Method for calculating the angle of repose of excavated material held in a bucket, system for calculating the angle of repose of excavated material held in a bucket, and loading machine

Abstract

To easily calculate the angle of repose. [Solution] A method for calculating the angle of repose of an excavated object held in a bucket, comprising the steps of: calculating the bucket angle, which indicates the angle of the bucket with respect to the horizontal plane, while the inclination of the surface of the excavated object held in the bucket is maintained; measuring the weight of the excavated object; and calculating the angle of repose of the excavated object from the bucket shape data, the bucket angle, and data of the excavated object including the measured weight.

Description

Technical Field

[0001] The present disclosure relates to a method for calculating the angle of repose of excavated material held in a bucket, a system for calculating the angle of repose of excavated material held in a bucket, and a loading machine.

Background Art

[0002] In the technical field related to loading machines having working devices, as disclosed in Patent Document 1, there is known a loading machine capable of determining the weight of a load material to be transported.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to optimize the loading operation of a loading machine, for example, when loading excavated material dug by a working device onto a transport vehicle, it is desirable for the loading machine to adjust the excavated material to an appropriate weight and load it so as to be an optimal weight for the transport vehicle. Therefore, using the angle of repose, the weight of the excavated material held by the working device before excavation can be predicted. Therefore, it is desired to easily calculate the angle of repose.

[0005] An object of the present disclosure is to easily calculate the angle of repose.

Means for Solving the Problems

[0006] A method for calculating the angle of repose of an excavated object held in a bucket according to this disclosure comprises the steps of: calculating the bucket angle, which indicates the angle of the bucket with respect to the horizontal plane, while the inclination of the surface of the excavated object held in the bucket is maintained; measuring the weight of the excavated object; and calculating the angle of repose of the excavated object from the bucket shape data, the bucket angle, and data of the excavated object including the measured weight.

[0007] The system for calculating the angle of repose of an excavated object held in a bucket according to this disclosure comprises a processor. The processor calculates the bucket angle, which is the angle of the bucket with respect to the horizontal plane while the inclination of the surface of the excavated object held in the bucket is maintained, measures the weight of the excavated object, and calculates the angle of repose of the excavated object from the bucket shape data, the bucket angle, and the excavated object data including the measured weight.

[0008] The loading machine according to this disclosure includes a processor. The processor calculates the bucket angle, which is the angle of the bucket with respect to the horizontal plane, while the inclination of the surface of the excavated material held in the bucket is maintained, measures the weight of the excavated material, and calculates the angle of repose of the excavated material from the bucket shape data, the bucket angle, and the excavated material data including the measured weight. [Effects of the Invention]

[0009] According to this disclosure, the angle of repose can be easily calculated. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a side view showing a loading machine according to an embodiment. [Figure 2] Figure 2 is a perspective view showing a bucket according to this embodiment. [Figure 3] Figure 3 is a schematic side view showing a bucket according to this embodiment. [Figure 4] Figure 4 is a diagram illustrating the operation of the work machine according to the embodiment. [Figure 5]Figure 5 is a diagram illustrating the operation of the loading machine according to the embodiment. [Figure 6] Figure 6 is a functional block diagram showing the control system of a loading machine according to an embodiment. [Figure 7] Figure 7 is a block diagram showing the controller of the loading machine according to this embodiment. [Figure 8] Figure 8 is a diagram illustrating the state of the excavated material held in the bucket according to the embodiment. [Figure 9] Figure 9 illustrates the angle of repose of the excavated material held in the bucket according to this embodiment. [Figure 10] Figure 10 is a flowchart showing the method for calculating the angle of repose according to the embodiment. [Figure 11] Figure 11 is a schematic diagram showing another example of a loading machine. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described below with reference to the drawings, but this disclosure is not limited to these embodiments. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0012] In this embodiment, a local coordinate system is set for the loading machine 1, and the positional relationships of each part are described using the local coordinate system. In the local coordinate system, the first axis along the left-right direction, which is the width direction of the loading machine 1, is defined as the X-axis, the second axis along the front-rear direction of the loading machine 1 is defined as the Y-axis, and the third axis along the up-down direction of the loading machine 1 is defined as the Z-axis. The X-axis and Y-axis are orthogonal. The Y-axis and Z-axis are orthogonal. The Z-axis and X-axis are orthogonal. The +X direction is to the right, and the -X direction is to the left. The +Y direction is forward, and the -Y direction is backward. The +Z direction is upward, and the -Z direction is downward.

[0013] <Loading Machinery> FIG. 1 is a side view showing the loading machine 1 according to the embodiment. The loading machine 1 according to the embodiment is, for example, a wheel loader. In the following description, the loading machine 1 is appropriately referred to as the wheel loader 1. The wheel loader 1 includes a vehicle body 2, a cab 4, wheels 5, and a working machine 6.

[0014] The vehicle body 2 supports the working machine 6. The cab 4 is supported by the vehicle body 2. In the embodiment, the cab 4 is disposed on the upper part of the vehicle body 2. Inside the cab 4, a working machine operating device 24 described later is disposed. The wheels 5 support the vehicle body 2. The wheels 5 include front wheels 5F and rear wheels 5R. In FIG. 1, only the left front wheel 5F and rear wheel 5R are shown.

[0015] The front wheel 5F is rotatable about a rotation axis CXf. The rear wheel 5R is rotatable about a rotation axis CXr. When the wheel loader 1 travels in a straight-ahead state, the rotation axis CXf of the front wheel 5F and the rotation axis CXr of the rear wheel 5R are parallel. In the embodiment, the X-axis is parallel to the rotation axis CXf of the front wheel 5F. The Z-axis is orthogonal to the ground contact surface of the front wheel 5F that contacts the ground 200.

[0016] The working machine 6 performs a predetermined work. The working machine 6 is supported by the vehicle body 2. The working machine 6 is connected to the vehicle body 2. The working machine 6 has a boom 12, a bucket 13, a bell crank 14, a bucket link 15, a lift cylinder 18, and a bucket cylinder 19.

[0017] The base end portion of the boom 12 is rotatably connected to the vehicle body 2. The boom 12 rotates about a rotation axis AXa with respect to the vehicle body 2. A bracket 16 is fixed to an intermediate portion of the boom 12.

[0018] The base end portion of the bucket 13 is rotatably connected to the tip end portion of the boom 12. The bucket 13 rotates about a rotation axis AXb with respect to the boom 12. The bucket 13 is disposed in front of the front wheel 5F. A bracket 17 is fixed to a part of the bucket 13.

[0019] The middle section of the bell crank 14 is rotatably connected to the bracket 16. The bell crank 14 rotates around the pivot axis AXc relative to the bracket 16. The lower end of the bell crank 14 is rotatably connected to the base end of the bucket link 15.

[0020] The tip of the bucket link 15 is rotatably connected to the bracket 17. The bucket link 15 rotates relative to the bracket 17 around the pivot axis AXd. The bell crank 14 is connected to the bucket 13 via the bucket link 15.

[0021] The lift cylinder 18 operates the boom 12. The base end of the lift cylinder 18 is connected to the vehicle body 2. The tip end of the lift cylinder 18 is connected to the boom 12. The boom 12 rotates around the pivot axis AXe relative to the lift cylinder 18.

[0022] The bucket cylinder 19 operates the bucket 13. The base end of the bucket cylinder 19 is connected to the vehicle body 2. The tip of the bucket cylinder 19 is connected to the upper end of the bell crank 14. The bell crank 14 rotates around the pivot axis AXf relative to the bucket cylinder 19.

[0023] Figure 2 is a perspective view showing a bucket 13 according to an embodiment. Figure 3 is a schematic side view showing a bucket 13 according to an embodiment. The bucket 13 is a working member for excavating an object to be excavated. The bucket 13 holds the excavated object. 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 is provided at the tip of the bottom plate portion 131. A cutting edge or blade is attached to the blade tip portion 13A. The tip of the upper plate portion 133 is the upper end portion 13B. The tip of the right plate portion 134 is the right end portion 13C. The tip of the left plate portion 135 is the left end portion 13D. The blade tip portion 13A extends along the left-right direction. The upper end portion 13B extends along the left-right direction. The right end portion 13C extends along the up-down direction or the front-back direction. The left end 13D extends along the vertical or front-to-back direction. In this embodiment, the blade tip 13A and the upper end 13B are parallel. The right end 13C and the left end 13D are parallel. The 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. In other words, the opening 136 of the bucket 13 is defined by the blade tip 13A, the upper end 13B, the right end 13C, and the left end 13D.

[0024] In this embodiment, the length L is defined as the dimension of the opening 136 in the YZ plane, that is, the dimension of the straight line connecting the blade tip 13A and the upper end 13B in the YZ plane. The width H is defined as the dimension of the opening 136 in the left-right direction. The cross-sectional area Abk is defined as the cross-sectional area of ​​the bucket 13 in the YZ plane. The blade tip opening angle θap is defined as the angle formed by the inner surface of the bottom plate 131 and the straight line connecting the blade tip 13A and the upper end 13B in the YZ plane. The upper opening angle θsp is defined as the angle formed by the inner surface of the bottom plate 131 and the inner surface of the top plate 133 in the YZ plane.

[0025] <Operation of the work machine> Figure 4 is a diagram illustrating the operation of the work machine 6 according to the embodiment. In this embodiment, the work machine 6 is a front-loading type work machine in which the opening 136 of the bucket 13 faces forward during excavation work. The boom 12 moves up or down as the lift cylinder 18 extends or retracts. The bucket 13 moves tilt or dump as the bucket cylinder 19 extends or retracts.

[0026] The raising motion of the boom 12 is the motion in which the boom 12 rotates around the pivot axis AXa so that the tip of the boom 12 is lifted off the ground 200. In this embodiment, the boom 12 is raised when the lift cylinder 18 is extended.

[0027] The lowering motion of the boom 12 is the motion in which the boom 12 rotates around the pivot axis AXa so that the tip of the boom 12 approaches the ground 200. In this embodiment, the boom 12 lowers when the lift cylinder 18 is retracted.

[0028] The tilting motion of the bucket 13 is the motion in which the bucket 13 rotates around the pivot axis AXb so that the cutting edge 13A is lifted away from the ground 200 with the opening 136 of the bucket 13 facing upward. 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 backward. When the lower end of the bell crank 14 moves backward, the bucket 13 is pulled backward by the bucket link 15 and tilts. By tilting the bucket 13 in this way, the material to be excavated is scooped up by the bucket 13 and held in the bucket 13.

[0029] The dumping operation of the bucket 13 is the movement of the bucket 13 around the pivot axis AXb such that the opening 136 of the bucket 13 faces downward and the cutting edge 13A approaches the ground 200. When the bucket cylinder 19 retracts, the bell crank 14 rotates so that the upper end of the bell crank 14 moves backward 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 and performs a dumping operation. By performing this dumping operation of the bucket 13, the material to be excavated held in the bucket 13 is discharged from the bucket 13.

[0030] <Wheel loader operation> Figure 5 is a diagram illustrating the operation of a wheel loader 1 according to an embodiment. The wheel loader 1 performs predetermined operations on a work object at a work site. The work object includes an excavation target and a loading target. The excavation target is, for example, at least one of a natural ground, a rocky mountain, coal, feed, and a wall surface. A natural ground is a mountain composed of soil and sand, and a rocky mountain is a mountain composed of rock or stone. In this embodiment, the excavation target is a natural ground 210 on the ground. The loading target is, for example, at least one of a transport vehicle, a predetermined area at the work site, a hopper, a belt conveyor, and a crusher. In this embodiment, the loading target is the dump body 230 of a transport vehicle 220 that can travel on the ground. The transport vehicle 220 is, for example, a dump truck. The predetermined operations include excavation work and loading work. The wheel loader 1 performs excavation work by excavating the excavation target with the bucket 13 of the work machine 6. The wheel loader 1 performs loading work by loading the excavated material excavated by the bucket 13 into the loading target. Loading operations are a concept that includes the discharge operations for removing excavated material.

[0031] During the excavation operation, the wheel loader 1 moves forward toward the ground 210 with no excavated material held in the bucket 13, as shown by arrow M1 in Figure 5. The operator moves the wheel loader 1 forward to approach the ground 210. To hold the excavated material in the bucket 13, the wheel loader 1 performs the excavation operation by tilting the bucket 13 while it is plunged into the ground 210. The operator operates the work machine 6 so that the ground 210 is excavated by the bucket 13. The ground 210 is excavated by the bucket 13, and the excavated material is scooped up by the bucket 13.

[0032] Next, with the excavated material held in the bucket 13, the wheel loader 1 reverses away from the ground 210, as indicated by arrow M2 in Figure 5. The operator reverses the wheel loader 1 away from the ground 210.

[0033] Next, the loading operation is carried out. During the loading operation, the wheel loader 1 moves forward toward the transport vehicle 220, as indicated by arrow M3 in Figure 5, with the excavated material held in the bucket 13. The operator moves the wheel loader 1 forward while rotating it to approach the transport vehicle 220. While the wheel loader 1 is moving forward toward the transport vehicle 220, the wheel loader 1 raises the boom 12 so that the bucket 13 is positioned above the dump body 230 of the transport vehicle 220. The operator operates the work implement 6 to raise the boom 12. After the boom 12 has been raised and the bucket 13 is positioned above the dump body 230 of the transport vehicle 220, the wheel loader 1 performs the loading operation by dumping the bucket 13 in order to discharge the excavated material from the bucket 13. The operator operates the work implement 6 to dump the bucket 13. The excavated material is discharged from the dumping bucket 13 and loaded onto the dump body 230 of the transport vehicle 220.

[0034] After the excavated material is loaded onto the dump body 230 of the transport vehicle 220, the wheel loader 1 reverses away from the transport vehicle 220, as indicated by arrow M4 in Figure 5, with no excavated material being held in the bucket 13. The operator reverses the wheel loader 1 while rotating it away from the transport vehicle 220.

[0035] The wheel loader 1 repeats the above operations until the dump body 230 of the transport vehicle 220 is fully loaded with excavated material, or until the excavation of the ground 210 is completed.

[0036] <Control System> Figure 6 is a functional block diagram showing the control system 40 of the wheel loader 1 according to the embodiment. Figure 7 is a block diagram showing the controller 50 of the wheel loader 1 according to the embodiment. The control system 40 performs various controls on the wheel loader 1. The control system 40 includes a work equipment operating device 24, a control valve 25, an operator command device 26, an inclination measuring device 30, a boom angle sensor 31, a bucket angle sensor 32, a weight measuring device 33, and a controller 50.

[0037] The implement operating device 24 is located inside the cab 4. The implement operating device 24 is operated by the operator. The implement operating device 24 generates operating signals to operate the implement 6. The operator operates the implement operating device 24 to operate the implement 6. The implement operating device 24 includes, for example, a boom operating unit 241 and a bucket operating unit 242.

[0038] The boom operating unit 241 is operated by an operator to move the boom 12. The controller 50 controls the control valve 25 based on the operation signal from the boom operating unit 241. When the control valve 25 is controlled, the lift cylinder 18 is driven and the boom 12 moves.

[0039] The bucket operating unit 242 is operated by an operator to move the bucket 13. The controller 50 controls the control valve 25 based on the operating signal generated by the bucket operating unit 242. When the control valve 25 is controlled, the bucket cylinder 19 is driven and the bucket 13 moves.

[0040] The operator command device 26 is operated by the operator to start the calculation process for the angle of repose θ, which will be described later. The operator command device 26 is, for example, a switch provided on the work equipment operating device 24. The operator command device 26 outputs an operation command signal to the controller 50 to start the calculation process for the angle of repose θ.

[0041] The inclination meter 30 measures the inclination of the vehicle body 2. More specifically, the inclination meter 30 measures the vehicle body inclination angle θa, which indicates the inclination of the vehicle body 2 with respect to the horizontal plane. The inclination meter 30 is positioned on at least a portion of the vehicle body 2. The inclination meter 30 is, for example, an inertial measurement unit (IMU). The inclination meter 30 outputs the measured vehicle body inclination angle data to the controller 50.

[0042] The boom angle sensor 31 measures the angle of the boom 12. More specifically, the boom angle sensor 31 measures the boom angle θb, which represents the angle of the boom 12 relative to the vehicle body 2 in the local coordinate system. The boom angle sensor 31 is, for example, an angle sensor placed at the connection point between the vehicle body 2 and the boom 12. In this embodiment, the boom angle θb is the angle formed by the line connecting the pivot axis AXa and the pivot axis AXb and the line connecting the rotation axis CXf and the rotation axis CXr. The boom angle sensor 31 may also be a stroke sensor that measures the stroke of the lift cylinder 18. The boom angle sensor 31 outputs the measured boom angle data to the controller 50.

[0043] The bucket angle sensor 32 measures the angle of the bucket 13. More specifically, the bucket angle sensor 32 measures the bell crank angle θc, which indicates the angle of the bell crank 14 relative to the boom 12 in the local coordinate system. The bucket angle sensor 32 is, for example, an angle sensor placed at the connection point between the boom 12 and the bell crank 14. In this embodiment, the bell crank angle θc is the angle formed by the line connecting the pivot axis AXc and pivot axis AXf and the line connecting the pivot axis AXa and pivot 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 measuring the bell crank angle θc, the angle of the bucket 13 relative to the boom 12 in the local coordinate system is calculated. The bucket angle sensor 32 may also be a stroke sensor that measures the stroke of the bucket cylinder 19. The bucket angle sensor 32 outputs the measured value, the bell crank angle data, to the controller 50.

[0044] The weight measuring device 33 measures the weight Wa of the excavated material 300 held in the bucket 13. The weight measuring device 33 is, for example, a pressure sensor that measures the pressure of the hydraulic fluid in the lift cylinder 18 or a pressure sensor that measures the pressure of the hydraulic fluid in the bucket cylinder 19. The load on the work machine 6 changes depending on whether the excavated material 300 is held in the bucket 13 or not. The weight measuring device 33 measures the weight Wa of the excavated material 300 held in the bucket 13 by measuring the change in the load on the work machine 6. The weight measuring device 33 may also be a load cell placed on at least a part of the work machine 6. The weight measuring device 33 may also directly measure the weight Wa of the excavated material 300. The weight measuring device 33 outputs the measured weight data of the excavated material 300 to the controller 50.

[0045] The controller 50 includes a computer system. The controller 50 outputs control commands to control the wheel loader 1. As shown in Figure 7, the controller 50 has a processor 51, main memory 52, storage 53, and interface 54. The processor 51 calculates the operation of the work machine 6 by executing a computer program. The processor 51 is, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The main memory 52 is, for example, non-volatile memory or volatile memory. Non-volatile memory is, for example, ROM (Read Only Memory). Volatile memory is RAM (Random Access Memory). The storage 53 is a tangible storage medium that is not temporary. The storage 53 is, for example, a magnetic disk, a magneto-optical disk, and semiconductor memory. The storage 53 may be an internal medium directly connected to the bus of the controller 50, or an external medium connected to the controller 50 via interface 54 or a communication line. The storage 53 stores the computer program for controlling the work machine 6.

[0046] As shown in Figure 6, the controller 50 includes a measurement value acquisition unit 60, a calculation unit 70, a target weight setting unit 90, a work machine control unit 100, a characteristic storage unit 120, a bucket data storage unit 130, a target load storage unit 140, and an actual load storage unit 150. The controller 50 communicates with the work machine operating device 24, the control valve 25, the inclination measuring instrument 30, the boom angle sensor 31, the bucket angle sensor 32, and the weight measuring device 33, respectively.

[0047] The measurement value acquisition unit 60 acquires measurement values ​​from the inclination measuring instrument 30, boom angle sensor 31, bucket angle sensor 32, and weight measuring device 33. The measurement value acquisition unit 60 acquires the vehicle body inclination angle θa from the inclination measuring instrument 30. The measurement value acquisition unit 60 acquires the boom angle θb from the boom angle sensor 31. The measurement value acquisition unit 60 acquires the bell crank angle θc from the bucket angle sensor 32. The measurement value acquisition unit 60 acquires the weight Wa of the excavated material 300 from the weight measuring device 33.

[0048] The calculation unit 70 calculates the angle of repose θ of the excavated material 300 held in the bucket 13. The calculation unit 70 calculates the angle of repose θ of the excavated material 300 held in the bucket 13 based on the various measurement values ​​acquired by the measurement value acquisition unit 60 and the data stored in the characteristic storage unit 120. The calculation unit 70 has a bucket angle calculation unit 71 and an angle of repose calculation unit 72.

[0049] The bucket angle calculation unit 71 calculates the bucket angle θbk, which indicates the angle of the bucket 13 with respect to the horizontal plane. The bucket angle calculation unit 71 calculates the bucket angle θbk based on the vehicle body tilt angle data, the boom angle data, and the bell crank angle data. The bucket angle calculation unit 71 calculates the bucket angle θbk based on the vehicle body tilt angle θa, the boom angle θb, and the bell crank angle θc.

[0050] The angle of repose calculation unit 72 calculates the angle of repose θ, which indicates the angle of the surface of the excavated material 300 starting from the blade tip 13A. The angle of repose calculation unit 72 calculates the angle of repose of the excavated material from the shape data of the bucket 13 stored in the bucket data storage unit 130, the bucket angle θbk calculated by the bucket angle calculation unit 71, and the data of the excavated material including the measured weight. In this embodiment, the angle of repose calculation unit 72 calculates the angle of repose θ from the shape data of the bucket 13 stored in the bucket data storage unit 130, the bucket angle θbk calculated by the bucket angle calculation unit 71, the data of the excavated material 300 including the weight Wa of the excavated material 300 measured by the weight measuring device 33 and the density ρ of the excavated material 300 stored in the characteristic storage unit 120.

[0051] The target weight setting unit 90 sets a target weight Wr, which indicates a target value for the weight Wa of the excavated material 300 held in the bucket 13. The target load amount Tr of the excavated material 300 relative to the dump body 230 is stored in the target load amount storage unit 140. The target load amount Tr is a unique value defined for the transport vehicle 220. The target weight setting unit 90 sets the target weight Wr based on the target load amount Tr stored in the target load amount storage unit 140.

[0052] The work machine control unit 100 controls the posture of the bucket 13 so that the weight of the excavated material 300 held by the bucket 13 becomes the target weight Wr. The posture of the bucket 13 includes the bucket angle θbk, which indicates the angle of the bucket 13 with respect to the horizontal plane. During the excavation operation, the work machine control unit 100 adjusts the bucket angle θbk by controlling at least one of the lift cylinder 18 and the bucket cylinder 19.

[0053] The characteristic memory unit 120 stores characteristic data of the excavated material 300. The characteristic memory unit 120 pre-stores the density ρ of the excavated material 300 as characteristic data. The characteristic memory unit 120 also stores the angle of repose θ of the excavated material 300, which is calculated by the angle of repose calculation unit 72, as characteristic data.

[0054] The bucket data storage unit 130 stores shape data of the bucket 13. More specifically, the bucket data storage unit 130 stores specification data or design data of the bucket 13, including the dimensions of the bucket 13. The bucket data storage unit 130 includes, for example, the cross-sectional area Abk, length L, width H, cutting edge side opening angle θap, and upper side opening angle θsp of the bucket 13.

[0055] The target load capacity storage unit 140 stores the target load capacity Tr of the excavated material 300 relative to the dump body 230.

[0056] The actual load capacity storage unit 150 stores the actual load capacity Tp, which indicates the actual amount of excavated material 300 loaded onto the dump body 230. For one transport vehicle 220, the predetermined operations, including excavation and loading, are performed multiple times. The weight calculation unit 84 adds the weights Wp of the excavated material 300 calculated for each of the multiple excavation operations and stores the actual load capacity Tp in the actual load capacity storage unit 150.

[0057] Figure 8 is a diagram illustrating the state of the excavated material 300 held in the bucket according to the embodiment. Figure 9 is a diagram illustrating the angle of repose of the excavated material 300 held in the bucket according to the embodiment. Various controls of the wheel loader 1 are performed using the angle of repose (stop angle of repose). The angle of repose is, for example, the angle that can be observed when the excavated material is piled up and the natural collapse has ended. That is, the angle of repose is the angle of inclination at which the excavated material remains in a predetermined position with respect to the horizontal plane without sliding. In this embodiment, the control system 40 of the wheel loader 1 calculates the angle of repose θ of the excavated material 300 held in the bucket 13.

[0058] The angle of repose θ is the inclination of the surface of the excavated material 300 relative to the horizontal plane. The angle of repose θ changes depending on the properties of the excavated material, for example, due to weather conditions. If the properties of the excavated material remain constant, the angle of repose θ does not change even if the bucket angle θbk, which indicates the angle of the bucket 13 relative to the horizontal plane, changes. If the properties of the excavated material change, the angle of repose θ changes. For example, if the weather changes from sunny to rainy, the properties of the excavated material change and the angle of repose θ changes.

[0059] As shown in Figure 8, when the bucket 13 is tilted from a state where it is fully filled with excavated material 300, a portion of the excavated material 300 is discharged from the bucket 13 due to the action of gravity. Once a portion of the excavated material 300 is discharged from the bucket 13, as shown in Figure 9, the surface of the excavated material 300 forms an inclination starting from the blade tip 13A. The angle of repose θ is the angle with respect to the horizontal plane of the inclination that the surface of the excavated material 300 remains on without sliding off, starting from the blade tip 13A. The angle of repose θ is the angle with respect to the horizontal plane of the inclination formed by the surface of the excavated material 300, which is exposed at the opening 136 of the bucket 13, starting from the blade tip 13A.

[0060] The method for calculating the angle of repose θ will be explained in detail. After filling the bucket 13 with excavated material 300, a portion of the excavated material 300 held in the bucket 13 is discharged, as shown in Figure 9. When a portion of the excavated material 300 held in the bucket 13 is discharged, the surface of the excavated material 300 remains in a state where it does not slide off, in other words, the surface of the excavated material 300 held in the bucket 13 is in a state where the slope is maintained. The cross-sectional area A of the excavated material 300 in this state is calculated from the cross-sectional area Abk of the bucket 13 stored in the bucket data storage unit 130 and the cross-sectional area As of the void 13S of the bucket 13, based on the following equation (1).

[0061]

number

[0062] In the YZ plane, with the angle of the surface of the excavated material 300 held in the bucket 13 being the angle of repose, the volume V of the excavated material 300 is calculated from the cross-sectional area A of the excavated material 300 and the width H of the opening 136 stored in the bucket data storage unit 130 based on the following equation (2).

[0063]

number

[0064] The volume V of the excavated material 300 is calculated from equations (1) and (2) to the following equation (3), using the length L, width H, cutting edge side opening angle θap, and upper side opening angle θsp when the bucket 13 is horizontal (hereinafter referred to as "when the bucket is horizontal") of the bucket 13 stored in the bucket data storage unit 130.

[0065]

number

[0066] The volume V of the excavated material 300 is calculated based on the following equation (4), using the weight Wa of the excavated material 300 held in the bucket 13 as measured by the weight measuring device 33, and the density ρ of the excavated material 300 stored in the characteristic memory unit 120.

[0067]

number

[0068] From equations (3) and (4), the following equation (5) holds. From equation (5), the angle of repose θ is calculated.

[0069]

number

[0070] <Method for calculating the angle of repose> Figure 10 is a flowchart illustrating the method for calculating the angle of repose according to the embodiment. Before the initial excavation work on the ground 210, the operator instructs the controller 50 to start the process of calculating the angle of repose θ.

[0071] The operator excavates the ground 210 with the bucket 13 and holds the excavated material 300 (step SP11). More specifically, as shown in Figure 8, the operator excavates the ground 210 so that the bucket 13 is full of excavated material 300, and then tilts the bucket 13 so that the excavated material 300 is held inside the bucket 13.

[0072] Next, the operator discharges some of the excavated material 300 from the bucket 13 (step SP12). More specifically, the operator dumps the bucket 13 from a state where the bucket 13 is full of excavated material 300 to the extent that the excavated material 300 is not completely discharged from the bucket 13. For example, the operator dumps the bucket between the tilt position of step SP11 and an angle where the bucket angle θbk is greater than 0°. Once some of the excavated material 300 has been discharged from the bucket 13, as shown in Figure 9, the surface of the excavated material 300 held in the bucket 13 maintains an inclination that keeps it in place without slipping, starting from the cutting edge 13A. The angle of the surface of the excavated material 300 in the bucket 13 maintains the angle of repose.

[0073] Next, in the state of step SP12, the operator sends a command to the controller 50 to start the calculation process of the angle of repose θ (step SP13). More specifically, when the operator operates the operator command device 26, the operator command device 26 outputs an operation command signal to the controller 50 to start the calculation process of the angle of repose θ.

[0074] The controller 50 acquires measured values ​​from multiple sensors (step SP14). More specifically, the measurement value acquisition unit 60 acquires the vehicle body tilt angle θa, boom angle θb, bell crank angle θc, and the weight Wa of the excavated material 300, while the surface of the excavated material 300 held in the bucket 13 maintains its angle of repose in the YZ plane.

[0075] The controller 50 calculates the bucket angle θbk (step SP15). More specifically, the bucket angle calculation unit 71 calculates the bucket angle θbk based on the vehicle body tilt angle θa, boom angle θb, and bell crank angle θc acquired by the measurement value acquisition unit 60.

[0076] The controller 50 calculates the angle of repose θ (step SP16). More specifically, the angle of repose calculation unit 72 calculates the angle of repose θ based on the detected angle data of the vehicle body 2, the specification data or design data of the bucket 13 stored in the bucket data storage unit 130, the weight Wa of the excavated material 300 obtained in step SP14, and the bucket angle θbk calculated in step SP15.

[0077] The controller 50 stores the angle of repose θ (step SP17). More specifically, the characteristic storage unit 120 stores the angle of repose θ calculated by the angle of repose calculation unit 72.

[0078] The angle of repose θ calculated in this way is used to perform various controls on the wheel loader 1.

[0079] <Effects> As described above, in this embodiment, the angle of repose θ of the excavated material 300 can be calculated from the shape data of the bucket 13 stored in the bucket data storage unit 130, the bucket angle θbk, and data on the excavated material 300 including the weight W of the excavated material 300 measured by the weight measuring device 33 and the density ρ of the excavated material 300 stored in the characteristic storage unit 120. In this embodiment, the angle of repose θ can be calculated without providing any sensors other than those installed to perform a predetermined operation on the wheel loader 1.

[0080] In this embodiment, the shape data of the bucket 13 is the length L, width H, cutting edge side opening angle θap, and upper side opening angle θsp of the bucket 13. According to this embodiment, the angle of repose θ can be calculated using the specification data or design data of the bucket 13. In this embodiment, the angle of repose θ can be calculated using the shape data of the bucket 13 stored in order to perform a predetermined operation on the wheel loader 1.

[0081] In this embodiment, the bucket angle θbk can be calculated based on the detected angle data of the wheel loader 1 body 2 supporting the work implement 6 and the detected angle data of the work implement 6.

[0082] In this embodiment, after filling the bucket 13 with excavated material 300, a portion of it is discharged to maintain the inclination of the surface of the excavated material 300 held in the bucket 13. In this embodiment, the angle of the surface of the excavated material 300 can be set to the angle of repose by the normal operation of the wheel loader 1. According to this embodiment, the angle of repose θ can be easily calculated without requiring the wheel loader 1 to perform any unusual operations.

[0083] <Example 1> Figure 11 is a schematic diagram showing another example of a loading machine. When multiple loading machines are operating at the same work site, the angle of repose θ may be calculated by the master unit, the first loading machine 1S, and the calculated angle of repose θ may be transmitted to the slave unit, the second loading machine 1T, via a communication system. The communication system may be, for example, the internet, a local area network (LAN), a mobile phone network, or a satellite communication network.

[0084] <Modification 2> In Figure 10 above, the order of steps SP12 and SP13 may be reversed. After step SP11, the operator sends a command to the controller 50 to start the calculation of the angle of repose θ. After that, the wheel loader 1 may automatically discharge some of the excavated material 300 in the bucket 13. <Other Embodiments> In the embodiment described above, steps SP11 and SP12 of the flowchart shown in Figure 10 may be performed autonomously by the loading machine 1 without operator intervention.

[0085] The operator command device 26 in the above-described embodiment is a switch, but is not limited to this. The operator command device 26 may be, for example, a touchscreen or a microphone. The touchscreen includes a display and a touch panel. The device may be configured so that when the operator operates the touchscreen, a command to start the calculation process of the angle of repose θ is output to the controller 50. Alternatively, the device may be configured so that a command to start the calculation process of the angle of repose θ is output to the controller 50 based on voice input via the microphone.

[0086] Furthermore, although the loading machine 1 according to the above embodiment has been described as being operated by an operator, it is not limited to this. The loading machine 1 may also be operated by a remote system. In this case, for example, a device having the functions of a controller 50 and a remote control device is provided at the remote control site. The calculation of the angle of repose θ may also be performed remotely.

[0087] Furthermore, in the embodiments described above, the loading machine 1 is a wheel loader, but it is not limited to this. For example, the loading machine 1 may be a hydraulic excavator with a loading-type work implement. Alternatively, the loading machine 1 may be a hydraulic excavator with a backhoe-type work implement in which the opening 136 of the bucket 13 faces rearward during excavation work. [Explanation of symbols]

[0088] 1...Wheel loader (loading machine), 2...Body, 4...Cab, 5...Wheels, 5F...Front wheels, 5R...Rear wheels, 6...Work implement, 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...Lift cylinder, 19...Bucket cylinder, 20...Power source, 21...PTO, 22...Power transmission device, 23...Hydraulic pump 24...Work equipment operating device, 241...Boom operating unit, 242...Bucket operating unit, 25...Control valve, 26...Operator command device, 30...Incline measuring instrument, 31...Boom angle sensor, 32...Bucket angle sensor, 33...Weight measuring device, 40...Control system, 50...Controller, 51...Processor, 52...Main memory, 53...Storage, 54...Interface, 70...Calculation unit, 71...Bucket angle calculation unit, 72...Angle of repose calculation unit, 90...Target weight Setting unit, 100...Work machine control unit, 120...Characteristics memory unit, 130...Bucket data memory unit, 131...Bottom plate unit, 132...Back plate unit, 133...Top plate unit, 134...Right plate unit, 135...Left plate unit, 136...Opening, 140...Target load amount memory unit, 150...Actual load amount memory unit, 200...Ground, 210...Natural ground (excavation target), 220...Transport vehicle, 230...Dump body (loading target), 300...Excavated material, A...Cross-sectional area of ​​excavated material, Abk...Cross-sectional area of ​​bucket, As ...Cross-sectional area of ​​the void, AXa...rotating axis, AXb...rotating axis, AXc...rotating axis, AXd...rotating axis, AXe...rotating axis, AXf...rotating axis, CXf...rotating axis, CXr...rotating axis, H...width, L...length, Tp...actual load capacity, Tr...target load capacity, V...volume of excavated material, Wa...weight, Wr...target weight, θ...angle of repose, θa...vehicle inclination angle, θb...boom angle, θap...cutting edge opening angle, θbk...bucket angle, θc...bell crank angle, θsp...upper side opening angle, ρ...density.

Claims

1. A method for calculating the angle of repose of excavated material held in a bucket, A step of calculating the bucket angle, which indicates the angle of the bucket with respect to the horizontal plane, while the inclination of the surface of the excavated material held in the bucket is maintained. A step of measuring the weight of the excavated material, A step of calculating the angle of repose of the excavated object from the shape data of the bucket, the bucket angle, and the data of the excavated object including the measured weight, A method for providing this.

2. The bucket includes a blade tip, an upper end facing the blade tip, and an opening defined between the blade tip and the upper end. The angle of repose is the angle of inclination of the surface exposed to the opening of the excavated work, with respect to the tip of the cutting edge. The method according to claim 1.

3. The angle of the bucket is calculated based on the detection data of the angle indicating the inclination of the vehicle body supporting the work machine and the detection data of the angle of the work machine. The method according to claim 1 or 2.

4. The step includes filling the bucket with the excavated material, then discharging a portion of the excavated material held in the bucket, thereby maintaining the inclination of the surface of the excavated material. The method according to any one of claims 1 to 3.

5. The data of the excavated material includes the density of the excavated material. The method according to any one of claims 1 to 4.

6. A system for calculating the angle of repose of excavated material held in a bucket, Equipped with a processor, The aforementioned processor, The bucket angle, which indicates the angle of the bucket with respect to the horizontal plane, is calculated while the inclination of the surface of the excavated material held in the bucket is maintained. The weight of the excavated material was measured, The angle of repose of the excavated material is calculated from the shape data of the bucket, the bucket angle, and the data of the excavated material including the measured weight. system.

7. It is a loading machine, A bucket and Processor and Equipped with, The aforementioned processor, The bucket angle, which indicates the angle of the bucket with respect to the horizontal plane, is calculated while the inclination of the surface of the excavated material held in the bucket is maintained. The weight of the excavated material was measured, The angle of repose of the excavated material is calculated from the shape data of the bucket, the bucket angle, and the data of the excavated material including the measured weight. Loading machine.

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