Patent Grant
12018452
The present disclosure relates to a work machine, a system, and a method of controlling a work machine.
In a work machine such as a hydraulic excavator, a bucket may naturally fall while the work machine waits for a dump truck with the bucket carrying a load. Natural fall of the bucket occurs due to a self-weight of the bucket, a weight of a load, leakage of hydraulic oil through a gap around a spool in a main valve, or leakage of hydraulic oil from the inside of a cylinder. Japanese Patent Laying-Open No. 2-88825 (see PTL 1) describes providing a pilot operation check valve in a circuit for activating a boom cylinder in order to prevent natural fall of the bucket.
According to a technique described in PTL 1, however, when a hydraulic excavator waits for arrival of a loaded machine such as a dump truck with a bucket carrying a load, natural fall of the bucket cannot completely be prevented. When the bucket naturally falls, the bucket may interfere with the loaded machine at the time of entry of the loaded machine.
An object of the present disclosure is to provide a work machine, a system, and a method of controlling a work machine that allow avoidance of interference of a bucket with a loaded machine at the time of entry of the loaded machine.
A work machine in the present disclosure is a work machine that loads a load onto a loaded machine, and the work machine includes a work implement and a controller. The work implement includes a bucket. The controller senses an amount of natural lowering of the bucket in a stand-by state in which the work machine waits for entry of the loaded machine and controls the work implement to raise the bucket based on the amount of natural lowering.
According to the present disclosure, a work machine, a system, and a method of controlling a work machine that allow avoidance of interference of a bucket with a loaded machine at the time of entry of the loaded machine can be provided.
An embodiment of the present disclosure will be described below with reference to the drawings.
The same or corresponding constituent elements in the specification and the drawings have the same reference characters allotted and redundant thereof will not be repeated. For the sake of convenience of description, a feature in the drawings may not be shown or may be simplified.
Though a hydraulic excavator is described by way of example of a work machine in the present disclosure, the present disclosure is applicable to a work machine including a bucket, other than the hydraulic excavator. The present disclosure is applicable, for example, also to a crane, an ultra large rope excavator that is not hydraulically driven, and an ultra large electric excavator driven by an electric motor. In the description below, “upward”, “downward”, “front”, “rear”, “left”, and “right” refer to directions with an operator sitting in an operator's seat 2b in an operator's cab 2a being defined as the reference.
<Construction of Work Machine>
Traveling unit 1 includes a pair of left and right crawler belt apparatuses 1a. Each of the pair of left and right crawler belt apparatuses 1a includes a crawler belt. As the pair of left and right crawler belts is rotationally driven, hydraulic excavator 100 is self-propelled.
Revolving unit 2 is provided as being revolvable with respect to traveling unit 1. Revolving unit 2 mainly includes operator's cab (cab) 2a, operator's seat 2b, an engine compartment 2c, and a counterweight 2d. Operator's cab 2a is arranged, for example, on a front left side (a front side of a vehicle) of revolving unit 2. In an internal space in operator's cab 2a, operator's seat 2b where an operator takes a seat is arranged.
Each of engine compartment 2c and counterweight 2d is arranged on a rear side of revolving unit 2 (on a rear side of the vehicle) with respect to operator's cab 2a. An engine unit (an engine, an exhaust treatment structure body, etc.) is accommodated in engine compartment 2c. An engine hood covers engine compartment 2c from above. Counterweight 2d is arranged in the rear of engine compartment 2c.
Work implement 3 is supported on a front side of revolving unit 2, for example, on the right side of operator's cab 2a. Work implement 3 includes, for example, a boom 3a, an arm 3b, a bucket 3c, a boom cylinder 4a, an arm cylinder 4b, and a bucket cylinder 4c. Boom 3a has a base end pivotably coupled to revolving unit 2 by a boom foot pin 5a. Arm 3b has a base end pivotably coupled to a tip end of boom 3a by a boom tip end pin 5b. Bucket 3c is pivotably coupled to a tip end of arm 3b by a pin 5c.
Boom 3a can be driven by boom cylinder 4a. As the boom is driven, boom 3a can pivot in an upward/downward direction with respect to revolving unit 2 around boom foot pin 5a. Arm 3b can be driven by arm cylinder 4b. As the arm is driven, arm 3b can pivot in the upward/downward direction with respect to boom 3a around boom tip end pin 5b. Bucket 3c can be driven by bucket cylinder 4c. As the bucket is driven, bucket 3c can pivot in the upward/downward direction with respect to arm 3b around pin 5c. Work implement 3 can thus be driven.
Work implement 3 includes a bucket link 3d. Bucket link 3d includes a first link member 3da and a second link member 3db. A tip end of first link member 3da and a tip end of second link member 3db are coupled to each other as being pivotable relative to each other with a bucket cylinder top pin 3dc being interposed. Bucket cylinder top pin 3dc is coupled to a tip end of bucket cylinder 4c. Therefore, first link member 3da and second link member 3db are coupled to bucket cylinder 4c with a pin being interposed.
First link member 3da has a base end pivotably coupled to arm 3b by a first link pin 3dd. Second link member 3db has a base end pivotably coupled to a bracket at a root of bucket 3c by a second link pin 3de.
A pressure sensor 6a is attached to a head side of boom cylinder 4a. Pressure sensor 6a can detect a pressure (a head pressure) of hydraulic oil in a cylinder head side oil chamber 40A of boom cylinder 4a. A pressure sensor 6b is attached to a bottom side of boom cylinder 4a. Pressure sensor 6b can detect a pressure (a bottom pressure) of hydraulic oil in a cylinder bottom side oil chamber 40B of boom cylinder 4a.
Stroke sensors (sensing units) 7a, 7b, and 7c are attached to boom cylinder 4a, arm cylinder 4b, and bucket cylinder 4c, respectively.
A boom angle θb can be calculated from an amount of displacement of a cylinder rod 4ab with respect to a cylinder 4aa in boom cylinder 4a. An arm angle θa can be calculated from an amount of displacement of a cylinder rod in arm cylinder 4b. A bucket angle θk can be calculated from an amount of displacement of a cylinder rod in bucket cylinder 4c.
Potentiometers 9a, 9b, and 9c may be attached around boom foot pin 5a, boom tip end pin 5b, and pin 5c, respectively. Boom angle θb can be calculated from a measurement value from potentiometer 9a. Arm angle θa can be calculated from a measurement value from potentiometer 9b. Bucket angle θk can be calculated from a measurement value from potentiometer 9c.
Inertial measurement units (IMUs) 8a, 8b, 8c, and 8d may be attached to revolving unit 2, boom 3a, arm 3b, and first link member 3da, respectively. IMU 8a measures an acceleration of revolving unit 2 in a front/rear direction, a lateral direction, and an upward/downward direction and an angular velocity of revolving unit 2 around the front/rear direction, the lateral direction, and the upward/downward direction. IMUs 8b, 8c, and 8d measure accelerations of boom 3a, arm 3b, and bucket 3c in the front/rear direction, the lateral direction, and the upward/downward direction and angular velocities of boom 3a, arm 3b, and bucket 3c around the front/rear direction, the lateral direction, and the upward/downward direction, respectively.
IMUs 8b, 8c, and 8d may calculate boom angle θb, arm angle θa, and bucket angle θk, respectively. An attitude of the work implement can be known from boom angle θb, arm angle θa, bucket angle θk, a boom length, an arm length, and the like.
Hydraulic excavator 100 includes a measurement apparatus 10, a receiver 11, and a revolution angle sensor 13. Measurement apparatus 10 is a three-dimensional distance sensor and used for measurement of a height of a loaded machine 50. Measurement apparatus 10 may be implemented, for example, by an image pick-up apparatus such as a stereo camera or laser imaging detection and ranging (LIDAR).
Receiver 11 receives a signal from a transmitter of loaded machine 50. The signal received by receiver 11 includes height information of loaded machine 50. Revolution angle sensor 13 senses an angle of revolution of revolving unit 2 relative to traveling unit 1. Revolution angle sensor 13 is implemented, for example, by a sensor provided in a swing motor, a sensor that detects a tooth of swing machinery, or IMU 8a.
<Operations Including Stand-by State of Work Machine>
Operations including a stand-by state of the work machine will now be described with reference to
As shown in
While bucket 3c is located at a set height, hydraulic excavator 100 stands by until loaded machine 50 enters a loading site. The set height of bucket 3c in the stand-by state may be a certain height determined in advance.
The set height of bucket 3c in the stand-by state may be a height calculated based on a height of loaded machine 50 obtained by vehicle-to-vehicle communication between hydraulic excavator 100 and loaded machine 50. Alternatively, the set height of bucket 3c in the stand-by state may be a height calculated based on a height of loaded machine 50 obtained by measurement (image pick-up or determination) by hydraulic excavator 100.
In hydraulic excavator 100 in the present embodiment, the set height of bucket 3c in the stand-by state is calculated based on the height of loaded machine 50 obtained by vehicle-to-vehicle communication or the like as set forth above. Since bucket 3c can thus stand by at an appropriate set height for each loaded machine 50, interference of bucket 3c with loaded machine 50 can be avoided.
In the stand-by state, bucket 3c naturally lowers due to the self-weight of bucket 3c and the weight of the load in bucket 3c. As bucket 3c naturally lowers in the stand-by state, bucket 3c may interfere with loaded machine 50 that enters the loading site.
Hydraulic excavator 100 in the present embodiment senses natural lowering of bucket 3c. When an amount of natural lowering is equal or larger than a prescribed value, work implement 3 is controlled to raise bucket 3c. Interference of bucket 3c in the stand-by state with loaded machine 50 can thus be avoided.
As loaded machine 50 enters the loading site, the load in bucket 3c is ejected from bucket 3c and loaded onto loaded machine 50. After the load in bucket 3c is ejected, hydraulic excavator 100 carries out descending and revolving movement so that bucket 3c of hydraulic excavator 100 reaches a next excavation position. After bucket 3c reaches the next excavation position, next excavation is done. Thereafter, operations similar to the above are repeated.
As a platform of loaded machine 50 is fully loaded with loads as a result of repeated operations, loaded machine 50 travels from the loading site to a load ejection site.
A series of operations including excavation, hoisting and revolving movement, stand-by, ejection of loads, and descending and revolving movement may be performed in an automatic control mode without an operation by an operator. Alternatively, the series of operations may be performed by an operation by the operator.
<Hydraulic Circuit and Operation Apparatus of Work Machine>
A hydraulic circuit and an operation apparatus of the work machine will now be described with reference to
A hydraulic pump 43 is coupled to engine 42. As rotational driving force of engine 42 is transmitted to hydraulic pump 43, hydraulic pump 43 is driven. Hydraulic pump 43 is, for example, a variable displacement hydraulic pump that includes a swash plate and varies a delivery capacity by changing a tilting angle of the swash plate.
Some of oil delivered from hydraulic pump 43 is supplied to a main valve 41 as hydraulic oil. Remainder of oil delivered from hydraulic pump 43 is supplied for pilot use, with a pressure thereof being reduced to a certain pressure by a self-pressure reduction valve 45. Oil with the pressure thereof being reduced to a certain pressure by self-pressure reduction valve 45 is supplied to main valve 41 through an electromagnetic proportional control (EPC) valve 46.
EPC valve 46 receives a current command from controller 20. EPC valve 46 generates a pilot pressure in accordance with a current value in the current command. EPC valve 46 drives a spool of main valve 41 with the pilot pressure.
Boom cylinder 4a, arm cylinder 4b, bucket cylinder 4c, and a revolution motor 44 are connected to main valve 41 as hydraulic actuators. Revolution motor 44 rotates revolving unit 2 relatively to traveling unit 1. As the spool of main valve 41 axially moves, an amount of supply of hydraulic oil to each of hydraulic actuators 4a, 4b, 4c, and 44 is adjusted. Operations of work implement 3 and revolution of revolving unit 2 are thus controlled.
In the present example, oil supplied to hydraulic actuators 4a, 4b, 4c, and 44 for activating hydraulic actuators 4a, 4b, 4c, and 44 is referred to as hydraulic oil. Oil supplied to main valve 41 for activating main valve 41 is referred to as pilot oil. A pressure of pilot oil is referred to as a pilot hydraulic pressure (PPC pressure).
Hydraulic pump 43 may deliver both of hydraulic oil and pilot oil as set forth above. Hydraulic pump 43 may include a hydraulic pump (a main hydraulic pump) that delivers hydraulic oil and a hydraulic pump (a pilot hydraulic pump) that delivers pilot oil separately from each other.
When hydraulic excavator 100 is in the automatic control mode, EPC valve 46 is controlled under a command from controller 20 without an operation command from an operation apparatus 25, to thereby adjust an amount of supply of hydraulic oil to each of hydraulic actuators 4a, 4b, 4c, and 44. When hydraulic excavator 100 is thus in the automatic control mode, the series of operations including excavation, hoisting and revolving movement, stand-by, ejection of loads, and descending and revolving movement is performed without an operation command from operation apparatus 25.
When hydraulic excavator 100 is not in the automatic control mode, EPC valve 46 is controlled under a command from controller 20 based on an operation command from operation apparatus 25. Thus, based on an operation onto operation apparatus 25, the series of operations including excavation, hoisting and revolving movement, stand-by, ejection of loads, and descending and revolving movement is performed.
Operation apparatus 25 is arranged in operator's cab 2a (
Operation apparatus 25 includes a first control lever 25R and a second control lever 25L. First control lever 25R is arranged, for example, on the right side of operator's seat 2b (
For example, boom 3a and bucket 3c are operated by operating first control lever 25R. An operation in the front/rear direction onto first control lever 25R corresponds, for example, to an operation of boom 3a, and an operation to raise and lower boom 3a is performed in accordance with an operation in the front/rear direction. An operation in the lateral direction onto first control lever 25R corresponds, for example, to an operation of bucket 3c, and an operation in the upward/downward direction of bucket 3c is performed in accordance with an operation in the lateral direction.
For example, arm 3b and revolving unit 2 are operated by operating second control lever 25L. An operation in the front/rear direction onto second control lever 25L corresponds, for example, to an operation of arm 3b, and an operation in the upward/downward direction of arm 3b is performed in accordance with an operation in the front/rear direction. An operation in the lateral direction onto second control lever 25L corresponds, for example, to revolution of revolving unit 2, and a right revolution operation and a left revolution operation of revolving unit 2 are performed in accordance with an operation in the lateral direction.
An operation in the lateral direction onto first control lever 25R may correspond to an operation of boom 3a, and an operation in the front/rear direction onto the same may correspond to an operation of bucket 3c. The front/rear direction of second control lever 25L may correspond to an operation of revolving unit 2, and an operation in the lateral direction onto the same may correspond to an operation of arm 3b.
Operation apparatus 25 provides an operation signal in accordance with an operation by an operator. An amount of operation is sensed by an operation amount sensor 26 based on an operation signal provided from operation apparatus 25. Operation amount sensor 26 is implemented, for example, by a potentiometer or a hall element. A signal indicating an amount of operation sensed by operation amount sensor 26 is provided to controller 20. Controller 20 controls EPC valve 46 based on an operation command from operation apparatus 25 as set forth above.
An amount of operation adjusted by an operation onto operation apparatus 25 and sensed by operation amount sensor 26 corresponds to an operation command value in the present embodiment.
Though operation apparatus 25 is, for example, an electric operation apparatus in the present example, the operation apparatus may be a pilot hydraulic operation apparatus. When operation apparatus 25 is a pilot hydraulic operation apparatus, an amount of operation onto operation apparatus 25 is sensed, for example, by a pressure sensor that senses a pressure of oil.
<Functional Block in Controller 20>
A functional block in controller 20 shown in
A set height of bucket 3c in the stand-by state, a threshold value of an amount of natural lowering, an additional height, and the like are stored in storage 23. Such stored information may be stored in advance in storage 23 at the time of shipment of hydraulic excavator 100 or stored in storage 23 after shipment.
Operation command value obtaining unit 31 obtains a signal indicating an amount of operation onto operation apparatus 25 as an operation command value from operation amount sensor 26. Operation command value obtaining unit 31 provides the obtained operation command value to stand-by state determination unit 35.
Load value calculator 32 obtains from a load value sensor 12, a signal of information necessary for calculating a value of a load in bucket 3c. Load value calculator 32 calculates a value of the load in bucket 3c based on the obtained information. Load value calculator 32 provides the calculated load value to stand-by state determination unit 35.
Load value sensor 12 senses information necessary for calculating the value of the load in bucket 3c. The value of the load in bucket 3c is calculated, for example, based on balance of moments of boom 3a, arm 3b, and bucket 3c around boom foot pin 5a. For calculating the value of the load, a distance from boom foot pin 5a to the center of gravity of boom 3a, a distance from boom foot pin 5a to the center of gravity of arm 3b, a distance from boom foot pin 5a to the center of gravity of bucket 3c, a weight of boom 3a, a weight of arm 3b, a weight of bucket 3c, and a head pressure and a bottom pressure of boom cylinder 4a are used. Therefore, stroke sensors 7a to 7c (or potentiometers 9a to 9c and IMUs 8a to 8c) for obtaining the distance and pressure sensors 6a and 6b that measure a head pressure and a bottom pressure of boom cylinder 4a fall under load value sensor 12.
Revolution angle obtaining unit 33 obtains from revolution angle sensor 13, a sensing signal indicating an angle of revolution of revolving unit 2 with respect to traveling unit 1. Revolution angle obtaining unit 33 provides the sensing signal indicating the obtained angle of revolution to stand-by state determination unit 35.
Work implement attitude sensing unit 34 obtains from a work implement attitude sensor 14, a signal of information necessary for finding an attitude of work implement 3. Work implement attitude sensing unit 34 senses the attitude of work implement 3 based on the obtained information. Work implement attitude sensing unit 34 provides information on the sensed attitude of work implement 3 to stand-by state determination unit 35.
Work implement attitude sensor 14 senses information necessary for finding the attitude of work implement 3. The attitude of work implement 3 can be found, for example, with stroke sensors 7a to 7c (or potentiometers 9a to 9c and IMUs 8a to 8c). Therefore, stroke sensors 7a to 7c (or potentiometers 9a to 9c and IMUs 8a to 8c) fall under work implement attitude sensor 14. A visual sensor (a stereo camera or a 3D scanner) may be adopted as work implement attitude sensor 14.
Stand-by state determination unit 35 determines whether or not hydraulic excavator 100 is in the stand-by state. The stand-by state refers to a state that hydraulic excavator 100 stands by with operations thereof remaining stopped until loaded machine 50 enters the loading site.
Stand-by state determination unit 35 determines that the stand-by state is set, for example, based on the fact that bucket 3c reaches a target ejection position by hoisting and revolving movement by hydraulic excavator 100.
Determination as to hoisting and revolving movement can be made by sensing of revolution of revolving unit 2 with respect to traveling unit 1 with bucket 3c carrying a load. Therefore, stand-by state determination unit 35 can determine whether or not hydraulic excavator 100 is carrying out hoisting and revolving movement based on information on the load value from load value calculator 32, information on the angle of revolution from revolution angle obtaining unit 33, and the like.
Determination as to whether or not bucket 3c reaches the target ejection position can be made based on sensing of the attitude of work implement 3, an angle of revolution of revolving unit 2 with respect to traveling unit 1, and the like. Therefore, stand-by state determination unit 35 can determine whether or not bucket 3c reaches the target ejection position based on information on the attitude of work implement 3 from work implement attitude sensing unit 34, information on the angle of revolution from revolution angle obtaining unit 33, and the like.
In making determination as to the stand-by state, stand-by state determination unit 35 may determine whether or not hydraulic excavator 100 remains stopped. When hydraulic excavator 100 is not in the automatic control mode, whether or not hydraulic excavator 100 remains stopped can be made by sensing whether or not first control lever 25R and second control lever 25L of operation apparatus 25 are in a neutral state. Therefore, stand-by state determination unit 35 can determine that hydraulic excavator 100 remains stopped based on information on the operation command value from operation command value obtaining unit 31. Alternatively, determination as to stop of hydraulic excavator 100 can also be made, for example, based on the fact that a value of an amount of spool stroke measured by a spool stroke sensor along each axis mounted on a main valve is in a dead zone of the spool. Alternatively, determination as to stop of hydraulic excavator 100 can also be made, for example, based on information on a speed of the cylinder along each axis and information on a revolution speed that are obtained from a mechatro smart (MS) cylinder and the IMU.
When stand-by state determination unit 35 determines that hydraulic excavator 100 is in the stand-by state, a determination signal is provided to bucket height sensing unit 36.
When bucket height sensing unit 36 receives a signal indicating the stand-by state from stand-by state determination unit 35, it senses the current height of bucket 3c based on information from work implement attitude sensor 14. Bucket height sensing unit 36 provides a signal indicating the sensed current height of bucket 3c to natural lowering amount calculator 37.
Natural lowering amount calculator 37 calculates an amount of natural lowering of bucket 3c in the stand-by state based on the current height obtained from bucket height sensing unit 36 and the set height of bucket 3c in the stand-by state stored in storage 23. Specifically, the amount of natural lowering ((set height)−(current height)) is calculated by subtracting the current height of bucket 3c from the set height of bucket 3c.
Alternatively, the amount of natural lowering may also be calculated, for example, by storing and holding information on the height and the attitude of bucket 3c at the moment of transition to the stand-by state, for example, in storage 23 and thereafter subtracting the current height of the bucket from the stored and held height of bucket 3c.
Natural lowering amount calculator 37 provides a signal indicating the amount of natural lowering calculated above to natural lowering amount determination unit 38.
Natural lowering amount determination unit 38 compares the amount of natural lowering obtained from natural lowering amount calculator 37 with a threshold value of the amount of natural lowering stored in storage 23. Natural lowering amount determination unit 38 determines whether or not the amount of natural lowering of bucket 3c in the stand-by state has exceeded the threshold value.
When natural lowering amount calculator 37 determines that the amount of natural lowering has exceeded the threshold value as a result of determination, it provides a determination signal to bucket height adjustment command unit 39.
Bucket height adjustment command unit 39 controls hydraulic actuators 4a, 4b, and 4c of work implement 3 to be driven based on the determination signal from natural lowering amount determination unit 38. Specifically, when natural lowering amount determination unit 38 determines that the amount of natural lowering has exceeded the threshold value, bucket height adjustment command unit 39 controls hydraulic actuators 4a, 4b, and 4c to be driven to raise bucket 3c by a height corresponding to the amount of natural lowering.
While work implement 3 is controlled to be driven, for example, work implement 3 may be controlled to be driven such that a cylinder length of each of cylinders 4a to 4c returns to the cylinder length of each of cylinders 4a to 4c before natural lowering. Alternatively, while work implement 3 is controlled to be driven, for example, a boom raising operation alone to raise the boom by the height corresponding to natural lowering of bucket 3c may be performed. Alternatively, while work implement 3 is controlled to be driven, for example, each of boom 3a, arm 3b, and bucket 3c may be driven to return to an angle of the work implement before natural lowering.
As set forth above, when natural lowering of bucket 3c is sensed and the amount of natural lowering is equal to or larger than a prescribed value, work implement 3 is controlled to raise bucket 3c.
Controller 20 includes a loaded machine height sensing unit 21 and a bucket set height determination unit 22. Loaded machine height sensing unit 21 obtains information from measurement apparatus 10 or receiver 11 and senses the height of loaded machine 50. Measurement apparatus 10 is a three-dimensional distance sensor as set forth above, and it is implemented, for example, by an image pick-up apparatus such as a stereo camera or LIDAR. When measurement apparatus 10 is implemented by a stereo camera, measurement apparatus 10 picks up an image of loaded machine 50. When measurement apparatus 10 is implemented by LIDAR, measurement apparatus 10 irradiates loaded machine 50 with pulsed laser and measures scattered light. The height of loaded machine 50 may be sensed by ultra wide band (UWB) positioning. Information obtained by measurement (image pick-up or determination) by measurement apparatus 10 is provided to loaded machine height sensing unit 21.
Receiver 11 receives a signal from a transmitter 53 of loaded machine 50 as set forth above. As receiver 11 and transmitter 53 directly communicate with each other, vehicle-to-vehicle communication between hydraulic excavator 100 and loaded machine 50 is carried out.
Alternatively, receiver 11 and transmitter 53 may communicate with each other via a management apparatus 60 (for example, a management server). In this case, each of communication between receiver 11 and management apparatus 60 and communication between transmitter 53 and management apparatus 60 is wirelessly established via a not-shown access point.
A signal received by receiver 11 includes height information of loaded machine 50. Height information of loaded machine 50 is stored, for example, in a storage 52 of loaded machine 50. In addition, a signal received by receiver 11 includes height information of the ground where loaded machine 50 is arranged (the ground at the loading site). The height of the ground where loaded machine 50 is arranged is obtained, for example, from an antenna 51 for global navigation satellite systems (GNSS) of loaded machine 50. The signal received by receiver 11 is provided to loaded machine height sensing unit 21.
Loaded machine height sensing unit 21 senses the height of loaded machine 50 based on information obtained from measurement apparatus 10 or receiver 11. Loaded machine height sensing unit 21 provides a signal indicating the sensed height of loaded machine 50 to bucket set height determination unit 22.
Bucket set height determination unit 22 obtains the height of loaded machine 50 and calculates a set height H2 of bucket 3c based on the height of loaded machine 50. As shown in
Bucket set height determination unit 22 provides the signal indicating the calculated set height to bucket height adjustment command unit 39.
Bucket height adjustment command unit 39 controls hydraulic actuators 4a, 4b, and 4c of work implement 3 to be driven based on the signal indicating the set height obtained from bucket set height determination unit 22. Specifically, bucket height adjustment command unit 39 controls hydraulic actuators 4a, 4b, and 4c to be driven such that bucket 3c is set to the set height.
As set forth above, set height H2 of bucket 3c in the stand-by state can be set to the height calculated based on the height of loaded machine 50 obtained by communication between hydraulic excavator 100 and loaded machine 50. Alternatively, set height H2 of bucket 3c in the stand-by state can be set to the height calculated based on the height of loaded machine 50 obtained by measurement (image pick-up or determination) by hydraulic excavator 100.
Bucket set height determination unit 22 may provide the signal indicating calculated set height H2 to natural lowering amount calculator 37. In this case, natural lowering amount calculator 37 may calculate an amount of natural lowering which is a difference between the current height obtained from bucket height sensing unit 36 and set height H2 obtained from bucket set height determination unit 22 ((set height)−(current height)). Natural lowering amount calculator 37 compares the amount of natural lowering with the threshold value stored in storage 23 and determines whether or not the amount of natural lowering of bucket 3c in the stand-by state has exceeded the threshold value. Based on a result of this determination, similarly to the above, bucket height adjustment command unit 39 may control hydraulic actuators 4a, 4b, and 4c of work implement 3 to be driven. Specifically, when natural lowering amount calculator 37 determines that the amount of natural lowering has exceeded the threshold value, bucket height adjustment command unit 39 controls hydraulic actuators 4a, 4b, and 4c to be driven to raise bucket 3c by the height corresponding to the amount of natural lowering.
As set forth above, controller 20 senses the amount of natural lowering of bucket 3c in the stand-by state in which hydraulic excavator 100 waits for entry of loaded machine 50 and controls work implement 3 to raise bucket 3c based on the amount of natural lowering.
Controller 20 senses the amount of natural lowering of bucket 3 based on the current height of bucket 3c sensed by work implement attitude sensor 14 (sensing unit) and set height H2 of bucket 3c in the stand-by state.
Controller 20 controls work implement 3 to raise bucket 3c by the height corresponding to the amount of natural lowering.
Controller 20 controls work implement 3 to adjust the height of bucket 3c to set height H2 (
Controller 20 is implemented, for example, by a computer, a server, or a portable terminal, or may be implemented by a central processing unit (CPU). Controller 20 may be mounted on hydraulic excavator 100 or may be provided at a remote location distant from hydraulic excavator 100.
Management apparatus 60 may be connected to a remote operator's cab 70 over a network. Remote operator's cab 70 may wirelessly be connected to the hydraulic excavator via an access point different from the above-described access point, without management apparatus 60 being interposed. Through this wireless connection, hydraulic excavator 100 may remotely be controlled from remote operator's cab 70. Remote operator's cab 70 is provided at a point distant from a work site.
Management apparatus 60 may receive a control signal for loaded machine 50 from hydraulic excavator 100 and remote operator's cab 70 and transmit the control signal to autonomous loaded machine 50. Examples of the control signal transmitted from hydraulic excavator 100 and remote operator's cab 70 to loaded machine 50 include an entry instruction signal and a pull-away instruction signal. The entry instruction signal is a signal instructing loaded machine 50 to enter the loading site. The pull-away instruction signal is a signal instructing loaded machine 50 to pull away from the loading site after completion of loading and to exit from the loading site.
<Method of Controlling Work Machine>
Control for raising bucket 3c when bucket 3c naturally lowers in the stand-by state will now be described with reference to
When hydraulic excavator 100 is determined as not being in the stand-by state, determination as to whether or not hydraulic excavator 100 is in the stand-by state is continued (step S1:
When hydraulic excavator 100 is determined as being in the stand-by state, the amount of natural lowering of bucket 3c is sensed (step S2:
The set height stored in storage 23 is used as the set height as shown in
After the amount of natural lowering of bucket 3c is sensed, whether or not the amount of natural lowering has exceeded the threshold value is determined (step S3:
When natural lowering amount determination unit 38 determines that the amount of natural lowering has exceeded the threshold value, work implement 3 is controlled to raise bucket 3c (step S4:
Thereafter, whether or not entry of loaded machine 50 into the loading site has been completed is determined (step S5). When it is determined that entry of loaded machine 50 into the loading site has not been completed, sensing of the amount of natural lowering is continued (step S2).
When it is determined that entry of loaded machine 50 into the loading site has been completed, a load in bucket 3c is ejected into a platform of loaded machine 50 (step S6). Thereafter, hydraulic excavator 100 carries out descending and revolving movement and does next excavation or quits excavation.
As set forth above, when bucket 3c naturally lowers in the stand-by state, bucket 3c is controlled to be raised.
Control for adjusting the height of bucket 3c in the stand-by state to the set height will now be described with reference to
In sensing the height of loaded machine 50, height information of the ground where loaded machine 50 is arranged (the ground at the loading site) is referred to. The height of the ground where loaded machine 50 is arranged is obtained by antenna 51 for GNSS of loaded machine 50 and transmitter 53 transmits the information to the receiver of hydraulic excavator 100.
Based on the height information of loaded machine 50 obtained above, the set height of bucket 3c in loading of the load onto loaded machine 50 by hydraulic excavator 100 is determined (step S12:
A height position of bucket 3c is adjusted to set bucket 3c to the set height (step S13:
As set forth above, control for adjusting the height of bucket 3c in the stand-by state to the set height is carried out.
In sensing the amount of natural lowering (step S2) shown in
Functions and effects of the present embodiment will now be described.
In the present embodiment, as shown in
Bucket 3c is raised based on the amount of natural lowering. Therefore, change in angle of bucket 3c in a direction of ejection of soil with natural lowering is suppressed, and drop of the load out of bucket 3c with change in angle of bucket 3c is suppressed.
According to the present embodiment, as shown in
According to the present embodiment, as shown in
According to the present embodiment, as shown in
According to the present embodiment, as shown in
According to the present embodiment, as shown in
According to the present embodiment, as shown in
It should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims rather than the description above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
1 traveling unit; la crawler belt apparatus; 2 revolving unit; 2a operator's cab; 2b operator's seat; 2c engine compartment; 2d counterweight; 3 work implement; 3a boom; 3b arm; 3c bucket; 3d bucket link; 3da first link member; 3db second link member; 3dc bucket cylinder top pin; 3dd first link pin; 3de second link pin; 4a boom cylinder; 4a hydraulic actuator; 4aa cylinder; 4ab cylinder rod; 4b arm cylinder; 4c bucket cylinder; 5a boom foot pin; 5b boom tip end pin; 5c pin; 6a, 6b pressure sensor; 7a, 7c stroke sensor; 9a, 9b, 9c potentiometer; 10 measurement apparatus; 11 receiver; 12 load value sensor; 13 revolution angle sensor; 14 work implement attitude sensor; 20 controller; 21 loaded machine height sensing unit; 22 bucket set height determination unit; 23, 52 storage; 25 operation apparatus; 25L second control lever; 25R first control lever; 26 operation amount sensor; 31 operation command value obtaining unit; 32 load value calculator; 33 revolution angle obtaining unit; 34 work implement attitude sensing unit; 35 stand-by state determination unit; 36 bucket height sensing unit; 37 natural lowering amount calculator; 38 natural lowering amount determination unit; 39 bucket height adjustment command unit; 41 main valve; 42 engine; 43 hydraulic pump; 44 revolution motor; 45 self-pressure reduction valve; 46 EPC valve; 50 loaded machine; 51 antenna; 53 transmitter; 60 management apparatus; 70 remote operator's cab; 100 hydraulic excavator
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-112654 | Jun 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/020445 | 5/25/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/255635 | 12/24/2020 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20050000703 | Furuno | Jan 2005 | A1 |
| 20110295433 | Evans | Dec 2011 | A1 |
| 20150147147 | Uchiyama | May 2015 | A1 |
| 20160078340 | Kirsch | Mar 2016 | A1 |
| 20180305902 | Tsukamoto | Oct 2018 | A1 |
| 20200018037 | Nakamura | Jan 2020 | A1 |
| 20200283993 | Minagawa et al. | Sep 2020 | A1 |
| 20210010239 | Ono | Jan 2021 | A1 |
| Number | Date | Country |
|---|---|---|
| 108474195 | Aug 2018 | CN |
| H02-088825 | Mar 1990 | JP |
| H11-181821 | Jul 1999 | JP |
| 2001-342648 | Dec 2001 | JP |
| 2003-322112 | Nov 2003 | JP |
| 3845597 | Nov 2006 | JP |
| 2011-094453 | May 2011 | JP |
| 5526299 | Jun 2014 | JP |
| 5752350 | Jul 2015 | JP |
| 2016-089389 | May 2016 | JP |
| 2016-089559 | May 2016 | JP |
| 6345080 | Jun 2018 | JP |
| 6373728 | Aug 2018 | JP |
| 2019-065660 | Apr 2019 | JP |
| 10-2018-0097614 | Aug 2018 | KR |
| WO-2017115809 | Jul 2017 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20220186461 A1 | Jun 2022 | US |
