US20190078289A1 - Work machine and control method for work machine - Google Patents

Work machine and control method for work machine Download PDF

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Publication number
US20190078289A1
US20190078289A1 US15/756,656 US201715756656A US2019078289A1 US 20190078289 A1 US20190078289 A1 US 20190078289A1 US 201715756656 A US201715756656 A US 201715756656A US 2019078289 A1 US2019078289 A1 US 2019078289A1
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United States
Prior art keywords
work implement
boom
speed
command
control
Prior art date
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Abandoned
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US15/756,656
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English (en)
Inventor
Toru Matsuyama
Ayumi OHKUMA
Takeo Yamada
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Komatsu Ltd
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Komatsu Ltd
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Assigned to KOMATSU LTD. reassignment KOMATSU LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MATSUYAMA, TORU, OHKUMA, Ayumi, YAMADA, TAKEO
Publication of US20190078289A1 publication Critical patent/US20190078289A1/en
Abandoned legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
    • E02F3/32—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom working downwardly and towards the machine, e.g. with backhoes
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2004—Control mechanisms, e.g. control levers
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2025—Particular purposes of control systems not otherwise provided for
    • E02F9/2037—Coordinating the movements of the implement and of the frame
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with two or more pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/26—Indicating devices
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/26—Indicating devices
    • E02F9/261—Surveying the work-site to be treated
    • E02F9/262—Surveying the work-site to be treated with follow-up actions to control the work tool, e.g. controller
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/26—Indicating devices
    • E02F9/264—Sensors and their calibration for indicating the position of the work tool
    • E02F9/265—Sensors and their calibration for indicating the position of the work tool with follow-up actions (e.g. control signals sent to actuate the work tool)

Definitions

  • the present invention relates to a work machine including a work implement, and a control method for a work machine.
  • intervention control For a work machine that includes a front device provided with a bucket, there has been proposed such control that shifts the bucket along a boundary surface defining a target shape of an object of execution (for example, see PTD 1). This control is referred to as intervention control.
  • the intervention control need not be performed any more.
  • Control that raises the work implement to stop invasion of the target shape by the work implement need not be performed any more.
  • a rapid speed change may be produced depending on the level of the difference between a rising speed of the work implement during the intervention control and a rising speed of the work implement in accordance with an operation command from the operation apparatus.
  • the operator may have a sense of discomfort.
  • An object of the present disclosure is to provide a work machine and a control method for a work machine capable of reducing discomfort caused during an operation of an operation apparatus by an operator.
  • a work machine includes a work implement, an operation apparatus for operating the work implement, and a controller for controlling the work implement.
  • the controller performs intervention control for raising the work implement based on an operation command from the operation apparatus, decides switching from the intervention control to control of the work implement in accordance with an operation command from the operation apparatus, determines whether or not the operation command from the operation apparatus for the switching performed based on a result of the decision is an operation command for raising the work implement, or a neutral command, determines a speed difference between a rising target speed of the work implement in the intervention control and a target speed in accordance with the operation command from the operation apparatus when the operation command from the operation apparatus is the operation command for raising the work implement or the neutral command based on a result of the determination, and makes an adjustment to gradually change the rising target speed of the work implement to the target speed in accordance with the operation command from the operation apparatus when the speed difference is greater than or equal to a predetermined value.
  • the controller preferably includes an intervention control unit for performing intervention control for raising the work implement based on an operation command from the operation apparatus, a switching decision unit for deciding switching from the intervention control to control of the work implement in accordance with an operation command from the operation apparatus, an operation command determination unit for determining whether or not the operation command from the operation apparatus for the switching performed based on a result of the decision of the switching decision unit is an operation command for raising the work implement, or a neutral command, a speed difference determination unit for determining a speed difference between a rising target speed of the work implement in the intervention control and a target speed in accordance with the operation command from the operation apparatus when the operation command from the operation apparatus is the operation command for raising the work implement or the neutral command based on a result of the determination of the operation command determination unit, and a speed adjustment unit for making an adjustment to gradually change the rising target speed of the work implement to the target speed in accordance with the operation command from the operation apparatus when the speed difference is greater than or equal to a predetermined value based on a result of the determination of the
  • the controller preferably switches the rising target speed of the work implement to the target speed in accordance with the operation command from the operation apparatus when the speed difference is less than the predetermined value.
  • a control method for a work machine is a method for a work machine including a work implement and an operation apparatus for operating the work implement. The method includes the steps of:
  • a work machine and a control method for a work machine are capable of reducing discomfort caused during an operation of an operation apparatus by an operator.
  • FIG. 1 is a perspective view of a work machine according to an embodiment.
  • FIG. 2 is a block diagram illustrating configurations of a control system 200 and a hydraulic system 300 included in a hydraulic excavator 100 according to the embodiment.
  • FIG. 3 is a diagram illustrating an example of a hydraulic circuit 301 included in a boom cylinder 10 according to the embodiment.
  • FIG. 4 is a block diagram of a work implement controller 26 according to the embodiment.
  • FIG. 5 is a chart illustrating target excavation topography data U and a bucket 8 according to the embodiment.
  • FIG. 6 is a diagram illustrating a boom speed limit Vcy_bm according to the embodiment.
  • FIG. 7 is a chart illustrating a speed limit Vc_lmt according to the embodiment.
  • FIG. 8 is a view illustrating a relationship between bucket 8 and target excavation topography 43 I according to the embodiment.
  • FIG. 9 is a chart illustrating a relationship between time t and a boom target speed Vbm representing a moving speed of a boom 6 according to the embodiment.
  • FIG. 10 is a chart illustrating a flow of a control method for the work machine according to the embodiment.
  • FIG. 1 is a perspective view of a work machine according to the embodiment.
  • FIG. 2 is a block diagram illustrating configurations of a control system 200 and a hydraulic system 300 included in a hydraulic excavator 100 according to the embodiment.
  • hydraulic excavator 100 provided as a work machine includes a vehicular body 1 and a work implement 2 .
  • Vehicular body 1 includes an upper revolving unit 3 provided as a revolving unit, and a traveling apparatus 5 provided as a traveling unit.
  • Upper revolving unit 3 accommodates an internal combustion engine provided as a power generator, hydraulic pumps, and other devices within an engine room 3 EG.
  • Engine room 3 EG is disposed at an end of upper revolving unit 3 .
  • the internal combustion engine provided as a power generator of hydraulic excavator 100 is constituted by a diesel engine, for example.
  • the power generator may be constituted by other types of power generator.
  • the power generator of hydraulic excavator 100 may be a hybrid type device constituted by a combination of an internal combustion engine, a generator motor, and an electrical storage device.
  • the power generator of hydraulic excavator 100 may be constituted by a combination of an electrical storage device and a generator motor, excluding an internal combustion engine.
  • Upper revolving unit 3 includes an operator's cab 4 .
  • Operator's cab 4 is disposed at the other end of upper revolving unit 3 .
  • Operator's cab 4 is positioned on the side opposite to the side of engine room 3 EG.
  • a display unit 29 and an operation apparatus 25 illustrated in FIG. 2 are disposed within operator's cab 4 .
  • Traveling apparatus 5 supports upper revolving unit 3 .
  • Traveling apparatus 5 includes crawler belts 5 a and 5 b
  • One or both of travel motors 5 c provided on the left and right of traveling apparatus 5 drive and rotate crawler belts 5 a and 5 b to allow traveling of hydraulic excavator 100 .
  • Work implement 2 is attached to a side of operator's cab 4 of upper revolving unit 3 .
  • Hydraulic excavator 100 may include a traveling apparatus provided with tires instead of crawler belts 5 a and 5 b , and transmit driving force of an engine to the tires via a transmission to allow traveling.
  • Examples of hydraulic excavator 100 of this type include a wheel hydraulic excavator.
  • Hydraulic excavator 100 may be a backhoe loader, for example.
  • the front of upper revolving unit 3 corresponds to the side where work implement 2 and operator's cab 4 are disposed, while the rear of upper revolving unit 3 corresponds to the side where engine room 3 EG is disposed.
  • the left side in the forward direction corresponds to the left of upper revolving unit 3
  • the right side in the forward direction corresponds to the right of upper revolving unit 3 .
  • the left/right direction of upper revolving unit 3 is also referred to as a width direction.
  • Traveling apparatus 5 side of hydraulic excavator 100 or vehicular body 1 with respect to upper revolving body 3 corresponds to the lower side
  • upper revolving unit 3 side with respect to traveling apparatus 5 corresponds to the upper side.
  • the fore/aft direction, the width direction, and the up/down direction of hydraulic excavator 100 correspond to an x direction, a y direction, and a z direction, respectively.
  • the lower side corresponds to the gravitating side in the direction of gravity identical to the perpendicular direction
  • the upper side corresponds to the side opposite to the gravitating side in the perpendicular direction.
  • Work implement 2 includes a boom 6 , a dipper stick 7 , a bucket 8 provided as a work tool, a boom cylinder 10 , a dipper stick cylinder 11 , and a bucket cylinder 12 .
  • a proximal end of boom 6 is attached to a front portion of vehicular body 1 via a boom pin 13 .
  • a proximal end of dipper stick 7 is attached to a distal end of boom 6 via a dipper stick pin 14 .
  • Bucket 8 is attached to a distal end of dipper stick 7 via a bucket pin 15 .
  • Bucket 8 is movable around bucket pin 15 .
  • a plurality of cutters 8 B are attached to bucket 8 on the side opposite to bucket pin 15 . Cutting edges 8 T correspond to distal ends of cutters 8 B.
  • rising of work implement 2 refers to a movement of work implement 2 in the direction from a ground engaging surface of hydraulic excavator 100 toward upper revolving unit 3 .
  • Lowering of work implement 2 refers to a movement of work implement 2 in the direction from upper revolving unit 3 of hydraulic excavator 100 toward the ground engaging surface.
  • the ground engaging surface of hydraulic excavator 100 is a flat surface defined by at least three points of engaging portions between crawler belts 5 a and 5 b and the ground.
  • rising of implement 2 refers to a movement of work implement 2 in the direction away from a ground engaging surface of the work machine.
  • Lowering of work implement 2 refers to a movement of work implement 2 in the direction of approach toward the ground engaging surface of the work machine.
  • the ground engaging surface is a flat surface defined by ground engaging portions of at least three wheels.
  • Bucket 8 is not required to have the plurality of cutters 8 B. Such a bucket is adoptable which does not have cutters 8 B illustrated in FIG. 1 , but has a cutting edge constituted by a steel plate in a straight shape.
  • Work implement 2 may include a tilt bucket having a single cutter, for example.
  • the tilt bucket herein is a bucket that includes a bucket tilt cylinder, and tilts toward the left and right to form or grade a slope or a flat land into a desired shape, and also perform rolling compaction by using a bottom plate even when the hydraulic excavator is on a slope area.
  • work implement 2 may include a drilling attachment provided with a slope bucket or a drilling chip as a work tool, for example, in place of bucket 8 .
  • Each of boom cylinder 10 , dipper stick cylinder 11 , and bucket cylinder 12 illustrated in FIG. 1 is a hydraulic cylinder driven by a pressure of hydraulic oil (hereinafter referred to as oil pressure where appropriate).
  • Boom cylinder 10 drives boom 6 to raise boom 6 .
  • Dipper stick cylinder 11 drives dipper stick 7 to move dipper stick 7 around dipper stick pin 14 .
  • Bucket cylinder 12 drives bucket 8 to move bucket 8 around bucket pin 15 .
  • a direction control valve 64 illustrated in FIG. 2 is provided between the hydraulic cylinders such as boom cylinder 10 , dipper stick cylinder 11 , and bucket cylinder 12 , and hydraulic pumps 36 and 37 illustrated in FIG. 2 .
  • Direction control valve 64 controls flow rates of hydraulic oil supplied from hydraulic pumps 36 and 37 to boom cylinder 10 , dipper stick cylinder 11 , bucket cylinder 12 and others, and switches flow directions of hydraulic oil.
  • Direction control valve 64 includes a travel direction control valve for driving travel motors 5 c , and a work implement direction control valve for controlling revolving motors that revolve boom cylinder 10 , dipper stick cylinder 11 , bucket cylinder 12 , and upper revolving unit 3 .
  • Work implement controller 26 illustrated in FIG. 2 controls a control valve 27 illustrated in FIG. 2 to control a pilot pressure of hydraulic oil supplied from operation apparatus 25 to direction control valve 64 .
  • Control valve 27 is included in a hydraulic system of boom cylinder 10 , dipper stick cylinder 11 , and bucket cylinder 12 .
  • Work implement controller 26 controls control valve 27 included in a pilot oil path 450 to control movements of boom cylinder 10 , dipper stick cylinder 11 , and bucket cylinder 12 .
  • Work implement controller 26 according to the embodiment closes control valve 27 to reduce respective speeds of boom cylinder 10 , dipper stick cylinder 11 , and bucket cylinder 12 .
  • Antennas 21 and 22 are attached to an upper part of upper revolving unit 3 . Antennas 21 and 22 are used to detect a current position of hydraulic excavator 100 . Antennas 21 and 22 are electrically connected with a position detection device 19 illustrated in FIG. 2 and provided as a position detector for detecting a current position of hydraulic excavator 100 .
  • Position detection device 19 detects a current position of hydraulic excavator 100 by utilizing real time kinematic-global navigation satellite systems (Real Time Kinematic-Global Navigation Satellite Systems).
  • antennas 21 and 22 are referred to as GNSS antennas 21 and 22 where appropriate.
  • GNSS antennas 21 and 22 receive a GNSS radio wave
  • a signal in the GNSS radio wave is input to position detection device 19 .
  • Position detection device 19 detects installation positions of GNSS antennas 21 and 22 .
  • Position detection device 19 includes a three-dimensional position sensor, for example.
  • hydraulic system 300 of hydraulic excavator 100 includes an internal combustion engine 35 provided as a power generation source, and hydraulic pumps 36 and 37 .
  • Hydraulic pumps 36 and 37 driven by internal combustion engine 35 discharge hydraulic oil.
  • the hydraulic oil discharged from hydraulic pumps 36 and 37 is supplied to boom cylinder 10 , dipper stick cylinder 11 , and bucket cylinder 12 .
  • Hydraulic excavator 100 includes a revolving motor 38 .
  • Revolving motor 38 is a hydraulic motor driven by hydraulic oil discharged from hydraulic pumps 36 and 37 .
  • Revolving motor 38 revolves upper revolving unit 3 . Note that only a single hydraulic pump may be provided instead of two hydraulic pumps 36 and 37 illustrated in FIG. 2 .
  • Revolving motor 38 may be a motor other than a hydraulic motor, such as an electric motor.
  • control system 200 provided as a control system for the work machine includes position detection device 19 , a global coordinate calculating unit 23 , operation apparatus 25 , work implement controller 26 provided as a controller of the work machine according to the embodiment, a sensor controller 39 , a display controller 28 , and display unit 29 .
  • Operation apparatus 25 is a device for operating work implement 2 and upper revolving unit 3 illustrated in FIG. 1 .
  • Operation apparatus 25 is a device for operating work implement 2 .
  • Operation apparatus 25 receives an operation for driving work implement 2 from the operator, and outputs a pilot oil pressure corresponding to a manipulated variable.
  • the pilot oil pressure corresponding to a manipulated variable is equivalent to an operation command.
  • This operation command is a command for moving work implement 2 .
  • the operation command is generated by operation apparatus 25 .
  • Operation apparatus 25 is operated by the operator, wherefore the operation command is a command for moving work implement 2 based on an operation input by the operator as a manual operation.
  • Control of work implement 2 based on a manual operation is equivalent to control of work implement 2 in accordance with an operation command issued from operation apparatus 25 . This control is therefore control of work implement 2 achieved by operating operation apparatus 25 included in work implement 2 .
  • operation apparatus 25 includes a left control lever 25 L provided on the left side of the operator, and a right control lever 25 R provided on the right side of the operator. Movements of left control lever 25 L and right control lever 25 R in the fore/aft and left/right directions are associated with movements of dipper stick 7 and the two axes of revolution.
  • an operation of right control lever 25 R in the fore/aft direction is associated with an operation of boom 6 .
  • boom 6 lowers.
  • boom 6 rises. The lowering and rising movements of boom 6 are performed in accordance with operations of right control lever 25 R in the fore/aft direction.
  • An operation of right control lever 25 R in the left/right direction is associated with an operation of bucket 8 .
  • bucket 8 When right control lever 25 R is operated leftward, bucket 8 performs excavation.
  • right control lever 25 R When right control lever 25 R is operated rightward, bucket 8 performs dumping. The excavation and dumping movements of bucket 8 are performed in accordance with operations of right control lever 25 R in the left/right direction.
  • left control lever 25 L An operation of left control lever 25 L in the fore/aft direction is associated with an operation of dipper stick 7 .
  • dipper stick 7 When left control lever 25 L is operated forward, dipper stick 7 performs dumping.
  • left control lever 25 L When left control lever 25 L is operated rearward, dipper stick 7 performs excavation.
  • left control lever 25 L in the left/right direction is associated with a revolving operation of upper revolving unit 3 .
  • left control lever 25 L is operated leftward, upper revolving unit 3 revolves leftward.
  • left control lever 25 L is operated rightward, upper revolving unit 3 revolves rightward.
  • operation apparatus 25 is a device of pilot hydraulic type. Hydraulic oil having a pressure reduced to a predetermined pilot pressure by pressure reducing valve 25 V is supplied from hydraulic pump 36 to operation apparatus 25 in accordance with a boom operation, a bucket operation, a dipper stick operation, and a revolving operation.
  • right control lever 25 R in the fore/aft direction allows supply of a pilot oil pressure to pilot oil path 450 .
  • the operation of boom 6 is received from the operator.
  • Hydraulic oil is supplied to pilot oil path 450 by opening of a valve device of right control lever 25 R in accordance with a manipulated variable of right control lever 25 R.
  • Pressure sensor 66 detects a pressure of hydraulic oil within pilot oil path 450 as a pilot pressure.
  • Pressure sensor 66 designates the detected pilot pressure as a boom manipulated variable MB, and transmits boom manipulated variable MB to work implement controller 26 .
  • a manipulated variable of right control lever 25 R in the fore/aft direction is hereinafter referred to as boom manipulated variable MB where appropriate.
  • a control valve (hereinafter referred to as intervention valve where appropriate) 27 C, and a shuttle valve 51 are included in pilot oil path 50 . Intervention valve 27 C and shuttle valve 51 will be detailed below.
  • right control lever 25 R in the left/right direction allows supply of a pilot oil pressure to pilot oil path 450 .
  • the operation of bucket 8 is received from the operator.
  • Hydraulic oil is supplied to pilot oil path 450 by opening of the valve device of right control lever 25 R in accordance with a manipulated variable of right control lever 25 R.
  • Pressure sensor 66 detects a pressure of hydraulic oil within pilot oil path 450 as a pilot pressure.
  • Pressure sensor 66 designates the detected pilot pressure as a bucket manipulated variable MT, and transmits bucket manipulated variable MT to work implement controller 26 .
  • a manipulated variable of right control lever 25 R in the left/right direction is hereinafter referred to as bucket manipulated variable MT where appropriate.
  • left control lever 25 L in the fore/aft direction allows supply of a pilot oil pressure to pilot oil path 450 .
  • the operation of dipper stick 7 is received from the operator.
  • Hydraulic oil is supplied to pilot oil path 450 by opening of a valve device of left control lever 25 L in accordance with a manipulated variable of left control lever 25 L.
  • Pressure sensor 66 detects a pressure of hydraulic oil within pilot oil path 450 as a pilot pressure.
  • Pressure sensor 66 designates the detected pilot pressure as an dipper stick manipulated variable MA, and transmits dipper stick manipulated variable MA to work implement controller 26 .
  • a manipulated variable of left control lever 25 L in the fore/aft direction is hereinafter referred to as dipper stick manipulated variable MA where appropriate.
  • operation apparatus 25 supplies to direction control valve 64 a pilot oil pressure at a level corresponding to a manipulated variable of right control lever 25 R.
  • operation apparatus 25 supplies to direction control valve 64 a pilot oil pressure at a level corresponding to a manipulated variable of left control lever 25 L.
  • Direction control valve 64 moves in accordance with a pilot oil pressure supplied from operation apparatus 25 to direction control valve 64 .
  • Control system 200 includes a first stroke sensor 16 , a second stroke sensor 17 , and a third stroke sensor 18 .
  • first stroke sensor 16 is included in boom cylinder 10
  • second stroke sensor 17 is included in dipper stick cylinder 11
  • third stroke sensor 18 is included in bucket cylinder 12 .
  • Sensor controller 39 includes a storage unit such as a random access memory (RAM) and a read only memory (ROM), and a processing unit such as a central processing unit (CPU).
  • a storage unit such as a random access memory (RAM) and a read only memory (ROM)
  • ROM read only memory
  • CPU central processing unit
  • Sensor controller 39 calculates an inclination angle ⁇ 1 of boom 6 with respect to a direction (z-axis direction) perpendicular to a horizontal plane (x-y plane) in a local coordinate system of hydraulic excavator 100 , more specifically, a local coordinate system of vehicular body 1 , based on a boom cylinder length LS1 detected by first stroke sensor 16 , and outputs calculated inclination angle ⁇ 1 to work implement controller 26 and display controller 28 .
  • Sensor controller 39 calculates an inclination angle ⁇ 2 of dipper stick 7 with respect to boom 6 based on an dipper stick cylinder length LS2 detected by second stroke sensor 17 , and outputs calculated inclination angle ⁇ 2 to work implement controller 26 and display controller 28 .
  • Sensor controller 39 calculates an inclination angle ⁇ 3 of cutting edges 8 T of bucket 8 with respect to dipper stick 7 based on a bucket cylinder length LS3 detected by third stroke sensor 18 , and outputs calculated inclination angle ⁇ 3 to work implement controller 26 and display controller 28 .
  • Inclination angles ⁇ 1, 02, and 03 may be detected by methods other than the use of first stroke sensor 16 , second stroke sensor 17 , and third stroke sensor 18 .
  • an angle sensor such as a potentiometer may be used to detect inclination angles ⁇ 1, ⁇ 2, and ⁇ 3.
  • IMU 24 is connected to sensor controller 39 .
  • IMU 24 acquires information about inclination of the vehicular body such as a pitch around the y axis and a roll around the x axis of hydraulic excavator 100 illustrated in FIG. 1 , and outputs the acquired information to sensor controller 39 .
  • Work implement controller 26 includes a storage unit 26 Q such as a RAM and a read only memory (ROM), and a processing unit 26 P such as a CPU.
  • storage unit 26 Q such as a RAM and a read only memory (ROM)
  • processing unit 26 P such as a CPU.
  • Work implement controller 26 controls intervention valve 27 C and control valve 27 based on boom manipulated variable MB, bucket manipulated variable MT, and dipper stick manipulated variable MA illustrated in FIG. 2 .
  • Direction control valve 64 illustrated in FIG. 2 is a proportional control valve, for example, and is controlled by hydraulic oil supplied from operation apparatus 25 .
  • Direction control valve 64 is disposed between the section of boom cylinder 10 , dipper stick cylinder 11 , bucket cylinder 12 , and a hydraulic actuator such as revolving motor 38 , and the section of hydraulic pumps 36 and 37 .
  • Direction control valve 64 controls flow rates and directions of hydraulic oil supplied from hydraulic pumps 36 and 37 to boom cylinder 10 , dipper stick cylinder 11 , bucket cylinder 12 , and revolving motor 38 .
  • Position detection device 19 contained in control system 200 includes GNSS antennas 21 and 22 described above.
  • GNSS antennas 21 and 22 receive a GNSS radio wave
  • a signal in the GNSS radio wave is input to global coordinate calculating unit 23 .
  • GNSS antenna 21 receives reference position data P1 indicating a self-position from a positioning satellite.
  • GNSS antenna 22 receives reference position data P2 indicating a self-position from the positioning satellite.
  • GNSS antennas 21 and 22 receive reference position data P1 and P2 in a predetermined cycle. Each of reference position data P1 and P2 is information indicating the installation position of the corresponding GNSS antenna. GNSS antennas 21 and 22 output reference position data P1 and P2 to global coordinate calculating unit 23 every time GNSS antennas 21 and 22 receive these data P1 and P2.
  • Global coordinate calculating unit 23 includes a storage unit such as a RAM and a ROM, and a processing unit such as a CPU. Global coordinate calculating unit 23 generates revolving unit position data indicating a position of upper revolving unit 3 based on two reference position data P1 and P2.
  • the revolving unit position data includes reference position data P corresponding to one of two reference position data P1 and P2, and revolving unit direction data Q generated based on two reference position data P1 and P2.
  • Revolving unit direction data Q indicates a direction in which work implement 2 , i.e., upper revolving unit 3 , faces.
  • Global coordinate calculating unit 23 updates reference position data P and revolving unit direction data Q each indicating revolving unit position data, and outputs the updated data to display controller 28 every time two reference position data P1 and P2 are acquired from GNSS antennas 21 and 22 in a predetermined cycle.
  • Display controller 28 includes a storage unit such as a RAM and a ROM, and a processing unit such as a CPU. Display controller 28 acquires reference position data P and revolving unit direction data Q each indicating revolving unit position data from global coordinate calculating unit 23 .
  • display controller 28 generates, as work implement position data, bucket cutting edge position data S indicating a three-dimensional position of cutting edges 8 T of bucket 8 .
  • Display controller 28 generates target excavation topography data U based on bucket cutting edge position data S and target execution information T.
  • Target execution information T is information indicating a service object by work implement 2 included in hydraulic excavator 100 , or a finishing target of an excavation object according to the embodiment.
  • Examples of target execution information T include design information about an execution object by hydraulic excavator 100 .
  • Examples of a service object by work implement 2 include land.
  • Examples of a service performed by work implement 2 include an excavation service and a land leveling service. However, the service by work implement 2 is not limited to these examples.
  • Display controller 28 derives target excavation landform data Ua for display based on target excavation landform data U, and displays a target shape of a service object by work implement 2 , such as a landform, on display unit 29 based on target excavation landform data Ua for display.
  • Display unit 29 is a liquid crystal display apparatus that receives input via a touch panel, for example.
  • display unit 29 is not limited to this type.
  • a switch 29 S is provided adjacent to display unit 29 .
  • Switch 29 S is an input device that executes intervention control described below, or stops the intervention control being performed.
  • Work implement controller 26 acquires boom manipulated variable MB, bucket manipulated variable MT, and arm manipulated variable MA from pressure sensor 66 .
  • Work implement controller 26 acquires inclination angle ⁇ 1 of boom 6 , inclination angle ⁇ 2 of arm 7 , and inclination angle ⁇ 3 of bucket 8 from sensor controller 39 .
  • Work implement controller 26 acquires target excavation topography data U from display controller 28 .
  • Target excavation topography data U is information included in target execution information T and indicating a range of a service that will be performed by hydraulic excavator 100 .
  • Target excavation topography data U is a part of target execution information T.
  • Target excavation topography data U indicates a shape of a finishing target of a service object of work implement 2 similarly to target execution information T.
  • the shape of the finishing target is hereinafter referred to as target excavation topography where appropriate.
  • Work implement controller 26 calculates a position of cutting edges 8 T of bucket 8 (hereinafter referred to as cutting edge position where appropriate) based on an angle of work implement 2 acquired from sensor controller 39 .
  • Work implement controller 26 controls a movement of work implement 2 based on a distance between target excavation topography data U and cutting edges 8 T of bucket 8 , and on a speed of work implement 2 such that cutting edges 8 T of bucket 8 can shift in accordance with target excavation topography data U.
  • Work implement controller 26 performs such control as to maintain a speed of work implement 2 in a direction of approach toward an execution object at a speed less than or equal to a speed limit to prevent bucket 8 from invading a target shape of a service object of work implement 2 indicated by target excavation topography data U.
  • This control is referred to as intervention control where appropriate.
  • the intervention control is performed when the operator of hydraulic excavator 100 selects performance of the intervention control by using switch 29 S illustrated in FIG. 2 .
  • a reference position of bucket 8 is not limited to the position of cutting edges 8 T but may be other appropriate positions.
  • work implement controller 26 During the intervention control, work implement controller 26 generates a boom command signal CBI, and outputs generated boom command signal CBI to intervention valve 27 C illustrated in FIG. 2 to control work implement 2 such that cutting edges 8 T of bucket 8 can shift in accordance with target excavation topography data U.
  • Boom 6 moves based on boom command signal CBI.
  • a speed of work implement 2 more specifically a speed of bucket 8 , is controlled by a movement of boom 6 based on boom command signal CBI.
  • An approaching speed of bucket 8 toward target excavation topography data U is regulated in accordance with a distance between bucket 8 and target excavation topography data U.
  • FIG. 3 is a diagram illustrating an example of hydraulic circuit 301 of boom cylinder 10 according to the embodiment.
  • hydraulic circuit 301 includes pilot oil path 450 between operation apparatus 25 and direction control valve 64 .
  • Direction control valve 64 is a valve for controlling a flow direction of hydraulic oil supplied to boom cylinder 10 .
  • direction control valve 64 is a spool valve that shifts a rod-shaped spool 64 S to switch a flow direction of hydraulic oil.
  • Spool 64 S is shifted by hydraulic oil supplied from operation apparatus 25 illustrated in FIG. 2 (hereinafter referred to as pilot oil where appropriate).
  • Direction control valve 64 supplies hydraulic oil to boom cylinder 10 by a shift of spool 64 S to move boom cylinder 10 .
  • Pilot oil path 50 and pilot oil path 450 B are connected to shuttle valve 51 .
  • Pilot oil path 50 includes intervention valve 27 C. Intervention valve 27 C adjusts a pilot pressure of pilot oil path 50 .
  • Pilot oil path 450 B includes a pressure sensor 66 B and a control valve 27 B.
  • Pilot oil path 450 A includes a pressure sensor 66 A provided between a control valve 27 A and operation apparatus 25 .
  • a detection value obtained by pressure sensor 66 is acquired by work implement controller 26 illustrated in FIG. 2 , and used for control of boom cylinder 10 .
  • Each of pressure sensor 66 A and pressure sensor 66 B corresponds to pressure sensor 66 illustrated in FIG. 2 .
  • Each of control valve 27 A and control valve 27 B corresponds to control valve 27 illustrated in FIG. 2 .
  • Hydraulic oil supplied from hydraulic pumps 36 and 37 is further supplied to boom cylinder 10 via direction control valve 64 .
  • Supply of hydraulic oil is switched between supply to a cap side oil chamber 48 R of boom cylinder 10 and supply to a rod side oil chamber 47 R of boom cylinder 10 by a shift of spool 64 S in the axial direction.
  • a flow rate of hydraulic oil i.e., a supply rate of hydraulic oil to boom cylinder 10 per unit time is adjusted by a shift of spool 64 S in the axial direction.
  • a moving speed of boom cylinder 10 is adjusted by adjustment of the flow rate of hydraulic oil to boom cylinder 10 .
  • the flow rate of hydraulic oil supplied to boom cylinder 10 and returned from boom cylinder 10 to direction control valve 64 changes in accordance with the adjustment of the shift amount of spool 64 S of direction control valve 64 .
  • each shift speed of piston 10 P and rod 10 L corresponding to a moving speed of boom cylinder 10 changes accordingly.
  • a movement of direction control valve 64 is controlled by operation apparatus 25 .
  • Hydraulic oil discharged from hydraulic pump 36 illustrated in FIG. 2 and subjected to pressure reduction by pressure reducing valve 25 V is supplied to operation apparatus 25 as pilot oil.
  • Operation apparatus 25 adjusts the pilot oil pressure based on operations of the respective control levers.
  • Direction control valve 64 is driven by the adjusted pilot oil pressure.
  • the shift amount and shift direction of spool 64 S in the axial direction are adjusted by adjustment of the level and direction of the pilot oil pressure by operation apparatus 25 . Accordingly, the moving speed and moving direction of boom cylinder 10 are allowed to change.
  • work implement controller 26 during the intervention control regulates a speed of boom 6 based on target excavation topography (target excavation topography data U) that indicates design topography corresponding to a target shape of an excavation object, and on inclination angles ⁇ 1, ⁇ 2, and ⁇ 3 used for obtaining a position of bucket 8 , such that an approaching speed of bucket 8 toward target excavation topography 43 I decreases in accordance with a distance between target excavation topography 43 I and bucket 8 .
  • target excavation topography data U target excavation topography data U
  • inclination angles ⁇ 1, ⁇ 2, and ⁇ 3 used for obtaining a position of bucket 8 , such that an approaching speed of bucket 8 toward target excavation topography 43 I decreases in accordance with a distance between target excavation topography 43 I and bucket 8 .
  • work implement controller 26 generates boom command signal CBI and controls a movement of boom 6 based on generated boom command signal CBI to prevent invasion of target excavation topography 43 I by cutting edges 8 T of bucket 8 when work implement 2 moves based on an operation from operation apparatus 25 .
  • work implement controller 26 raises boom 6 to prevent invasion of target excavation topography 43 I by cutting edges 8 T during the intervention control.
  • the control for raising boom 6 performed during the intervention control is referred to as boom intervention control where appropriate.
  • work implement controller 26 generates boom command signal CBI about the boom intervention control, and outputs generated boom command signal CBI to intervention valve 27 C to achieve the boom intervention control.
  • Intervention valve 27 C is capable of adjusting a pilot oil pressure of pilot oil path 50 .
  • Shuttle valve 51 includes two inlet ports 511 a and 511 b , and one outlet port 51 E.
  • Inlet port 511 a provided as one of the inlet ports is connected to intervention valve 27 C.
  • Inlet port 511 b provided as the other inlet port is connected to control valve 27 B.
  • Outlet port 51 E is connected to oil path 452 B connected to direction control valve 64 .
  • Shuttle valve 51 connects oil path 452 B and the inlet port having a higher pilot oil pressure in two inlet ports 511 a and 511 b.
  • shuttle valve 51 When the pilot oil pressure of inlet port 511 a is higher than the pilot oil pressure of inlet port 511 b , for example, shuttle valve 51 connects intervention valve 27 C and oil path 452 B. As a result, the pilot oil having passed through intervention valve 27 C is supplied to oil path 452 B via shuttle valve 51 .
  • shuttle valve 51 connects control valve 27 B with oil path 452 B. As a result, the pilot oil having passed through control valve 27 B is supplied to oil path 452 B via shuttle valve 51 .
  • direction control valve 64 is driven based on a pilot oil pressure adjusted by an operation from operation apparatus 25 .
  • work implement controller 26 opens (full-opens) pilot oil path 450 B by controlling control valve 27 B, and closes pilot oil path 50 by controlling intervention valve 27 C to drive direction control valve 64 based on a pilot oil pressure adjusted by an operation from operation apparatus 25 .
  • work implement controller 26 controls control valve 27 to drive direction control valve 64 based on a pilot oil pressure adjusted by intervention valve 27 C. For example, when performing control for regulating a shift of bucket 8 toward target excavation topography 43 I as the boom intervention control, work implement controller 26 controls intervention valve 27 C to raise a pilot oil pressure of pilot oil path 50 adjusted by intervention valve 27 C to a pressure higher than a pilot oil pressure of pilot oil path 450 B adjusted by operation apparatus 25 . In this manner, pilot oil from intervention valve 27 C is supplied to direction control valve 64 via shuttle valve 51 .
  • boom intervention control When performing the boom intervention control, work implement controller 26 generates boom command signal CBI as a speed command for raising boom 6 to control intervention valve 27 C, for example. In this manner, direction control valve 64 of boom cylinder 10 supplies sufficient hydraulic oil to boom cylinder 10 to raise boom 6 at a speed corresponding to boom command signal CBI. Accordingly, boom cylinder 10 is allowed to raise boom 6 .
  • Each of the hydraulic circuit of arm cylinder 11 and the hydraulic circuit of bucket cylinder 12 has a configuration similar to the configuration of hydraulic circuit 301 of boom cylinder 10 described above, except that intervention valve 27 C, shuttle valve 51 , and pilot oil path 50 are eliminated.
  • the boom intervention control included in the intervention control is control for raising boom 6 .
  • work implement controller 26 may raise at least either arm 7 or bucket 8 in addition to or in place of raising boom 6 in the intervention control.
  • work implement controller 26 raises at least one of boom 6 , arm 7 , and bucket 8 constituting work implement 2 to shift work implement 2 in the direction away from the target shape of the service object of work implement 2 , or target excavation topography 43 I according to the embodiment.
  • the intervention control is defined as control performed by work implement controller 26 to move at least one of boom 6 , arm 7 , and bucket 8 constituting work implement 2 when work implement 2 moves based on an operation from operation apparatus 25 .
  • the intervention control is control performed by work implement controller 26 to achieve movement of the work implement when work implement 2 moves based on a manual operation corresponding to an operation from operation apparatus 25 .
  • the boom intervention control described above is a mode of the intervention control.
  • FIG. 4 is a block diagram illustrating work implement controller 26 according to the embodiment.
  • FIG. 5 is a chart illustrating target excavation topography data U and bucket 8 according to the embodiment.
  • FIG. 6 is a diagram illustrating a boom speed limit Vcy_bm according to the embodiment.
  • FIG. 7 is a chart illustrating a speed limit Vc_lmt according to the embodiment.
  • Work implement controller 26 includes a decision unit 26 J and a control unit 26 CNT.
  • Control unit 26 CNT includes a relative position calculation unit 26 A, a distance calculation unit 26 B, a target speed calculation unit 26 C, an intervention speed calculation unit 26 D, an intervention command calculation unit 26 E, and an intervention speed correction unit 26 F.
  • work implement controller 26 For performing the intervention control, work implement controller 26 generates boom command signal CBI necessary for the intervention control based on boom manipulated variable MB, arm manipulated variable MA, bucket manipulated variable MT, target excavation topography data U and bucket cutting edge position data S acquired from display controller 28 , and inclination angles ⁇ 1, ⁇ 2, and ⁇ 3 acquired from sensor controller 39 , and generates an arm command signal and a bucket command signal as necessary to control work implement 2 by driving control valve 27 and intervention valve 27 C based on the generated command signal.
  • boom command signal CBI necessary for the intervention control based on boom manipulated variable MB, arm manipulated variable MA, bucket manipulated variable MT, target excavation topography data U and bucket cutting edge position data S acquired from display controller 28 , and inclination angles ⁇ 1, ⁇ 2, and ⁇ 3 acquired from sensor controller 39 , and generates an arm command signal and a bucket command signal as necessary to control work implement 2 by driving control valve 27 and intervention valve 27 C based on the generated command signal.
  • Relative position calculation unit 26 A acquires bucket cutting edge position data S from display controller 28 , and acquires inclination angles ⁇ 1, ⁇ 2, and ⁇ 3 from sensor controller 39 . Relative position calculation unit 26 A obtains a cutting edge position Pb indicating a position of cutting edges 8 T of bucket 8 based on acquired inclination angles ⁇ 1, ⁇ 2, and ⁇ 3.
  • Distance calculation unit 26 B calculates a distance d indicating a minimum distance between cutting edges 8 T of bucket 8 and target excavation topography 43 I expressed by target excavation topography data U as a part of target execution information T based on cutting edge position Pb obtained by relative position calculation unit 26 A and target excavation topography data U acquired from display controller 28 .
  • Distance d is a distance between cutting edge position Pb, and a position Pu corresponding to an intersection of target excavation topography data U and a line crossing target excavation topography 43 I at right angles and passing through cutting edge position Pb.
  • Target excavation topography 43 I is obtained as a line of intersection formed by a plane of work implement 2 defined in the fore/aft direction of upper revolving unit 3 and passing through an excavation target position Pdg, and target execution information T expressed by a plurality of target execution surfaces.
  • target excavation topography 43 I is the line of intersection described above, and formed by a single or a plurality of inflection points fore and after excavation target position Pdg of target execution information T, and lines fore and after the inflection points.
  • target excavation topography 43 I is formed by two inflection points Pv1 and Pv2, and lines fore and after inflection points Pv1 and Pv2.
  • Excavation target position Pdg is a point located directly below cutting edge position Pb corresponding to the position of cutting edges 8 T of bucket 8 . Accordingly, target excavation topography 43 I is a part of target execution information T.
  • Target excavation topography 43 I is generated by display controller 28 illustrated in FIG. 2 .
  • Target speed calculation unit 26 C determines a boom target speed Vc_bm, a arm target speed Vc_am, and a bucket target speed Vc_bkt.
  • Boom target speed Vc_bm is a speed of cutting edges 8 T during driving of boom cylinder 10 .
  • Dipper stick target speed Vc_am is a speed of cutting edges 8 T during driving of arm cylinder 11 .
  • Bucket target speed Vc_bkt is a speed of cutting edges 8 T during driving of bucket cylinder 12 .
  • Boom target speed Vc_bm is calculated based on boom manipulated variable MB.
  • Dipper stick target speed Vc_am is calculated based on arm manipulated variable MA.
  • Bucket target speed Vc_bkt is calculated based on bucket manipulated variable MT.
  • Intervention speed calculation unit 26 D obtains speed limit (boom speed limit) Vcy_bm of boom 6 based on distance d between cutting edges 8 T of bucket 8 and target excavation topography 43 I.
  • intervention speed calculation unit 26 D calculates boom speed limit Vcy_bm by subtracting arm target speed Vc_am and bucket target speed Vc_bkt from speed limit Vc_lmt indicating the overall speed limit of work implement 2 illustrated in FIG. 1 .
  • Speed limit Vc_lmt is an allowable shift speed of cutting edges 8 T in the direction of approach of cutting edges 8 T of bucket 8 toward target excavation topography 43 I.
  • speed limit Vc_lmt is a lowering speed of work implement 2 .
  • work implement 2 has a positive value and rises when distance d is a negative value.
  • limiting speed Vc_lmt is a rising speed of work implement 2 .
  • a negative value of distance d indicates an invaded state of target excavation topography 43 I by bucket 8 .
  • the absolute value of speed limit Vc_lmt decreases as distance d decreases. After a change of distance d to a negative value, the absolute value of the speed increases as the absolute value of distance d increases.
  • Decision unit 26 J decides whether to correct boom speed limit Vcy_bm.
  • intervention speed correction unit 26 F corrects boom speed limit Vcy_bm, and outputs corrected boom speed limit Vcy_bm.
  • the corrected boom speed limit is expressed as Vcy_bm′.
  • intervention speed correction unit 26 F When decision unit 26 J decides not to correct boom speed limit Vcy_bm, intervention speed correction unit 26 F outputs boom speed limit Vcy_bm without correction. Intervention command calculation unit 26 E generates boom command signal CBI based on boom speed limit Vcy_bm obtained by intervention speed correction unit 26 F.
  • Boom command signal CBI is a command for setting an opening of intervention valve 27 C to a degree sufficient for providing a pilot pressure for shuttle valve 51 to raise boom 6 at boom speed limit Vcy_bm. According to the embodiment, boom command signal CBI is a current value corresponding to the boom command speed.
  • Decision unit 26 J includes a switching decision unit 26 K, an operation command determination unit 26 L, and a speed difference determination unit 26 M.
  • Switching decision unit 26 K decides whether or not the intervention control is unnecessary.
  • Operation command determination unit 26 L determines whether or not the operator is operating right control lever 25 R to perform an operation for raising boom 6 or a neutral operation.
  • the neutral operation is an operation for producing such a state where neither a raising operation nor a lowering operation is being performed. In this state, right control lever 25 R is located at an intermediate position.
  • Speed difference determination unit 26 M determines a speed difference between boom speed limit Vcy_bm, and boom target speed Vc_bm in accordance with an operation input to right control lever 25 R from the operator to raise boom 6 .
  • speed difference determination unit 26 M determines a speed difference between boom speed limit Vcy_bm, and a boom target speed of zero in accordance with the neutral operation input to right control lever 25 R from the operator. More specifically, speed difference determination unit 26 M determines whether or not the speed difference is greater than or equal to a threshold Dr.
  • decision unit 26 J corrects boom speed limit Vcy_bm when the speed difference between boom speed limit Vcy_bm and boom target speed Vc_bm in accordance with the operation input to right control lever 25 R from the operator to raise boom 6 is greater than or equal to threshold Dr.
  • decision unit 26 J corrects boom speed limit Vcy_bm when the speed difference between boom speed limit Vcy_bm and boom target speed of zero in accordance with the neutral operation input to right control lever 25 R from the operator is greater than or equal to threshold Dr.
  • FIG. 8 is a view illustrating a relationship between bucket 8 and target excavation topography 43 I according to the embodiment.
  • the intervention control is control for shifting bucket 8 to prevent invasion of target excavation topography 43 I by bucket 8 .
  • work implement controller 26 starts the boom intervention control.
  • the intervention control starts when the work implement attempts to invade target excavation topography 43 I based on an operation by the operator.
  • the intervention control stops when invasion of target excavation topography 43 I by the work implement stops based on an operation by the operator for shifting bucket 8 in a direction indicated by an arrow Y in FIG. 8 .
  • the intervention control When the intervention control is canceled by a shift of bucket 8 out of an area containing target excavation topography 43 I as illustrated in FIG. 8 , the intervention control is switched to control of work implement 2 by manual operation.
  • FIG. 9 is a chart illustrating a relationship between time t, and a boom target speed Vbm indicating a moving speed of boom 6 according to the embodiment.
  • the vertical axis represents boom target speed Vbm
  • the horizontal axis represents time t.
  • a positive value of boom target speed Vbm indicates a rising speed of boom 6 during rising
  • a negative value of boom target speed Vbm indicates a lowering speed of boom 6 during lowering.
  • Boom 6 is provided as a part of work implement 2 , wherefore boom target speed Vbm is equivalent to a speed of work implement 2 .
  • the rising speed of boom 6 corresponds to a rising speed of work implement 2
  • the lowering speed of boom 6 corresponds to a lowering speed of work implement 2 .
  • each of the rising speed and the lowering speed of work implement 2 is referred to as a shift speed of work implement 2 .
  • the shift speed of work implement 2 during rising has a positive value, while the shift speed of work implement 2 during lowering has a negative value.
  • work implement controller 26 sets boom target speed Vbm to a boom target speed Vbop determined based on an operation by the operator of hydraulic excavator 100 .
  • work implement controller 26 decreases boom target speed Vbm at a fixed change rate VRC to change a boom speed limit Vcy_bm1 indicated before elimination of the necessity of the boom intervention control to boom target speed Vbop.
  • the intervention control of work implement 2 is switched to control of work implement 2 based on an operation command issued from operation apparatus 25 .
  • work implement controller 26 compares boom speed limit Vcy_bm1 in accordance with the boom intervention control with boom target speed Vbop or zero determined based on the operation by the operator when the operation command from operation apparatus 25 is the command for raising boom 6 or the neutral command in the state that the necessity of the boom intervention control is eliminated. Subsequently, a difference D between boom speed limit Vcy_bm1 and boom target speed Vbop or zero is calculated. Note that a speed change increases as difference D between boom speed limit Vcy_bm1 and boom target speed Vbop or zero increases.
  • Work implement controller 26 decreases boom target speed Vbm at fixed change rate VRC to change boom target speed Vbm indicated before elimination of the necessity of the boom intervention control to boom target speed Vbop when difference D between boom speed limit Vcy_bm1 and boom target speed Vbop or zero is greater than or equal to threshold Dr in the state that the command for raising boom 6 or the neutral command has been issued as an operation command from operation apparatus 25 and in the state that the necessity of the boom intervention control has been eliminated.
  • boom target speed Vbm gradually changes from boom speed limit Vcy_bm1 to boom target speed Vbop or zero instructed by the operator. This change reduces a rapid speed decrease of boom 6 , wherefore discomfort given to the operator decreases.
  • shock caused by a rapid speed decrease of boom 6 decreases, wherefore effects on soil loaded on bucket 8 also decrease.
  • intervention speed calculation unit 26 D of the work implement controller illustrated in FIG. 4 obtains boom speed limit Vcy_bm.
  • switching decision unit 26 K of decision unit 26 J included in work implement controller 26 illustrated in FIG. 4 decides whether or not the boom intervention control is unnecessary.
  • Operation command determination unit 26 L determines whether or not the operator is inputting the operation for raising boom 6 or the neutral operation to right control lever 25 R when it is determined that the boom intervention control is unnecessary.
  • Speed difference determination unit 26 M determines a speed difference between boom speed limit Vcy_bm, and boom target speed Vc_bm in accordance with the operation by the operator for raising boom 6 or the boom target speed of zero in accordance with the neutral operation when the operator is inputting the operation for raising boom 6 or the neutral operation to right control lever 25 R in the state that the boom intervention control is unnecessary.
  • speed difference determination unit 26 M determines that the speed difference is greater than or equal to threshold Dr
  • decision unit 26 J decides to correct boom speed limit Vcy_bm, and instructs intervention speed correction unit 26 F to correct boom speed limit Vcy_bm.
  • Intervention speed correction unit 26 F of control unit 26 CNT obtains corrected boom speed limit Vcy_bm′, and outputs boom speed limit Vcy_bm′ to intervention command calculation unit 26 E of control unit 26 CNT.
  • Intervention command calculation unit 26 E of control unit 26 CNT generates boom command signal CBI based on corrected boom speed limit Vcy_bm′ to control intervention valve 27 C.
  • Work implement controller 26 changes a rising speed of boom 6 by this process.
  • intervention speed correction unit 26 F performs control to change boom speed limit Vcy_bm to boom target speed Vbop at change rate VRC.
  • change rate VRC is determined based on sensory evaluation of the operator, for example. However, other methods may be employed to determine change rate VRC.
  • FIG. 10 is a chart illustrating a flow of a control method for the work machine according to the embodiment.
  • control method for the work machine is performed by work implement controller 26 .
  • step S 2 switching decision unit 26 K of work implement controller 26 illustrated in FIG. 4 decides whether or not the boom intervention control is unnecessary.
  • operation command determination unit 26 L in step S 4 determines whether or not the operator is performing the operation for raising boom 6 or the neutral operation (step S 4 ).
  • step S 4 When operation command determination unit 26 L in step S 4 determines that the operator is performing the operation for raising boom 6 or the neutral operation (YES in step S 4 ), speed difference determination unit 26 M determines a difference between boom speed limit Vcy_bm, and boom target speed Vc_bm in accordance with the operation for raising boom 6 by the operator or the boom target speed of zero (step S 5 ).
  • Speed difference determination unit 26 M determines whether or not the speed difference is greater than or equal to threshold Dr (step S 6 ).
  • intervention command calculation unit 26 E of work implement controller 26 in step S 8 When speed difference determination unit 26 M in step S 6 determines that the speed difference is greater than or equal to threshold Dr (YES in step S 6 ), intervention command calculation unit 26 E of work implement controller 26 in step S 8 generates boom command signal CBI based on corrected boom speed limit Vcy_bm′ obtained by intervention speed correction unit 26 F, and controls intervention valve 27 C based on the generated boom command signal.
  • intervention command calculation unit 26 E of work implement controller 26 in step S 16 controls intervention valve 27 C based on boom command signal CBI generated from boom speed limit Vcy_bm that has not been corrected.
  • step S 4 when determining in step S 4 that the operator is not performing the operation for raising boom 6 or the neutral operation (NO in step S 4 ), or when determining in step S 6 that the speed difference is less than threshold Dr (NO in step S 6 ), work implement controller 26 generates boom command signal CBI from a target speed in accordance with a command input by the control lever, and controls intervention valve 27 C based on the boom command signal (step S 12 ).
  • operation apparatus 25 includes pilot hydraulic control levers.
  • operation apparatus 25 may include an electric left control lever 25 La and an electric right control lever 25 Ra.
  • Work implement controller 26 having detected an operation signal of the electric control lever performs control similar to the corresponding control performed by using the pilot hydraulic control lever.
  • the boom speed limit Vcy_bm is corrected when a speed difference between boom speed limit Vcy_bm, and boom target speed Vc_bm in accordance with the operation for raising boom 6 or the boom target speed of zero in accordance with the neutral operation is greater than or equal to threshold Dr in the state that the operator is inputting the operation for raising boom 6 or the neutral operation to right control lever 25 R and in the state that the intervention control is unnecessary.
  • Boom speed limit Vcy_bm is reduced at fixed change rate VRC to change boom speed limit Vcy_bm to boom target speed Vbop instructed by the operator or zero.
  • Work implement 2 includes boom 6 , dipper stick 7 , and bucket 8 .
  • the attachment of work implement 2 is not limited to them, and other types of attachment than bucket 8 may be employed.
  • the work machine is only required to include a certain work implement.
  • the work implement included in the work machine is not limited to hydraulic excavator 100 .
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