Work machine control system, work machine, work machine remote operation system, and work machine control method

Abstract

To suppress deterioration of a work machine.SOLUTION: A work machine control system comprises a controller. The controller includes: an operation signal acquisition unit that acquires an operation signal from an operation device to be operated for activating an implement of the work machine; and an implement control unit that when a variation rate of the operation signal is large in a state in which the implement is performing lowering action from a raised posture of the implement being raised at a height equal to of larger than a prescribed height, outputs a control command so that the variation rate becomes smaller.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a work machine control system, a work machine, a work machine remote operation system, and a work machine control method. [Background technology]

[0002] In the technical field related to work machines, a remote control system for a wheel loader is known, as disclosed in Patent Document 1. In Patent Document 1, the wheel loader has a camera and an antenna. An on-board controller of the wheel loader receives a remote signal from an off-board controller via the antenna. The off-board controller receives a camera image from the camera and displays it on a display. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent Application Publication No. 3926107 Summary of the Invention [Problem to be solved by the invention]

[0004] A work machine has a vehicle body and a working implement connected to the vehicle body. The work implement operates based on an operation signal from an operating device operated by an operator. For example, if the operating device is operated to suddenly interrupt the lowering operation while the work implement is in the process of lowering, the weight balance of the work machine may be disrupted. If the weight balance of the work machine is disrupted, a load may be placed on the work machine, which may cause the work machine to deteriorate.

[0005] The present disclosure aims to suppress deterioration of a work machine. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a control system for a work machine including a controller. The controller has an operation signal acquisition unit that acquires an operation signal from an operation device that is operated to operate a work implement of the work machine, and a work implement control unit that, when the rate of change of the operation signal is large while the work implement is being lowered from a raised position in which it is elevated above a predetermined height, outputs a control command to reduce the rate of change. [Effects of the Invention]

[0007] According to the present disclosure, deterioration of the work machine is suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a remote control system for a work machine according to an embodiment. [Figure 2] FIG. 2 is a configuration diagram showing a work machine and an operating device according to the embodiment. [Figure 3] FIG. 3 is a hardware configuration diagram showing the in-vehicle controller according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating the operation of the work machine according to the embodiment. [Figure 5] FIG. 5 is a functional block diagram showing a control system for a work machine according to an embodiment. [Figure 6] FIG. 6 is a flowchart showing a control method for a work machine according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of the relationship between the operation signal from the boom lever and the height of the boom according to the embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of the relationship between the operation signal from the boom lever and the height of the boom according to the 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] [Remote Control System] 1 is a diagram showing a remote operation system 200 for a work machine 1 according to an embodiment. The remote operation system 200 remotely operates a work machine 1 located at a work site 201. At least a part of the remote operation system 200 is disposed in a remote operation room 202 provided outside the work machine 1. The remote operation system 200 comprises an operation device 7, a display device 8, and a remote controller 9.

[0011] The operation device 7 is arranged in the remote control room 202. The operation device 7 is operated by an operator in the remote control room 202. The operator can operate the operation device 7 while seated in the pilot seat 10. The operator may also operate a portable operation device 700. The operation device 700 may also be operated outside the remote control room 202.

[0012] The display device 8 is disposed in the remote control room 202. An example of the display device 8 is a flat panel display such as a liquid crystal display or an organic EL display. The display device 8 displays at least an image of the work site 201. The display device 8 may also output audio of the work site 201.

[0013] The operator operates the operation device 7 while checking an image of the work site 201 displayed on the display device 8. The work machine 1 is remotely controlled by the operation device 7.

[0014] The remote controller 9 is placed in a remote operation room 202. The remote controller 9 and the work machine 1 communicate with each other via a communication system 203. Examples of the communication system 203 include the internet, a local area network (LAN), a mobile phone communication network, and a satellite communication network.

[0015] [Work machinery] In the embodiment, the work machine 1 is a wheel loader. As shown in Fig. 1, the work machine 1 includes a body 2, an articulating mechanism 3, a cab 4, wheels 5, a work implement 6, and a camera 29. The work machine 1 travels on the wheels 5 at a work site 201. The work machine 1 performs work using the work implement 6 at the work site 201. Examples of work that the work machine 1 can perform include excavation work, loading work, transporting work, and snow removal work.

[0016] The vehicle body 2 supports the work machine 6. The vehicle body 2 includes a front frame 2F and a rear frame 2R. The front frame 2F is located forward of the rear frame 2R. The front frame 2F and the rear frame 2R are connected by an articulation mechanism 3. The articulation mechanism 3 includes an articulation cylinder 11. The articulation cylinder 11 is a hydraulic cylinder. The articulation cylinder 11 connects the front frame 2F and the rear frame 2R. When the articulation cylinder 11 extends and retracts, the front frame 2F bends left and right relative to the rear frame 2R. When the front frame 2F bends relative to the rear frame 2R, the traveling direction of the work machine 1 is adjusted. The cab 4 is located on top of the rear frame 2R.

[0017] The wheels 5 support the vehicle body 2. The wheels 5 include front wheels 5F attached to the front frame 2F and rear wheels 5R attached to the rear frame 2R. The front wheels 5F rotate about a rotation axis CXf. The rear wheels 5R rotate about a rotation axis CXr. When the work machine 1 travels in a straight line, the rotation axis CXf of the front wheels 5F and the rotation axis CXr of the rear wheels 5R are parallel to each other.

[0018] The work implement 6 is supported by the vehicle body 2. The work implement 6 is connected to the front frame 2F. The work implement 6 has a boom 12, a bucket 13, a bell crank 14, and a bucket link 15.

[0019] A base end of the boom 12 is rotatably connected to the front frame 2F. The boom 12 rotates about a rotation axis AXa relative to the front frame 2F. A bracket 16 is fixed to the middle of the boom 12.

[0020] The bucket 13 is a working member that excavates an excavation target. The bucket 13 holds the excavated material. The bucket 13 has a cutting edge 13A, an opening 13B, and a bottom surface 13C.

[0021] 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.

[0022] An intermediate portion of the bell crank 14 is rotatably connected to a bracket 16 of the boom 12. The bell crank 14 rotates about a rotation axis AXc relative to the bracket 16 of the boom 12. A lower end portion of the bell crank 14 is rotatably connected to a base end portion of a bucket link 15.

[0023] The tip end of the bucket link 15 is rotatably connected to a bracket 17 of the bucket 13. The bucket link 15 rotates about a rotation axis AXd relative to the bracket 17 of the bucket 13. The bell crank 14 is connected to the bucket 13 via the bucket link 15.

[0024] The boom 12 is operated by a boom cylinder 18. The boom cylinder 18 is a hydraulic cylinder. A base end of the boom cylinder 18 is connected to the front frame 2F. A tip end of the boom cylinder 18 is connected to the boom 12. The boom 12 rotates relative to the boom cylinder 18 about a rotation axis AXe.

[0025] The bucket 13 is operated by a bucket cylinder 19. The bucket cylinder 19 is a hydraulic cylinder. A base end of the bucket cylinder 19 is connected to the front frame 2F. A tip end of the bucket cylinder 19 is connected to an upper end of a bell crank 14. The bell crank 14 rotates relative to the bucket cylinder 19 about a rotation axis AXf.

[0026] The pivot axis AXa, the pivot axis AXb, the pivot axis AXc, the pivot axis AXd, the pivot axis AXe, the pivot axis AXf, and the rotation axis CXf of the front wheel 5F are parallel to each other. When the work machine 1 travels in a straight line, the pivot axis AXa of the work implement 6 and the rotation axis CXr of the rear wheel 5R are parallel to each other.

[0027] The camera 29 captures an image of the work site 201. The camera 29 captures an image of at least the work site 201 in front of the work machine 1. The camera 29 captures an image of at least a portion of the work implement 6. In this embodiment, the camera 29 is arranged in the cab 4.

[0028] [Configuration of work machine and operating device] Fig. 2 is a configuration diagram showing a work machine 1 and an operating device 7 according to the embodiment. As shown in Fig. 2, the work machine 1 is equipped with an engine 20, a power take-off (PTO) 21, a power transmission device 22, a braking device 23, a steering pump 24, a steering control valve 37, an articulating cylinder 11, a work implement pump 26, a boom control valve 38, a bucket control valve 39, a boom cylinder 18, a bucket cylinder 19, a work implement attitude sensor 28, a load sensor 27, a camera 29, and an on-board controller 30.

[0029] The engine 20 is a drive source for the work machine 1. The engine 20 is supported on the vehicle body 2. A power take-off 21 distributes the drive power of the engine 20 to a power transmission device 22, a steering pump 24, and a work implement pump 26. The power transmission device 22 transmits the drive power of the engine 20 to the wheels 5. A brake device 23 reduces the traveling speed of the work machine 1.

[0030] The steering pump 24 is a hydraulic pump that is operated by the driving force generated by the engine 20. The hydraulic oil discharged from the steering pump 24 is supplied to the articulated cylinder 11 via a steering control valve 37. The steering control valve 37 controls the flow rate and direction of the hydraulic oil supplied from the steering pump 24 to the articulated cylinder 11.

[0031] The work implement pump 26 is a hydraulic pump that is operated by the driving force generated by the engine 20. The hydraulic oil discharged from the work implement pump 26 is supplied to the boom cylinder 18 via a boom control valve 38. The hydraulic oil discharged from the work implement pump 26 is supplied to the bucket cylinder 19 via a bucket control valve 39. The boom control valve 38 controls the flow rate and direction of the hydraulic oil supplied from the work implement pump 26 to the boom cylinder 18. The bucket control valve 39 controls the flow rate and direction of the hydraulic oil supplied from the work implement pump 26 to the bucket cylinder 19. The work implement 6 is operated by the hydraulic oil from the work implement pump 26.

[0032] The work implement attitude sensor 28 detects the attitude of the work implement 6. The attitude of the work implement 6 includes the angle of the work implement 6. The work implement attitude sensor 28 includes a boom angle sensor 28A that detects the attitude of the boom 12, and a bucket angle sensor 28B that detects the attitude of the bucket 13.

[0033] The attitude of the boom 12 includes the angle of the boom 12. The boom angle sensor 28A detects the boom angle that indicates the angle of the boom 12. The boom angle refers to the angle of the boom 12 with respect to the vehicle body 2 in the local coordinate system. In the embodiment, the boom angle is the angle between a line connecting the rotation axis AXa and the rotation axis AXb and a line connecting the rotation axis CXf and the rotation axis CXr when the work machine 1 is traveling in a straight line. An example of the boom angle sensor 28A is an angle sensor that is arranged at the connection between the front frame 2F and the boom 12.

[0034] The attitude of the bucket 13 includes the angle of the bucket 13. Bucket angle sensor 28B detects the bucket angle that indicates the angle of the bucket 13. An angle sensor disposed at the connection portion between the boom 12 and the bell crank 14 is exemplified as bucket angle sensor 28B.

[0035] The boom angle and bucket angle are each angles in the operating plane of the work implement 6 that is perpendicular to the rotation axis AXa. The line connecting the rotation axis AXa and the rotation axis AXb, and the line connecting the rotation axis CXf and the rotation axis CXr when the work machine 1 is traveling in a straight line, are each lines in the operating plane of the work implement 6.

[0036] The load sensor 27 detects the load state of the work implement 6. The load sensor 27 detects whether the bucket 13 is in a loaded state holding excavated material, or in an empty state not holding any excavated material. In the embodiment, the load sensor 27 includes a weight sensor that detects the weight of the work implement 6. The weight of the work implement 6 differs between a loaded state in which the bucket 13 holds excavated material and an empty state in which it does not hold any excavated material. The load sensor 27 can detect whether the work implement 6 is in a loaded state or an empty state by detecting the weight of the work implement 6. An example of the load sensor 27 is a bottom pressure sensor that detects the bottom pressure of the boom cylinder 18.

[0037] The camera 29 captures an image of the work site 201. The camera 29 captures an image of at least a portion of the work machine 6. Image data captured by the camera 29 is transmitted to the remote controller 9 via the on-board controller 30 and the communication system 203. The remote controller 9 displays the image data captured by the camera 29 on the display device 8.

[0038] The operation device 7 is operated by an operator. When operated by the operator, the operation device 7 generates an operation signal for operating the work machine 1. The operation signal generated by the operation device 7 is transmitted to the on-vehicle controller 30 via the remote controller 9 and the communication system 203. The on-vehicle controller 30 outputs a control command for operating the work machine 1 based on the operation signal transmitted from the remote controller 9. The operation device 7 includes a traveling system operation device 7A and a work implement operation device 7B.

[0039] The traveling system operation device 7A is operated by an operator to operate at least one of the engine 20, the power transmission device 22, and the brake device 23. The traveling system operation device 7A generates an operation signal to operate at least one of the engine 20, the power transmission device 22, and the brake device 23. The traveling system operation device 7A includes an accelerator pedal 71, a brake pedal 72, a steering wheel 73, and a forward / reverse switch lever 74.

[0040] The work implement operating device 7B is operated by an operator to operate the work implement 6. The work implement operating device 7B generates an operation signal to operate the work implement 6. The work implement operating device 7B includes a boom lever 75 and a bucket lever 76. The boom lever 75 is operated to operate the boom 12. The bucket lever 76 is operated to operate the bucket 13.

[0041] When the boom lever 75 is operated, the spool of the boom control valve 38 moves. When the boom lever 75 is operated to one side from the neutral position of the boom lever 75 and the spool of the boom control valve 38 is located in the bottom position, the boom cylinder 18 extends. When the boom lever 75 is operated to the other side from the neutral position of the boom lever 75 and the spool of the boom control valve 38 is located in the rod position, the boom cylinder 18 retracts. When the spool of the boom control valve 38 is located in the neutral position, the extension and contraction of the boom cylinder 18 is stopped.

[0042] When the bucket lever 76 is operated, the spool of the bucket control valve 39 moves. When the spool of the bucket control valve 39 is located in the bottom position, the bucket cylinder 19 extends. When the spool of the bucket control valve 39 is located in the rod position, the bucket cylinder 19 retracts. When the spool of the bucket control valve 39 is located in the neutral position, the bucket cylinder 19 stops extending and retracting.

[0043] [In-vehicle controller] FIG. 3 is a hardware configuration diagram showing an in-vehicle controller 30 according to an embodiment. The in-vehicle controller 30 includes a computer system. The in-vehicle controller 30 includes a processor 31 such as a central processing unit (CPU), a main memory 32 including a non-volatile memory such as a read-only memory (ROM) and a volatile memory such as a random access memory (RAM), a storage 33, an input / output interface 34 including an input / output circuit, and a communication interface 35 including a communication circuit. The functions of the in-vehicle controller 30 are stored in the storage 33 as a computer program. The processor 31 reads the computer program from the storage 33, loads it into the main memory 32, and executes processing in accordance with the computer program. The computer program may be distributed to the in-vehicle controller 30 via a network.

[0044] The remote controller 9 also includes a computer system. Like the in-vehicle controller 30, the remote controller 9 has a processor, a main memory, a storage, an input / output interface, and a communication interface.

[0045] [Work machine operation] 4 is a diagram illustrating the operation of the work machine 1 according to the embodiment. In the embodiment, the work implement 6 is a front-loading type work implement in which the opening 13B of the bucket 13 faces forward during excavation work. The boom cylinder 18 extends and retracts to cause the boom 12 to perform a raising or lowering operation. The bucket cylinder 19 extends and retracts to cause the bucket 13 to perform a tilting or dumping operation.

[0046] 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. The lowering operation of the boom 12 refers to the operation of the boom 12 rotating about the rotation axis AXa so that the tip of the boom 12 moves closer to the ground. The boom 12 performs a raising operation when the boom cylinder 18 extends. The boom 12 performs a lowering operation when the boom cylinder 18 retracts.

[0047] The tilting operation of the bucket 13 refers to the operation of the bucket 13 rotating about the rotation axis AXb so that the opening 13B of the bucket 13 faces upward and the blade tip 13A moves away from the ground. The dumping operation of the bucket 13 refers to the operation of the bucket 13 rotating about the rotation axis AXb so that the opening 13B of the bucket 13 faces downward and the blade tip 13A moves closer to the ground. The bucket 13 tilts when the bucket cylinder 19 extends. The bucket 13 dumps when the bucket cylinder 19 retracts.

[0048] When the bucket 13 performs a tilting operation, the excavated material is scooped up by the bucket 13 and held in the bucket 13. When the bucket 13 performs a dumping operation, the excavated material held in the bucket 13 is discharged from the bucket 13.

[0049] As shown in Fig. 4, the work machine 1 can perform loading work to load excavated material into the dump body of the dump truck 300. The operator operates the work implement operating device 7B to control the attitude of the work implement 6 so that the excavated material held in the bucket 13 is loaded into the dump body of the dump truck 300. The operator controls the attitude of the work implement 6 so that the excavated material does not spill out of the bucket 13 and so that the bucket 13 is positioned higher than the upper end of the dump body.

[0050] When performing loading work, the operator operates the work implement operating device 7B so that the work implement 6 is in a raised posture. The raised posture of the work implement 6 refers to a posture in which the work implement 6 is elevated to a predetermined height Hp or higher. In the embodiment, the raised posture refers to a posture in which the rotation axis AXb at the tip of the boom 12 is elevated to the predetermined height Hp or higher.

[0051] In order to load excavated material into the dump body of the dump truck 300, the operator performs a dump operation with the bucket 13 in a state in which the tip of the boom 12 is raised, and then moves the work machine 1 backward so as to move away from the dump truck 300. The operator also operates the work machine operating device 7B to lower the work machine 6.

[0052] [Control System] 5 is a functional block diagram showing a control system 100 for a work machine 1 according to an embodiment. The control system 100 has an operation device 7, a remote controller 9, an on-board controller 30, a work machine attitude sensor 28, a load sensor 27, and a camera 29.

[0053] The on-board controller 30 has a sensor data acquisition unit 101, an operation signal acquisition unit 102, an attitude determination unit 103, an operation determination unit 104, a threshold setting unit 105, a travel control unit 106, a work machine control unit 107, and a transmission unit 108.

[0054] The sensor data acquisition unit 101 acquires detection data from the work machine attitude sensor 28 and detection data from the load sensor 27. The detection data from the work machine attitude sensor 28 includes detection data from the boom angle sensor 28A indicating the boom angle and detection data from the bucket angle sensor 28B indicating the bucket angle.

[0055] The operation signal acquisition unit 102 acquires operation signals from the operation device 7. The operation signals from the operation device 7 include an operation signal from the boom lever 75 that is operated to operate the boom 12, and an operation signal from the bucket lever 76 that is operated to operate the bucket 13.

[0056] The attitude determination unit 103 determines whether the attitude of the work implement 6 satisfies predetermined attitude conditions based on detection data from the work implement attitude sensor 28. Satisfying the attitude conditions includes the work implement 6 being in a raising attitude. The attitude determination unit 103 determines whether the work implement 6 is in a raising attitude. The attitude determination unit 103 determines whether the boom 12 is in a raising attitude based on detection data from the boom angle sensor 28A.

[0057] The operation determination unit 104 determines whether the operation of the work implement 6 satisfies predetermined operation conditions based on an operation signal from the work implement operating device 7B. Satisfying the operation conditions includes the work implement 6 being in a lowering operation. The operation determination unit 104 determines whether the boom 12 is in a lowering operation based on an operation signal from the boom lever 75. Note that the operation determination unit 104 may also determine whether the boom 12 is in a lowering operation based on detection data from the boom angle sensor 28A.

[0058] The threshold setting unit 105 sets a threshold Sh related to an operation signal from the boom lever 75. The threshold setting unit 105 changes the threshold Sh based on detection data from the load sensor 27. The threshold Sh includes a threshold Shc when the work implement 6 is in a loaded state and a threshold She when the work implement 6 is in an unloaded state. The threshold setting unit 105 determines whether the work implement 6 is in a loaded state or an unloaded state based on the detection data from the load sensor 27. The threshold setting unit 105 sets the threshold Sh to the threshold Shc when the work implement 6 is in a loaded state, and sets the threshold Sh to the threshold She when the work implement 6 is in an unloaded state. The threshold Shc when the work implement 6 is in a loaded state is smaller than the threshold She when the work implement 6 is in an unloaded state.

[0059] The traveling control unit 106 controls the traveling of the work machine 1 based on operation signals from the traveling system operation device 7A. Based on operation signals from the traveling system operation device 7A, the traveling control unit 106 adjusts the traveling speed of the work machine 1, adjusts the traveling direction of the work machine 1, and switches the work machine 1 between forward and reverse traveling.

[0060] The work implement control unit 107 controls the work implement 6 based on an operation signal from the work implement operating device 7B. The work implement control unit 107 controls the boom control valve 38 based on an operation signal from the boom lever 75. By controlling the boom control valve 38, the boom cylinder 18 extends and retracts, and the boom 12 performs a raising and lowering operation. The work implement control unit 107 controls the bucket control valve 39 based on an operation signal from the bucket lever 76. By controlling the bucket control valve 39, the bucket cylinder 19 extends and retracts, and the bucket 13 performs a tilting operation and a dumping operation.

[0061] The work implement control unit 107 also performs intervention control of the boom 12. Intervention control of the boom 12 refers to controlling the boom control valve 38 so that the boom control valve 38 is driven under predetermined conditions while the boom lever 75 is being operated. In other words, intervention control of the boom 12 refers to outputting a control command from the work implement control unit 107 so that the boom 12 operates under predetermined conditions while the operation signal from the boom lever 75 is being acquired by the operation signal acquisition unit 102.

[0062] The transmission unit 108 transmits image data captured by the camera 29 to the remote controller 9. The transmission unit 108 may also transmit detection data of the work machine attitude sensor 28 to the remote controller 9.

[0063] [Work machine control method] 6 is a flowchart showing a method for controlling the work machine 1 according to the embodiment. The operation signal acquisition unit 102 acquires an operation signal from the operation device 7. The traveling control unit 106 controls the traveling of the work machine 1 based on an operation signal from the traveling system operation device 7A. The work implement control unit 107 controls the work implement 6 based on an operation signal from the work implement operation device 7B. The sensor data acquisition unit 101 acquires detection data from the work implement attitude sensor 28 and detection data from the load sensor 27 (step S1).

[0064] The attitude determination unit 103 determines whether or not the work implement 6 is in a raising attitude based on detection data from the work implement attitude sensor 28 that detects the attitude of the work implement 6 (step S2).

[0065] The working implement 6 being in a raising position includes the boom 12 being in a raising position. The boom 12 being in a raising position includes the rotation axis AXb between the boom 12 and the bucket 13 being positioned higher than the rotation axis AXa between the front frame 2F and the boom 12. In other words, the working implement 6 being in a raising position includes the distance between the rotation axis AXb and the ground in the vertical direction being longer than the distance between the rotation axis AXa and the ground. Furthermore, the boom 12 being in a raising position includes the rotation axis AXb at the tip of the boom 12 being raised to or above a predetermined height Hp in the local coordinate system of the working machine 1.

[0066] If the specified line is a line parallel to the line connecting the rotation axis CXf of the front wheel 5F and the rotation axis CXr of the rear wheel 5R, the working implement 6 being in the raised posture may include the line connecting the rotation axis AXa and the rotation axis AXb being inclined upward and forward relative to the specified line.If the specified line is parallel to the horizontal plane, the working implement 6 being in the raised posture includes the distance in the vertical direction between the rotation axis AXb and the specified line being longer than the distance between the rotation axis AXa and the specified line.

[0067] 4, when excavated material is loaded onto the dump body of the dump truck 300, the bucket 13 performs a dumping operation with the tip of the boom 12 raised. The raised posture of the work implement 6 may be considered to be the posture of the work implement 6 when loading excavated material onto the dump body of the dump truck 300.

[0068] If it is determined in step S2 that the work implement 6 is in the raising posture (step S2: Yes), the operation determination unit 104 determines whether the boom 12 is moving from the raised posture to the lowering posture based on the operation signal from the boom lever 75. Note that the operation determination unit 104 may also determine whether the boom 12 is moving from the raised posture to the lowering posture based on the detection data of the boom angle sensor 28A (step S3).

[0069] 7 and 8 are diagrams showing an example of the relationship between the operation signal from the boom lever 75 according to the embodiment and the height of the boom 12. In the following description, the operation signal from the boom lever 75 will be referred to as the boom lever signal as appropriate. In Fig. 7 and Fig. 8, the horizontal axis represents the elapsed time from the point in time when it is determined that the work implement 6 is in the raised posture, and the vertical axis represents the height of the tip of the boom 12, the boom lever signal, and the rate of change of the boom lever signal.

[0070] A positive value of the boom lever signal means that the boom lever 75 has been operated to one side from the neutral position of the boom lever 75 so as to raise the boom 12, and a negative value of the boom lever signal means that the boom lever 75 has been operated to the other side from the neutral position of the boom lever 75 so as to lower the boom 12. In other words, a positive value of the boom lever signal means that the boom 12 has been raised, and a negative value of the boom lever signal means that the boom 12 has been lowered.

[0071] The boom lever signal includes the amount of operation of the boom lever 75. The larger the absolute value of the boom lever signal, the larger the amount of operation of the boom lever 75. There is a one-to-one correspondence between the boom lever signal and the boom speed, which indicates the extension / retraction speed of the boom cylinder 18. The larger the absolute value of the boom lever signal, the higher the boom speed. The smaller the absolute value of the boom lever signal, the lower the boom speed.

[0072] The rate of change of the boom lever signal refers to the amount of change in the boom lever signal per unit time. The rate of change of the boom lever signal includes the rate of change in the amount of operation of the boom lever 75. A larger rate of change of the boom lever signal means that the boom lever 75 is operated more suddenly. There is a one-to-one correspondence between the rate of change of the boom lever signal and the boom acceleration, which indicates the extension / retraction acceleration of the boom cylinder 18. A larger rate of change of the boom lever signal means that the boom acceleration is higher. A smaller rate of change of the boom lever signal means that the boom acceleration is lower.

[0073] When the boom lever 75 is operated suddenly, the rate of change of the boom lever signal becomes larger. As described with reference to FIG. 4 , the operator loads excavated material onto the dump body of the dump truck 300, and then lowers the boom 12. When the boom lever 75 is operated to interrupt the lowering operation while the boom lever 75 is being operated to lower the boom 12, the rate of change of the boom lever signal becomes larger. Examples of operations of the boom lever 75 to interrupt the lowering operation of the boom 12 include operating the boom lever 75 to suddenly decelerate or suddenly stop the boom 12 while the boom 12 is lowering, and operating the boom lever 75 to suddenly raise the boom 12 while the boom 12 is lowering. When the boom lever 75 is operated to interrupt the lowering operation of the boom 12, the rate of change of the operation signal from the boom lever 75 becomes larger.

[0074] In step S3, if it is determined that the boom 12 is lowering (step S3: Yes), the work machine control unit 107 determines whether to start intervention control of the boom 12 based on the operation signal from the boom lever 75 (step S4).

[0075] The work implement control unit 107 determines whether or not the rate of change in the operation signal from the boom lever 75 acquired by the operation signal acquisition unit 102 exceeds a predetermined threshold Sh when the work implement 6 is in a loaded state and a threshold She when the work implement 6 is in an unloaded state.

[0076] FIG. 7 shows an example in which the rate of change of the boom lever signal does not exceed the threshold value She or the threshold value Shc. The threshold value Shc when the work implement 6 is in a loaded state is smaller than the threshold value She when the work implement 6 is in an unloaded state. As described above, when the work implement 6 is in a loaded state, the threshold value Sh is set to the threshold value Shc. When the work implement 6 is in an unloaded state, the threshold value Sh is set to the threshold value She. When the work implement 6 is in a loaded state, the work implement control unit 107 determines whether the rate of change of the boom lever signal has exceeded the threshold value Shc. When the work implement 6 is in an unloaded state, the work implement control unit 107 determines whether the rate of change of the boom lever signal has exceeded the threshold value She. In the following description, it is assumed, as an example, that the work implement 6 is in an unloaded state and the threshold value Sh is set to the threshold value She.

[0077] In Figure 7, time t1 is the time when operation of the boom lever 75 is started to lower the boom 12, which is in the raised position. Time t2 is the time when the boom lever 75 is operated from the neutral position to the other side and reaches a certain position. Time t3 is the time when operation of the boom lever 75 is started to complete the lowering operation of the boom 12. Time t4 is the time when the boom lever 75 is placed in the neutral position.

[0078] FIG. 8 shows an example in which the rate of change of the boom lever signal exceeds the threshold value She. In the example shown in FIG. 8, time t3 is the time when the boom lever 75 is operated to suddenly stop the lowering operation of the boom 12. Because the lowering operation of the boom 12 suddenly stops at time t3, the rate of change of the boom lever signal becomes large from time t3 onwards. In FIG. 8, time t3a is the time when the rate of change of the boom lever signal exceeds the threshold value She. Time t3a is after time t3 and before time t4. Time t4a is the time when the boom lever 75 is placed in the neutral position. Time 4a is after time t3a and before time t4. Because the boom lever 75 is suddenly operated to return to the neutral position so as to suddenly stop the boom 12 while the boom 12 is lowering, the rate of change of the boom lever signal becomes large from time t3 to time t4a.

[0079] In the case of the rate of change of the boom lever signal shown in Fig. 7, the work implement control unit 107 determines that the rate of change of the boom lever signal does not exceed the threshold value She. In the case of the rate of change of the boom lever signal shown in Fig. 8, the work implement control unit 107 determines that the rate of change of the boom lever signal exceeds the threshold value She.

[0080] If the work implement control unit 107 determines that the rate of change of the boom lever signal does not exceed the threshold value She, it determines not to start intervention control of the boom 12. If the work implement control unit 107 determines that the rate of change of the boom lever signal exceeds the threshold value She, it determines to start intervention control of the boom 12.

[0081] In step S4, if it is determined that intervention control of the boom 12 is to be started (step S4: Yes), the work implement control unit 107 outputs a control command so that the rate of change of the boom lever signal becomes equal to or less than the threshold value She. In the example shown in Fig. 8, since the work implement 6 is in an unloaded state, the work implement control unit 107 outputs a control command so that the rate of change of the boom lever signal becomes equal to or less than the threshold value She. Note that, if the work implement 6 is in a loaded state, the work implement control unit 107 outputs a control command so that the rate of change of the boom lever signal becomes equal to or less than the threshold value Shc.

[0082] In the embodiment, the intervention control of the boom 12 includes implementing a restriction process to reduce the rate of change of the boom lever signal while the boom lever signal is being acquired by the operation signal acquisition unit 102. The work implement control unit 107 implements the restriction process to reduce the rate of change of the boom lever signal while the boom lever signal is being acquired by the operation signal acquisition unit 102 (step S5).

[0083] 8, the dotted lines indicate the height of the boom 12, the boom lever signal, and the rate of change of the boom lever signal when intervention control is performed, and the solid lines indicate the height of the boom 12, the boom lever signal, and the rate of change of the boom lever signal when intervention control is not performed.

[0084] As indicated by the dotted line in FIG. 8, the work implement control unit 107 performs limiting processing on the boom lever signal acquired by the operation signal acquisition unit 102 to reduce the rate of change of the boom lever signal. The limiting processing generates a boom lever signal with a small rate of change. The limiting processing suppresses the rate of change of the boom lever signal to a value equal to or less than the threshold value She. The work implement control unit 107 outputs a control command to control the bucket control valve 39 based on the limited boom lever signal. The bucket control valve 39 is driven based on the limited bucket lever signal (step S6).

[0085] The work implement control unit 107 performs intervention control so as to reduce the rate of change of the boom lever signal after time t3a when the rate of change of the boom lever signal exceeds the threshold value She. The work implement control unit 107 performs restriction processing so as to reduce the rate of change of the boom lever signal after time t3a. By performing intervention control, the rate of change of the boom lever signal after time t3a becomes smaller. Because the rate of change of the boom lever signal becomes smaller, the operating acceleration of the boom 12 is reduced. By performing intervention control, the boom 12 transitions from a lowering operation to a stopped state at low acceleration.

[0086] Note that when the intervention control is performed while the boom 12 is being lowered, the stop position of the boom 12 is lower than the stop position of the boom 12 when the intervention control is not performed. As shown in Fig. 8, for example, when the operator wants to stop the boom 12, which is being lowered, at height Hg, when the intervention control is performed, the boom 12 is lowered to height Ha, which is lower than height Hg. In other words, when the intervention control is performed, the work implement 6 is lowered to height Ha, which is lower than height Hg intended by the operator.

[0087] The work machine control unit 107 determines whether or not to end the intervention control (step S7). If it is determined in step S7 that the intervention control should not be ended (step S7: No), the work machine control unit 107 returns to the processing of step S5. If it is determined in step S7 that the intervention control should be ended (step S7: Yes), the work machine control unit 107 returns to the processing of step S1.

[0088] If it is determined in step S2 that the work implement 6 is not in a raising posture (step S2: No), if it is determined in step S3 that the boom 12 is not in a lowering operation (step S3: No), or if it is determined in step S4 that intervention control of the boom 12 will not be started (step S4: No), the work implement control unit 107 does not perform limiting processing on the boom lever signal, and outputs a control command to control the boom control valve 38 based on the operation signal acquired by the operation signal acquisition unit 102. The boom control valve 38 is driven based on the boom lever signal that has not been limited (step S8).

[0089] [effect] As described above, according to the embodiment, the on-board controller 30 has an operation signal acquisition unit 102 that acquires an operation signal from the operation device 7 that is operated to operate the work implement 6 of the work machine 1, and a work implement control unit 107 that outputs a control command to reduce the rate of change of the operation signal when the rate of change of the operation signal is large while the work implement 6 is being lowered from a raised position in which it has risen to a predetermined height Hp or higher. In the embodiment, when the work implement control unit 107 determines that the rate of change of the operation signal exceeds the threshold value Sh, it outputs a control command to reduce the rate of change to less than or equal to the threshold value Sh.

[0090] If the boom lever 75 is operated to interrupt the lowering operation of the boom 12, there is a possibility that the weight balance of the work machine 1 will be disrupted. If the boom lever 75 is operated to suddenly decelerate or stop the boom 12 while the boom 12 is in the lowering operation, or if the boom lever 75 is operated to suddenly raise the boom 12 while the boom 12 is in the lowering operation, the weight balance of the work machine 1 will change so that the rear wheel 5R of the work machine 1 lifts off the ground. If the weight balance of the work machine 1 changes, a localized load will be applied to the work machine 1, which may cause the body 2 and work implement 6 of the work machine 1 to deteriorate prematurely.

[0091] According to this embodiment, when an operation signal is acquired from the boom lever 75 to interrupt the lowering operation of the boom 12, intervention control is performed to prevent the lowering operation of the boom 12 from being suddenly interrupted. As a result, deterioration of the body 2 and the work implement 6 of the work machine 1 is suppressed.

[0092] When the work machine 1 is remotely operated, the operator in the remote control room 202 is unlikely to feel that the weight balance of the work machine 1 is disrupted even if the boom lever 75 is suddenly operated. For this reason, the operator in the remote control room 202 may suddenly operate the boom lever 75 unconsciously. According to the embodiment, when the boom lever 75 is suddenly operated, intervention control is implemented so that the lowering operation of the boom 12 is not suddenly interrupted. As a result, deterioration of the work machine 1 is suppressed.

[0093] In the embodiment, the threshold value Sh includes a threshold value Shc when the work implement 6 is in a loaded state and a threshold value She when the work implement 6 is in an unloaded state. The moment applied from the work implement 6 to the vehicle body 2 when the work implement 6 is in a loaded state is greater than the moment applied from the work implement 6 to the vehicle body 2 when the work implement 6 is in an unloaded state. Therefore, when the work implement 6 is in a loaded state, there is a possibility that the weight balance of the work machine 1 will be significantly disrupted if the lowering operation of the boom 12 is suddenly interrupted. According to the embodiment, since the threshold value Sh is set to the small threshold value Shc when the work implement 6 is in a loaded state, during intervention control, the rate of change of the boom lever signal when the work implement 6 is in a loaded state is smaller than the rate of change of the boom lever signal when the work implement 6 is in an unloaded state. Therefore, even when the work implement 6 is in a loaded state, the weight balance of the work machine 1 is prevented from being significantly disrupted.

[0094] [Other embodiments] As described above, when intervention control is performed while the boom 12 is lowering, the stop position of the boom 12 is lower than the stop position of the boom 12 when intervention control is not performed. As described with reference to Fig. 8, for example, when the operator wants to stop the boom 12, which is lowering, at height Hg, if intervention control is performed, the boom 12 is lowered to height Ha, which is lower than height Hg. If height Ha is higher than the ground, even when intervention control is performed, the bucket 13 can be stopped at height Ha without coming into contact with the ground.

[0095] In the above-described embodiment, when the work implement control unit 107 determines that the rate of change of the boom lever signal exceeds the threshold value Sh, it outputs a control command so that the rate of change of the boom lever signal becomes equal to or less than the threshold value Sh. The work implement control unit 107 may output a control command without using the threshold value Sh. When the rate of change of the boom lever signal is large, the work implement control unit 107 may output a control command so that the rate of change of the boom lever signal becomes small.

[0096] For example, when the work implement control unit 107 outputs a control command at a fixed control cycle, it calculates a weighted average of the command value of the previous control command and the command value of the control command corresponding to the current boom lever signal, and sets the calculated weighted average value as the command value of the current control command. When the rate of change of the boom lever signal is large, the work implement control unit 107 changes the weight w1 for the command value of the previous control command to a larger value, and changes the weight w2 for the command value of the control command corresponding to the current boom lever signal to a smaller value. The command value of the current control command is calculated, for example, based on the following equation (1): [Command value of the current control command] = w1 × [Command value of the previous control command] + w2 × [Command value of the control command corresponding to the current boom lever signal] ... (1) The weight w1 and the weight w2 satisfy the relationship of the following equation (2). w1+w2=1 …(2) For example, if the control period by the work machine control unit 107 is 10 msec, the initial value of weight w1 is 0.91, and the initial value of weight w2 is 0.09, and the rate of change of the boom lever signal is large, the work machine control unit 107 changes weight w1 to 0.98 and weight w2 to 0.02.

[0097] In the above-described embodiment, the load sensor 27 that detects the load state of the work implement 6 includes a weight sensor that detects the weight of the work implement 6. The load sensor 27 may include, for example, a camera that captures an image of the bucket 13. The camera can capture an image of the excavated material held in the bucket 13. Image data of the excavated material acquired by the camera is transmitted to the on-board controller 30. Density data indicating the density of the excavated material is pre-stored in the on-board controller 30. The sensor data acquisition unit 101 of the on-board controller 30 estimates the volume of the excavated material held in the bucket 13 based on the image data of the excavated material. The sensor data acquisition unit 101 can calculate the weight of the excavated material held in the bucket 13 based on the estimated volume of the excavated material and the density data of the excavated material. Note that the three-dimensional shape of the excavated material may be detected by a three-dimensional sensor such as a laser scanner or a stereo camera. The sensor data acquisition unit 101 may estimate the volume of the excavated material held in the bucket 13 based on the three-dimensional shape of the excavated material.

[0098] In the above-described embodiment, when the camera 29 captures an image of the work implement 6, the operation determination unit 104 may determine whether the boom 12 is lowering based on the image data of the work implement 6 captured by the camera 29.

[0099] In the above-described embodiment, when intervention control is started, notification data indicating that intervention control has been started may be output from the display device 8.

[0100] In the above-described embodiment, some or all of the functions of the in-vehicle controller 30 may be provided in the remote controller 9. For example, the attitude determination unit 103 and the movement determination unit 104 may be provided in the remote controller 9.

[0101] In the above-described embodiment, the work machine 1 does not have to be remotely controlled. An operator may operate the work machine 1 by getting into the cab 4 of the work machine 1.

[0102] In the above-described embodiment, the work machine 1 is a wheel loader. The work machine 1 may also be a hydraulic excavator having a front-loading type work implement. The work machine 1 may also be a hydraulic excavator having a backhoe type work implement in which the opening of the bucket faces rearward during excavation work.

[0103] [Note] The present disclosure may also have the following configurations. (Appendix 1) Equipped with a controller, The controller an operation signal acquisition unit that acquires an operation signal from an operation device that is operated to operate a work implement of the work machine; a work machine control unit that outputs a control command to reduce the rate of change of the operation signal when the rate of change of the operation signal is large while the work machine is being lowered from a raised posture in which the work machine is elevated to a predetermined height or higher, Work machine control systems. (Appendix 2) The controller an attitude determination unit that determines whether the work machine is in the raising attitude based on detection data from a work machine attitude sensor that detects the attitude of the work machine; A control system for a work machine as described in (Appendix 1). (Appendix 3) The controller an operation determination unit that determines whether the work machine is performing the lowering operation based on the detection data of a work machine attitude sensor that detects the attitude of the work machine or the operation signal; A control system for a work machine according to (Appendix 1) or (Appendix 2). (Appendix 4) The work implement includes a boom connected to a vehicle body of the work machine so as to be rotatable about a first rotation shaft, and a bucket connected to the boom so as to be rotatable about a second rotation shaft, The raised posture includes the second rotation shaft being disposed above the first rotation shaft. A control system for a work machine according to any one of (Appendix 1) to (Appendix 3). (Appendix 5) When it is determined that the rate of change of the operation signal exceeds a threshold, the work machine control unit outputs a control command so that the rate of change is equal to or less than the threshold. A control system for a work machine according to any one of (Appendix 1) to (Appendix 4). (Appendix 6) The controller a threshold setting unit that changes the threshold based on detection data from a load sensor that detects a load state of the work machine; (Appendix 5) A control system for a work machine. (Appendix 7) the threshold setting unit determines whether the work machine is in a loaded state or an unloaded state based on the detection data of the load sensor, and sets a threshold value when the work machine is in the loaded state to be smaller than a threshold value when the work machine is in the unloaded state. (Appendix 6) A control system for a work machine. (Appendix 8) The load sensor includes a weight sensor that detects the weight of the work machine. A control system for a work machine according to (Appendix 6) or (Appendix 7). (Appendix 9) A work machine control system according to any one of (Appendix 1) to (Appendix 8), Work machinery. (Appendix 10) A work machine control system according to any one of (Appendix 1) to (Appendix 9), Remote control system for work machines. (Appendix 11) The controller acquiring an operation signal from an operation device that is operated to operate a work implement of the work machine; When the rate of change of the operation signal is large in a state in which the work machine is performing a lowering operation from a raising posture in which the work machine is elevated to a predetermined height or more, a control command is output so as to reduce the rate of change. A method for controlling a work machine. [Explanation of symbols]

[0104] 1...work machine, 2...body, 2F...front frame, 2R...rear frame, 3...articulation mechanism, 4...cab, 5...wheel, 5F...front wheels, 5R...rear wheels, 6...work implement, 7...operation device, 7A...traveling system operation device, 7B...work implement operation device, 8...display device, 9...remote controller, 10...operator seat, 11...articulation cylinder, 12...boom, 13...bucket, 13A...blade tip, 13B...opening, 13C...bottom, 14... Bell crank, 15...bucket link, 16...bracket, 17...bracket, 18...boom cylinder, 19...bucket cylinder, 20...engine, 21...power take-off, 22...power transmission device, 23...brake device, 24...steering pump, 26...work implement pump, 27...load sensor, 28...work implement attitude sensor, 28A...boom angle sensor, 28B...bucket angle sensor, 29...camera, 30...on-board controller, 31...processor, 32...main memory, 33...storage, 34...input / output interface, 35...communication interface, 37...steering control valve, 38...boom control valve, 39...bucket control valve, 71...accelerator pedal, 72...brake pedal, 73...steering wheel, 74...forward / reverse selector lever, 75...boom lever, 76...bucket lever, 100...control system, 101...sensor data acquisition unit, 102...operation signal acquisition unit , 103...attitude determination unit, 104...movement determination unit, 105...threshold setting unit, 106...travel control unit, 107...work machine control unit, 108...transmission unit, 200...remote operation system, 201...work site, 202...remote operation room, 203...communication system, 300...dump truck, AXa...rotating axis (first rotating axis), AXb...rotating axis (second rotating axis), AXc...rotating axis, AXd...rotating axis, AXe...rotating axis, AXf...rotating axis, CXf...rotating axis, CXr...rotating axis.

Claims

1. Equipped with a controller, The controller an operation signal acquisition unit that acquires an operation signal from an operation device that is operated to operate a work implement of the work machine; a work machine control unit that outputs a control command to reduce the rate of change of the operation signal when the rate of change of the operation signal is large while the work machine is being lowered from a raised posture in which the work machine is elevated to a predetermined height or higher, Work machine control systems.

2. The controller an attitude determination unit that determines whether the work machine is in the raising attitude based on detection data from a work machine attitude sensor that detects the attitude of the work machine; 2. A control system for a work machine according to claim 1.

3. The controller an operation determination unit that determines whether the work machine is performing the lowering operation based on the detection data of a work machine attitude sensor that detects the attitude of the work machine or the operation signal; 2. A control system for a work machine according to claim 1.

4. The work implement includes a boom connected to a vehicle body of the work machine so as to be rotatable about a first rotation axis, and a bucket connected to the boom so as to be rotatable about a second rotation axis, The raised posture includes the second rotation shaft being disposed above the first rotation shaft.

2. A control system for a work machine according to claim 1.

5. When it is determined that the rate of change of the operation signal exceeds a threshold, the work machine control unit outputs a control command so that the rate of change is equal to or less than the threshold.

2. A control system for a work machine according to claim 1.

6. The controller a threshold setting unit that changes the threshold based on detection data from a load sensor that detects a load state of the work machine; A control system for a work machine according to claim 5.

7. the threshold setting unit determines whether the work machine is in a loaded state or an unloaded state based on the detection data of the load sensor, and sets a threshold value when the work machine is in the loaded state to be smaller than a threshold value when the work machine is in the unloaded state.

7. A control system for a work machine according to claim 6.

8. The load sensor includes a weight sensor that detects the weight of the work machine.

7. A control system for a work machine according to claim 6.

9. A work machine control system comprising: a control system for controlling a work machine according to claim 1; Work machinery.

10. A work machine control system comprising: a control system for controlling a work machine according to claim 1; Remote control system for work machines.

11. The controller acquiring an operation signal from an operation device that is operated to operate a work implement of the work machine; When the rate of change of the operation signal is large in a state in which the work machine is performing a lowering operation from a raising posture in which the work machine is elevated to a predetermined height or more, a control command is output so as to reduce the rate of change. A method for controlling a work machine.

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