Control system for work machine, work machine, remote operation system for work machine, and control method for work machine

Abstract

This control system for a work machine comprises a controller. The controller determines the presence or absence of a prescribed action in which a work equipment bucket of the work machine repeats a tilting action and a dumping action, and when it is determined that the prescribed action has been performed and the action speed of the prescribed action has exceeded a threshold value, the controller outputs a control command such that the action speed becomes less than or equal to the threshold value.

Description

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

[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.

[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.

[0003] EP 3926107

[0004] A work machine has a working implement. When the work implement operates based on an operation signal from an operating device operated by an operator, violent operation of the operating device causes the work implement to operate violently. Violent operation of the work implement may cause early deterioration of the work machine.

[0005] 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.

[0006] The present disclosure aims to suppress deterioration of a work machine.

[0007] According to the present disclosure, there is provided a control system for a work machine including a controller. The controller determines whether or not a predetermined operation in which a bucket of a work implement of the work machine repeatedly performs a tilt operation and a dump operation is occurring, and if it determines that the predetermined operation has occurred and that the operating speed of the predetermined operation has exceeded a threshold, it outputs a control command to make the operating speed equal to or less than the threshold.

[0008] According to the present disclosure, there is provided a control system for a work machine including a controller, which receives an operation signal from an operation device operated to operate a work implement of the work machine, and outputs a control command to reduce the rate of change of the operation signal when the operation device is suddenly operated while the work implement is lowering from a raised position, changing the weight balance of the work machine.

[0009] According to the present disclosure, deterioration of the work machine is suppressed.

[0010] FIG. 1 is a diagram showing a remote control system for a work machine according to a first embodiment. FIG. 2 is a configuration diagram showing a work machine and an operation device according to the first embodiment. FIG. 3 is a hardware configuration diagram showing an on-board controller according to the first embodiment. FIG. 4 is a diagram explaining the operation of the work machine according to the first embodiment. FIG. 5 is a functional block diagram showing a control system for a work machine according to the first embodiment. FIG. 6 is a flowchart showing a control method for a work machine according to the first embodiment. FIG. 7 is a diagram explaining the attitude of the work machine according to the first embodiment. FIG. 8 is a diagram showing an example of an operation signal from a bucket lever according to the first embodiment. FIG. 9 is a diagram showing an example of an operation signal from a bucket lever according to the first embodiment. FIG. 10 is a diagram explaining the operation of a work machine according to a second embodiment. FIG. 11 is a functional block diagram showing a control system for a work machine according to the second embodiment. FIG. 12 is a flowchart showing a control method for a work machine according to the second embodiment. FIG. 13 is a diagram showing an example of the relationship between the operation signal from the boom lever and the height of the boom according to the second embodiment. FIG. 14 is a diagram showing an example of the relationship between the operation signal from the boom lever and the height of the boom according to the second embodiment.

[0011] 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.

[0012] First Embodiment A first embodiment will be described.

[0013] <Remote Control System> Figure 1 is a diagram showing a remote control system 200 for a work machine 1 according to an embodiment. The remote control system 200 remotely controls a work machine 1 that is located at a work site 201. At least a part of the remote control system 200 is disposed in a remote control room 202 provided outside the work machine 1. The remote control system 200 comprises an operation device 7, a display device 8, and a remote controller 9.

[0014] The operation device 7 is disposed 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.

[0015] 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.

[0016] 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.

[0017] The remote controller 9 is disposed 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.

[0018] <Work Machine> In this embodiment, the work machine 1 is a wheel loader. As shown in Figure 1 , the work machine 1 includes a vehicle 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.

[0019] The vehicle body 2 supports the work implement 6. The vehicle body 2 includes a front frame 2F and a rear frame 2R. The front frame 2F is 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.

[0020] The wheels 5 support the vehicle body 2. The wheels 5 include tires. The wheels 5 come into contact with the ground at the work site. 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. The rotation of the wheels 5 causes the work machine 1 to travel on the ground at the work site 201.

[0021] 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.

[0022] 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 portion of the boom 12.

[0023] The bucket 13 is a work member used to excavate an object to be excavated. The bucket 13 holds the excavated material. The bucket 13 has a cutting edge 13A, an opening 13B, and a bottom surface 13C.

[0024] A base end of the bucket 13 is rotatably connected to the tip end of the boom 12. The bucket 13 rotates about 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.

[0025] 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 with respect to the bracket 16 of the boom 12. A lower end of the bell crank 14 is rotatably connected to a base end of a bucket link 15.

[0026] A 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] <Configuration of Work Machine and Operating Device> Figure 2 is a configuration diagram showing a work machine 1 and an operating device 7 according to an embodiment. As shown in Figure 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 articulate 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.

[0032] The engine 20 is a drive source for the work machine 1. The engine 20 is supported by the vehicle body 2. An example of the engine 20 is a diesel engine. 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.

[0033] The power transmission device 22 transmits the driving force of the engine 20 to the wheels 5. The power transmission device 22 controls the speed range and traveling direction of the work machine 1. The power transmission device 22 may be a transmission having a torque converter, or may be a transmission having a plurality of speed change gears. The brake device 23 reduces the traveling speed of the work machine 1.

[0034] 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 articulate 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 articulate cylinder 11. The articulate mechanism 3 is operated by the hydraulic oil from the steering pump 24.

[0035] 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.

[0036] 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. The attitude of the boom 12 includes the angle of the boom 12. The attitude of the bucket 13 includes the angle of the bucket 13.

[0037] The attitude of the boom 12 includes the angle of the boom 12. The boom angle sensor 28A detects a 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.

[0038] The attitude of the bucket 13 includes the angle of the bucket 13. The bucket angle sensor 28B detects a bucket angle that indicates the angle of the bucket 13. The bucket angle refers to the angle of the bucket 13 with respect to the boom 12 in a local coordinate system. In this embodiment, the bucket angle is the angle between a line connecting the rotation axis AXb and the cutting edge 13A and a line connecting the rotation axis AXa and the rotation axis AXb. An example of the bucket angle sensor 28B is an angle sensor that is disposed at the connection between the boom 12 and the bell crank 14. In this embodiment, the bucket angle sensor 28B detects a bell crank angle that indicates the angle of the bell crank 14 with respect to the boom 12 in the local coordinate system. The bell crank angle is the angle 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. The bucket angle and the bell crank angle have a one-to-one correspondence. The bucket angle sensor 28B detects the bell crank angle. The bucket angle is calculated based on the detected data of the bell crank angle and the detected data of the boom angle.

[0039] 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, the line connecting the rotation axis AXc and the rotation axis AXf, the line connecting the rotation axis AXb and the cutting edge 13A, 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.

[0040] 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, in which it holds excavated material, or in an empty state, in which it does not hold any excavated material. In this 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.

[0041] 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. The 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.

[0042] 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.

[0043] 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 selector lever 74. The accelerator pedal 71 is operated to increase the traveling speed of the work machine 1. The brake pedal 72 is operated to decrease the traveling speed of the work machine 1 or to stop the traveling of the work machine 1. The steering wheel 73 is operated to change the traveling direction of the work machine 1. The forward / reverse selector lever 74 is operated to switch the work machine 1 between forward and reverse travel.

[0044] 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 for operating 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. The boom lever 75 and the bucket lever 76 are each operated to a neutral position, a first operating position on one side of the neutral position, and a second operating position rearward of the neutral position.

[0045] When the boom lever 75 is operated, the spool of the boom control valve 38 moves. When the boom lever 75 is placed in the neutral position of the boom lever 75, the spool of the boom control valve 38 is placed in a neutral position where hydraulic oil does not flow. When the boom lever 75 is operated to one side from the neutral position of the boom lever 75, the spool of the boom control valve 38 is placed in a bottom position where hydraulic oil discharged from the work implement pump 26 is supplied to the bottom chamber of the boom cylinder 18. When the spool of the boom control valve 38 is placed 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, the spool of the boom control valve 38 is placed in a rod position where hydraulic oil discharged from the work implement pump 26 is supplied to the rod chamber of the boom cylinder 18. When the spool of the boom control valve 38 is placed in the rod position, the boom cylinder 18 retracts. 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 at 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 at the rod position, the boom cylinder 18 retracts. When the spool of the boom control valve 38 is located at the neutral position, the extension and contraction of the boom cylinder 18 is stopped.

[0046] When the bucket lever 76 is operated, the spool of the bucket control valve 39 moves. When the bucket lever 76 is placed in the neutral position of the bucket lever 76, the spool of the bucket control valve 39 is placed in a neutral position where hydraulic oil does not flow. When the bucket lever 76 is operated to one side from the neutral position of the bucket lever 76, the spool of the bucket control valve 39 is placed in a bottom position where hydraulic oil discharged from the work implement pump 26 is supplied to a bottom chamber of the bucket cylinder 19. When the spool of the bucket control valve 39 is placed in the bottom position, the bucket cylinder 19 extends. When the bucket lever 76 is operated to the other side from the neutral position of the bucket lever 76, the spool of the bucket control valve 39 is placed in a rod position where hydraulic oil discharged from the work implement pump 26 is supplied to a rod chamber of the bucket cylinder 19. When the spool of the bucket control valve 39 is placed in the rod position, the bucket cylinder 19 retracts. When the spool of the bucket control valve 39 is placed in the bottom position, the bucket cylinder 19 extends. When the spool of the bucket control valve 39 is positioned in the rod position, the bucket cylinder 19 contracts. When the spool of the bucket control valve 39 is positioned in the neutral position, the bucket cylinder 19 stops extending and contracting.

[0047] <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.

[0048] 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.

[0049] <Operation of the Work Machine> Figure 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 perform a raising or lowering operation of the boom 12. The bucket cylinder 19 extends and retracts to perform a tilting or dumping operation of the bucket 13.

[0050] 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.

[0051] The boom lever 75 is operated to one side from the neutral position of the boom lever 75 to extend the boom cylinder 18, thereby raising the boom 12. The boom lever 75 is operated to the other side from the neutral position of the boom lever 75 to retract the boom cylinder 18, thereby lowering the boom 12.

[0052] 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 cutting edge 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 cutting edge 13A moves closer to the ground.

[0053] When the bucket lever 76 is operated to one side from the neutral position of the bucket lever 76 and the bucket cylinder 19 extends, the bell crank 14 rotates so that the upper end of the bell crank 14 moves forward and the lower end of the bell crank 14 moves rearward. When the lower end of the bell crank 14 moves rearward, the bucket 13 is pulled rearward by the bucket link 15, performing a tilt operation. When the bucket lever 76 is operated to the other side from the neutral position of the bucket lever 76 and the bucket cylinder 19 retracts, the bell crank 14 rotates so that the upper end of the bell crank 14 moves rearward and the lower end of the bell crank 14 moves forward. When the lower end of the bell crank 14 moves forward, the bucket 13 is pushed forward by the bucket link 15, performing a dump operation.

[0054] 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.

[0055] As shown in Figure 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 machine operating device 7B to control the attitude of the work machine 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 machine 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.

[0056] In order to load excavated material into the dump body of the dump truck 300, the operator may perform a dump operation with the bucket 13 while raising the front end of the boom 12, and then operate the bucket 13 so that the excavated material adhering to the bucket 13 is shaken off from the bucket 13. When shaking off the excavated material adhering to the bucket 13 from the bucket 13, the operator operates the bucket lever 76 to reciprocate from one side to the other side of the neutral position. As the bucket lever 76 is operated to reciprocate, the bucket 13 repeatedly performs a tilt operation and a dump operation. As the bucket 13 repeatedly performs a tilt operation and a dump operation, the excavated material adhering to the bucket 13 is shaken off from the bucket 13. In the following description, the operation of the bucket 13 to repeat the excavation operation and the dump operation will be referred to as a predetermined operation, as appropriate.

[0057] 5 is a functional block diagram showing a control system 100 of the work machine 1 according to the 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, and a camera 29.

[0058] 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 travel control unit 106 , a work machine control unit 107 , and a transmission unit 108 .

[0059] The sensor data acquisition unit 101 acquires detection data from the work machine attitude sensor 28. The detection data from the work machine attitude sensor 28 includes detection data from a boom angle sensor 28A that indicates the boom angle, and detection data from a bucket angle sensor 28B that indicates the bucket angle.

[0060] 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.

[0061] The attitude determination unit 103 determines whether the attitude of the work machine 6 satisfies a predetermined attitude condition based on detection data from the work machine attitude sensor 28. Satisfying the attitude condition includes the work machine 6 being in a predetermined attitude where the height of the work machine 6 is equal to or greater than a predetermined height. The attitude determination unit 103 determines whether the height of the work machine 6 is equal to or greater than a predetermined height. The attitude determination unit 103 determines whether the height of the work machine 6 is equal to or greater than a predetermined height based on detection data from the work machine attitude sensor 28 that detects the attitude of the work machine 6.

[0062] In the embodiment, the work machine 6 being in the predetermined posture includes the bottom surface 13C of the bucket 13 being inclined downward toward the front. The posture determination unit 103 determines whether the bottom surface 13C of the bucket 13 is in the predetermined posture in which it is inclined downward toward the front.

[0063] The operation determination unit 104 determines whether the operation of the bucket 13 satisfies predetermined operation conditions based on the operation signal from the bucket lever 76. Satisfying the operation conditions includes causing the bucket 13 to perform a predetermined operation of repeating tilting and dumping. The operation determination unit 104 determines whether the bucket 13 has performed the predetermined operation of repeating tilting and dumping.

[0064] 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 travel.

[0065] 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.

[0066] The work machine control unit 107 also performs intervention control of the bucket 13. Intervention control of the bucket 13 refers to controlling the bucket control valve 39 so that the bucket control valve 39 is driven under predetermined conditions while the bucket lever 76 is being operated. In other words, intervention control of the bucket 13 refers to outputting a control command from the work machine control unit 107 so that the bucket 13 operates under predetermined conditions while the operation signal from the bucket lever 76 is being acquired by the operation signal acquisition unit 102.

[0067] 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.

[0068] <Construction machine control method> Figure 6 is a flowchart showing a control method for the construction machine 1 according to the embodiment. The operation signal acquisition unit 102 acquires an operation signal from the operation device 7. The travel control unit 106 controls the travel of the construction 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 (step S1).

[0069] The attitude determination unit 103 determines whether the work machine 6 is in a predetermined attitude based on the detection data of the work machine attitude sensor 28 that detects the attitude of the work machine 6 (step S2).

[0070] 7 is a diagram illustrating the posture of the work machine 6 according to the embodiment. The bucket 13 has a cutting edge 13A, an opening 13B, and a bottom surface 13C. The opening 13B is provided in the front portion of the bucket 13. The cutting edge 13A is provided at the lower end of the opening 13B. The bottom surface 13C is provided to extend rearward from the cutting edge 13A. The bottom surface 13C is a substantially flat surface.

[0071] The work implement 6 being in a predetermined posture includes the work implement 6 being at or above a predetermined height. When the boom 12 and the bucket 13 are connected via a rotation axis AXb, the height of the work implement 6 includes the height of the rotation axis AXb from the ground. If a line connecting the rotation axis CXf of the front wheels 5F and the rotation axis CXr of the rear wheels 5R is defined as a predetermined line RL, the predetermined height includes the height of the predetermined line RL from the ground. That is, in the embodiment, the work implement 6 being at or above a predetermined height includes the work implement 6 being at or above a predetermined height including the work implement 6 being positioned above the predetermined line RL. Note that the work implement 6 being at or above a predetermined height may also include the work implement 6 being positioned above the bottom surface of the vehicle body 2. Note that the height of the work implement 6 may also be the height of the bottom surface 13C of the bucket 13 from the ground. The height of the bottom surface 13C of the bucket 13 may change due to a tilting operation or a dumping operation of the bucket 13.

[0072] Furthermore, the work implement 6 being in the predetermined posture includes the bottom surface 13C of the bucket 13 being inclined downward toward the front. In the embodiment, if the line connecting the rotation axis CXf of the front wheels 5F and the rotation axis CXr of the rear wheels 5R is defined as the predetermined line RL, the work implement 6 being in the predetermined posture includes the bottom surface 13C of the bucket 13 being inclined downward toward the front with respect to the predetermined line RL. The posture determination unit 103 determines whether the bottom surface 13C of the bucket 13 is inclined downward toward the front with respect to the predetermined line RL. If the predetermined line RL is parallel to the horizontal plane, the work implement 6 being in the predetermined posture includes the cutting edge 13A being positioned below the rear of the bottom surface 13C. The work implement 6 being in the predetermined posture includes the vertical distance between the cutting edge 13A and the ground being shorter than the distance between the rear of the bottom surface 13C and the ground.

[0073] Note that the work implement 6 being in a predetermined posture may also include 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 work implement 6 being in a predetermined posture may also include 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. The posture determination unit 103 may determine whether the rotation axis AXb is positioned higher than the rotation axis AXa.

[0074] 4 , when excavated material is loaded onto the dump body of the dump truck 300, the bucket 13 performs a dumping operation with the front end of the boom 12 raised. The predetermined posture of the work implement 6 may be considered to be the posture of the work implement 6 immediately after the work implement 6 has loaded excavated material onto the dump body of the dump truck 300.

[0075] In step S2, if it is determined that the work implement 6 is in a predetermined posture (step S2: Yes), the operation determination unit 104 determines whether or not a predetermined operation in which the bucket 13 repeats tilting and dumping operations is occurring, based on the operation signal from the bucket lever 76 (step S3).

[0076] 8 and 9 are diagrams showing examples of an operation signal from the bucket lever 76 according to the embodiment. In the following description, the operation signal from the bucket lever 76 will be referred to as the bucket lever signal as appropriate. In FIGS. 8 and 9 , the horizontal axis represents the time elapsed since it was determined that the work implement 6 was in a predetermined posture, and the vertical axis represents the bucket lever signal. A positive value of the bucket lever signal means that the bucket lever 76 has been operated to one side from the neutral position of the bucket lever 76, and a negative value of the bucket lever signal means that the bucket lever 76 has been operated to the other side from the neutral position of the bucket lever 76. In other words, a positive value of the bucket lever signal means that the bucket 13 has performed a tilt operation, and a negative value of the bucket lever signal means that the bucket 13 has performed a dump operation.

[0077] The bucket lever signal includes the amount of operation of the bucket lever 76. The larger the absolute value of the bucket lever signal, the larger the amount of operation of the reciprocating bucket lever 76. The larger the absolute value of the bucket lever signal, the higher the operating speed of the bucket 13 that repeats tilting and dumping operations.

[0078] As described above, after loading excavated material into the dump body of the dump truck 300, the operator may perform a predetermined operation of the bucket 13 so that the excavated material adhering to the bucket 13 is shaken off from the bucket 13. When performing a predetermined operation of the bucket 13, the operator operates the bucket lever 76 to reciprocate to one side and the other side of the neutral position of the bucket lever 76. As shown in Fig. 8 , the bucket lever 76 is operated to reciprocate, causing the bucket lever signal to alternate between a positive value and a negative value.

[0079] The operation determination unit 104 determines that a predetermined operation of the bucket 13 has occurred when it determines that the number of times the bucket lever 76 has been operated back and forth to one side and the other side of the neutral position is equal to or greater than a predetermined number of times within a predetermined time Tm. The number of times the bucket lever 76 has been operated back and forth is the number of times the bucket lever signal has changed from one of a positive value state and a negative value state to the other state. For example, when the bucket lever signal changes from a positive value state to a negative value state and then changes back to a positive value state, the operation determination unit 104 determines that the number of times the bucket lever 76 has been operated back and forth is one.

[0080] The predetermined time Tm is a time from the point in time when it is determined that the work implement 6 is in the predetermined posture, and is a predetermined time. The predetermined number of times is a predetermined number of times. As an example, the predetermined time Tm is one second, and the predetermined number of times is two.

[0081] If it is determined in step S3 that a predetermined operation of the bucket 13 has occurred (step S3: Yes), the work machine control unit 107 determines whether or not to start intervention control of the bucket 13 based on the operating speed of the predetermined operation (step S4).

[0082] There is a one-to-one correspondence between the amplitude of the bucket lever signal when the bucket lever 76 is operated back and forth and the operating speed of the bucket 13 that repeats tilting and dumping operations. The greater the amplitude of the bucket lever signal, the higher the operating speed of the bucket 13 that performs the predetermined operation. The bucket lever signal includes the operation amount of the bucket lever 76. A larger amplitude of the bucket lever signal means that the absolute value of the operation amount of the bucket lever 76 that is operated back and forth is large. A larger amplitude of the bucket lever signal means that the operating speed of the bucket 13 that performs the predetermined operation is high. The operation determination unit 104 determines whether the operating speed of the predetermined operation of the bucket 13 exceeds a threshold value based on the amplitude of the bucket lever signal. The threshold value is a predetermined value.

[0083] The work machine control unit 107 compares the amplitude of the bucket lever signal at a time when a predetermined time Tm has elapsed since it was determined that the work machine 6 was in the predetermined posture with a threshold value Sh related to the bucket lever signal. That is, the work machine control unit 107 compares the absolute value of the operation amount of the bucket lever 76 at the time when the predetermined time Tm has elapsed with the threshold value Sh. The threshold value Sh is a predetermined value. If the work machine control unit 107 determines that the amplitude of the bucket lever signal (absolute value of the operation amount) at the time when the predetermined time Tm has elapsed is equal to or less than the threshold value Sh, it determines that the operating speed of the predetermined operation of the bucket 13 does not exceed the threshold value. If the work machine control unit 107 determines that the amplitude of the bucket lever signal (absolute value of the operation amount) at the time when the predetermined time Tm has elapsed exceeds the threshold value Sh, it determines that the operating speed of the predetermined operation of the bucket 13 has exceeded the threshold value.

[0084] In the example shown in Fig. 8 , as indicated by the symbol PK, the amplitude of the bucket lever signal at the time when the predetermined time Tm has elapsed does not exceed the threshold value Sh. In the example shown in Fig. 9 , as indicated by the symbol PK, the amplitude of the bucket lever signal at the time when the predetermined time Tm has elapsed exceeds the threshold value Sh. In the case of the amplitude of the bucket lever signal shown in Fig. 8 , the work implement control unit 107 determines that the operating speed of the predetermined operation of the bucket 13 does not exceed the threshold value. In the case of the amplitude of the bucket lever signal shown in Fig. 9 , the work implement control unit 107 determines that the operating speed of the predetermined operation of the bucket 13 has exceeded the threshold value.

[0085] If the work machine control unit 107 determines that the operating speed of the predetermined operation of the bucket 13 does not exceed the threshold value, it determines not to start intervention control of the bucket 13. If the work machine control unit 107 determines that the operating speed of the predetermined operation of the bucket 13 exceeds the threshold value, it determines to start intervention control of the bucket 13.

[0086] If it is determined in step S4 that intervention control of the bucket 13 should be started (step S4: Yes), the work machine control unit 107 outputs a control command so that the operating speed of the predetermined operation of the bucket 13 is equal to or less than a threshold. In the embodiment, the intervention control of the bucket 13 includes performing a limiting process to reduce the amplitude of the bucket lever signal while the bucket lever signal is being acquired by the operation signal acquisition unit 102. While the bucket lever signal is being acquired by the operation signal acquisition unit 102, the work machine control unit 107 performs the limiting process to reduce the amplitude of the bucket lever signal (step S5).

[0087] As shown in FIG. 9 , the work machine control unit 107 performs limiting processing on the bucket lever signal acquired by the operation signal acquisition unit 102 to generate a bucket lever signal with a small amplitude. As a result of the limiting processing, the amplitude of the bucket lever signal decreases after a predetermined time Tm has elapsed. As a result of the limiting processing, the amplitude of the bucket lever signal is suppressed to a value equal to or less than the threshold value Sh. The work machine control unit 107 outputs a control command to control the bucket control valve 39 based on the bucket lever signal that has been limited. The bucket control valve 39 is driven based on the bucket lever signal that has been limited (step S6).

[0088] In the embodiment, the work machine control unit 107 changes the amplitude so as to reduce the amplitude (absolute value of the operation amount) of the bucket lever signal acquired by the operation signal acquisition unit 102. The work machine control unit 107 does not change the timing at which the bucket lever signal acquired by the operation signal acquisition unit 102 switches from one of a positive value state and a negative value state to the other state. In other words, when the bucket lever 76 is operated to one side and the other side of the neutral position at regular time intervals, the work machine control unit 107 does not change the period of the bucket lever signal acquired by the operation signal acquisition unit 102.

[0089] As the amplitude of the bucket lever signal decreases, the operating speed of the predetermined operation of the bucket 13 decreases.

[0090] The work machine control unit 107 determines whether or not to end the intervention control based on the bucket lever signal acquired by the operation signal acquisition unit 102 (step S7).

[0091] The work machine control unit 107 determines to end the intervention control when it determines that the amplitude of the bucket lever signal acquired by the operation signal acquisition unit 102 is equal to or less than the threshold value Sh. For example, when the operator reduces the amount of operation of the bucket lever 76 or stops operating the bucket lever 76, it determines to end the intervention control.

[0092] In step S7, if it is determined not to end the intervention control (step S7: No), the work machine control unit 107 returns to the processing of step S5. In step S7, if it is determined to end the intervention control (step S7: Yes), the work machine control unit 107 returns to the processing of step S1.

[0093] If it is determined in step S2 that the work implement 6 is not in the predetermined posture (step S2: No), if it is determined in step S3 that the bucket 13 has performed the predetermined operation (step S3: No), or if it is determined in step S4 that intervention control of the bucket 13 will not be started (step S4: No), the work implement control unit 107 does not perform limiting processing on the bucket lever signal, and outputs a control command to control the bucket control valve 39 based on the operation signal acquired by the operation signal acquisition unit 102. The bucket control valve 39 is driven based on the bucket lever signal that has not been limited (step S8).

[0094] <Effects> As described above, according to the embodiment, the on-board controller 30 includes an attitude determination unit 103 that determines whether the height of the work implement 6 of the work machine 1 is equal to or greater than a predetermined height; an operation determination unit 104 that, when it is determined that the height of the work implement 6 is equal to or greater than the predetermined height, determines whether the bucket 13 has performed a predetermined operation in which the bucket 13 repeatedly performs a tilt operation and a dump operation; and a work implement control unit 107 that, when it is determined that the bucket 13 has performed the predetermined operation and that the operation speed of the predetermined operation has exceeded a threshold, outputs a control command so that the operation speed becomes equal to or less than the threshold.

[0095] According to the embodiment, for example, when the bucket lever 76 is violently operated by the operator so that excavated material adhering to the bucket 13 is shaken off from the bucket 13, intervention control is implemented so that the tilting and dumping operations of the bucket 13 do not accelerate deterioration of the work implement 6. Therefore, deterioration of the work machine 1 is suppressed.

[0096] When the work machine 1 is remotely operated, the operator in the remote control room 202 is unlikely to feel that the bucket 13 is moving violently, even if the bucket lever 76 is operated violently. Therefore, the operator in the remote control room 202 may unintentionally operate the bucket lever 76 violently. According to the embodiment, when the bucket lever 76 is operated violently, intervention control is implemented to prevent the tilting and dumping operations of the bucket 13 from becoming violent. Therefore, deterioration of the work implement 6 is suppressed.

[0097] Other Embodiments In the above-described embodiments, the operation determination unit 104 determines whether or not the bucket 13 is performing a predetermined operation based on the bucket lever signal. Furthermore, the work implement control unit 107 determines whether or not the operating speed of the bucket 13 performing a predetermined operation has exceeded a threshold value based on the amplitude of the bucket lever signal. The operation determination unit 104 may determine whether or not the bucket 13 is performing a predetermined operation based on detection data from the work implement attitude sensor 28 (bucket angle sensor 28B). The work implement control unit 107 may determine whether or not the operating speed of the bucket 13 performing a predetermined operation has exceeded a threshold value based on detection data from the work implement attitude sensor 28 (bucket angle sensor 28B). If a pressure sensor that detects the pressure of the hydraulic oil in the bucket cylinder 19 (the bottom pressure of the bucket cylinder 19) is provided, the operation determination unit 104 may determine whether or not the bucket 13 is performing a predetermined operation based on detection data from the pressure sensor. The work implement control unit 107 may determine whether or not the operating speed of the bucket 13 performing a predetermined operation has exceeded a threshold value based on detection data from the pressure sensor.

[0098] Furthermore, when camera 29 captures an image of work machine 6, operation determination unit 104 may determine whether or not bucket 13 has performed a predetermined operation based on image data of work machine 6 captured by camera 29. Work machine control unit 107 may determine whether or not the amplitude of bucket 13 performing a predetermined operation has exceeded a threshold value based on image data of work machine 6 captured by 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 operated. 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. However, the work machine 1 may also be a hydraulic excavator having a work implement.

[0103] Second Embodiment A second embodiment will be described below. In the following description, the same or equivalent components as those in the above-described embodiment will be denoted by the same reference numerals, and the description of those components will be simplified or omitted.

[0104] <Operation of the Work Machine> Figure 10 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 12 is raised or lowered by extending or contracting the boom cylinder 18. The bucket cylinder 19 is extended or contracted by extending or contracting the bucket 13, causing the bucket 13 to tilt or dump.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 10 , 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.

[0109] 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.

[0110] 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.

[0111] 11 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.

[0112] 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.

[0113] 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 a boom angle sensor 28A that indicates the boom angle, and detection data from a bucket angle sensor 28B that indicates the bucket angle.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 travel.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] <Construction machine control method> Figure 12 is a flowchart showing a control method for the construction machine 1 according to the embodiment. The operation signal acquisition unit 102 acquires an operation signal from the operation device 7. The travel control unit 106 controls the travel of the construction 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).

[0123] The attitude determination unit 103 determines whether the work implement 6 is in a raising attitude based on the detection data of the work implement attitude sensor 28 that detects the attitude of the work implement 6 (step S2).

[0124] The working implement 6 being in a raising posture includes the boom 12 being in a raising posture. The boom 12 being in a raising posture 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 posture 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 posture 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.

[0125] 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 with respect 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.

[0126] 10 , 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.

[0127] If it is determined in step S2 that the work implement 6 is in the raised posture (step S2: Yes), the operation determination unit 104 determines whether the boom 12 is moving from the raised posture to the lowered 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 to the lowered posture based on the detection data of the boom angle sensor 28A (step S3).

[0128] 13 and 14 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. 13 and Fig. 14, 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.

[0129] 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.

[0130] 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.

[0131] 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 indicates that the boom lever 75 has been 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 indicates a higher boom acceleration. A smaller rate of change of the boom lever signal indicates a lower boom acceleration.

[0132] 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. 10 , after the operator loads excavated material into the dump body of the dump truck 300, the operator lowers the boom 12. When the boom lever 75 is operated to interrupt the lowering operation while the boom lever 75 is operating 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.

[0133] 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).

[0134] The work implement control unit 107 determines whether 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 value Sh 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.

[0135] FIG. 13 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.

[0136] In Figure 13, time t1 is the time when operation of the boom lever 75 is started to lower the boom 12 from 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 located in the neutral position.

[0137] FIG. 14 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. 14 , 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. 14 , 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 being lowered, the rate of change of the boom lever signal becomes large from time t3 to time t4a.

[0138] In the case of the rate of change of the boom lever signal shown in Fig. 13, 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. 14, the work implement control unit 107 determines that the rate of change of the boom lever signal exceeds the threshold value She.

[0139] 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 has exceeded the threshold value She, it determines to start intervention control of the boom 12.

[0140] 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. 14, 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.

[0141] 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).

[0142] 14, 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.

[0143] As indicated by the dotted line in FIG. 14 , 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).

[0144] 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 is reduced. Because the rate of change of the boom lever signal is reduced, 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.

[0145] 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. 14, 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.

[0146] The work machine control unit 107 determines whether 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.

[0147] 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 lowering (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).

[0148] <Effects> 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, when the rate of change in the operation signal is large while the work implement 6 is being lowered from a raised posture in which it has risen to or above a predetermined height Hp, outputs a control command to reduce the rate of change. In the embodiment, when the work implement control unit 107 determines that the rate of change in the operation signal exceeds the threshold value Sh, it outputs a control command to reduce the rate of change to equal to or less than the threshold value Sh.

[0149] 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 lowering, or if the boom lever 75 is operated to suddenly raise the boom 12 while the boom 12 is lowering, the weight balance of the work machine 1 will change so that the rear wheels 5R of the work machine 1 lift 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 early deterioration of the body 2 and work implement 6 of the work machine 1.

[0150] 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 implemented to prevent the lowering operation of the boom 12 from being suddenly interrupted. This prevents deterioration of the vehicle body 2 and the work implement 6 of the work machine 1.

[0151] 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.

[0152] 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 when 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, a significant disruption of the weight balance of the work machine 1 is suppressed.

[0153] Other Embodiments As described above, when 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 intervention control is not performed. As described with reference to Fig. 14, for example, when the operator wants to stop the boom 12 being lowered at height Hg, if intervention control is performed, the boom 12 is lowered to height Ha, which is lower than height Hg. When height Ha is higher than the ground, the bucket 13 can be stopped at height Ha without coming into contact with the ground, even when intervention control is performed.

[0154] 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.

[0155] For example, when the work implement control unit 107 outputs a control command at a constant 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 current control command] = w1 × [Command value of previous control command] + w2 × [Command value of 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.

[0156] 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.

[0157] 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.

[0158] 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 .

[0159] 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.

[0160] In the above-described embodiment, the work machine 1 does not have to be remotely operated. An operator may operate the work machine 1 by getting into the cab 4 of the work machine 1.

[0161] In the above-described embodiment, the work machine 1 is a wheel loader. However, 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.

[0162] [Supplementary Notes] The present disclosure may also adopt the following configurations. (Supplementary Note 1) A work machine control system including a controller, which determines whether a bucket of a work implement of a work machine is performing a predetermined operation in which the bucket repeatedly performs a tilt operation and a dump operation, and if it determines that the predetermined operation has occurred and that the operating speed of the predetermined operation has exceeded a threshold, outputs a control command so that the operating speed is at or below the threshold. (Supplementary Note 2) The work machine control system described in (Supplementary Note 1), in which the controller determines whether the height of the work implement is at or above a predetermined height based on detection data from a work implement attitude sensor that detects the attitude of the work implement. (Supplementary Note 3) The work machine control system described in (Supplementary Note 1) or (Supplementary Note 2), in which the controller determines whether the bottom surface of the bucket is inclined downward toward the front. (Supplementary Note 4) The work machine control system described in (Supplementary Note 3), wherein the work machine has front and rear wheels, and when a line connecting the rotational axes of the front wheels and the rotational axes of the rear wheels is defined as a specified line, the controller determines whether or not the bottom surface of the bucket is inclined downward toward the front with respect to the specified line. (Supplementary Note 5) The work machine control system described in (Supplementary Note 4), wherein the work implement has a boom connected to a body of the work machine so as to be rotatable about a first rotation axis, and the bucket is connected to the boom so as to be rotatable about a second rotation axis, and the controller determines whether or not the second rotation axis is located above the first rotation axis. (Supplementary Note 6) The work machine control system described in any one of (Supplementary Note 1) to (Supplementary Note 5), wherein the controller determines whether or not the predetermined operation has occurred based on an operation signal from a bucket lever that is operated to operate the bucket.(Supplementary Note 7) The work machine control system described in (Supplementary Note 6), wherein the bucket tilts when the bucket lever is operated to one side from a neutral position of the bucket lever, and dumps when the bucket is operated to the other side from the neutral position, and the controller determines that the predetermined operation has occurred when it determines that the number of times the bucket lever has been operated back and forth between one side and the other side from the neutral position is equal to or greater than a predetermined number of times in a predetermined time. (Supplementary Note 8) The work machine control system described in (Supplementary Note 7), wherein the controller determines whether the operation speed of the predetermined operation has exceeded the threshold value based on the amplitude of the operation signal. (Supplementary Note 9) The work machine control system described in (Supplementary Note 8), wherein the controller outputs the control command so as to reduce the amplitude of the operation signal when an operation signal from the bucket lever has been acquired. (Supplementary Note 10) A work machine comprising the work machine control system described in any one of (Supplementary Note 1) to (Supplementary Note 9). (Supplementary Note 11) A work machine remote operation system comprising the work machine control system described in any one of (Supplementary Note 1) to (Supplementary Note 9). (Supplementary Note 12) A work machine control method including: a controller determining whether the height of a work implement possessed by the work machine is in a predetermined posture where it is equal to or greater than a predetermined height; if it is determined that the work machine is in the predetermined posture, determining whether or not a predetermined operation in which the bucket of the work implement repeats tilting and dumping operations has occurred; and if it is determined that the predetermined operation has occurred and that the operating speed of the predetermined operation has exceeded a threshold, outputting a control command so that the operating speed is equal to or less than the threshold. (Supplementary Note 13) A work machine control system comprising a controller, wherein the controller acquires an operation signal from an operating device operated to operate the work implement possessed by the work machine, and if the operating device is suddenly operated to change the weight balance of the work machine while the work implement is lowering from a raised position in which it is raised, outputs a control command so that the rate of change of the operation signal becomes smaller.(Supplementary Note 14) The work machine control system described in (Supplementary Note 13), wherein the controller 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. (Supplementary Note 15) The work machine control system described in (Supplementary Note 13) or (Supplementary Note 14), wherein the controller determines whether the work machine is performing the lowering operation based on the detection data from a work machine attitude sensor that detects the attitude of the work machine or the operation signal. (Supplementary Note 16) The work machine control system described in any one of (Supplementary Note 13) to (Supplementary Note 15), wherein the work machine has a boom that is rotatably connected to a body of the work machine about a first rotation shaft, and a bucket that is rotatably connected to the boom about a second rotation shaft, and being in the raising attitude includes the second rotation shaft being positioned above the first rotation shaft. (Supplementary Note 17) A work machine control system as set forth in any one of (Supplementary Note 13) to (Supplementary Note 16), wherein, when it is determined that the rate of change of the operation signal exceeds a threshold, the controller outputs a control command so that the rate of change is equal to or less than the threshold. (Supplementary Note 18) A work machine control system as set forth in (Supplementary Note 17), wherein the controller has a threshold setting unit that changes the threshold based on detection data from a load sensor that detects the load state of the work machine. (Supplementary Note 19) A work machine control system as set forth in (Supplementary Note 18), wherein the controller determines whether the work machine is in a loaded state or an unloaded state based on the detection data from the load sensor, and sets the threshold for the loaded state to be smaller than the threshold for the unloaded state. (Supplementary Note 20) A work machine control system as set forth in (Supplementary Note 18) or (Supplementary Note 19), wherein the load sensor includes a weight sensor that detects the weight of the work machine. (Supplementary Note 21) A work machine comprising the work machine control system as set forth in any one of (Supplementary Note 13) to (Supplementary Note 20). (Supplementary Note 22) A remote control system for a work machine, comprising the work machine control system according to any one of (Supplementary Note 13) to (Supplementary Note 21).(Supplementary Note 23) A control method for a work machine, comprising: a controller acquiring an operation signal from an operation device that is operated to operate a work implement of the work machine; and, 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 has risen to a predetermined height or higher, outputting a control command to reduce the rate of change.

[0163] 1...working machine, 2...body, 2F...front frame, 2R...rear frame, 3...articulating mechanism, 4...cab, 5...wheels, 5F...front wheels, 5R...rear wheels, 6...working machine, 7...operating device, 7A...traveling system operating device, 7B...working machine operating device, 8...display device, 9...remote controller, 10...operating seat, 11...articulating cylinder, 12...boom, 13...bucket, 13A...blade tip, 13B...opening, 13C...bottom, 14...bell run 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-vehicle 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 switch 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 ...Operation determination unit, 105...Threshold setting unit, 106...Travel control unit, 107...Work machine control unit, 108...Transmitter unit, 200...Remote operation system, 201...Work site, 202...Remote operation room, 203...Communication system, 300...Dump truck, 700...Operation device, AXa...Rotation axis (first rotation axis), AXb...Rotation axis (second rotation axis), AXc...Rotation axis, AXd...Rotation axis, AXe...Rotation axis, AXf...Rotation axis, CXf...Rotation axis, CXr...Rotation axis, RL...Specified line.

Claims

1. A control system for a work machine, comprising: a controller that determines whether or not a predetermined operation in which a bucket of a work implement of the work machine repeats tilting and dumping operations is occurring; and, if it is determined that the predetermined operation has occurred and that the operating speed of the predetermined operation has exceeded a threshold, outputs a control command to reduce the operating speed to below the threshold.

2. A work machine control system as described in claim 1, wherein the controller determines whether the height of the work machine is equal to or greater than a predetermined height based on detection data from a work machine attitude sensor that detects the attitude of the work machine.

3. The control system for a work machine according to claim 1, wherein the controller determines whether or not the bottom surface of the bucket is inclined downward toward the front.

4. A control system for a work machine as described in claim 3, wherein the work machine has front and rear wheels, and when a line connecting the rotational axes of the front wheels and the rear wheels is defined as a specified line, the controller determines whether the bottom surface of the bucket is inclined downward toward the front with respect to the specified line.

5. A work machine control system as described in claim 4, wherein the work implement has a boom that is rotatably connected to the body of the work machine around a first rotation axis, and the bucket is rotatably connected to the boom around a second rotation axis, and the controller determines whether the second rotation axis is positioned above the first rotation axis.

6. A work machine control system according to claim 1, wherein the controller determines whether or not the predetermined operation is occurring based on an operation signal from a bucket lever that is operated to operate the bucket.

7. A work machine control system according to claim 6, wherein the bucket tilts when the bucket lever is operated to one side from a neutral position of the bucket lever, and dumps when the bucket is operated to the other side from the neutral position, and the controller determines that the predetermined operation has occurred when it determines that the number of times the bucket lever has been operated back and forth between one side and the other side from the neutral position is equal to or greater than a predetermined number of times within a predetermined period of time.

8. A work machine control system according to claim 7, wherein the controller determines whether or not the operating speed of the predetermined operation exceeds the threshold value based on the amplitude of the operation signal.

9. A work machine control system according to claim 8, wherein the controller outputs the control command while an operation signal is being acquired from the bucket lever so as to reduce the amplitude of the operation signal.

10. A work machine comprising the work machine control system according to claim 1.

11. A remote control system for a work machine, comprising the work machine control system according to claim 1.

12. A control method for a work machine, comprising: a controller determining whether the height of a work implement of the work machine is equal to or greater than a predetermined height; if it is determined that the height of the work implement is equal to or greater than the predetermined height, determining whether or not a predetermined operation in which the bucket of the work implement repeats tilting and dumping operations has occurred; and if it is determined that the predetermined operation has occurred and that the operating speed of the predetermined operation has exceeded a threshold, outputting a control command so that the operating speed becomes equal to or less than the threshold.

13. A control system for a work machine, comprising: a controller that acquires an operation signal from an operation device that is operated to operate a work implement of the work machine; and, when the operation device is suddenly operated and the weight balance of the work machine changes while the work implement is lowering from a raised position, the controller outputs a control command to reduce the rate of change in the operation signal.

14. A work machine control system according to claim 13, wherein the controller determines whether the work machine is in the raised posture based on detection data from a work machine posture sensor that detects the posture of the work machine.

15. A work machine control system according to claim 13, wherein the controller determines whether the work machine is performing the lowering operation based on the operation signal or on detection data from a work machine attitude sensor that detects the attitude of the work machine.

16. A work machine control system as described in claim 13, wherein the work implement has a boom rotatably connected to the body of the work machine around a first rotation shaft, and a bucket rotatably connected to the boom around a second rotation shaft, and the raised posture includes the second rotation shaft being positioned higher than the first rotation shaft.

17. A work machine control system according to claim 13, wherein, when it is determined that the rate of change of the operation signal exceeds a threshold, the controller outputs a control command so that the rate of change becomes equal to or less than the threshold.

18. A work machine control system according to claim 17, wherein the controller changes the threshold value based on detection data from a load sensor that detects the load state of the work machine.

19. A work machine control system as set forth in claim 18, wherein the controller 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 the threshold value for the loaded state to be smaller than the threshold value for the unloaded state.

20. A work machine control system according to claim 18, wherein the load sensor includes a weight sensor that detects the weight of the work machine.

21. A work machine comprising the work machine control system according to claim 13.

22. A remote control system for a work machine, comprising the work machine control system according to claim 13.

23. A control method for a work machine, in which a controller acquires an operation signal from an operation device that is operated to operate a work implement of the work machine, and 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 has risen to a predetermined height or higher, outputs a control command to reduce the rate of change.

Images