Systems, work machines, and methods

Abstract

Calculating the density of the material held in the bucket. A system for calculating the density of material held in a bucket includes a processor that acquires a change in weight of the material held in the bucket during a discharge period in which the material is discharged from the bucket, acquires a change in angle of the bucket during the discharge period, and calculates the density of the material based on the change in weight of the material and the change in angle of the bucket.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to a system for calculating the density of material held in a bucket, a loading machine, and a method for calculating the density of material held in a bucket. [Background technology]

[0002] BACKGROUND ART In the technical field related to loading machines, a technique for estimating the weight of an excavated object held in a bucket, as disclosed in Patent Document 1, is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-057516 Summary of the Invention [Problem to be solved by the invention]

[0004] A loading machine performs a loading operation by using a bucket to load material onto a loading target. During the loading operation, if the density of the material held in the bucket is not known, it may be difficult to perform the loading operation optimally.

[0005] The present disclosure is directed to calculating the density of material held in a bucket. [Means for solving the problem]

[0006] A system for calculating the density of material held in a bucket according to the present disclosure includes a processor that acquires a change in weight of the material held in the bucket during a discharge period in which the material is discharged from the bucket, acquires a change in angle of the bucket during the discharge period, and calculates the density of the material based on the change in weight of the material and the change in angle of the bucket. [Effects of the Invention]

[0007] According to the present disclosure, the density of the material held in the bucket can be calculated. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing a loading machine according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing a bucket according to the embodiment. [Figure 3] FIG. 3 is a side view showing the bucket according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating the operation of the work machine according to the embodiment. [Figure 5] FIG. 5 is a configuration diagram showing a wheel loader according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining the operation of the wheel loader according to the embodiment. [Figure 7] FIG. 7 is a diagram for explaining the loading operation of the wheel loader according to the embodiment. [Figure 8] FIG. 8 is a block diagram showing a control system for a wheel loader according to this embodiment. [Figure 9] FIG. 9 is a diagram showing the cross-sectional shape of the bucket and the material held in the bucket according to the embodiment. [Figure 10] FIG. 10 is a diagram for explaining a method for calculating the density of the material held in the bucket according to the embodiment. [Figure 11] FIG. 11 is a diagram for explaining correlation data according to the embodiment. [Figure 12] FIG. 12 is a diagram showing the cross-sectional shapes of a plurality of buckets. [Figure 13] FIG. 13 is a diagram for explaining correlation data for each of a plurality of buckets. [Figure 14] FIG. 14 is a diagram for explaining the change in cross-sectional area when each of the first bucket and the third bucket performs a dumping operation. [Figure 15] FIG. 15 is a diagram for explaining a method for calculating the angle of repose of a material according to an embodiment. [Figure 16] FIG. 16 is a flowchart showing a method for calculating the density and angle of repose of a material according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiments. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0010] In the embodiment, a local coordinate system is set in the loading machine 1, and the positional relationship of each part will be described with reference to the local coordinate system. In the local coordinate system, the first axis extending in the left-right direction (vehicle width direction) of the loading machine 1 is the X axis, the second axis extending in the front-rear direction of the loading machine 1 is the Y axis, and the third axis extending in the up-down direction of the loading machine 1 is the Z axis. The X axis and Y axis are perpendicular to each other. The Y axis and Z axis are perpendicular to each other. The Z axis and X axis are perpendicular to each other. The +X direction is the right direction, and the -X direction is the left direction. The +Y direction is the forward direction, and the -Y direction is the backward direction. The +Z direction is the upward direction, and the -Z direction is the downward direction.

[0011] [Loading Machine Overview] 1 is a side view showing a loading machine 1 according to an embodiment. The loading machine 1 according to an embodiment is a wheel loader. In the following description, the loading machine 1 will be referred to as the wheel loader 1 where appropriate.

[0012] As shown in Fig. 1, the wheel loader 1 includes a vehicle body 2, an articulating mechanism 3, a cab 4, wheels 5, and a work implement 6. The wheel loader 1 travels on the ground 200 at a work site using the wheels 5. The wheel loader 1 performs work at the work site using the work implement 6. The wheel loader 1 can use the work implement 6 to perform work such as excavation work, loading work, transport work, and snow removal work.

[0013] The vehicle body 2 supports the work implement 6. The vehicle body 2 includes a front frame 2F and a rear frame 2R. The front frame 2F is positioned forward of the rear frame 2R. The front frame 2F and the rear frame 2R are connected by an articulation mechanism 3. The articulation mechanism 3 includes an articulation cylinder 11. The articulation cylinder 11 connects the front frame 2F and the rear frame 2R. When the articulation cylinder 11 extends and retracts, the front frame 2F bends left and right relative to the rear frame 2R. When the front frame 2F bends relative to the rear frame 2R, the traveling direction of the wheel loader 1 is adjusted. The articulation cylinder 11 is, for example, a hydraulic cylinder.

[0014] The cab 4 is supported by the vehicle body 2. In this embodiment, the cab 4 is disposed on an upper portion of the rear frame 2R. Inside the cab 4, a seat for an operator and an operating device 25, which will be described later, are disposed.

[0015] The wheels 5 support the vehicle body 2. The wheels 5 include a front wheel 5F and a rear wheel 5R. The front wheel 5F is disposed forward of the rear wheel 5R. The front wheel 5F is attached to the front frame 2F. The rear wheel 5R is attached to the rear frame 2R. Note that only the left front wheel 5F and rear wheel 5R are shown in FIG. 1.

[0016] In this embodiment, the X axis is parallel to the rotation axis CXf of the front wheels 5F. The Z axis is perpendicular to the contact surface of the front wheels 5F that contacts the ground 200 at the work site. When the wheel loader 1 travels in a straight line, the rotation axis CXf of the front wheels 5F and the rotation axis CXr of the rear wheels 5R are parallel.

[0017] The work implement 6 is supported by the vehicle body 2. The work implement 6 is connected to the front frame 2F. The work implement 6 has a boom 12, a bucket 13, a bell crank 14, a bucket link 15, a boom cylinder 18, and a bucket cylinder 19.

[0018] A base end of the boom 12 is rotatably connected to the front frame 2F. The boom 12 rotates about a rotation axis AXa relative to the front frame 2F. A bracket 16 is fixed to the middle of the boom 12.

[0019] A base end of the bucket 13 is rotatably connected to the tip end of the boom 12. The bucket 13 rotates around a rotation axis AXb relative to the boom 12. The bucket 13 is disposed forward of the front wheels 5F. A bracket 17 is fixed to a part of the bucket 13.

[0020] An intermediate portion of the bell crank 14 is rotatably connected to a bracket 16 of the boom 12. The bell crank 14 rotates about a rotation axis AXc relative to the bracket 16 of the boom 12. A lower end portion of the bell crank 14 is rotatably connected to a base end portion of a bucket link 15.

[0021] The tip end of the bucket link 15 is rotatably connected to a bracket 17 of the bucket 13. The bucket link 15 rotates about a rotation axis AXd relative to the bracket 17 of the bucket 13. The bell crank 14 is connected to the bucket 13 via the bucket link 15.

[0022] The boom cylinder 18 operates the boom 12. A base end of the boom cylinder 18 is connected to the front frame 2F. A tip end of the boom cylinder 18 is connected to the boom 12. The boom 12 rotates about a rotation axis AXe relative to the boom cylinder 18. The boom cylinder 18 is, for example, a hydraulic cylinder.

[0023] The bucket cylinder 19 operates the bucket 13. A base end of the bucket cylinder 19 is connected to the front frame 2F. A tip end of the bucket cylinder 19 is connected to an upper end of the bell crank 14. The bell crank 14 rotates about a rotation axis AXf relative to the bucket cylinder 19. The bucket cylinder 19 is, for example, a hydraulic cylinder.

[0024] [Bucket] FIG. 2 is a perspective view of a bucket 13 according to the embodiment. FIG. 3 is a side view of the bucket 13 according to the embodiment. The bucket 13 is a work member that excavates an excavation target. The bucket 13 holds material 300. The material 300 is an excavated material generated by excavating an excavation target. An example of the material 300 is earth and sand. The bucket 13 includes a bottom plate portion 131, a back plate portion 132, an upper plate portion 133, a right plate portion 134, and a left plate portion 135. A blade tip portion 13A, which is a lower end portion, is provided at the tip of the bottom plate portion 131. An upper end portion 13B is provided at the tip of the upper plate portion 133. A right end portion 13C is provided at the tip of the right plate portion 134. A left end portion 13D is provided at the tip of the left plate portion 135. The blade tip portion 13A extends in the left-right direction. The upper end portion 13B extends in the left-right direction. The right end 13C extends in the up-down direction or the front-rear direction. The left end 13D extends in the up-down direction or the front-rear direction. In this embodiment, the blade tip 13A and the upper end 13B are parallel to each other. The right end 13C and the left end 13D are parallel to each other. An opening 136 of the bucket 13 is defined between the blade tip 13A, the upper end 13B, the right end 13C, and the left end 13D. The opening 136 of the bucket 13 is defined by the blade tip 13A, the upper end 13B facing the blade tip 13A, the right end 13C, and the left end 13D facing the right end 13C. A blade is attached to the blade tip 13A.

[0025] In the embodiment, the dimension of opening 136 in the up-down or front-rear direction, i.e., the dimension of the line connecting cutting edge 13A and upper end 13B in the YZ plane, is defined as bucket length L. The dimension of opening 136 in the left-right direction is defined as bucket width H. The angle formed by the inner surface of bottom plate portion 131 of bucket 13 and the line connecting cutting edge 13A and upper end 13B in the YZ plane is defined as opening angle θ3.

[0026] [Work equipment operation] 4 is a diagram illustrating the operation of the work implement 6 according to the embodiment. In the embodiment, the work implement 6 is a front-loading type work implement in which the opening 136 of the bucket 13 faces forward during excavation work. The boom cylinder 18 extends and retracts to cause the boom 12 to perform a raising or lowering operation. The bucket cylinder 19 extends and retracts to cause the bucket 13 to perform a tilting or dumping operation.

[0027] The raising operation of the boom 12 refers to the operation of the boom 12 rotating about the rotation axis AXa so that the tip of the boom 12 moves away from the ground 200. The lowering operation of the boom 12 refers to the operation of the boom 12 rotating about the rotation axis AXa so that the tip of the boom 12 moves closer to the ground 200.

[0028] When the boom cylinder 18 extends, the boom 12 moves up. When the boom cylinder 18 retracts, the boom 12 moves down.

[0029] The tilting operation of the bucket 13 refers to the operation of the bucket 13 rotating about the rotation axis AXb so that the opening 136 of the bucket 13 faces upward and the cutting edge 13A moves away from the ground 200. The dumping operation of the bucket 13 refers to the operation of the bucket 13 rotating about the rotation axis AXb so that the opening 136 of the bucket 13 faces downward and the cutting edge 13A moves closer to the ground 200.

[0030] More specifically, when the bucket cylinder 19 extends, the bell crank 14 rotates so that the upper end of the bell crank 14 moves forward and the lower end of the bell crank 14 moves rearward. When the lower end of the bell crank 14 moves rearward, the bucket 13 is pulled rearward by the bucket link 15, performing a tilt operation. When the bucket cylinder 19 retracts, the bell crank 14 rotates so that the upper end of the bell crank 14 moves rearward and the lower end of the bell crank 14 moves forward. When the lower end of the bell crank 14 moves forward, the bucket 13 is pushed forward by the bucket link 15, performing a dump operation.

[0031] When the bucket 13 performs a tilting operation, the material 300 is scooped up into the bucket 13 and held in the bucket 13. When the bucket 13 performs a dumping operation, the material 300 held in the bucket 13 is discharged from the bucket 13.

[0032] [Loading machine configuration] Fig. 5 is a configuration diagram showing a wheel loader 1 according to an embodiment. As shown in Fig. 5, the wheel loader 1 includes a power source 20, a PTO (Power Take Off) 21, a power transmission device 22, a hydraulic pump 23, a control valve 24, an operation device 25, an operator command device 26, and a controller 50.

[0033] The power source 20 is, for example, a diesel engine, but the power source 20 may also be an electric motor.

[0034] The PTO 21 transmits at least a portion of the driving force of the power source 20 to the hydraulic pump 23. The PTO 21 distributes the driving force of the power source 20 to the power transmission device 22 and the hydraulic pump 23.

[0035] The power transmission device 22 transmits the driving force of the power source 20 to the wheels 5. The power transmission device 22 controls the speed range and traveling direction of the wheel loader 1. The power transmission device 22 may be, for example, an HST (Hydro Static Transmission) or an HMT (Hydraulic Mechanical Transmission). The power transmission device 22 may be, for example, a transmission having a torque converter or a transmission having a plurality of speed change gears.

[0036] The hydraulic pump 23 is driven by the power source 20 and discharges hydraulic oil. At least a portion of the hydraulic oil discharged from the hydraulic pump 23 is supplied to the articulate cylinder 11. At least a portion of the hydraulic oil discharged from the hydraulic pump 23 is supplied to each of the boom cylinder 18 and the bucket cylinder 19 via a control valve 24. The control valve 24 controls the flow rate and direction of the hydraulic oil supplied from the hydraulic pump 23 to each of the boom cylinder 18 and the bucket cylinder 19. The articulate mechanism 3 and the work implement 6 each operate using the hydraulic oil from the hydraulic pump 23.

[0037] The operation device 25 is disposed inside the cab 4. The operation device 25 is operated by an operator. The operation device 25 includes a drive system operation device 25A and a work implement operation device 25B.

[0038] The drive train operation device 25A generates an operation signal for operating one or both of the power source 20 and the power transmission device 22. The operator operates the drive train operation device 25A to operate the power transmission device 22. The drive train operation device 25A includes a forward / reverse operation device 253.

[0039] The forward / reverse operation device 253 is operated to switch between forward and reverse movement of the wheel loader 1. The controller 50 controls the power transmission device 22 based on the operation signal generated by the forward / reverse operation device 253. By controlling the power transmission device 22, the wheel loader 1 is switched between forward and reverse movement.

[0040] The work implement operating device 25B generates an operation signal for operating the work implement 6. The operator operates the work implement operating device 25B to operate the work implement 6. The work implement operating device 25B includes a boom operating unit 254 and a bucket operating unit 255.

[0041] The boom operation unit 254 is operated to operate the boom 12. The controller 50 controls the control valve 24 based on an operation signal generated by the boom operation unit 254. By controlling the control valve 24, the boom cylinder 18 is driven and the boom 12 operates.

[0042] The bucket operating unit 255 is operated to operate the bucket 13. The controller 50 controls the control valve 24 based on the operation signal generated by the bucket operating unit 255. By controlling the control valve 24, the bucket cylinder 19 is driven and the bucket 13 operates.

[0043] The operator command device 26 is operated by the operator to start the process of calculating the density ρ and the angle of repose θ2 of the material 300, which will be described later. The operator command device 26 is, for example, a button switch disposed in the cab 4. The operator command device 26 outputs an operation signal to the controller 50 to start the process of calculating the density ρ and the angle of repose θ2.

[0044] The wheel loader 1 also has an inclination sensor 30, a boom angle sensor 31, a bucket angle sensor 32, a weight sensor 33, and a shape sensor .

[0045] The inclination sensor 30 detects the inclination of the vehicle body 2. More specifically, the inclination sensor 30 detects a vehicle body inclination angle θa, which indicates the inclination angle of the vehicle body 2 with respect to a horizontal plane. The inclination sensor 30 is disposed on at least a part of the vehicle body 2. An inertial measurement unit (IMU) is exemplified as the inclination sensor 30. Detection data of the vehicle body inclination angle θa detected by the inclination sensor 30 is transmitted to the controller 50.

[0046] The boom angle sensor 31 detects the angle of the boom 12. More specifically, the boom angle sensor 31 detects a boom angle θb that indicates the angle of the boom 12 with respect to the vehicle body 2 in the local coordinate system. An example of the boom angle sensor 31 is an angle sensor that is disposed at the connection between the front frame 2F and the boom 12. In the embodiment, the boom angle θb is the angle formed by a line connecting the rotation axis AXa and the rotation axis AXb and a line connecting the rotation axis CXf and the rotation axis CXr. Detection data of the boom angle θb detected by the boom angle sensor 31 is transmitted to the controller 50. The boom angle sensor 31 may be a stroke sensor that detects the stroke of the boom cylinder 18.

[0047] The bucket angle sensor 32 detects the angle of the bucket 13. More specifically, the bucket angle sensor 32 detects a bell crank angle θc that indicates the angle of the bell crank 14 relative to the boom 12 in the local coordinate system. An example of the bucket angle sensor 32 is an angle sensor disposed at the connection between the boom 12 and the bell crank 14. In the embodiment, the bell crank angle θc is the angle formed by a line connecting the rotation axis AXc and the rotation axis AXf and a line connecting the rotation axis AXa and the rotation axis AXb. There is a one-to-one correspondence between the angle of the bucket 13 relative to the boom 12 in the local coordinate system and the bell crank angle θc. By detecting the bell crank angle θc, the angle of the bucket 13 relative to the boom 12 in the local coordinate system is detected. Detection data of the bell crank angle θc detected by the bucket angle sensor 32 is transmitted to the controller 50. Note that the bucket angle sensor 32 may be a stroke sensor that detects the stroke of the bucket cylinder 19. The bucket angle sensor 32 may be an inclination sensor such as an inertial sensor (IMU: Inertial Measurement Unit) attached to the bucket 13. The inertial sensor detects the inclination angle with respect to the direction of gravity and can detect the angle of the bucket 13 with respect to the horizontal plane.

[0048] The weight sensor 33 detects the weight W of the material 300 held in the bucket 13. Examples of the weight sensor 33 include a pressure sensor that detects the pressure of the hydraulic oil in the boom cylinder 18 or a pressure sensor that detects the pressure of the hydraulic oil in the bucket cylinder 19. The load on the work implement 6 changes depending on whether the material 300 is held in the bucket 13 or not. The weight sensor 33 can detect the presence or absence of the material 300 in the bucket 13 and the weight W of the material 300 held in the bucket 13 by detecting the change in the load on the work implement 6. The detection data of the weight W of the material 300 detected by the weight sensor 33 is transmitted to the controller 50. The weight sensor 33 may be a load meter arranged in at least a part of the work implement 6. The weight sensor 33 may also directly detect the weight W of the material 300.

[0049] The shape sensor 34 detects the shape of a detection target located ahead of the vehicle body 2. As shown in FIGS. 1 and 4, the shape sensor 34 is disposed on an upper portion of the cab 4. The shape sensor 34 may also be disposed on the front frame 2F. The shape sensor 34 is a non-contact sensor that detects the shape of a detection target without coming into contact with the detection target. The shape sensor 34 may be an optical sensor or a camera. Examples of the shape sensor 34 include a laser sensor (LIDAR: Light Detection and Ranging) that detects a detection target by emitting laser light, a radar sensor (RADAR: Radio Detection and Ranging) that detects a detection target by emitting radio waves, an infrared sensor that detects a detection target by emitting infrared light, a monocular camera, and a stereo camera.

[0050] [Loading machine operation] 6 is a diagram for explaining the work of the wheel loader 1 according to the embodiment. The wheel loader 1 operates in a plurality of work modes. The work modes of the wheel loader 1 include an excavation operation M1, an excavation target leaving operation M2, a loading operation M3, and a loading target leaving operation M4.

[0051] The excavation operation M1 is a work mode in which the wheel loader 1 moves forward to approach the excavation target and excavates the excavation target with the bucket 13. In this embodiment, the excavation target is a stockpile 210 placed on the ground 200. The stockpile 210 refers to a pile made up of material 300. In the excavation operation M1, the wheel loader 1 moves forward to approach the stockpile 210 and excavates the stockpile 210 with the bucket 13.

[0052] The excavation target moving away operation M2 is a work mode in which the wheel loader 1 moves backward to move away from the excavation target while holding the material 300 in the bucket 13. After the excavation work M1 is completed, the wheel loader 1 moves backward to move away from the stockpile 210 while holding the material 300 in the bucket 13.

[0053] The loading operation M3 is a work mode in which the wheel loader 1 moves forward to approach the loading target and loads the material 300 held in the bucket 13 onto the loading target. In the embodiment, the loading target is the dump body 230 of the transport vehicle 220 that can travel on the ground 200. An example of the transport vehicle 220 is a dump truck. After the excavation target leaving operation M2 is completed, the wheel loader 1 moves forward while swinging to approach the transport vehicle 220, unloads the material 300 from the bucket 13, and loads it into the dump body 230.

[0054] The loading target moving away operation M4 is a work mode in which the wheel loader 1 moves backward to move away from the loading target. After the loading operation M3 is completed, the wheel loader 1 moves backward to move away from the transport vehicle 220.

[0055] The wheel loader 1 repeats the excavation operation M1, the excavation target separating operation M2, the loading operation M3, and the loading target separating operation M4 until the material 300 is loaded onto the transport vehicle 220 at the target load amount.

[0056] [Loading work] Figure 7 is a diagram illustrating a loading operation M3 of the wheel loader 1 according to the embodiment. As shown in Figure 7(A), in loading operation M3, the controller 50 moves the wheel loader 1 forward so that the wheel loader 1 approaches the transport vehicle 220. The controller 50 controls the attitude of the work implement 6 so that the material 300 held in the bucket 13 is loaded into the dump body 230 of the transport vehicle 220. The controller 50 controls the attitude of the work implement 6 so that the material 300 does not spill from the bucket 13 and so that the bucket 13 is positioned higher than the upper end of the dump body 230.

[0057] As shown in FIG. 7(B), after the bucket 13 is positioned above the dump body 230, the controller 50 causes the bucket 13 to perform a dumping operation. As the bucket 13 performs the dumping operation, the material 300 is discharged from the bucket 13. The material 300 is loaded into the dump body 230.

[0058] [Control System] 8 is a block diagram showing a control system 40 of the wheel loader 1 according to this embodiment. The control system 40 has a controller 50, an operation device 25, an operator command device 26, a control valve 24, a tilt sensor 30, a boom angle sensor 31, a bucket angle sensor 32, a weight sensor 33, and a shape sensor 34. The controller 50 communicates with each of the operation device 25, the operator command device 26, the control valve 24, the tilt sensor 30, the boom angle sensor 31, the bucket angle sensor 32, the weight sensor 33, and the shape sensor 34.

[0059] The controller 50 includes a computer. The controller 50 has a processor 51, a main memory 52, a storage 53, and an input / output interface 54. The processor 51 includes a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The main memory 52 includes a non-volatile memory such as a ROM (Read Only Memory) or a volatile memory such as a RAM (Random Access Memory). The storage 53 is a non-transitory tangible storage medium. Examples of the storage 53 include a magnetic disk, a magneto-optical disk, or a semiconductor memory. The input / output interface 54 includes an input / output circuit and a communication circuit. The functions of the controller 50 are stored in the storage 53 as a computer program. The processor 51 reads the computer program from the storage 53, loads it into the main memory 52, and executes processing in accordance with the computer program. The computer program may be distributed to the controller 50 via a network.

[0060] 8, the processor 51 includes a sensor data calculation unit 41, a density calculation unit 42, a repose angle calculation unit 43, and an operation control unit 44. The storage 53 includes a bucket data storage unit 45, a correlation data storage unit 46, and a characteristic data storage unit 47.

[0061] The sensor data calculation unit 41 acquires detection data from the inclination sensor 30, the boom angle sensor 31, the bucket angle sensor 32, the weight sensor 33, and the shape sensor 34. The detection data from the inclination sensor 30 indicates a vehicle body inclination angle θa, which indicates the inclination angle of the vehicle body 2 with respect to a horizontal plane. The detection data from the boom angle sensor 31 indicates a boom angle θb, which indicates the angle of the boom 12 with respect to the vehicle body 2 in a local coordinate system. The detection data from the bucket angle sensor 32 indicates a bell crank angle θc, which indicates the angle of the bell crank 14 with respect to the boom 12 in a local coordinate system. The detection data from the weight sensor 33 indicates the weight W of the material 300 held in the bucket 13. The detection data from the shape sensor 34 indicates the shape of a detection target ahead of the vehicle body 2. In this embodiment, the detection target of the shape sensor 34 includes the material 300 held in the bucket 13. The detection data from the shape sensor 34 includes the shape (outline) of the material 300 held in the bucket 13.

[0062] The sensor data calculation unit 41 calculates the bucket angle θbk, which indicates the angle of the bucket 13 with respect to the horizontal plane. The sensor data calculation unit 41 can calculate the bucket angle θbk based on the vehicle body inclination angle θa detected by the inclination sensor 30, the boom angle θb detected by the boom angle sensor 31, and the bell crank angle θc detected by the bucket angle sensor 32.

[0063] As described with reference to FIG. 7 , during the loading operation M3, the material 300 held in the bucket 13 is discharged from the bucket 13 into the dump body 230. The loading period during which the loading operation M3 is performed includes a discharge period during which the material 300 is discharged from the bucket 13. The bucket 13 performs a dumping operation, causing the material 300 to be discharged from the bucket 13. As the material 300 is discharged from the bucket 13, the weight W of the material 300 held in the bucket 13 gradually decreases. As the bucket 13 starts a dumping operation, the bucket angle θbk gradually decreases. The bucket angle θbk, which indicates the angle of the bucket 13, gradually changes, causing the material 300 to be discharged from the bucket 13. The sensor data calculation unit 41 calculates the amount of change in the weight W of the material 300 held in the bucket 13 during the discharge period during which the material 300 is discharged from the bucket 13. The sensor data calculation unit 41 calculates the amount of change in the bucket angle θbk during the discharge period during which the material 300 is discharged from the bucket 13.

[0064] The density calculation unit 42 calculates the density ρ of the material 300 held in the bucket 13. The repose angle calculation unit 43 calculates the repose angle θ2 of the material 300 held in the bucket 13. The methods for calculating the density ρ and the repose angle θ2 will be described later.

[0065] The operation control unit 44 controls the operation of the wheel loader 1. The operation control unit 44 controls the operation of the wheel loader 1 based on an operation signal from the operation device 25. The operation control unit 44 outputs a control command for operating one or both of the power source 20 and the power transmission device 22 based on an operation signal from the drive system operation device 25A. The operation control unit 44 outputs a control command for operating the control valve 24 based on an operation signal from the work implement operation device 25B.

[0066] The bucket data storage unit 45 stores bucket data related to the bucket 13. The bucket data includes shape data indicating the shape of the bucket 13 and dimensional data indicating the dimensions of the bucket 13. The bucket data includes the bucket length L and bucket width H described with reference to FIGS. 2 and 3. The bucket data includes an opening angle θ3. The bucket data includes a bucket cross-sectional area Sbk indicating the cross-sectional area of ​​the bucket 13 parallel to the YZ plane. The bucket data is known data derived from design data or specification data of the bucket 13. The bucket data is stored in advance in the bucket data storage unit 45.

[0067] The correlation data storage unit 46 stores correlation data indicating the relationship between the angle θt (described later) and the volume V of the material 300 held in the bucket 13. The volume V is the product of the cross-sectional area S of the material 300 held in the bucket 13 parallel to the YZ plane and the bucket width H (V=S×H). The bucket width H is a constant value. The volume V and the cross-sectional area S correspond one-to-one. In the embodiment, the correlation data indicates the relationship between the angle θt and the cross-sectional area S of the material 300. The correlation data is calculated in advance. The correlation data is stored in the correlation data storage unit 46 in advance. The correlation data will be described later.

[0068] The characteristic data storage unit 47 stores the density ρ of the material 300 calculated by the density calculation unit 42 and the angle of repose θ2 of the material 300 calculated by the angle of repose calculation unit 43.

[0069] [Calculation method of density ρ] Next, a method for calculating the density ρ of the material 300 held in the bucket 13 will be described. In this embodiment, the density calculation unit 42 calculates the density ρ of the material 300 based on the amount of change in the weight W of the material 300 and the amount of change in the bucket angle θbk during the discharge period in which the material 300 is discharged from the bucket 13. As described above, the sensor data calculation unit 41 calculates the amount of change in the weight W of the material 300 held in the bucket 13 and the amount of change in the bucket angle θbk during the discharge period in which the material 300 is discharged from the bucket 13. The density calculation unit 42 acquires the amount of change in the weight W of the material 300 held in the bucket 13 during the discharge period from the sensor data calculation unit 41, and acquires the amount of change in the bucket angle θbk during the discharge period. The density calculation unit 42 calculates the density ρ of the material 300 based on the amount of change in the weight W of the material 300 and the amount of change in the bucket angle θbk during the discharge period, which are acquired from the sensor data calculation unit 41.

[0070] FIG. 9 is a diagram showing the cross-sectional shapes of the bucket 13 and the material 300 held in the bucket 13 according to the embodiment. FIG. 9 shows the cross-sectional shapes of the bucket 13 and the material 300 during the discharge period. During the discharge period, the front end of the material 300 held in the bucket 13 coincides with the blade tip 13A, and the rear end of the material 300 is positioned below the upper end 13B of the bucket 13. The surface 340 of the material 300 slopes downward toward the front. The angle θt formed between the surface 340 of the material 300 held in the bucket 13 and the bottom plate portion 131 of the bucket 13 is the sum of the bucket angle θbk and the angle of repose θ2 of the material 300 (θt = θbk + θ2).

[0071] FIG. 10 is a diagram illustrating a method for calculating the density ρ of the material 300 held in the bucket 13 according to the embodiment. In FIG. 10, [State 1] shows the cross-sectional shape of the bucket 13 and the material 300 at a first time point t1 during the discharge period. [State 2] shows the cross-sectional shape of the bucket 13 and the material 300 at a second time point t2 during the discharge period, which occurs after the first time point t1. [State 2] shows a state in which the discharge of the material 300 from the bucket 13 has progressed more than in [State 1]. [State 2] shows a state in which the dumping operation of the bucket 13 has progressed more than in [State 1]. At the first time point t1, the bucket angle θbk is a first angle θbk1. At the second time point t2, the bucket angle θbk is a second angle θbk2 that is smaller than the first angle θbk1. The sensor data calculation unit 41 calculates the first angle θbk1, which is the bucket angle θbk at the first time point t1, and the second angle θbk2, which is the bucket angle θbk at the second time point t2. The sensor data calculation unit 41 also acquires a first weight W1, which is the weight W of the material 300 when the bucket angle θbk is a first angle θbk1, and a second weight W2, which is the weight W of the material 300 when the bucket angle θbk is a second angle θbk2, from the weight sensor 33. The first weight W1 is the weight W of the material 300 held in the bucket 13 at a first point in time t1. The second weight W2 is the weight W of the material 300 held in the bucket 13 at a second point in time t2.

[0072] The density calculation unit 42 acquires a first weight W1, which is the weight W of the material 300 when the bucket angle θbk is a first angle θbk1. The density calculation unit 42 acquires a second weight W2, which is the weight W of the material 300 when the bucket angle θbk is a second angle θbk2. As shown in [Difference Between State 1 and State 2] in FIG. 10, the density calculation unit 42 calculates the density ρ of the material 300 based on the difference ΔW between the first weight W1 and the second weight W2 and the difference Δθbk between the first angle θbk1 and the second angle θbk2. The difference ΔW is the value obtained by subtracting the second weight W2 from the first weight W1 (ΔW = W1 - W2). The difference Δθbk is the value obtained by subtracting the second angle θbk2 from the first angle θbk1 (Δθbk = θbk1 - θbk2).

[0073] The correlation data storage unit 46 stores correlation data that indicates the relationship between the angle θt formed between the surface 340 of the material 300 held in the bucket 13 and the bottom plate portion 131 of the bucket 13, and the cross-sectional area S of the material 300 held in the bucket 13. As described above, the volume V is the product of the cross-sectional area S of the material 300 held in the bucket 13, which is parallel to the YZ plane, and the bucket width H (V = S × H). The bucket width H is a constant value. Therefore, the correlation data can be considered to indicate the relationship between the angle θt formed between the surface 340 of the material 300 held in the bucket 13 and the bottom plate portion 131 of the bucket 13, and the volume V of the material 300 held in the bucket 13.

[0074] The density calculation unit 42 calculates a first cross-sectional area S1 (first volume V1), which is the cross-sectional area S (volume V) of the material 300 when the bucket angle θbk is the first angle θbk1, and a second cross-sectional area S2 (second volume V2), which is the cross-sectional area S (volume V) of the material 300 when the bucket angle θbk is the second angle θbk2, based on the correlation data stored in the correlation data storage unit 46 and the first angle θbk1 and the second angle θbk2. The density calculation unit 42 calculates the density ρ of the material 300 based on the difference ΔW between the first weight W1 and the second weight W2 and the difference ΔS (difference ΔV) between the first cross-sectional area S1 (first volume V1) and the second cross-sectional area S2 (second volume V2). The difference ΔS is a value obtained by subtracting the second cross-sectional area S2 from the first cross-sectional area S1 (ΔS = S1 - S2). The difference ΔV is the value obtained by subtracting the second volume V2 from the first volume V1 (ΔV=V1-V2=(S1-S2)×H).

[0075] The difference ΔS is a function of the difference Δθbk. The density calculation unit 42 can calculate the density ρ of the material 300 based on the difference Δθbk and the difference ΔW. The density ρ is the value obtained by dividing the difference ΔW by the difference ΔV (= ΔS × H) (ρ = ΔW / (ΔS × H)).

[0076] Fig. 11 is a diagram for explaining correlation data according to the embodiment. In Fig. 11, the horizontal axis represents the angle θt (= θbk + θ2), and the vertical axis represents the cross-sectional area S of the material 300. As shown by line Cd in Fig. 11, the smaller the bucket angle θbk, that is, the further the dumping operation of the bucket 13 progresses, the smaller the cross-sectional area S of the material 300 becomes.

[0077] As shown in FIG. 11 , the amount of change (decrease) from the first angle θbk1 to the second angle θbk2 is substantially proportional to the amount of change (decrease) from the first cross-sectional area S1 (first volume V1) to the second cross-sectional area S2 (second volume V2). The density calculation unit 42 calculates the difference ΔS in the cross-sectional area S from the difference Δθbk in the bucket angle θbk based on the first angle θbk1 and the second angle θbk2 and the first cross-sectional area S1 and the second cross-sectional area S2 in a proportional interval in which the angle θbk and the cross-sectional area S are substantially proportional. The angle of repose θ2 remains constant even when the bucket angle θbk changes. By calculating the difference Δθbk in a proportional interval in which the rate of change of the cross-sectional area S with respect to the bucket angle θbk is substantially constant, the density calculation unit 42 can accurately calculate the difference ΔS by multiplying the difference Δθbk by a proportionality constant.

[0078] The proportional interval changes based on the shape of the bucket 13. The proportional interval is an interval in which the angle θt is equal to or greater than a predetermined angle determined based on the shape of the bucket 13. In the embodiment, the predetermined angle is approximately 35 degrees. The proportional interval is an interval in which the angle θt is equal to or greater than approximately 35 degrees. The relationship between the shape of the bucket 13 and the proportional interval will be described below.

[0079] FIG. 12 is a diagram showing the cross-sectional shapes of multiple buckets 1301, 1302, and 1303. FIG. 13 is a diagram for explaining correlation data for each of the multiple buckets 1301, 1302, and 1303. FIG. 12 shows the cross-sectional shapes of the first bucket 1301, the second bucket 1302, and the third bucket 1303. The cross-sectional shape of the first bucket 1301 is the same as or similar to the cross-sectional shape of the bucket 13 described above. The volume of the second bucket 1302 is larger than the volume of the first bucket 1301. The cross-sectional shapes of the upper plate and back plate of the third bucket 1303 are arc-shaped. The third bucket 1303 has an arc portion in a cross section parallel to the YZ plane. In FIG. 13, line Cd1 shows correlation data for the first bucket 1301. Line Cd2 shows correlation data for the second bucket 1302. Line Cd3 shows the correlation data for the third bucket 1303.

[0080] FIG. 14 is a diagram illustrating the change in the cross-sectional area S when the first bucket 1301 and the third bucket 1303 each perform a dumping operation. Because the third bucket 1303 has an arc portion centered on the blade tip 13A, as the dumping operation of the third bucket 1303 progresses and the bucket angle θbk gradually decreases, the cross-sectional area S decreases in proportion to the bucket angle θbk. As the dumping operation of the third bucket 1303 progresses and the bucket angle θbk gradually decreases, the surface 340 of the material 300 moves along the arc portion. Until the surface 340 reaches the bottom end of the arc portion, that is, until the surface 340 reaches the bottom plate portion of the third bucket 1303, the cross-sectional area S decreases in proportion to the bucket angle θbk. As shown by line Cd3 in FIG. 13 , in the correlation data for the third bucket 1303, the angle θt and the cross-sectional area S are proportional until the bucket angle θbk becomes 0 degrees.

[0081] The upper plate portion 133 of the first bucket 1301 can be considered to be a portion that approximates a circular arc. The back plate portion 132 of the first bucket 1301 has a shape that deviates from the circular arc portion of the third bucket 1303. Therefore, as the dumping operation of the first bucket 1301 progresses and the bucket angle θbk gradually decreases, the cross-sectional area S decreases substantially in proportion to the bucket angle θbk during the period when the surface 340 of the material 300 moves along the upper plate portion 133. During the period when the surface 340 of the material 300 moves along the back plate portion 132, the change in the bucket angle θbk and the change in the cross-sectional area S are no longer proportional. 14, when a line Ls is defined that connects the boundaries between cutting edge portion 13A, upper plate portion 133, and back plate portion 132, cross-sectional area S decreases substantially in proportion to bucket angle θbk until surface 340 reaches line Ls, but after surface 340 passes line Ls, the amount of change in bucket angle θbk is no longer proportional to the amount of change in cross-sectional area S. In this embodiment, the bucket angle θbk at which surface 340 reaches line Ls is a predetermined angle of 35 degrees.

[0082] Thus, in the correlation data for the general bucket 13 applied to the wheel loader 1, the proportional interval is the interval where the bucket angle θbk is approximately 35 degrees or more. As shown by lines Cd1 and Cd2 in Fig. 13, in the correlation data for the first bucket 1301 and second bucket 1302, which are general buckets 13, the bucket angle θbk and the cross-sectional area S are substantially proportional in the interval where the bucket angle θbk is approximately 35 degrees or more, but are not proportional in the interval where the bucket angle is less than 35 degrees.

[0083] [How to calculate the angle of repose θ2] Next, a method for calculating the angle of repose θ2 of the material 300 held in the bucket 13 will be described. FIG. 15 is a diagram for explaining a method for calculating the angle of repose θ2 of the material 300 according to an embodiment. The angle of repose θ2 is calculated during excavation work M1. As shown in FIG. 15, when the bucket 13 excavates the stockpile 210, at least a portion of the material 300 is positioned outside the bucket 13 relative to the opening 136, forming an exposed portion 330 of the material 300. The exposed portion 330 of the material 300 refers to the material 300 positioned outside the bucket 13 relative to the opening 136.

[0084] The surface of exposed portion 330 includes first surface 310 and second surface 320. In the YZ plane, first surface 310 slopes upward from upper end 13B of bucket 13 toward the front. In the YZ plane, second surface 320 slopes upward from blade tip 13A of bucket 13 toward the rear.

[0085] The repose angle calculation unit 43 acquires a load angle θ1 indicating the angle of the first surface 310 relative to the horizontal plane, acquires an opening angle θ3 of the bucket 13, and calculates an angle of repose θ2 of the material 300 based on the dimensions of the bucket 13, the load angle θ1, the opening angle θ3, and the volume V of the material 300 held in the bucket 13. The dimensions of the bucket 13 include the bucket cross-sectional area Sbk, the bucket length L, and the bucket width H.

[0086] The relationship between the volume V, weight W, and density ρ of the material 300 held in the bucket 13 is expressed by the following equation (1).

[0087]

number

[0088] The weight W is detected by the weight sensor 33. The density ρ is calculated by the density calculation unit 42. The angle of repose calculation unit 43 can calculate the volume V of the material 300 in the state shown in FIG. 15 based on equation (1).

[0089] Furthermore, as disclosed in JP 2022-057516 A, the relationship between the volume V, the load angle θ1, the angle of repose θ2, the opening angle θ3, the bucket cross-sectional area Sbk, the bucket length L, the bucket width H, and the bucket angle θbk is expressed by the following equation (2).

[0090]

number

[0091] The load angle θ1 is detected by the shape sensor 34. The bucket angle θbk is calculated by the sensor data calculation unit 41 based on the detection data of the tilt sensor 30, the detection data of the boom angle sensor 31, and the detection data of the bucket angle sensor 32. The bucket cross-sectional area Sbk, the bucket length L, the bucket width H, and the opening angle θ3 are known data derived from the design data or specification data of the bucket 13 and are stored in advance in the bucket data storage unit 45. In equation (2), the only unknown is the angle of repose θ2, so the angle of repose calculation unit 43 can calculate the angle of repose θ2 of the material 300 based on equation (2).

[0092] The above-described method for calculating the angle of repose θ2 is an example. For example, the angle of repose θ2 may be calculated using a calculation method such as that disclosed in Japanese Patent Application Laid-Open No. 2023-126041.

[0093] [Calculation method for density and angle of repose] 16 is a flowchart showing a method for calculating the density ρ and the angle of repose θ2 of the material 300 according to an embodiment. The operator operates the operation device 25 to start the loading operation M3. By operating the operation device 25, the bucket 13 holding the material 300 starts a dumping operation. Note that the dumping operation of the bucket 13 may be performed based on an automatic control signal from the controller 50, rather than by operating the operation device 25. As the bucket 13 starts the dumping operation, the bucket angle θbk gradually decreases. As the bucket angle θbk gradually decreases, the discharge of the material 300 from the bucket 13 begins.

[0094] In loading operation M3, the operator operates operator command device 26 to start the calculation process of density ρ. An operation signal generated by operating operator command device 26 is transmitted to controller 50. Controller 50 receives the operation signal to start the calculation process of density ρ (step SP1).

[0095] The sensor data calculation unit 41 starts calculating the bucket angle θbk during the discharge period when the material 300 is discharged from the bucket 13 and when the angle θt is equal to or greater than a predetermined angle (35 degrees or greater). The sensor data calculation unit 41 calculates the bucket angle θbk based on the detection data of the inclination sensor 30, the detection data of the boom angle sensor 31, and the detection data of the bucket angle sensor 32. The sensor data calculation unit 41 calculates a first weight W1 of the material 300 when the bucket angle θbk is the first angle θbk1 (step SP2). The sensor data calculation unit 41 calculates a second weight W2 of the material 300 when the bucket angle θbk is the second angle θbk2 (step SP3).

[0096] The density calculation unit 42 acquires a first weight W1 of the material 300 when the bucket angle θbk is a first angle θbk1 from the sensor data calculation unit 41. The density calculation unit 42 acquires a second weight W2 of the material 300 when the bucket angle θbk is a second angle θbk2. The density calculation unit 42 calculates a difference ΔW between the first weight W1 and the second weight W2, and a difference Δθbk between the first angle θbk1 and the second angle θbk2. The density calculation unit 42 calculates a difference ΔS in the cross-sectional area S of the material 300 based on the difference Δθbk and the correlation data described with reference to FIG. 11 (step SP4).

[0097] The density calculation unit 42 calculates the density ρ of the material 300 based on the difference ΔW in weight W, the difference ΔS in cross-sectional area S, and the bucket width H. As described with reference to FIG. 10, the density calculation unit 42 can calculate the density ρ by calculating the formula [ρ=ΔW / (ΔS×h)] (step SP5).

[0098] After the loading operation M3 is completed and the loading target separating operation M4 is completed, the operator operates the operating device 25 to start the excavation operation M1. As the bucket 13 excavates the stockpile 210, the first surface 310 and the second surface 320 of the material 300 are formed, as described with reference to FIG.

[0099] During excavation work M1, the operator operates operator command device 26 to start the process of calculating the angle of repose θ2. An operation signal generated by operating operator command device 26 is transmitted to controller 50. Controller 50 receives the operation signal to start the process of calculating the angle of repose θ2.

[0100] The sensor data calculation unit 41 acquires detection data from the weight sensor 33. The detection data from the weight sensor 33 indicates the weight W of the material 300 held in the bucket 13. The angle of repose calculation unit 43 calculates the volume V of the material 300 held in the bucket 13 based on the weight W of the material 300 detected by the weight sensor 33 and the density ρ of the material 300 calculated in step SP5. The angle of repose calculation unit 43 can calculate the volume V by operating equation (1).

[0101] The sensor data calculation unit 41 acquires detection data from the shape sensor 34. The detection data from the shape sensor 34 indicates the load angle θ1 of the first surface 310. The sensor data calculation unit 41 calculates the bucket angle θbk based on the detection data from the tilt sensor 30, the detection data from the boom angle sensor 31, and the detection data from the bucket angle sensor 32. The repose angle calculation unit 43 acquires the bucket cross-sectional area Sbk, the opening angle θ3, the bucket length L, and the bucket width H from the bucket data storage unit 45. The repose angle calculation unit 43 calculates the repose angle θ2 of the material 300 based on the volume V, the load angle θ1, the opening angle θ3, the bucket cross-sectional area Sbk, the bucket length L, the bucket width H, and the bucket angle θbk. The repose angle calculation unit 43 can calculate the repose angle θ2 based on equation (2) (step SP6).

[0102] The density ρ calculated in step SP5 and the angle of repose θ2 calculated in step SP6 are stored in the characteristic data storage unit 47 (step SP7). Various controls of the wheel loader 1 are performed based on the density ρ and the angle of repose θ2.

[0103] [effect] As described above, the processor 51 obtains the difference ΔW indicating the amount of change in the weight W of the material 300 held in the bucket 13 during the discharge period in which the material 300 is discharged from the bucket 13, and obtains the difference Δθbk indicating the amount of change in the bucket angle θbk during the discharge period. The processor 51 calculates the density ρ of the material 300 based on the difference ΔW in the weight W of the material 300 and the difference Δθbk in the bucket angle θbk. The processor 51 can determine the density ρ of the material 300 held in the bucket 13 during the loading operation M3. By determining the density ρ, the load amount of the material 300 loaded from the wheel loader 1 onto the transport vehicle 220 is optimized, and the loading operation M3 by the wheel loader 1 is optimized.

[0104] 11 , correlation data indicating the relationship between the angle θt formed between the surface 340 of the material 300 held in the bucket 13 and the bottom plate portion 131 of the bucket 13 and the cross-sectional area S of the material 300 held in the bucket 13 is obtained in advance and stored in the storage 53. Based on the correlation data, the processor 51 can calculate a first cross-sectional area S1 of the material 300 when the bucket angle θbk is a first angle θbk1 and a second cross-sectional area S2 of the material 300 when the bucket angle θbk is a second angle θbk2. After calculating the difference ΔS between the first cross-sectional area S1 and the second cross-sectional area S2, the processor 51 can calculate the density ρ of the material 300 by calculating the equation [ρ=ΔW / (ΔS×h)].

[0105] The processor 51 calculates the difference Δθbk in the bucket angle θbk in the proportional interval of the correlation data, and calculates the difference ΔS in the cross-sectional area S of the material 300 from the difference Δθbk. Because the difference Δθbk and the difference ΔS are calculated in the proportional interval of the correlation data, the density calculation unit 42 can use the proportional interval to accurately calculate the density ρ even when the angle of repose θ2 is unknown.

[0106] [Other embodiments] In the above-described embodiment, the loading machine 1 is a wheel loader. The loading machine 1 may be a hydraulic excavator having a front-loading type working implement. The loading machine 1 may be a hydraulic excavator having a backhoe type working implement in which the opening of the bucket faces rearward during excavation work.

[0107] [Note] The present technology can also be configured as follows. (Appendix 1) 1. A system for calculating density of material held in a bucket, comprising: a processor; The processor: obtaining a change in weight of the material held in the bucket during a discharge period in which the material is discharged from the bucket; A change in the angle of the bucket during the discharge period is obtained; calculating a density of the material based on the change in weight of the material and the change in angle of the bucket; system. (Appendix 2) The processor: obtaining a first weight, which is the weight of the material when the bucket angle is a first angle; obtaining a second weight, which is the weight of the material when the bucket angle is a second angle; calculating a density of the material based on a difference between the first weight and the second weight and a difference between the first angle and the second angle; 10. The system of claim 1. (Appendix 3) The processor: calculating a first volume, which is the volume of the material when the angle of the bucket is the first angle, and a second volume, which is the volume of the material when the angle of the bucket is the second angle, based on correlation data indicating the relationship between the angle between the surface of the material held in the bucket and the bottom plate portion of the bucket and the volume of the material held in the bucket, and the first angle and the second angle; calculating a density of the material based on a difference between the first weight and the second weight and a difference between the first volume and the second volume; 1. The system described in Appendix 2. (Appendix 4) The amount of change from the first angle to the second angle is proportional to the amount of change from the first volume to the second volume. 10. The system described in Appendix 3. (Appendix 5) 1. A system according to any one of claims 1 to 4; a bucket; Work machinery. (Appendix 6) 1. A method for calculating density of material held in a bucket, comprising: The processor: obtaining a change in weight of the material held in the bucket during a discharge period in which the material is discharged from the bucket; A change in the angle of the bucket during the discharge period is obtained; calculating a density of the material based on the change in weight of the material and the change in angle of the bucket; method. [Explanation of symbols]

[0108] 1...wheel loader (loading machine), 2...body, 2F...front frame, 2R...rear frame, 3...articulation mechanism, 4...cab, 5...wheel, 5F...front wheel, 5R...rear wheel, 6...work implement, 11...articulation cylinder, 12...boom, 13...bucket, 13A...blade tip, 13B...upper end, 13C...right end, 13D...left end, 14...bell crank, 15...bucket link, 16...bracket, 17...bracket, 18...boom cylinder, 19...bucket cylinder, 20...power source, 21...PTO, 22...power transmission device, 23...hydraulic pump , 24...control valve, 25...operation device, 25A...drive system operation device, 25B...work machine operation device, 26...operator command device, 30...inclination sensor, 31...boom angle sensor, 32...bucket angle sensor, 33...weight sensor, 34...shape sensor, 40...control system, 41...sensor data calculation unit, 42...density calculation unit, 43...angle of repose calculation unit, 44...operation control unit, 45...bucket data storage unit, 46...correlation data storage unit, 47...characteristic data storage unit, 50...controller, 51...processor, 52...main memory, 53...storage, 54...input / output interface, 131...bottom plate portion, 132...back plate portion, 133...upper plate portion, 134...right plate portion, 135...left plate portion, 136...opening, 200...ground, 210...stockpile, 220...transport vehicle, 230...dump body, 253...forward / reverse operation device, 254...boom operation portion, 255...bucket operation portion, 300...material, 310...first surface, 320...second surface, 330...exposed portion, 340...surface, 1301...first bucket, 1302...second bucket, 1303...third bucket, AXa...rotating axis, AXb...rotating axis, AXc...rotating axis, AXd...rotating axis, AXe...rotating axis, A Xf...rotation axis, Cd...line, Cd1...line, Cd2...line, Cd3...line, CXf...rotation axis, CXr...rotation axis, H...bucket width, L...bucket length, Ls...line, M1...digging operation, M2...excavation target clearance operation, M3...loading operation, M4...loading target clearance operation, S...cross-sectional area, t1...first point in time, t2...second point in time, W...weight, W1...first weight, W2...second weight, θ1...load angle, θ2...angle of repose, θ3...opening angle, θa...vehicle body tilt angle, θb...boom angle, θbk...bucket angle, θbk1...first angle, θbk2...second angle, θc...bell crank angle, ρ...density.

Claims

1. 1. A system for calculating density of material held in a bucket, comprising: a processor; The processor: obtaining a change in weight of the material held in the bucket during a discharge period in which the material is discharged from the bucket; A change in the angle of the bucket during the discharge period is obtained; calculating a density of the material based on the change in weight of the material and the change in angle of the bucket; system.

2. The processor: obtaining a first weight, which is the weight of the material when the angle of the bucket is a first angle; obtaining a second weight, which is the weight of the material when the bucket angle is a second angle; calculating a density of the material based on a difference between the first weight and the second weight and a difference between the first angle and the second angle; The system of claim 1 .

3. The processor: calculating a first volume, which is the volume of the material when the angle of the bucket is the first angle, and a second volume, which is the volume of the material when the angle of the bucket is the second angle, based on correlation data indicating the relationship between the angle between the surface of the material held in the bucket and the bottom plate portion of the bucket and the volume of the material held in the bucket, and the first angle and the second angle; calculating a density of the material based on a difference between the first weight and the second weight and a difference between the first volume and the second volume; The system of claim 2 .

4. A change amount from the first angle to the second angle is proportional to a change amount from the first volume to the second volume. The system of claim 3 .

5. A system according to claim 1; a bucket; Work machinery.

6. 1. A method for calculating density of material held in a bucket, comprising: The processor: obtaining a change in weight of the material held in the bucket during a discharge period in which the material is discharged from the bucket; A change in the angle of the bucket during the discharge period is obtained; calculating a density of the material based on the change in weight of the material and the change in angle of the bucket; method.

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