Control system, loading machine, and control method

Abstract

To provide a loading machine capable of optimizing loading operations.SOLUTION: A control system of a loading machine with work equipment having a bucket includes a controller. The loading machine excavates a ground composed of earth and sand placed on the ground with a bucket while moving forward. The surface of the excavated material that is excavated and held in a bucket includes a first surface that slopes upward toward the front and a second surface that connects to the front end of the first surface and slopes downward toward the front. The controller obtains the bucket angle indicating the angle of the bucket with respect to the horizontal plane during excavation work and determines the front loading angle which is the angle of the first surface with respect to the horizontal plane as the specified angle based on the bucket angle since excavation work started.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a control system, a loading machine, and a control method. [Background technology]

[0002] BACKGROUND ART In the technical field relating to loading machines equipped with working implements, a loading machine capable of carrying out an efficient excavation operation, such as that disclosed in Patent Document 1, is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-203381 Summary of the Invention [Problem to be solved by the invention]

[0004] According to a specific work cycle, the loading machine excavates an excavation target with a work implement and then loads the excavated material onto a transport vehicle. When loading the excavated material onto the transport vehicle, it is desirable for the loading machine to adjust the weight of the excavated material so that it is an optimal weight for the transport vehicle.

[0005] The technology disclosed in this specification aims to optimize loading operations by a loading machine. [Means for solving the problem]

[0006] This specification discloses a control system for a loading machine. The loading machine includes a work implement with a bucket. The control system includes a controller. The loading machine excavates a pile of earth and sand placed on the ground with the bucket while moving forward. The surface of the excavated material, which is the pile of earth and sand excavated and held by the bucket, includes a first surface that slopes upward toward the front and a second surface that is connected to the front end of the first surface and slopes downward toward the front. The controller acquires a bucket angle that indicates the angle of the bucket with respect to the horizontal plane during excavation work. The controller determines a predetermined angle for the front load angle, which indicates the angle of the first surface with respect to the horizontal plane, based on the bucket angle after excavation work has started. [Effects of the Invention]

[0007] According to the technology disclosed in this specification, loading operations by a loading machine are optimized. [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 configuration diagram showing the loading machine according to the embodiment. [Figure 3] FIG. 3 is a perspective view showing a bucket according to the embodiment. [Figure 4] FIG. 4 is a side view schematically showing the bucket according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating the operation of the work machine according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating the operation of the loading machine according to the embodiment. [Figure 7] FIG. 7 is a functional block diagram showing the control system of the loading machine according to the embodiment. [Figure 8] FIG. 8 is a block diagram showing the control device of the loading machine according to the embodiment. [Figure 9] FIG. 9 is a diagram illustrating the state of an excavated object held in a bucket according to the embodiment. [Figure 10]FIG. 10 is a schematic diagram illustrating a method for calculating the weight of the excavated material based on the first calculation method according to the embodiment. [Figure 11] FIG. 11 is a diagram illustrating the state of an excavated object held in a bucket according to the embodiment. [Figure 12] FIG. 12 is a diagram illustrating the relationship between traction force and earth pressure according to the embodiment. [Figure 13] FIG. 13 is a schematic diagram illustrating a method for calculating the weight of the excavated material based on the second calculation method according to the embodiment. [Figure 14] FIG. 14 is a diagram illustrating the angle of repose and the ground angle according to the embodiment. [Figure 15] FIG. 15 is a diagram showing the relationship between the ground angle and the angle of repose according to the embodiment. [Figure 16] FIG. 16 is a diagram showing the relationship between the bucket and the excavated object during excavation work according to the embodiment. [Figure 17] FIG. 17 is a diagram showing the relationship between the bucket angle and the front load angle according to the embodiment. [Figure 18] FIG. 18 is a diagram illustrating the angle of repose of the excavated material held in the bucket according to the embodiment. [Figure 19] FIG. 19 is a flowchart showing a method for calculating the angle of repose according to this embodiment. [Figure 20] FIG. 20 is a flowchart showing an excavation method 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] 1 is a side view showing a loading machine 1 according to an embodiment. In the embodiment, the loading machine 1 is, for example, 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, a cab 4, wheels 5, and a work implement 6.

[0013] The vehicle body 2 supports the work implement 6. The cab 4 is supported by the vehicle body 2. In the embodiment, the cab 4 is disposed on an upper part of the vehicle body 2. The wheels 5 support the vehicle body 2. The wheels 5 include front wheels 5F and rear wheels 5R.

[0014] The front wheels 5F are rotatable about rotation axes CXf. The rear wheels 5R are rotatable about rotation axes CXr. When the wheel loader 1 travels in a straight line, the rotation axes CXf of the front wheels 5F and the rotation axes CXr of the rear wheels 5R are parallel to each other. In this embodiment, the X axis is parallel to the rotation axes CXf of the front wheels 5F.

[0015] The work implement 6 performs a predetermined task. The work implement 6 is supported by the vehicle body 2. The work implement 6 is connected to the vehicle body 2. The work implement 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.

[0016] A base end of the boom 12 is rotatably connected to the vehicle body 2. The boom 12 rotates about a rotation axis AXa relative to the vehicle body 2. A bracket 16 is fixed to the middle portion of the boom 12.

[0017] 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.

[0018] An intermediate portion of the bell crank 14 is rotatably connected to the bracket 16. The bell crank 14 rotates around a rotation axis AXc relative to the bracket 16. A lower end portion of the bell crank 14 is rotatably connected to a base end portion of the bucket link 15.

[0019] The tip end of the bucket link 15 is rotatably connected to a bracket 17. The bucket link 15 rotates about a rotation axis AXd relative to the bracket 17. The bell crank 14 is connected to the bucket 13 via the bucket link 15.

[0020] 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 relative to the lift cylinder 18 about a rotation axis AXe.

[0021] The bucket cylinder 19 operates the bucket 13. A base end of the bucket cylinder 19 is connected to the vehicle body 2. A tip end of the bucket cylinder 19 is connected to an upper end of the bell crank 14. The bell crank 14 rotates relative to the bucket cylinder 19 about a rotation axis AXf.

[0022] 2 is a configuration diagram showing the loading machine 1 according to the embodiment. The loading machine 1 includes a power source 3, a power take-off (PTO) 8, a power transmission device 9, a hydraulic pump 20, a control valve 21, and a controller 50.

[0023] The power source 3 generates driving force for operating the wheel loader 1. The power source 3 is, for example, a diesel engine.

[0024] The power take-off 8 distributes the driving force from the power source 3 to the power transmission device 9 and the hydraulic pump 20. The driving force of the power source 3 is transmitted to both the power transmission device 9 and the hydraulic pump 20 via the power take-off 8.

[0025] The power transmission device 9 has an input shaft to which driving force from the power source 3 is input, and an output shaft that changes the speed of the driving force input to the input shaft and outputs it. The input shaft of the power transmission device 9 is connected to the power take-off 8. The output shafts of the power transmission device 9 are connected to the front wheels 5F and the rear wheels 5R, respectively. The driving force of the power source 3 is transmitted to the front wheels 5F and the rear wheels 5R, respectively, via the power transmission device 9. The power transmission device 9 may include an axle device or a differential device.

[0026] The hydraulic pump 20 discharges hydraulic oil. The hydraulic pump 20 is a variable displacement hydraulic pump. The hydraulic pump 20 is driven based on the driving force of the power source 3. The hydraulic oil discharged from the hydraulic pump 20 is supplied to the lift cylinder 18 and the bucket cylinder 19 via a control valve 21.

[0027] The control valve 21 controls the flow rate and direction of hydraulic oil supplied to each of the lift cylinder 18 and the bucket cylinder 19. The work machine 6 is operated by hydraulic oil supplied from the hydraulic pump 20 via the control valve 21.

[0028] The controller 50 controls the wheel loader 1. The controller 50 includes a computer system.

[0029] [Bucket] Fig. 3 is a perspective view showing the bucket 13 according to the embodiment. Fig. 4 is a side view schematically showing the bucket 13 according to the embodiment. The bucket 13 is a work member that excavates an excavation target. The bucket 13 holds an excavation object 300. The excavation object 300 is an excavation target that is excavated and held by the bucket 13.

[0030] 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. The tip of the bottom plate portion 131 is a blade tip portion 13A. A cutting edge or blade is attached to the blade tip portion 13A. The tip of the upper plate portion 133 is a spill guard end portion 13B. The tip of the right plate portion 134 is a right end portion 13C. The tip of the left plate portion 135 is a left end portion 13D. The blade tip portion 13A extends in the left-right direction. The spill guard end portion 13B extends in the left-right direction. The right end portion 13C extends in the up-down direction or the front-to-back direction. The left end portion 13D extends in the up-down direction or the front-to-back direction. The blade tip portion 13A and the spill guard end portion 13B face each other. The right end portion 13C and the left end portion 13D face each other. The blade tip 13A and the spill guard end 13B are parallel to each other, and the right end 13C and the left end 13D are parallel to each other.

[0031] An opening 136 of the bucket 13 is defined between the cutting edge 13A, the spill guard end 13B, the right end 13C, and the left end 13D. The opening 136 is defined by the cutting edge 13A, the spill guard end 13B, the right end 13C, and the left end 13D.

[0032] In the embodiment, the dimension of the opening 136 in the up-down or front-back direction, i.e., the dimension of the straight line connecting the cutting edge 13A and the spill guard end 13B in the YZ plane, is defined as the bucket length L. The dimension of the opening 136 in the left-right direction is defined as the bucket width B. The cross-sectional area of ​​the bucket 13 parallel to the YZ plane is defined as the bucket cross-sectional area Abk. The angle formed by the inner surface of the bottom plate portion 131 and the straight line connecting the cutting edge 13A and the spill guard end 13B in the YZ plane is defined as the cutting edge side opening angle θ3. The angle formed by the plane parallel to the inner surface of the bottom plate portion 131 and the inner surface of the top plate portion 133 in the YZ plane is defined as the upper side opening angle θsp.

[0033] [Work equipment operation] 5 is a diagram illustrating the operation of the work machine 6 according to the embodiment. In the 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.

[0034] 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 lift cylinder 18 extends, causing the boom 12 to perform the raising operation.

[0035] 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 approaches the ground 200. The lift cylinder 18 contracts, causing the boom 12 to perform the lowering operation.

[0036] The tilting movement of the bucket 13 refers to the movement of the bucket 13 pivoting about the pivot axis AXb so that the cutting edge 13A of the bucket 13 is separated from the ground surface 200. When the bucket cylinder 19 extends, the bell crank 14 pivots 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, causing the bucket 13 to tilt. As the bucket 13 tilts, the object to be excavated is scooped up by the bucket 13, and the excavated material 300 is held in the bucket 13.

[0037] The dumping operation of the bucket 13 refers to the operation of the bucket 13 rotating about the rotation axis AXb so that the cutting edge 13A of the bucket 13 approaches the ground surface 200. 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 dumping operation. When the bucket 13 performs a dumping operation, the excavated material 300 held in the bucket 13 is ejected from the bucket 13.

[0038] [Loading machine operation] 6 is a diagram illustrating the operation of the wheel loader 1 according to the embodiment. The wheel loader 1 performs predetermined work on a work object at a work site. The work object includes an excavation object and a loading object. The predetermined work includes an excavation work and a loading work.

[0039] The excavation target is, for example, natural ground, rock pile, coal, feed, or a wall surface. The natural ground is a pile of earth and sand placed on the ground 200. The rock pile is a pile of rocks or stones placed on the ground 200. In the embodiment, the excavation target is the natural ground 210. The excavated object 300 is the natural ground 210 excavated and held by the bucket 13.

[0040] The loading target is, for example, a transport vehicle, a predetermined area at a work site, a hopper, a belt conveyor, or a crusher. In the embodiment, the loading target is a dump body 230 of a transport vehicle 220 that can travel on the ground 200. The transport vehicle 220 is, for example, a dump truck.

[0041] The wheel loader 1 performs excavation work to excavate the ground 210 with the bucket 13. The wheel loader 1 excavates the ground 210 with the bucket 13 while moving forward toward the ground 210. The wheel loader 1 performs loading work to load the excavated material 300 held in the bucket 13 by the excavation work into the dump body 230. The loading work is a concept that includes the discharge work of discharging the excavated material 300.

[0042] During excavation work, the wheel loader 1 moves forward toward the ground 210 without the bucket 13 holding the excavated object 300, as shown by arrow M1 in Figure 6. The wheel loader 1 performs excavation work by tilting the bucket 13 with the bucket 13 inserted into the ground 210. By tilting the bucket 13, the ground 210 is excavated by the bucket 13, and the excavated object 300 is held in the bucket 13.

[0043] Next, with the excavated object 300 held in the bucket 13, the wheel loader 1 moves backward so as to move away from the natural ground 210 as shown by the arrow M2 in FIG.

[0044] Next, the loading operation is carried out. In the loading operation, the wheel loader 1, with the excavated material 300 held in the bucket 13, moves forward while swinging towards the transport vehicle 220, as shown by arrow M3 in FIG. 6. While moving forward towards the transport vehicle 220, the wheel loader 1 performs a raising operation of the boom 12 so that the bucket 13 is positioned above the dump body 230. After the boom 12 has performed the raising operation and the bucket 13 has been positioned above the dump body 230, the wheel loader 1 performs a dumping operation of the bucket 13, thereby carrying out the loading operation. Due to the dumping operation of the bucket 13, the excavated material 300 held in the bucket 13 is discharged from the bucket 13 and loaded into the dump body 230.

[0045] After the excavated material 300 has been loaded into the dump body 230, the wheel loader 1, without the excavated material 300 held in the bucket 13, moves backward while turning away from the transport vehicle 220, as shown by arrow M4 in Figure 6.

[0046] The wheel loader 1 repeats the above-described operations until the dump body 230 of the transport vehicle 220 is fully loaded with the excavated material 300 or until excavation of the natural ground 210 is completed.

[0047] [Control System] Fig. 7 is a functional block diagram showing the control system 40 of the wheel loader 1 according to the embodiment. Fig. 8 is a block diagram showing the controller 50 of the wheel loader 1 according to the embodiment.

[0048] The wheel loader 1 includes a control system 40. The control system 40 includes a control valve 21, an operating device 22, an operator command device 23, a tilt sensor 31, a boom angle sensor 32, a bucket angle sensor 33, a weight sensor 34, a rotation speed sensor 35, a pump pressure sensor 37, a pump capacity sensor 38, and a controller 50.

[0049] The operating device 22 is disposed inside the cab 4. The operating device 22 is operated by an operator. The operating device 22 generates operation signals for operating each of the power source 3, the power transmission device 9, and the work implement 6. The controller 50 controls the power source 3 and the power transmission device 9 based on the operation signals generated by the operating device 22. The controller 50 controls the control valve 21 based on the operation signals generated by the operating device 22.

[0050] The operator command device 23 is disposed inside the cab 4. The operator command device 23 includes, for example, a switch button. The operator command device 23 is operated by an operator. The operator command device 23 generates a command signal for calculating the angle of repose θr, which will be described later. The controller 50 calculates the angle of repose θr based on the operation signal generated by the operator command device 23.

[0051] The inclination sensor 31 detects the inclination of the vehicle body 2. More specifically, the inclination sensor 31 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 31 is disposed on at least a part of the vehicle body 2. The inclination sensor 31 is, for example, an inertial measurement unit (IMU). Detection data of the vehicle body inclination angle θa detected by the inclination sensor 31 is transmitted to the controller 50.

[0052] The boom angle sensor 32 detects the angle of the boom 12. More specifically, the boom angle sensor 32 detects a boom angle θb that indicates the angle of the boom 12 relative to the vehicle body 2 in the local coordinate system. The boom angle sensor 32 is, for example, an angle sensor disposed at the connection between the vehicle body 2 and the boom 12. In this embodiment, the boom angle θb is the angle formed by a line connecting the pivot axis AXa and the pivot 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 32 is transmitted to the controller 50. The boom angle sensor 32 may be a stroke sensor that detects the stroke of the lift cylinder 18.

[0053] The bucket angle sensor 33 detects the angle of the bucket 13. More specifically, the bucket angle sensor 33 detects a bell crank angle θc that indicates the angle of the bell crank 14 relative to the boom 12 in a local coordinate system. The bucket angle sensor 33 is an angle sensor that is disposed, for example, at a connection between the boom 12 and the bell crank 14. In this embodiment, the bell crank angle θc is the angle formed between 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 33 is transmitted to the controller 50. The bucket angle sensor 33 may be a stroke sensor that detects the stroke of the bucket cylinder 19.

[0054] The weight sensor 34 detects the weight Wa of the excavated object 300, which is the object to be excavated and held in the bucket 13. The weight sensor 34 is, for example, a pressure sensor that detects the pressure of the hydraulic oil in the lift 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 excavated object 300 is held in the bucket 13 or not. The weight sensor 34 detects the change in the load on the work implement 6, thereby detecting the weight Wa of the excavated object 300 held in the bucket 13. The detection data of the weight Wa of the excavated object 300 detected by the weight sensor 34 is transmitted to the controller 50. The weight sensor 34 may be a load meter arranged in at least a part of the work implement 6. The weight sensor 34 may also directly detect the weight Wa of the excavated object 300.

[0055] The rotation speed sensor 35 detects the rotation speed of the power source 3 .

[0056] The pump pressure sensor 37 detects the discharge pressure indicating the pressure of the hydraulic oil discharged from the hydraulic pump 20 .

[0057] The pump displacement sensor 38 detects the displacement of the hydraulic pump 20 based on the swash plate angle of the hydraulic pump 20 .

[0058] The controller 50 includes a computer system. The controller 50 outputs control commands for controlling the wheel loader 1.

[0059] As shown in FIG. 8 , the controller 50 has a processor 51, a main memory 52, a storage 53, and an interface 54. The processor 51 executes a computer program to perform arithmetic processing for the operation of the work implement 6. Examples of the processor 51 include a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). The main memory 52 is, for example, a non-volatile memory or a volatile memory. The non-volatile memory is, for example, a ROM (Read Only Memory). The volatile memory is, for example, a RAM (Random Access Memory). The storage 53 is a non-transitory tangible storage medium. The storage 53 is, for example, a magnetic disk, a magneto-optical disk, or a semiconductor memory. The storage 53 may be an internal medium directly connected to the bus of the controller 50, or may be an external medium connected to the controller 50 via the interface 54 or a communication line. The storage 53 stores a computer program for controlling the work implement 6.

[0060] 7, controller 50 has a characteristics storage unit 61, a bucket data storage unit 62, a detection data acquisition unit 71, a bucket angle calculation unit 72, a tractive force calculation unit 73, a weight calculation unit 81, a front load angle determination unit 82, an angle of repose calculation unit 91, and a work machine control unit 100. Controller 50 communicates with each of control valve 21, operation device 22, operator command device 23, tilt sensor 31, boom angle sensor 32, bucket angle sensor 33, weight sensor 34, rotation speed sensor 35, pump pressure sensor 37, and pump capacity sensor 38.

[0061] <Characteristics memory section> The characteristic storage unit 61 stores characteristic data of the excavation target. The characteristic data of the excavation target includes a ground angle θg indicating the angle between the ground 200 and the surface of the ground 210, an angle of repose θr of the soil and sand that make up the ground 210, a density ρ of the ground 210, and an earth pressure coefficient K of the ground 210. The characteristic storage unit 61 also stores correlation data that indicates the relationship between the ground angle θg and the angle of repose θr.

[0062] <Bucket data storage unit> The bucket data storage unit 62 stores bucket data that indicates the shape or dimensions of the bucket 13. The bucket data includes the bucket length L, bucket width B, cutting edge side opening angle θ3, upper side opening angle θsp, and bucket cross-sectional area Abk. The bucket data is known data derived from specification data or design data.

[0063] <Detection data acquisition section> The detection data acquisition unit 71 acquires detection data from each of the inclination sensor 31, the boom angle sensor 32, the bucket angle sensor 33, the weight sensor 34, the rotation speed sensor 35, the pump pressure sensor 37, and the pump capacity sensor 38. The detection data acquisition unit 71 acquires the vehicle body inclination angle θa from the inclination sensor 31. The detection data acquisition unit 71 acquires the boom angle θb from the boom angle sensor 32. The detection data acquisition unit 71 acquires the bell crank angle θc from the bucket angle sensor 33. The detection data acquisition unit 71 acquires the weight Wa of the excavated object 300 from the weight sensor 34. The detection data acquisition unit 71 acquires the rotation speed of the power source 3 from the rotation speed sensor 35. The detection data acquisition unit 71 acquires the discharge pressure of the hydraulic pump 20 from the pump pressure sensor 37. The detection data acquisition unit 71 acquires the capacity of the hydraulic pump 20 from the pump capacity sensor 38.

[0064] <Bucket angle calculation section> The bucket angle calculation unit 72 calculates the bucket angle θbk, which indicates the angle of the bucket 13 with respect to the horizontal plane.

[0065] Bucket angle calculation unit 72 calculates bucket angle θbk based on detection data for the angle of the vehicle body 2 and detection data for the angle of the work implement 6. The detection data for the angle of the work implement 6 includes detection data for boom angle θb that indicates the angle of the boom 12 in the local coordinate system detected by boom angle sensor 32, and detection data for bell crank angle θc that indicates the angle of the bell crank 14 in the local coordinate system detected by bucket angle sensor 33. Bucket angle calculation unit 72 can calculate bucket angle θbk based on detection data for vehicle body tilt angle θa, detection data for boom angle θb, and detection data for bell crank angle θc.

[0066] <Traction force calculation section> The tractive force calculation unit 73 calculates the tractive force F of the wheel loader 1 based on the detection data acquired by the detection data acquisition unit 71. The tractive force calculation unit 73 calculates the tractive force F during excavation work in which the bucket 13 excavates the natural ground 210.

[0067] For example, if the power transmission device 9 has a continuously variable transmission, the tractive force calculation unit 73 calculates the tractive force F in the following procedure. The tractive force calculation unit 73 calculates the output torque of the power source 3 using the detection data of the rotation speed sensor 35. The tractive force calculation unit 73 also calculates the load torque of the hydraulic pump 20 based on the detection data of the pump pressure sensor 37 and the detection data of the pump displacement sensor 38. The tractive force calculation unit 73 multiplies the traveling torque obtained by subtracting the load torque from the output torque by the reduction ratio and torque efficiency of the power transmission device 9, and divides this by the effective diameter of the wheel to calculate the tractive force F.

[0068] For example, if the power transmission device 9 has a torque converter, the tractive force calculation unit 73 calculates the tractive force F in the following procedure. The tractive force calculation unit 73 calculates the traveling torque by multiplying the square of the value obtained by dividing the rotation speed of the power source 3 by 1000 rpm by the primary torque coefficient and torque ratio of the torque converter. The primary torque coefficient and torque ratio are characteristic values ​​determined by the input / output rotation ratio of the torque converter. The tractive force calculation unit 73 calculates the tractive force F by multiplying the traveling torque by the reduction ratio and torque efficiency of the power transmission device 9 and dividing this by the effective diameter of the wheels 5.

[0069] <Weight calculation section> The weight calculation unit 81 calculates the weight Wa of the excavation object 300 that is the excavation target held in the bucket 13. When the inside of the bucket 13 is filled with the excavation object 300, the weight calculation unit 81 calculates the weight Wa based on the first calculation method. When a portion of the inside of the bucket 13 is filled with the excavation object 300 and a void portion 340 is formed in a portion of the inside of the bucket 13, the weight calculation unit 81 calculates the weight Wa based on the second calculation method.

[0070] Fig. 9 is a diagram illustrating the state of the excavated object 300 held in the bucket 13 according to the embodiment. Fig. 9 shows a state in which the inside of the bucket 13 is filled with the excavated object 300, and a part of the excavated object 300 is positioned outside the bucket 13 relative to the opening 136. In the following description, the excavated object 300 positioned outside the bucket 13 relative to the opening 136 will be referred to as an exposed portion 330 of the excavated object 300, as appropriate.

[0071] The surface of the excavated object 300 includes a first surface 310 and a second surface 320. The second surface 320 is located forward of the first surface 310. The first surface 310 slopes upward toward the front. The second surface 320 slopes downward toward the front. The rear end of the first surface 310 is connected to the spill guard end 13B. The front end of the second surface 320 is connected to the cutting edge 13A. The rear end of the second surface 320 is connected to the front end of the first surface 310. In a cross section perpendicular to the pivot axis AXb, the first surface 310, the second surface 320, and the right end 13C (left end 13D) substantially form a triangle.

[0072] In the embodiment, the angle of the first surface 310 with respect to the horizontal plane is appropriately referred to as the front load angle θ1, and the angle of the second surface 320 with respect to the horizontal plane is appropriately referred to as the cutting edge load angle θ2.

[0073] The near side load angle θ1 changes based on the bucket angle θbk during excavation. As the bucket angle θbk increases, the near side load angle θ1 increases. As the bucket angle θbk decreases, the near side load angle θ1 decreases.

[0074] The cutting edge side load angle θ2 indicates the angle of repose θr (stop angle of repose) of the excavated material 300. Even if the bucket angle θbk during excavation changes, the cutting edge side load angle θ2 does not substantially change because it is formed when the bucket 13 is removed after excavation. The cutting edge side load angle θ2 is uniquely determined based on the properties of the excavated material 300 (natural ground 210). If the properties of the excavated material 300 are constant, the cutting edge side load angle θ2 does not substantially change even if the bucket angle θbk during excavation changes.

[0075] 9, the weight calculation unit 81 calculates the weight Wa of the excavated object 300 based on the first calculation method. The weight calculation unit 81 calculates the weight Wa of the excavated object 300 held in the bucket 13 based on the front load angle θ1, the cutting edge load angle θ2, the bucket angle θbk, the density ρ of the excavated object 300, and the bucket data.

[0076] FIG. 10 is a schematic diagram illustrating a method for calculating the weight Wa of the excavated object 300 based on the first calculation method according to the embodiment.

[0077] As shown in FIG. 10, an exposed portion cross-sectional area A1, which indicates the cross-sectional area of ​​the exposed portion 330 perpendicular to the rotation axis AXb, is calculated based on the following formula (1).

[0078]

number

[0079] The bucket cross-sectional area Abk, which indicates the cross-sectional area of ​​the bucket 13 perpendicular to the rotation axis AXb, is stored in the bucket data storage unit 62. The load cross-sectional area Aa, which indicates the cross-sectional area of ​​the excavated object 300 perpendicular to the rotation axis AXb, is calculated based on the following equation (2).

[0080]

number

[0081] The volume Va of the excavated object 300 is calculated based on the following formula (3).

[0082]

number

[0083] The density ρ of the excavated material 300 is stored in the characteristic storage unit 61. The weight Wa of the excavated material 300 in the state shown in FIG.

[0084]

number

[0085] Fig. 11 is a diagram illustrating the state of the excavated object 300 held in the bucket 13 according to the embodiment. Fig. 11 shows a state in which part of the inside of the bucket 13 is filled with the excavated object 300, and a void 340 is formed in part of the inside of the bucket 13.

[0086] 11, the weight calculation unit 81 calculates the weight Wa of the excavated object 300 based on the second calculation method. The weight calculation unit 81 calculates the weight Wa of the excavated object 300 held in the bucket 13 based on the tractive force F, the bucket angle θbk, the density ρ of the excavated object 300, and the bucket data.

[0087] 12 is a diagram showing the relationship between traction force F and earth pressure P according to the embodiment. The amount of insertion of bucket 13 into natural ground 210 is determined based on traction force F. Bucket 13 is also subjected to earth pressure P, which indicates the excavation resistance from natural ground 210. If the height of the excavation target taken from cutting edge 13A inside bucket 13 during excavation work is defined as load height H, the relationship between earth pressure P and load height H is expressed by the following equation (5), which is called Coulomb's earth pressure equation. In equation (5), K is the earth pressure coefficient.

[0088]

number

[0089] The state in which the wheel loader 1 cannot move forward and stops when the bucket 13 is inserted into the natural ground 210 is a state in which the tractive force F and the earth pressure P are balanced. When the tractive force F and the earth pressure P are balanced, the following equation (6) holds true.

[0090]

number

[0091] The weight calculation unit 81 calculates the cargo height H based on the tractive force F. As shown in the following equation (7), the cargo height H is calculated based on the tractive force F, density ρ, and earth pressure coefficient K.

[0092]

number

[0093] The tractive force F is calculated by the tractive force calculation unit 73. The density ρ and the earth pressure coefficient K are stored in the characteristic storage unit 61. Therefore, the weight calculation unit 81 can calculate the cargo height H based on the tractive force F, the density ρ, and the earth pressure coefficient K.

[0094] In the following description, the boundary between the inner surface of the bucket 13 and the upper end of the excavated object 300 is defined as the load contact point 13E, and the distance in the horizontal direction (front-to-back direction) between the load contact point 13E and the cutting edge 13A is defined as the load depth x. The load depth x can be calculated based on the load height H, the bucket angle θbk, and the bucket data.

[0095] The weight calculation unit 81 calculates the weight Wa of the excavated object 300 based on the load height H calculated based on the tractive force F and the earth pressure coefficient K, the bucket angle θbk, and the bucket data.

[0096] FIG. 13 is a schematic diagram illustrating a method for calculating the weight Wa of the excavated object 300 based on the second calculation method according to the embodiment.

[0097] As shown in Figure 13, a gap cross-sectional area A2 and a cargo-shaped cross-sectional area A3 are defined. If the gap space is defined between a first plane connecting the load contact point 13E and the cutting edge 13A and perpendicular to the YZ plane, and a second plane defined by the opening 136, the gap cross-sectional area A2 indicates the cross-sectional area of ​​the gap space perpendicular to the rotation axis AXb. If the excavated object 300 existing between the first plane and the second plane is defined as the cargo-shaped space, the cargo-shaped cross-sectional area A3 indicates the cross-sectional area of ​​the cargo-shaped space perpendicular to the rotation axis AXb.

[0098] The gap cross-sectional area A2 is calculated based on the following equation (8): As shown in equation (8), the weight calculation unit 81 calculates the gap cross-sectional area A2 based on the cargo height H, the bucket angle θbk, and the bucket data.

[0099]

number

[0100] The cargo shape cross-sectional area A3 is calculated based on the following equation (9): As shown in equation (9), the weight calculation unit 81 calculates the cargo shape cross-sectional area A3 based on the cargo height H, the front side cargo angle θ1, and the cutting edge side cargo angle θ2.

[0101]

number

[0102] The cargo cross-sectional area Aa is calculated based on the following equation (10).

[0103]

number

[0104] By calculating the cargo cross-sectional area Aa, the weight calculation unit 81 can calculate the weight Wa based on the equations (3) and (4).

[0105] <Front load angle determination section> The near side load angle determination unit 82 determines the near side load angle θ1 to a predetermined angle based on the bucket angle increment Δθbk, which indicates the increase in the bucket angle θbk after the start of excavation work. The predetermined angle includes at least one of the ground angle θg, the sum of the ground angle θg and the bucket angle increment Δθbk, and the angle of repose θr.

[0106] FIG. 14 is a diagram illustrating the angle of repose θr and the ground angle θg according to the embodiment.

[0107] The angle of repose θr is the angle of the slope of the soil relative to the horizontal plane when the soil remains stable without collapsing when piled up. The angle of repose θr is a physical property that is uniquely determined based on the properties of the soil. When bucket 13 inserted into natural ground 210 is removed from natural ground 210, cutting edge side load angle θ2 becomes equal to the angle of repose θr.

[0108] The ground angle θg is the angle between the ground 200 and the surface of the ground 210 made up of soil and sand placed on the ground 200. The ground angle θg is generally equal to the angle of repose θr, but may vary based on the formation conditions of the ground 210. The formation conditions of the ground 210 include the fall height and the amount of soil and sand when soil and sand are dropped onto the ground 200 to form the ground 210.

[0109] In other words, the angle of repose θr is the inclination angle of the surface of the soil and sand generated by gently dropping the soil and sand onto a horizontal surface, whereas the ground angle θg is the inclination angle of the surface of the ground 210, which may change based on the impact the soil and sand receive when dropped onto a horizontal surface and the volume of the ground 210.

[0110] Figure 15 is a diagram showing the relationship between the ground angle θg and the angle of repose θr according to the embodiment. In Figure 15, the horizontal axis represents the angle of repose θr, and the vertical axis represents the ground angle θg. For example, in the case of soil with a small angle of repose θr, the angle of repose θr of the soil and the ground angle θg of the ground 210 made up of that soil are approximately equal. On the other hand, in the case of soil with a large angle of repose θr, the ground angle θg of the ground 210 made up of that soil is likely to be smaller than the angle of repose θr of the soil.

[0111] 15, correlation data indicating the relationship between the ground angle θg and the angle of repose θr is stored in the characteristic storage unit 61. The front load angle determination unit 82 can calculate the ground angle θg based on, for example, the angle of repose θr and the correlation data.

[0112] The ground angle θg may be actually measured and stored in the characteristic storage unit 61.

[0113] FIG. 16 is a diagram showing the relationship between the bucket 13 and the excavation object 300 during excavation work according to this embodiment.

[0114] Times T1, T2, T3, and T4 shown in Figure 16 indicate the respective times after the start of excavation work. Time T1 is the time immediately after the start of excavation work. Time T2 is a time later than time T1. Time T3 is a time later than time T2. Time T4 is a time later than time T3.

[0115] As shown in Figure 16, the bucket angle θbk gradually increases during excavation work. At the start of excavation work, the bucket angle θbk is, for example, 0 degrees. The start of excavation work is the point at which the blade tip 13A of the bucket 13 is inserted into the natural ground 210. The wheel loader 1 inserts the bucket 13 into the natural ground 210 while moving forward, and excavates the natural ground 210 with the bucket 13. The wheel loader 1 tilts the bucket 13 with the bucket 13 inserted into the natural ground 210. As the bucket 13 tilts, the bucket angle θbk gradually increases.

[0116] Time point T1 is the time immediately after bucket 13 is inserted into natural ground 210. At time point T1, bucket angle θbk is small, and a gap 340 is formed inside bucket 13. Load height H at time point T1 is first load height H1.

[0117] The bucket angle θbk at time T2 is greater than the bucket angle θbk at time T1. The bucket angle θbk increases while the load height H is maintained at the first load height H1. As the bucket angle θbk increases, the load contact point 13E approaches the spill guard end 13B of the bucket 13.

[0118] The bucket angle θbk at time T3 is greater than the bucket angle θbk at time T2. The bucket angle θbk increases while the load height H is maintained at the first load height H1. As the bucket angle θbk increases, the load contact point 13E reaches the spill guard end 13B of the bucket 13. That is, at time T3, the height of the spill guard end 13B, relative to the cutting edge 13A, matches the load height H. The inside of the bucket 13 is filled with the excavated material 300.

[0119] The bucket angle θbk at time T4 is greater than the bucket angle θbk at time T3. After the height of the spill guard end 13B and the cargo height H coincide, as the bucket angle θbk increases further, the cargo height H gradually decreases. At time T4, the cargo height H becomes a second cargo height H2 that is smaller than the first cargo height H1.

[0120] 17 is a diagram showing the relationship between the bucket angle θbk and the front load angle θ1 according to the embodiment. As shown in FIG. 17, the front load angle θ1 changes based on the bucket angle θbk.

[0121] At the time points before the load contact point 13E reaches the spill guard end 13B (for example, at time points T1 and T2), the near side load angle θ1 is the ground angle θg.

[0122] Even at time T3 when the load contact point 13E reaches the spill guard end 13B and the height of the spill guard end 13B coincides with the load height H, the near side load angle θ1 is the ground angle θg.

[0123] After the point T3 when the load contact point 13E reaches the spill guard end 13B and the height of the spill guard end 13B matches the load height H, the near side load angle θ1 becomes greater than the ground angle θg based on the bucket angle increase Δθbk from the point when it was determined that the load height H was higher than the height of the spill guard end 13B.

[0124] For example, between time T3 and time T4, the near side load angle θ1 is the sum of the ground angle θg and the bucket angle increment Δθbk. For example, after time T4, the near side load angle θ1 is the angle of repose θr.

[0125] In this way, the front load angle θ1 changes based on the bucket angle increment Δθbk, which indicates the increase in the bucket angle θbk from the point in time when it was determined that the load height H was higher than the height of the spill guard end 13B. The front load angle determiner 82 determines the front load angle θ1 to a predetermined angle based on the bucket angle increment Δθbk.

[0126] The front load angle determination unit 82 determines the front load angle θ1 based on the difference between the height of the spill guard end 13B and the load height H, which changes based on the bucket angle θbk.

[0127] The front load angle determination unit 82 determines whether the load height H is higher than the height of the spill guard end 13B. The front load angle determination unit 82 determines the front load angle θ1 to be the ground angle θg until it determines that the load height H is higher than the height of the spill guard end 13B. In other words, if the front load angle determination unit 82 determines that the height of the spill guard end 13B is higher than the load height H, it determines the front load angle θ1 to be the ground angle θg. In other words, if the bucket angle θbk is in a state before time T3, the front load angle determination unit 82 determines the front load angle θ1 to be the ground angle θg.

[0128] After determining that the cargo height H is higher than the height of the spill guard end 13B, the front cargo angle determination unit 82 determines the front cargo angle θ1 to be an angle greater than the ground angle θg based on the bucket angle increment Δθbk.

[0129] If the sum of the ground angle θg and the bucket angle increment Δθbk is smaller than the angle of repose θr of the soil, the front load angle determination unit 82 determines the front load angle θ1 to be the sum of the ground angle θg and the bucket angle increment Δθbk. For example, if the bucket angle θbk is in a state between time T3 and time T4, the front load angle determination unit 82 determines the front load angle θ1 to be the sum of the ground angle θg and the bucket angle increment Δθbk.

[0130] If the sum of the ground angle θg and the bucket angle increment Δθbk is greater than the angle of repose θr of the soil and sand, the front load angle determination unit 82 determines the front load angle θ1 to be the angle of repose θr. In other words, if the bucket angle θbk is in a state after time T4, the front load angle determination unit 82 determines the front load angle θ1 to be the angle of repose θr.

[0131] <Angle of repose calculation section> The repose angle calculation unit 91 calculates the repose angle θr of the earth and sand based on the excavated object 300 held by the bucket 13. The repose angle θr calculated by the repose angle calculation unit 91 is stored in the characteristic storage unit 61.

[0132] The angle of repose θr is a physical property value of the soil that is determined based on the properties of the soil. For example, if the properties of the soil change due to weather or the like, the angle of repose θr may change. For example, the angle of repose θr may be different on sunny days and on rainy days. The angle of repose calculation unit 91 calculates the angle of repose θr and stores it in the characteristic storage unit 61.

[0133] The angle of repose calculation unit 91 calculates the angle of repose θr based on the bucket data stored in the bucket data memory unit 62, the bucket angle θbk calculated by the bucket angle calculation unit 72, the weight Wa of the excavated material 300 detected by the weight sensor 34, and the density ρ of the excavated material 300 stored in the characteristic memory unit 61.

[0134] FIG. 18 is a diagram illustrating the angle of repose θr of the excavated material 300 held in the bucket 13 according to the embodiment. As shown in FIG. 18 , when the bucket 13 is fully loaded with the excavated material 300 and the bucket 13 is dumped to tilt the opening 136 of the bucket 13 forward, gravity causes a portion of the excavated material 300 to be discharged from the bucket 13. When a portion of the excavated material 300 is discharged from the bucket 13, the surface of the excavated material 300 forms an incline with the cutting edge 13A as the base point, as shown in FIG. 18 . The angle of repose θr is the angle with respect to the horizontal plane of the incline formed by the surface of the excavated material 300 exposed at the opening 136 of the bucket 13 and with the cutting edge 13A as the base point ...

[0135] A method for calculating the angle of repose θr will be described in detail. After the bucket 13 is fully filled with the excavated material 300, a portion of the excavated material 300 held in the bucket 13 is discharged, as shown in Fig. 18. When a portion of the excavated material 300 held in the bucket 13 is discharged, the surface of the excavated material 300 maintains an inclination that prevents it from sliding off; in other words, the inclination of the surface of the excavated material 300 held in the bucket 13 in the YZ plane is maintained at the angle of repose θr. The unfilled portion cross-sectional area A4 of the unfilled portion 350 of the bucket 13 in this state is calculated based on the following equation (11) using the bucket length L, cutting edge side opening angle θ3, and upper side opening angle θsp when the bucket 13 is horizontal (hereinafter referred to as "when the bucket is horizontal") stored in the bucket data storage unit 62.

[0136]

number

[0137] The load cross-sectional area Aa in this state is calculated from the bucket cross-sectional area Abk stored in the bucket data storage unit 62 and the unfilled portion cross-sectional area A4 of the unfilled portion 350 of the bucket 13 based on the following equation (12).

[0138]

number

[0139] The volume Va of the excavated object 300 is calculated based on the formula (3), and the weight Wa of the excavated object 300 is calculated based on the formula (4).

[0140] Furthermore, the following equation (13) is established based on equations (11), (3), (4), and (12): The angle of repose calculation unit 91 calculates the angle of repose θr based on equation (13).

[0141]

number

[0142] <Work machine control unit> The work implement control unit 100 controls the attitude of the work implement 6 so that the weight Wa calculated by the weight calculation unit 81 becomes the target weight Wr. The attitude of the work implement 6 includes the bucket angle θbk, which indicates the angle of the bucket 13 with respect to the horizontal plane. When the bucket angle θbk changes, the front load angle θ1 changes. The work implement control unit 100 controls at least one of the lift cylinder 18 and the bucket cylinder 19 to adjust the bucket angle θbk during excavation work. By adjusting the bucket angle θbk, the front load angle θ1 is adjusted. By adjusting the front load angle θ1, the weight Wa of the excavated object 300 is adjusted. The work implement control unit 100 controls the bucket angle θbk, which indicates the attitude of the bucket 13, so that the weight Wa calculated by the weight calculation unit 81 becomes the target weight Wr.

[0143] The work implement control unit 100 removes the bucket 13 from the natural ground 210 while maintaining the front load angle θ1 and bucket angle θbk that were set when the weight Wa reached the target weight Wr. This reduces the difference between the weight Wa of the excavated object 300 held in the bucket 13 and the target weight Wr.

[0144] [How to calculate the angle of repose] 19 is a flowchart showing a method for calculating the angle of repose θr according to the embodiment. Before the first excavation work of the natural ground 210, the operator causes the controller 50 to start the calculation process of the angle of repose θr.

[0145] The operator excavates the natural ground 210 with the bucket 13 and holds the excavated material 300 (step SA1). More specifically, the operator excavates the natural ground 210 so that the inside of the bucket 13 is filled with the excavated material 300, as shown in FIG. 9, for example, and then tilts the bucket 13 so that the excavated material 300 is held inside the bucket 13.

[0146] Next, the operator discharges a portion of the excavated material 300 from the bucket 13 (step SA2). More specifically, the operator performs a dumping operation on the bucket 13 from a state in which the bucket 13 is fully loaded with the excavated material 300 to an extent that the excavated material 300 is not completely discharged from the bucket 13. For example, the operator performs a dumping operation between the tilt operation position of step SA1 and an angle in which the bucket angle θbk is greater than 0 degrees. When a portion of the excavated material 300 is discharged from the bucket 13, as shown in FIG. 18, the surface of the excavated material 300 held in the bucket 13 maintains an inclination that keeps it in a predetermined position without slipping, with the cutting edge 13A as the base point. The angle of the surface of the excavated material 300 in the bucket 13 maintains the angle of repose θr.

[0147] Next, in the state of step SA2, the operator transmits a command to the controller 50 to start the calculation process of the angle of repose θr (step SA3). More specifically, the operator operates the operator command device 23, which causes the operator command device 23 to output an operation command signal to the controller 50 to start the calculation process of the angle of repose θr.

[0148] The detection data acquisition unit 71 acquires the vehicle body inclination angle θa, boom angle θb, bell crank angle θc, and weight Wa of the excavated object 300 when the surface of the excavated object 300 held by the bucket 13 maintains the angle of repose θr in the YZ plane (step SA4).

[0149] The bucket angle calculation unit 72 calculates the bucket angle θbk based on the vehicle body tilt angle θa, the boom angle θb, and the bell crank angle θc acquired by the detection data acquisition unit 71 (step SA5).

[0150] The angle of repose calculation unit 91 calculates the angle of repose θr based on the detection data of the angle of the vehicle body 2, the bucket data stored in the bucket data memory unit 62, the weight Wa of the excavated material 300 obtained in step SA4, and the bucket angle θbk calculated in step SA5 (step SA6).

[0151] The characteristic storage unit 61 stores the angle of repose θr calculated by the angle of repose calculation unit 91 (step SA7).

[0152] [Drilling method] FIG. 20 is a flowchart showing an excavation method according to an embodiment.

[0153] When excavation work is started and at least a portion of bucket 13 is inserted into natural ground 210, work implement control section 100 tilts bucket 13 (step SC1). As bucket 13 tilts, bucket angle θbk changes.

[0154] The tractive force calculation unit 73 calculates the tractive force F during excavation work (step SC2).

[0155] The weight calculation unit 81 acquires the density ρ from the characteristic storage unit 61 (step SC3).

[0156] The weight calculation unit 81 acquires the earth pressure coefficient K from the characteristic storage unit 61 (step SC4).

[0157] The weight calculation unit 81 calculates the cargo height H based on equation (7) (step SC5).

[0158] The front cargo angle determination unit 82 determines whether the cargo height H is higher than the height of the spill guard end 13B (step SC6).

[0159] In step SC6, if it is determined that the cargo height H is higher than the height of the spill guard end 13B (step SC6: Yes), the front cargo angle determination unit 82 obtains the angle of repose θr from the characteristic memory unit 61 (step SC7).

[0160] The front load angle determination unit 82 stores the bucket angle θbk (θbka) at the time of step SC6. The front load angle determination unit 82 acquires the bucket angle θbk (θbkb) calculated by the bucket angle calculation unit 72 during excavation work. The front load angle determination unit 82 counts the bucket angle increment Δθbk, which indicates the difference between the bucket angle θbkb and the bucket angle θbka (step SC8).

[0161] The front load angle determination unit 82 acquires the ground angle θg from the characteristics storage unit 61 (step SC9).

[0162] The front load angle determination unit 82 determines whether the sum of the ground angle θg and the bucket angle increment Δθbk is smaller than the angle of repose θr (step SC10).

[0163] In step SC10, if it is determined that the sum of the ground angle θg and the bucket angle increment Δθbk is smaller than the angle of repose θr (step SC10: Yes), the front load angle determination unit 82 determines the front load angle θ1 to be the sum of the ground angle θg and the bucket angle increment Δθbk (step SC11).

[0164] In step SC10, if it is determined that the sum of the ground angle θg and the bucket angle increment Δθbk is greater than or equal to the angle of repose θr (step SC10: No), the front load angle determination unit 82 determines the front load angle θ1 to be the angle of repose θr (step SC12).

[0165] In step SC6, if it is determined that the cargo height H is less than or equal to the spill guard end 13B (step SC6: No), the front cargo angle determination unit 82 obtains the ground angle θg from the characteristic memory unit 61 and then determines the front cargo angle θ1 to be the ground angle θg (step SC13).

[0166] The weight calculation unit 81 acquires the bucket angle θbk calculated by the bucket angle calculation unit 72 during excavation work (step SC14).

[0167] The weight calculation unit 81 acquires the bucket length L, the upper side opening angle θsp, and the cutting edge side opening angle θ3 as bucket data from the bucket data storage unit 62 (step SC15).

[0168] The weight calculation unit 81 calculates the cargo depth x based on the cargo height H calculated in step SC5, the bucket angle θbk acquired in step SC14, and the bucket data acquired in step SC15 (step SC16).

[0169] The weight calculation unit 81 calculates the gap cross-sectional area A2 based on the formula (8) (step SC17).

[0170] The weight calculation unit 81 acquires the angle of repose θr from the characteristic storage unit 61. The weight calculation unit 81 determines the cutting edge side load angle θ2 as the angle of repose θr. The weight calculation unit 81 also acquires the front side load angle θ1 determined by the front side load angle determination unit 82 based on the processing from step SC6 to step SC13 (step SC18).

[0171] The weight calculation unit 81 calculates the cargo shape cross-sectional area A3 based on equation (9) (step SC19).

[0172] The weight calculation unit 81 calculates the cargo cross-sectional area Aa based on equation (10) (step SC20).

[0173] The weight calculation unit 81 acquires the bucket width B as bucket data from the bucket data storage unit 62 (step SC21).

[0174] The weight calculation unit 81 acquires the density ρ from the characteristic storage unit 61 (step SC22).

[0175] The weight calculation unit 81 calculates the weight Wa based on the cargo cross-sectional area Aa calculated in step SC20, the bucket width B acquired in step SC21, and the density ρ acquired in step SC22. That is, after calculating the cargo cross-sectional area Aa in step SC20, the weight calculation unit 81 calculates the weight Wa based on equations (3) and (4) (step SC23).

[0176] The work machine control section 100 determines whether the difference between the weight Wa calculated in step SC23 and the target weight Wr is equal to or less than a predetermined threshold value (step SC24).

[0177] In step SC24, if it is determined that the difference between weight Wa and target weight Wr is equal to or less than the threshold value, that is, if it is determined that weight Wa and target weight Wr match or are close to each other (step SC24: Yes), work implement control unit 100 removes bucket 13 from the ground 210 while maintaining bucket angle θbk that was set when it was determined that the difference between weight Wa and target weight Wr was equal to or less than the threshold value (step SC25). After bucket 13 is removed from ground 210, the operator loads excavated material 300 held in bucket 13 into dump body 230.

[0178] In step SC24, if it is determined that the difference between the weight Wa and the target weight Wr is not less than the threshold value, that is, if it is determined that the weight Wa and the target weight Wr are different (step SC24: No), the work machine control unit 100 continues the tilt operation of the bucket 13 (step SC1).

[0179] [effect] As described above, in the embodiment, the weight calculation unit 81 can calculate the weight Wa of the excavated object 300 held in the bucket 13 based on the tractive force F, the bucket angle θbk, and the bucket data. The weight calculation unit 81 can determine the weight Wa of the excavated object 300 that will be held in the bucket 13 after the excavation operation during the excavation operation. By determining the weight Wa of the excavated object 300 during the excavation operation, the work implement control unit 100 can control the work implement 6 during the excavation operation so as to reduce the difference between the weight Wa and the target weight Wr. As a result, the weight Wa of the excavated object 300 relative to the transport vehicle 220 is automatically adjusted, and the excavated object 300 is loaded onto the transport vehicle 220 at the target load amount. Therefore, the loading operation by the wheel loader 1 is optimized.

[0180] The front load angle determination unit 82 determines the front load angle θ1 to a predetermined angle based on the bucket angle θbk. This allows the front load angle θ1 to be appropriately determined without detecting the front load angle θ1 with an optical sensor, for example. The weight calculation unit 81 can accurately calculate the weight Wa based on the front load angle θ1 determined by the front load angle determination unit 82.

[0181] [Other embodiments] In the above-described embodiment, the weight Wa of the excavated object 300 is measured by the weight sensor 34 provided on the wheel loader 1. The weight Wa of the excavated object 300 may be detected by a weight sensor provided on the transport vehicle 220. The load on the transport vehicle 220 changes when the excavated object 300 is loaded onto the dump body 230 by the bucket 13. The weight sensor provided on the transport vehicle 220 detects a first load applied to the transport vehicle 220 before the excavated object 300 is loaded onto the dump body 230, and a second load applied to the transport vehicle 220 after the excavated object 300 is loaded onto the dump body 230. Detection data from the weight sensor provided on the transport vehicle 220 is transmitted to the controller 50 of the wheel loader 1. The weight Wa of the excavated object 300 held in the bucket 13 corresponds to the difference between the first load and the second load.

[0182] In the above-described embodiment, the angle of repose θr is calculated based on the excavated object 300 held by the bucket 13. However, the angle of repose θr may also be calculated based on the excavated object 300 not held by the bucket 13. For example, the angle of repose θr may be calculated in a testing facility or an evaluation facility. Furthermore, if the angle of repose θr is known, the process of calculating the angle of repose θr may be omitted. It is only necessary that the angle of repose θr be stored in the characteristic storage unit 61 before the excavation work.

[0183] In the above-described embodiment, the loading machine 1 has been described as being operated by an operator, but this is not limiting. The loading machine 1 may be operated by a remote system. In this case, for example, a device having the functions of the controller 50 and a remote operation device is provided at a remote operation location.

[0184] 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. [Explanation of symbols]

[0185] 1...Wheel loader (loading machine), 2...Vehicle body, 3...Power source, 4...Cab, 5...Wheels, 5F...Front wheels, 5R...Rear wheels, 6...Work equipment, 8...Power take-off, 9...Power transmission device, 12...Boom, 13...Bucket, 13A...Cutter tip, 13B...Spill guard end, 13C...Right end, 13D...Left end, 13E...Load contact point, 14...Bell crank, 15...Bucket link, 16...Bracket, 17...Bracket, 18...Lift cylinder, 19...Bucket cylinder, 20...Hydraulic pump, 21...Control valve, 22...Operating device, 23...Operator command device, 31...Tilt sensor sensor, 32...boom angle sensor, 33...bucket angle sensor, 34...weight sensor, 35...rotation speed sensor, 37...pump pressure sensor, 38...pump capacity sensor, 40...control system, 50...controller, 51...processor, 52...main memory, 53...storage, 54...interface, 61...characteristics storage unit, 62...bucket data storage unit, 71...detection data acquisition unit, 72...bucket angle calculation unit, 73...traction force calculation unit, 81...weight calculation unit, 82...front load angle determination unit, 91...angle of repose calculation unit, 100...work implement control unit, 131...bottom plate unit, 132...back plate unit, 133...upper plate portion, 134...right plate portion, 135...left plate portion, 136...opening, 200...ground, 210...natural ground (excavation target), 220...transport vehicle, 230...dump body (loading target), 300...excavated material, 310...first surface, 320...second surface, 330...exposed portion, 340...void portion, 350...unfilled portion, A1...exposed portion cross-sectional area, A2...void portion cross-sectional area, A3...load shape portion cross-sectional area, A4...unfilled portion cross-sectional area, Aa...load cross-sectional area, Abk...bucket cross-sectional area, AXa...rotating axis, AXb...rotating axis, AXc...rotating axis, AXd...rotating axis, AXe...rotating axis, AXf...rotating axis, B... Bucket width, CXf...rotation axis, CXr...rotation axis, F...traction force, H...load height, K...earth pressure coefficient, L...bucket length, M1...arrow, M2...arrow, M3...arrow, M4...arrow, P...earth pressure, T1...point in time, T2...point in time, T3...point in time, T4...point in time, Va...volume, Wa...weight, Wr...target weight, x...load depth, θ1...front load angle, θ2...load angle at cutting edge, θ3...opening angle at cutting edge, θa...body tilt angle, θb...boom angle, θbk...bucket angle, θc...bell crank angle, θg...ground angle, θr...angle of repose, θsp...upper opening angle, ρ...density, Δθbk...bucket angle increase.

Claims

1. A control system for controlling a loading machine equipped with a work implement having a bucket, Equipped with a controller, The loading machine excavates a pile of earth and sand placed on the ground with the bucket while moving forward, a surface of the excavated material, which is the natural ground excavated and held by the bucket, includes a first surface sloping upward toward the front, and a second surface connected to a front end of the first surface and sloping downward toward the front, The bucket includes a cutting edge and a spill guard end opposite the cutting edge, The controller acquiring a bucket angle indicating an angle of the bucket relative to a horizontal plane during excavation work; determining a first front loading angle indicating the angle of the first surface with respect to a horizontal plane based on the bucket angle after the excavation operation is started to a predetermined angle including a ground angle indicating the angle between the ground and the surface of the ground; obtaining a cutting edge load angle indicating the angle of the second surface relative to a horizontal plane; calculating a tractive force of the loading machine during an excavation operation in which the bucket is used to excavate an excavation target; Calculating a weight of the excavated material held in the bucket based on the first front load angle, the cutting edge load angle, the bucket angle, the density of the excavated material, and bucket data indicating dimensions of the bucket; Calculating a load height indicating a height of the excavation target inside the bucket based on the tractive force; determining a second nearside load angle based on a difference between the height of the spill guard end and the load height, the difference varying based on the bucket angle; After determining that the cargo height is higher than the height of the spill guard end, the second front cargo angle is determined to be greater than the ground angle based on the bucket angle increase from the time when it was determined that the cargo height was higher than the height of the spill guard end. Control system.

2. A control system for controlling a loading machine equipped with a work implement having a bucket, Equipped with a controller, The loading machine excavates a pile of earth and sand placed on the ground with the bucket while moving forward, a surface of the excavated material, which is the natural ground excavated and held by the bucket, includes a first surface sloping upward toward the front, and a second surface connected to a front end of the first surface and sloping downward toward the front, The bucket includes a cutting edge and a spill guard end opposite the cutting edge, The controller acquiring a bucket angle indicating an angle of the bucket relative to a horizontal plane during excavation work; determining a first front loading angle indicating the angle of the first surface with respect to a horizontal plane based on the bucket angle after the excavation operation is started to a predetermined angle including a ground angle indicating the angle between the ground and the surface of the ground; obtaining a cutting edge load angle indicating the angle of the second surface relative to a horizontal plane; calculating a tractive force of the loading machine during an excavation operation in which the bucket is used to excavate an excavation target; Calculating a weight of the excavated material held in the bucket based on the first front load angle, the cutting edge load angle, the bucket angle, the density of the excavated material, and bucket data indicating dimensions of the bucket; If the sum of the ground angle and the bucket angle increment is smaller than the angle of repose of the soil, a second front loading angle is determined to be the sum of the ground angle and the bucket angle increment; When the sum of the ground angle and the bucket angle increase amount is greater than the angle of repose of the soil and sand, the second front loading angle is determined to be the angle of repose. Control system.

3. The controller Determining whether the cargo height is higher than the height of the spill guard end; The second front load angle is determined to be the ground angle until it is determined that the load height is higher than the height of the spill guard end. The control system of claim 1 .

4. The controller storing the earth pressure coefficient of the ground; Calculating the cargo height based on the traction force and the earth pressure coefficient. The control system of claim 1 .

5. The controller storing the angle of repose of the soil and sand; The cutting edge load angle includes the angle of repose. The control system of claim 4.

6. The controller controlling the attitude of the work machine so that the calculated weight becomes a target weight; 6. A control system according to claim 4 or claim 5.

7. A control system according to any one of claims 1 to 6, Loading machinery.

8. A control method for controlling a loading machine equipped with a work implement having a bucket, comprising: excavating a pile of earth and sand placed on the ground with the bucket while moving the loading machine forward; a surface of the excavated material, which is the natural ground excavated and held by the bucket, includes a first surface sloping upward toward the front, and a second surface connected to a front end of the first surface and sloping downward toward the front, The bucket includes a cutting edge and a spill guard end opposite the cutting edge, acquiring a bucket angle indicating an angle of the bucket relative to a horizontal plane during excavation work; determining a first front loading angle indicating the angle of the first surface with respect to a horizontal plane based on the bucket angle after the excavation operation is started to a predetermined angle including a ground angle indicating the angle between the ground and the surface of the ground; obtaining a cutting edge load angle indicating the angle of the second surface relative to a horizontal plane; calculating a tractive force of the loading machine during an excavation operation in which the bucket is used to excavate an excavation target; Calculating a weight of the excavated material held in the bucket based on the first front load angle, the cutting edge load angle, the bucket angle, the density of the excavated material, and bucket data indicating dimensions of the bucket; Calculating a load height indicating a height of the excavation target inside the bucket based on the tractive force; determining a second nearside load angle based on a difference between the height of the spill guard end and the load height, the difference varying based on the bucket angle; After determining that the cargo height is higher than the height of the spill guard end, the second front cargo angle is determined to be greater than the ground angle based on the bucket angle increase from the time when it was determined that the cargo height was higher than the height of the spill guard end. Control method.

9. A control method for controlling a loading machine equipped with a work implement having a bucket, comprising: excavating a pile of earth and sand placed on the ground with the bucket while moving the loading machine forward; a surface of the excavated material, which is the natural ground excavated and held by the bucket, includes a first surface sloping upward toward the front, and a second surface connected to a front end of the first surface and sloping downward toward the front, The bucket includes a cutting edge and a spill guard end opposite the cutting edge, acquiring a bucket angle indicating an angle of the bucket relative to a horizontal plane during excavation work; determining a first front loading angle indicating the angle of the first surface with respect to a horizontal plane based on the bucket angle after the excavation operation is started to a predetermined angle including a ground angle indicating the angle between the ground and the surface of the ground; obtaining a cutting edge load angle indicating the angle of the second surface relative to a horizontal plane; calculating a tractive force of the loading machine during an excavation operation in which the bucket is used to excavate an excavation target; Calculating a weight of the excavated material held in the bucket based on the first front load angle, the cutting edge load angle, the bucket angle, the density of the excavated material, and bucket data indicating dimensions of the bucket; If the sum of the ground angle and the bucket angle increment is smaller than the angle of repose of the soil, a second front loading angle is determined to be the sum of the ground angle and the bucket angle increment; When the sum of the ground angle and the bucket angle increase amount is greater than the angle of repose of the soil and sand, the second front loading angle is determined to be the angle of repose. Control method.

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