet 6A or bucket 6), which are measured from the angle sensors S1, S2, and S3, as well as the length of each attachment. The center of gravity of the load may be determined by any method, for example, it may be predetermined, or it may be estimated by a predetermined calculation during the lifting operation of the boom 4.

[0127] The fifth arithmetic unit 1712 calculates the weight of the load by dividing the torque generated by the load by the distance from the center of the link mechanism 4A (e.g., the boom foot pin) to the center of gravity of the load.

[0128] Figure 8 shows the correspondence between the angular velocity of the boom 4 and the speed-dependent torque generated at that angular velocity, as stored in the speed-dependent torque memory unit ST3 according to this embodiment. Line 1801 in Figure 8 shows the correspondence between the angular velocity of the boom derived in a conventional calibration process and the speed-dependent torque generated at that angular velocity. On the other hand, line 1802 shows the correspondence between the angular velocity of the boom 4 and the speed-dependent torque generated at that angular velocity, as set in the speed-dependent torque setting unit 301 according to this embodiment.

[0129] The velocity-dependent torques of line 1801 and line 1802 are nearly identical up to an angular velocity of 15 degrees for the boom (4). However, beyond an angular velocity of 15 degrees, the velocity-dependent torque generated by line 1802 is smaller than that of line 1801. This is because line 1801 includes not only the velocity-dependent torque generated by angular velocity but also the inertial torque generated by angular acceleration.

[0130] In other words, when calculating the weight of the load using the velocity-dependent torque generated by conventional calibration work, a situation arose where the inertial torque was being overcorrected when subtracting the velocity-dependent torque (as shown by line 1801) and the inertial torque generated by angular acceleration from the boom link torque.

[0131] In contrast, the controller 30 according to this embodiment can suppress redundant correction of the inertial torque when subtracting the velocity-dependent torque shown by line 1802 and the inertial torque generated by angular acceleration from the boom link torque. Therefore, it is possible to improve the accuracy of calculating the weight of the load.

[0132] This embodiment describes a technique used to calculate the weight of a load using an attachment to the work machine 100. In this embodiment, the work machine 100 may perform the above-described operations based on operations by an operator, or it may perform the above-described operations fully automatically by autonomous control. When autonomous control is performed, calibration work may be automatically performed at a predetermined timing, such as the start time of work, to update the speed-dependent torque storage unit ST3.

[0133] Furthermore, the work machine 100 according to this embodiment may be operated based on remote control by an operator located in a remote control room. For example, when the operator located in the remote control room requests the start of a calibration operation, the speed-dependent torque storage unit ST3 may be updated by the control described above.

[0134] In the embodiment described above, the load that the work machine 100 loads with its attachment can be any object, such as soil or metal scrap.

[0135] <effect> In the above-described embodiment, when the weight calculation unit 302 calculates the weight of the load loaded on the end attachment, it subtracts the inertia torque, the speed-dependent torque (with the influence of inertia torque removed), and the no-load torque from the boom link torque derived from the boom rod pressure and boom bottom pressure acquired by the boom rod pressure sensor S7R and boom bottom pressure sensor S7B, and calculates the weight of the load based on the torque after the subtraction and the attitude of the attachment. Therefore, in the above-described embodiment, overcorrection due to inertia torque is suppressed, thereby improving the accuracy of calculating the weight of the load.

[0136] The work machine 100 according to the above embodiment can accurately calculate the weight of soil and scrap materials to be loaded onto a dump truck or trailer, thereby improving the accuracy of the loaded weight. As a result, rework due to weighing adjustments is reduced, work efficiency at the loading site is improved, and transportation efficiency is enhanced. Furthermore, overloading of dump trucks or trailers can be suppressed, thereby reducing road damage.

[0137] Preferred embodiments of the present disclosure have been described above. However, the inventions of the present disclosure are not limited to the embodiments described above. Various modifications, substitutions, etc., can be applied to the embodiments described above without departing from the scope of the inventions of the present disclosure. Furthermore, each of the features described with reference to the embodiments described above may be combined as appropriate, as long as they do not contradict each other technically. [Explanation of Symbols]

[0138] 100 working machines 1. Lower running body 2. Swivel mechanism 3. Upper rotating body 4 Boom 5 Arms 6 buckets 7 Boom Cylinder 8 Arm Cylinder S1 Boom Angle Sensor S2 Arm Angle Sensor S3 Bucket Angle Sensor S5 Swivel Sensor S6 imaging device S7R Boom Rod Pressure Sensor S7B and boom bottom pressure sensor S8R Arm Rod Pressure Sensor S8B Arm Bottom Pressure Sensor S9R Bucket Rod Pressure Sensor S9B Bucket Bottom Pressure Sensor ST auxiliary storage ST1 No-load torque memory unit ST2 Inertia Torque Parameter Storage Unit ST3 Speed-dependent torque memory unit 30 controllers 301 Speed-dependent torque setting unit 1401 No-load torque calculation unit 1402 Inertial Torque Calculation Unit 1403 Boom Cylinder Thrust Calculation Unit 1404 Gain Multiplier 1405 1st computing unit 1406 2nd computing unit 1407 Averaging Process 302 Weight calculation section 1701 No-load torque calculation unit 1702 Inertial Torque Calculation Unit 1703 Speed-dependent torque calculation unit 1704 Centrifugal force torque calculation unit 1705 Boom Cylinder Thrust Calculation Unit 1706 Gain Multiplier 1707 1st computing unit 1708 2nd computing unit 1709 Third computing unit 1710 4th computing unit 1711 Distance Calculation Unit 1712 5th arithmetic unit

Claims

1. Lower running body and The lower traveling body is equipped with an upper slewing body that is rotatable, An attachment having a boom, arm, and end attachment, An attitude sensor that acquires the attitude of the aforementioned attachment, A sensor that acquires information for deriving the torque related to the boom, A control device that calculates the torque generated by the load loaded on the attachment based on the torque related to the boom derived from the aforementioned information, the inertial torque calculated based on the attitude information acquired by the attitude sensor, the speed-dependent torque calculated based on the torque acquired by the attitude sensor and pre-associated with the attitude information, and the no-load torque calculated based on the attitude and the weight of the attachment acquired by the attitude sensor, and calculates the weight of the load based on the calculated torque and the attitude, A work machine equipped with the following features.

2. The control device is While the attachment is being operated without the aforementioned load loaded, the velocity-dependent torque is calculated by removing the no-load torque and the inertial torque from the torque derived from the information acquired by the sensor, and the calculated velocity-dependent torque and the rate of change of the attitude acquired by the attitude sensor are stored in the memory unit in association with each other. When calculating the weight of the load, the rate of change in attitude obtained by the attitude sensor and the rate-dependent torque associated with it in the memory unit are used. The work machine according to claim 1.

3. The control device operates the attachment at each of the multiple speeds when no load is loaded. While the attachment is operating at each of the aforementioned multiple speeds, the speed-dependent torque is calculated by removing the no-load torque and the inertial torque from the torque derived from the information acquired by the sensor, and the calculated speed-dependent torque and the speed are associated and stored in the storage unit. The working machine according to claim 2.

4. When the control device receives a predetermined operation, and with no load loaded on the attachment, it controls the attachment to perform an upward and downward movement each time the rotational speed of the drive source that operates the attachment is changed. The work machine according to claim 3.

5. The aforementioned posture and the no-load torque generated in that posture based on the weight of the attachment are stored in the memory unit in association with each other. The control device uses the attitude acquired by the attitude sensor and the no-load torque associated with the memory unit. The work machine according to claim 1.

6. Parameters for calculating the inertial torque based on the rate of change in attitude acquired by the attitude sensor are stored in the storage unit. The control device calculates the inertial torque based on the rate of change of the attitude acquired by the attitude sensor and the parameters stored in the memory unit. The work machine according to claim 1.

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