U.S. patent application number 15/756656 was filed with the patent office on 2019-03-14 for work machine and control method for work machine.
This patent application is currently assigned to KOMATSU LTD.. The applicant listed for this patent is KOMATSU LTD.. Invention is credited to Toru MATSUYAMA, Ayumi OHKUMA, Takeo YAMADA.
Application Number | 20190078289 15/756656 |
Document ID | / |
Family ID | 65002558 |
Filed Date | 2019-03-14 |
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United States Patent
Application |
20190078289 |
Kind Code |
A1 |
MATSUYAMA; Toru ; et
al. |
March 14, 2019 |
WORK MACHINE AND CONTROL METHOD FOR WORK MACHINE
Abstract
A work machine according an aspect 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, 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.
Inventors: |
MATSUYAMA; Toru; (Minato-ku,
Tokyo, JP) ; OHKUMA; Ayumi; (Minato-ku, Tokyo,
JP) ; YAMADA; Takeo; (Minato-ku, Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMATSU LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
KOMATSU LTD.
Tokyo
JP
|
Family ID: |
65002558 |
Appl. No.: |
15/756656 |
Filed: |
July 14, 2017 |
PCT Filed: |
July 14, 2017 |
PCT NO: |
PCT/JP2017/025778 |
371 Date: |
March 1, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 9/2292 20130101;
E02F 9/2004 20130101; E02F 9/2235 20130101; E02F 9/26 20130101;
E02F 3/435 20130101; E02F 9/2296 20130101; E02F 3/32 20130101; E02F
9/2203 20130101; E02F 9/265 20130101; E02F 9/262 20130101; E02F
9/22 20130101 |
International
Class: |
E02F 3/43 20060101
E02F003/43; E02F 3/32 20060101 E02F003/32; E02F 9/22 20060101
E02F009/22; E02F 9/20 20060101 E02F009/20; E02F 9/26 20060101
E02F009/26 |
Claims
1. A work machine comprising: a work implement; an operation
apparatus for operating the work implement; and a controller for
controlling the work implement, wherein 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.
2. The work machine according to claim 1, wherein the controller
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
speed difference determination unit.
3. The work machine according to claim 1, wherein the controller
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.
4. A control method for a work machine including a work implement
and an operation apparatus for operating the work implement, the
method comprising the steps of: performing intervention control for
raising the work implement based on an operation command from the
operation apparatus; deciding switching from the intervention
control to control of the work implement in accordance with an
operation command from the operation apparatus; determining 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; 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; and
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.
Description
TECHNICAL FIELD
[0001] The present invention relates to a work machine including a
work implement, and a control method for a work machine.
BACKGROUND ART
[0002] 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.
[0003] When the target shape of the object of execution disappears,
or when invasion of the target shape by a work implement is stopped
by an operation of an operator during the intervention control, for
example, 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.
CITATION LIST
Patent Document
PTD 1: WO 2016/111384
SUMMARY OF INVENTION
Technical Problem
[0004] When performance of the intervention control stops, current
control switches to control of the work implement in accordance
with an operation command issued from an operation apparatus.
[0005] At the time of switching of control, 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. When such a rapid
speed change is produced, the operator may have a sense of
discomfort.
[0006] The present disclosure has been developed to solve the
aforementioned problems. 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.
Solution to Problem
[0007] A work machine according an aspect 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.
[0008] 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
speed difference determination unit.
[0009] 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.
[0010] A control method for a work machine according to an aspect
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:
performing intervention control for raising the work implement
based on an operation command from the operation apparatus;
deciding switching from the intervention control to control of the
work implement in accordance with an operation command from the
operation apparatus; determining 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; 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; and 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.
Advantageous Effects of Invention
[0011] 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.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a perspective view of a work machine according to
an embodiment.
[0013] 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.
[0014] FIG. 3 is a diagram illustrating an example of a hydraulic
circuit 301 included in a boom cylinder 10 according to the
embodiment.
[0015] FIG. 4 is a block diagram of a work implement controller 26
according to the embodiment.
[0016] FIG. 5 is a chart illustrating target excavation topography
data U and a bucket 8 according to the embodiment.
[0017] FIG. 6 is a diagram illustrating a boom speed limit Vcy_bm
according to the embodiment.
[0018] FIG. 7 is a chart illustrating a speed limit Vc_lmt
according to the embodiment.
[0019] FIG. 8 is a view illustrating a relationship between bucket
8 and target excavation topography 43I according to the
embodiment.
[0020] 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.
[0021] FIG. 10 is a chart illustrating a flow of a control method
for the work machine according to the embodiment.
DESCRIPTION OF EMBODIMENT
[0022] An embodiment of the present invention is hereinafter
described with reference to the drawings. In the following
description, identical parts are given identical reference numbers.
These identical parts have identical names and functions, wherefore
details of these parts are not repeatedly described herein. Note
that "upper", "lower", "fore", "after", "left", and "right" in the
following description are terms defined as viewed from a reference
corresponding to an operator sitting on an operator's seat.
<General Configuration of Work Machine>
[0023] FIG. 1 is a perspective view of a work machine according to
the embodiment.
[0024] 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.
[0025] Referring to FIG. 1, hydraulic excavator 100 provided as a
work machine includes a vehicular body 1 and a work implement
2.
[0026] 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 3EG. Engine room 3EG is
disposed at an end of upper revolving unit 3.
[0027] The internal combustion engine provided as a power generator
of hydraulic excavator 100 is constituted by a diesel engine, for
example. However, the power generator may be constituted by other
types of power generator.
[0028] For example, 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.
[0029] 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.
[0030] 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 3EG. A display unit 29 and an operation
apparatus 25 illustrated in FIG. 2 are disposed within operator's
cab 4.
[0031] Traveling apparatus 5 supports upper revolving unit 3.
Traveling apparatus 5 includes crawler belts 5a and 5b One or both
of travel motors 5c provided on the left and right of traveling
apparatus 5 drive and rotate crawler belts 5a and 5b 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.
[0032] Hydraulic excavator 100 may include a traveling apparatus
provided with tires instead of crawler belts 5a and 5b, 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.
[0033] Hydraulic excavator 100 may be a backhoe loader, for
example.
[0034] 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 3EG is disposed. The left side in the forward direction
corresponds to the left of upper revolving unit 3, while 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, while 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. When hydraulic excavator 100 is disposed on a
horizontal plane, the lower side corresponds to the gravitating
side in the direction of gravity identical to the perpendicular
direction, while the upper side corresponds to the side opposite to
the gravitating side in the perpendicular direction.
[0035] 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 8B are attached to
bucket 8 on the side opposite to bucket pin 15. Cutting edges 8T
correspond to distal ends of cutters 8B.
[0036] According to the embodiment, 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 5a and 5b and the ground.
[0037] In case of a work machine not provided with upper revolving
unit 3, 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. When the work machine has
wheels instead of crawler belts, the ground engaging surface is a
flat surface defined by ground engaging portions of at least three
wheels.
[0038] Bucket 8 is not required to have the plurality of cutters
8B. Such a bucket is adoptable which does not have cutters 8B
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. Alternatively, 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.
[0039] 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.
[0040] 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 5c, 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.
[0041] 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.
[0042] 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.
[0043] 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). In the following description, antennas 21 and
22 are referred to as GNSS antennas 21 and 22 where appropriate.
When 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>
[0044] Referring to FIG. 2, 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.
[0045] 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>
[0046] Referring to FIG. 2, 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] According to the embodiment, operation apparatus 25 includes
a left control lever 25L provided on the left side of the operator,
and a right control lever 25R provided on the right side of the
operator. Movements of left control lever 25L and right control
lever 25R in the fore/aft and left/right directions are associated
with movements of dipper stick 7 and the two axes of
revolution.
[0052] For example, an operation of right control lever 25R in the
fore/aft direction is associated with an operation of boom 6. When
right control lever 25R is operated forward, boom 6 lowers. When
right control lever 25R is operated rearward, boom 6 rises. The
lowering and rising movements of boom 6 are performed in accordance
with operations of right control lever 25R in the fore/aft
direction.
[0053] An operation of right control lever 25R in the left/right
direction is associated with an operation of bucket 8. When right
control lever 25R is operated leftward, bucket 8 performs
excavation. When right control lever 25R 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 25R in the left/right direction.
[0054] An operation of left control lever 25L in the fore/aft
direction is associated with an operation of dipper stick 7. When
left control lever 25L is operated forward, dipper stick 7 performs
dumping. When left control lever 25L is operated rearward, dipper
stick 7 performs excavation.
[0055] An operation of left control lever 25L in the left/right
direction is associated with a revolving operation of upper
revolving unit 3. When left control lever 25L is operated leftward,
upper revolving unit 3 revolves leftward. When left control lever
25L is operated rightward, upper revolving unit 3 revolves
rightward.
[0056] According to the embodiment, 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 25V 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.
[0057] An operation of right control lever 25R in the fore/aft
direction allows supply of a pilot oil pressure to pilot oil path
450. In this state, 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 25R in accordance
with a manipulated variable of right control lever 25R.
[0058] Pressure sensor 66 detects a pressure of hydraulic oil
within pilot oil path 450 as a pilot pressure.
[0059] 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 25R 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) 27C, and a shuttle valve 51 are included in pilot oil
path 50. Intervention valve 27C and shuttle valve 51 will be
detailed below.
[0060] An operation of right control lever 25R in the left/right
direction allows supply of a pilot oil pressure to pilot oil path
450. In this state, 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 25R in
accordance with a manipulated variable of right control lever
25R.
[0061] Pressure sensor 66 detects a pressure of hydraulic oil
within pilot oil path 450 as a pilot pressure.
[0062] 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 25R in the left/right direction is
hereinafter referred to as bucket manipulated variable MT where
appropriate.
[0063] An operation of left control lever 25L in the fore/aft
direction allows supply of a pilot oil pressure to pilot oil path
450. In this state, 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 25L in
accordance with a manipulated variable of left control lever
25L.
[0064] Pressure sensor 66 detects a pressure of hydraulic oil
within pilot oil path 450 as a pilot pressure.
[0065] 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 25L in the fore/aft
direction is hereinafter referred to as dipper stick manipulated
variable MA where appropriate.
[0066] When right control lever 25R is operated, 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 25R.
[0067] When left control lever 25L is operated, 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
25L. Direction control valve 64 moves in accordance with a pilot
oil pressure supplied from operation apparatus 25 to direction
control valve 64.
[0068] Control system 200 includes a first stroke sensor 16, a
second stroke sensor 17, and a third stroke sensor 18. For example,
first stroke sensor 16 is included in boom cylinder 10, second
stroke sensor 17 is included in dipper stick cylinder 11, and third
stroke sensor 18 is included in bucket cylinder 12.
[0069] 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).
[0070] Sensor controller 39 calculates an inclination angle
.theta.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 .theta.1 to work implement controller
26 and display controller 28.
[0071] Sensor controller 39 calculates an inclination angle
.theta.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 .theta.2 to work
implement controller 26 and display controller 28.
[0072] Sensor controller 39 calculates an inclination angle
.theta.3 of cutting edges 8T 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 .theta.3
to work implement controller 26 and display controller 28.
[0073] Inclination angles .theta.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. For example, an angle sensor
such as a potentiometer may be used to detect inclination angles
.theta.1, .theta.2, and .theta.3.
[0074] An inertial measurement unit (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.
[0075] Work implement controller 26 includes a storage unit 26Q
such as a RAM and a read only memory (ROM), and a processing unit
26P such as a CPU.
[0076] Work implement controller 26 controls intervention valve 27C
and control valve 27 based on boom manipulated variable MB, bucket
manipulated variable MT, and dipper stick manipulated variable MA
illustrated in FIG. 2.
[0077] 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.
[0078] 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.
[0079] Position detection device 19 contained in control system 200
includes GNSS antennas 21 and 22 described above. When 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.
[0080] 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.
[0081] 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.
[0082] 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.
[0083] According to the embodiment, 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.
[0084] 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.
[0085] 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.
[0086] According to the embodiment, display controller 28
generates, as work implement position data, bucket cutting edge
position data S indicating a three-dimensional position of cutting
edges 8T 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.
[0087] 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.
[0088] 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.
[0089] Display unit 29 is a liquid crystal display apparatus that
receives input via a touch panel, for example. However, display
unit 29 is not limited to this type. According to the embodiment, a
switch 29S is provided adjacent to display unit 29. Switch 29S is
an input device that executes intervention control described below,
or stops the intervention control being performed.
[0090] 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 .theta.1 of boom 6, inclination angle
.theta.2 of arm 7, and inclination angle .theta.3 of bucket 8 from
sensor controller 39.
[0091] 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.
[0092] 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.
[0093] Work implement controller 26 calculates a position of
cutting edges 8T 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.
[0094] Work implement controller 26 controls a movement of work
implement 2 based on a distance between target excavation
topography data U and cutting edges 8T of bucket 8, and on a speed
of work implement 2 such that cutting edges 8T of bucket 8 can
shift in accordance with target excavation topography data U.
[0095] 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.
[0096] For example, the intervention control is performed when the
operator of hydraulic excavator 100 selects performance of the
intervention control by using switch 29S illustrated in FIG. 2.
When a distance between target excavation topography described
below and bucket 8 is calculated, a reference position of bucket 8
is not limited to the position of cutting edges 8T but may be other
appropriate positions.
[0097] During the intervention control, work implement controller
26 generates a boom command signal CBI, and outputs generated boom
command signal CBI to intervention valve 27C illustrated in FIG. 2
to control work implement 2 such that cutting edges 8T of bucket 8
can shift in accordance with target excavation topography data
U.
[0098] 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.
<Configuration of Hydraulic Circuit 301>
[0099] FIG. 3 is a diagram illustrating an example of hydraulic
circuit 301 of boom cylinder 10 according to the embodiment.
[0100] Referring to FIG. 3, 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.
[0101] According to the embodiment, direction control valve 64 is a
spool valve that shifts a rod-shaped spool 64S to switch a flow
direction of hydraulic oil.
[0102] Spool 64S 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 64S
to move boom cylinder 10.
[0103] Pilot oil path 50 and pilot oil path 450B are connected to
shuttle valve 51.
[0104] Shuttle valve 51 and one end of direction control valve 64
are connected with each other via an oil path 452B. The other end
of direction control valve 64 and operation apparatus 25 are
connected with each other via a pilot oil path 450A and a pilot oil
path 452A. Pilot oil path 50 includes intervention valve 27C.
Intervention valve 27C adjusts a pilot pressure of pilot oil path
50.
[0105] Pilot oil path 450B includes a pressure sensor 66B and a
control valve 27B. Pilot oil path 450A includes a pressure sensor
66A provided between a control valve 27A 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.
[0106] Each of pressure sensor 66A and pressure sensor 66B
corresponds to pressure sensor 66 illustrated in FIG. 2. Each of
control valve 27A and control valve 27B corresponds to control
valve 27 illustrated in FIG. 2.
[0107] 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 48R of boom cylinder 10 and supply to a rod side
oil chamber 47R of boom cylinder 10 by a shift of spool 64S in the
axial direction.
[0108] 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 64S 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.
[0109] When spool 64S of direction control valve 64 shifts in a
first direction, hydraulic oil is supplied from direction control
valve 64 to cap side oil chamber 48R. When hydraulic oil is
returned from rod side oil chamber 47R to direction control valve
64, a piston 10P of boom cylinder 10 shifts from cap side oil
chamber 48R toward rod side oil chamber 47R. As a result, a rod 10L
connected to piston 10P extends from boom cylinder 10.
[0110] When spool 64S of direction control valve 64 shifts in a
second direction corresponding to a direction opposite to the first
direction based on a command from operation apparatus 25, hydraulic
oil is returned from cap side oil chamber 48R to direction control
valve 64. When hydraulic oil is supplied from direction control
valve 64 to rod side oil chamber 47R, piston 10P of boom cylinder
10 shifts from rod side oil chamber 47R toward cap side oil chamber
48R. As a result, rod 10L connected to piston 10P contracts into
boom cylinder 10. In this manner, a moving direction of boom
cylinder 10 changes in accordance with adjustment of the shift
direction of spool 64S of direction control valve 64.
[0111] 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 64S of direction control valve 64. In this case, each shift
speed of piston 10P and rod 10L corresponding to a moving speed of
boom cylinder 10 changes accordingly.
[0112] As described above, 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 25V is supplied to
operation apparatus 25 as pilot oil.
[0113] 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 64S 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.
[0114] As described above, 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 .theta.1, .theta.2,
and .theta.3 used for obtaining a position of bucket 8, such that
an approaching speed of bucket 8 toward target excavation
topography 43I decreases in accordance with a distance between
target excavation topography 43I and bucket 8.
[0115] According to the embodiment, 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 43I by cutting edges 8T of bucket 8
when work implement 2 moves based on an operation from operation
apparatus 25.
[0116] More specifically, work implement controller 26 raises boom
6 to prevent invasion of target excavation topography 43I by
cutting edges 8T during the intervention control. The control for
raising boom 6 performed during the intervention control is
referred to as boom intervention control where appropriate.
[0117] According to the embodiment, work implement controller 26
generates boom command signal CBI about the boom intervention
control, and outputs generated boom command signal CBI to
intervention valve 27C to achieve the boom intervention
control.
[0118] Intervention valve 27C is capable of adjusting a pilot oil
pressure of pilot oil path 50. Shuttle valve 51 includes two inlet
ports 511a and 511b, and one outlet port 51E. Inlet port 511a
provided as one of the inlet ports is connected to intervention
valve 27C. Inlet port 511b provided as the other inlet port is
connected to control valve 27B. Outlet port 51E is connected to oil
path 452B connected to direction control valve 64.
[0119] Shuttle valve 51 connects oil path 452B and the inlet port
having a higher pilot oil pressure in two inlet ports 511a and
511b.
[0120] When the pilot oil pressure of inlet port 511a is higher
than the pilot oil pressure of inlet port 511b, for example,
shuttle valve 51 connects intervention valve 27C and oil path 452B.
As a result, the pilot oil having passed through intervention valve
27C is supplied to oil path 452B via shuttle valve 51. When the
pilot oil pressure of inlet port 511b is higher than the pilot oil
pressure of inlet port 511a, shuttle valve 51 connects control
valve 27B with oil path 452B. As a result, the pilot oil having
passed through control valve 27B is supplied to oil path 452B via
shuttle valve 51.
[0121] During a stop of the boom intervention control, direction
control valve 64 is driven based on a pilot oil pressure adjusted
by an operation from operation apparatus 25. For example, work
implement controller 26 opens (full-opens) pilot oil path 450B by
controlling control valve 27B, and closes pilot oil path 50 by
controlling intervention valve 27C to drive direction control valve
64 based on a pilot oil pressure adjusted by an operation from
operation apparatus 25.
[0122] When performing the boom intervention control, work
implement controller 26 controls control valve 27 to drive
direction control valve 64 based on a pilot oil pressure adjusted
by intervention valve 27C. For example, when performing control for
regulating a shift of bucket 8 toward target excavation topography
43I as the boom intervention control, work implement controller 26
controls intervention valve 27C to raise a pilot oil pressure of
pilot oil path 50 adjusted by intervention valve 27C to a pressure
higher than a pilot oil pressure of pilot oil path 450B adjusted by
operation apparatus 25. In this manner, pilot oil from intervention
valve 27C is supplied to direction control valve 64 via shuttle
valve 51.
[0123] 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 27C,
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.
[0124] 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 27C, shuttle valve
51, and pilot oil path 50 are eliminated.
[0125] The boom intervention control included in the intervention
control is control for raising boom 6. However, 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.
[0126] During 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 43I according to the embodiment.
[0127] 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.
[0128] 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.
[0129] FIG. 4 is a block diagram illustrating work implement
controller 26 according to the embodiment.
[0130] FIG. 5 is a chart illustrating target excavation topography
data U and bucket 8 according to the embodiment.
[0131] FIG. 6 is a diagram illustrating a boom speed limit Vcy_bm
according to the embodiment.
[0132] FIG. 7 is a chart illustrating a speed limit Vc_lmt
according to the embodiment. Work implement controller 26 includes
a decision unit 26J and a control unit 26CNT. Control unit 26CNT
includes a relative position calculation unit 26A, a distance
calculation unit 26B, a target speed calculation unit 26C, an
intervention speed calculation unit 26D, an intervention command
calculation unit 26E, and an intervention speed correction unit
26F.
[0133] Functions of decision unit 26J, relative position
calculation unit 26A, distance calculation unit 26B, target speed
calculation unit 26C, intervention speed calculation unit 26D,
intervention command calculation unit 26E, and intervention speed
correction unit 26F are performed by processing unit 26P of work
implement controller 26 illustrated in FIG. 2.
[0134] 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
.theta.1, .theta.2, and .theta.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 27C based on the generated command
signal.
[0135] Relative position calculation unit 26A acquires bucket
cutting edge position data S from display controller 28, and
acquires inclination angles .theta.1, .theta.2, and .theta.3 from
sensor controller 39. Relative position calculation unit 26A
obtains a cutting edge position Pb indicating a position of cutting
edges 8T of bucket 8 based on acquired inclination angles .theta.1,
.theta.2, and .theta.3.
[0136] Distance calculation unit 26B calculates a distance d
indicating a minimum distance between cutting edges 8T of bucket 8
and target excavation topography 43I 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 26A 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 43I at right angles and
passing through cutting edge position Pb.
[0137] Target excavation topography 43I 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.
[0138] More specifically, target excavation topography 43I 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.
[0139] According to an example illustrated in FIG. 5, target
excavation topography 43I 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 8T of bucket 8. Accordingly, target excavation topography 43I
is a part of target execution information T. Target excavation
topography 43I is generated by display controller 28 illustrated in
FIG. 2.
[0140] Target speed calculation unit 26C 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 8T
during driving of boom cylinder 10. Dipper stick target speed Vc_am
is a speed of cutting edges 8T during driving of arm cylinder 11.
Bucket target speed Vc_bkt is a speed of cutting edges 8T 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.
[0141] Intervention speed calculation unit 26D obtains speed limit
(boom speed limit) Vcy_bm of boom 6 based on distance d between
cutting edges 8T of bucket 8 and target excavation topography
43I.
[0142] Referring to FIG. 6, intervention speed calculation unit 26D
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.
[0143] Speed limit Vc_lmt is an allowable shift speed of cutting
edges 8T in the direction of approach of cutting edges 8T of bucket
8 toward target excavation topography 43I.
[0144] Referring to FIG. 7, work implement 2 has a negative value
and lowers when distance d is a positive value. In this case, speed
limit Vc_lmt is a lowering speed of work implement 2. On the other
hand, work implement 2 has a positive value and rises when distance
d is a negative value. In this case, limiting speed Vc_lmt is a
rising speed of work implement 2.
[0145] A negative value of distance d indicates an invaded state of
target excavation topography 43I 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.
[0146] Decision unit 26J decides whether to correct boom speed
limit Vcy_bm.
[0147] When decision unit 26J decides to correct boom speed limit
Vcy_bm, intervention speed correction unit 26F corrects boom speed
limit Vcy_bm, and outputs corrected boom speed limit Vcy_bm. The
corrected boom speed limit is expressed as Vcy_bm'.
[0148] When decision unit 26J decides not to correct boom speed
limit Vcy_bm, intervention speed correction unit 26F outputs boom
speed limit Vcy_bm without correction. Intervention command
calculation unit 26E generates boom command signal CBI based on
boom speed limit Vcy_bm obtained by intervention speed correction
unit 26F.
[0149] Boom command signal CBI is a command for setting an opening
of intervention valve 27C 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.
[0150] Decision unit 26J includes a switching decision unit 26K, an
operation command determination unit 26L, and a speed difference
determination unit 26M.
[0151] Switching decision unit 26K decides whether or not the
intervention control is unnecessary.
[0152] Operation command determination unit 26L determines whether
or not the operator is operating right control lever 25R 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 25R is located at an intermediate
position.
[0153] Speed difference determination unit 26M 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
25R from the operator to raise boom 6. Alternatively, speed
difference determination unit 26M 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
25R from the operator. More specifically, speed difference
determination unit 26M determines whether or not the speed
difference is greater than or equal to a threshold Dr.
[0154] According to the embodiment, on the assumption that the
operator is operating right control lever 25R to raise boom 6 in
the state that the intervention control is unnecessary, decision
unit 26J 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 25R from
the operator to raise boom 6 is greater than or equal to threshold
Dr. On the other hand, on the assumption that the operator is
performing the neutral operation of right control lever 25R in the
state that the intervention control is unnecessary, decision unit
26J 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
25R from the operator is greater than or equal to threshold Dr.
<Mode of Boom Intervention Control>
[0155] FIG. 8 is a view illustrating a relationship between bucket
8 and target excavation topography 43I according to the
embodiment.
[0156] Referring to FIG. 8, the intervention control is control for
shifting bucket 8 to prevent invasion of target excavation
topography 43I by bucket 8. When bucket 8 attempts to invade target
excavation topography 43I under the intervention control by work
implement controller 26, work implement controller 26 starts the
boom intervention control.
[0157] Referring to FIG. 8, the intervention control starts when
the work implement attempts to invade target excavation topography
43I based on an operation by the operator.
[0158] The intervention control stops when invasion of target
excavation topography 43I 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.
[0159] The necessity of the intervention control is eliminated when
invasion of target excavation topography 43I by the work implement
stops based on the operation by the operator.
[0160] During the intervention control by work implement controller
26, the operator of hydraulic excavator 100 performs an operation
for shifting work implement 2 and bucket 8 upward in some
cases.
[0161] When the intervention control is canceled by a shift of
bucket 8 out of an area containing target excavation topography 43I
as illustrated in FIG. 8, the intervention control is switched to
control of work implement 2 by manual operation.
[0162] At the time of switching from the intervention control to
the control of work implement 2 by manual operation, a rapid speed
change is produced and may give a sense of discomfort to the
operator.
[0163] 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.
[0164] Referring to FIG. 9, the vertical axis represents boom
target speed Vbm, while the horizontal axis represents time t. A
positive value of boom target speed Vbm indicates a rising speed of
boom 6 during rising, while a negative value of boom target speed
Vbm indicates a lowering speed of boom 6 during lowering.
[0165] 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, while the lowering speed of boom 6 corresponds to a
lowering speed of work implement 2.
[0166] According to the embodiment, 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.
[0167] When the necessity of the boom intervention control is
eliminated by a shift of bucket 8 out of the area containing target
excavation topography 43I, 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.
[0168] Under predetermined conditions, 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.
[0169] When the necessity of the boom intervention control is
eliminated, 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.
[0170] According to the embodiment, 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.
[0171] According to the embodiment, it is determined whether or not
difference D between boom speed limit Vcy_bm1 and boom target speed
Vbop or zero is greater than or equal to threshold Dr.
[0172] 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.
[0173] When boom target speed Vbm during rising of boom 6 has a
positive value, the rising speed decreases with a change of boom
target speed Vbm at change rate VRC. Accordingly, change rate VRC
represents a deceleration of the rising speed.
[0174] When a large speed change is produced after switching to the
control of work implement 2 based on the operation command from
operation apparatus 25, the speed of boom 6 rapidly decreases. In
this case, the operator has a sense of discomfort.
[0175] When the necessity of the boom intervention control is
eliminated as a result of a shift of bucket 8 out of the area
containing target excavation topography 43I in the state that the
operator is performing the operation for raising boom 6 or the
neutral operation during the boom intervention control, 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.
[0176] Moreover, shock caused by a rapid speed decrease of boom 6
decreases, wherefore effects on soil loaded on bucket 8 also
decrease.
[0177] More specifically, intervention speed calculation unit 26D
of the work implement controller illustrated in FIG. 4 obtains boom
speed limit Vcy_bm.
[0178] Subsequently, switching decision unit 26K of decision unit
26J included in work implement controller 26 illustrated in FIG. 4
decides whether or not the boom intervention control is
unnecessary. Operation command determination unit 26L determines
whether or not the operator is inputting the operation for raising
boom 6 or the neutral operation to right control lever 25R when it
is determined that the boom intervention control is unnecessary.
Speed difference determination unit 26M 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 25R
in the state that the boom intervention control is unnecessary.
[0179] When speed difference determination unit 26M determines that
the speed difference is greater than or equal to threshold Dr,
decision unit 26J decides to correct boom speed limit Vcy_bm, and
instructs intervention speed correction unit 26F to correct boom
speed limit Vcy_bm.
[0180] Intervention speed correction unit 26F of control unit 26CNT
obtains corrected boom speed limit Vcy_bm', and outputs boom speed
limit Vcy_bm' to intervention command calculation unit 26E of
control unit 26CNT.
[0181] Intervention command calculation unit 26E of control unit
26CNT generates boom command signal CBI based on corrected boom
speed limit Vcy_bm' to control intervention valve 27C. Work
implement controller 26 changes a rising speed of boom 6 by this
process.
[0182] More specifically, intervention speed correction unit 26F
performs control to change boom speed limit Vcy_bm to boom target
speed Vbop at change rate VRC.
[0183] When change rate VRC is large, rising of boom 6 immediately
stops in response to elimination of the boom intervention control.
However, a rapid change of boom target speed Vbop thus produced
causes shock, or gives discomfort to the operator. Accordingly,
change rate VRC is limited to such a range as not to produce an
excessively rapid change to boom target speed Vbop. According to
the embodiment, 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.
<Control Method for Work Machine of Embodiment>
[0184] FIG. 10 is a chart illustrating a flow of a control method
for the work machine according to the embodiment.
[0185] Referring to FIG. 10, the control method for the work
machine according to the embodiment is performed by work implement
controller 26.
[0186] In step S2, switching decision unit 26K of work implement
controller 26 illustrated in FIG. 4 decides whether or not the boom
intervention control is unnecessary. When switching decision unit
26K decides that the boom intervention control is unnecessary (YES
in step S2), operation command determination unit 26L in step S4
determines whether or not the operator is performing the operation
for raising boom 6 or the neutral operation (step S4).
[0187] When operation command determination unit 26L in step S4
determines that the operator is performing the operation for
raising boom 6 or the neutral operation (YES in step S4), speed
difference determination unit 26M 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 S5).
[0188] Speed difference determination unit 26M determines whether
or not the speed difference is greater than or equal to threshold
Dr (step S6).
[0189] When speed difference determination unit 26M in step S6
determines that the speed difference is greater than or equal to
threshold Dr (YES in step S6), intervention command calculation
unit 26E of work implement controller 26 in step S8 generates boom
command signal CBI based on corrected boom speed limit Vcy_bm'
obtained by intervention speed correction unit 26F, and controls
intervention valve 27C based on the generated boom command
signal.
[0190] Thereafter, the process ends (END).
[0191] When switching decision unit 26K in step S2 decides that the
boom intervention control is not unnecessary (YNO in step S2),
intervention command calculation unit 26E of work implement
controller 26 in step S16 controls intervention valve 27C based on
boom command signal CBI generated from boom speed limit Vcy_bm that
has not been corrected.
[0192] On the other hand, when determining in step S4 that the
operator is not performing the operation for raising boom 6 or the
neutral operation (NO in step S4), or when determining in step S6
that the speed difference is less than threshold Dr (NO in step
S6), 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 27C based on the
boom command signal (step S12).
[0193] Thereafter, the process ends (END).
<Electric Control Lever>
[0194] According to the embodiment, operation apparatus 25 includes
pilot hydraulic control levers. However, operation apparatus 25 may
include an electric left control lever 25La and an electric right
control lever 25Ra.
[0195] When each of left control lever 25La and right control lever
25Ra is constituted by an electric lever, a manipulated variable
input by each control lever is detected by a potentiometer. The
manipulated variable input by each of left control lever 25La and
right control lever 25Ra and detected by the potentiometer is
acquired by work implement controller 26.
[0196] 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.
[0197] According to the embodiment described above, 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 25R 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.
[0198] Work implement 2 includes boom 6, dipper stick 7, and bucket
8. However, 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.
[0199] The embodiment disclosed herein is presented by way of
example, and therefore is not limited to the specific details
described herein. It is intended that the scope of the present
invention is defined only by the appended claims, and therefore
includes all changes made within meanings and ranges equivalent to
the scope of the appended claims.
REFERENCE SIGNS LIST
[0200] 1: vehicular body, 2: work implement, 3: upper revolving
unit, 4: operator's cab, 5: traveling apparatus, 6: boom, 7: dipper
stick, 8: bucket, 10: boom cylinder, 11: dipper stick cylinder, 12:
bucket cylinder, 13: boom pin, 14: dipper stick pin, 15: bucket
pin, 16: first stroke sensor, 17: second stroke sensor, 18: third
stroke sensor, 19: position detection device, 26: work implement
controller, 26A: relative position calculation unit, 26B: distance
calculation unit, 26C: target speed calculation unit, 26CNT:
control unit, 26D: intervention speed calculation unit, 26E:
intervention command calculation unit, 26F: intervention speed
correction unit, 26J: decision unit, 26K: switching decision unit,
26L: operation command determination unit, 26M: speed difference
determination unit, 26P: processing unit, 26Q: storage unit.
* * * * *