U.S. patent application number 14/782937 was filed with the patent office on 2016-02-11 for construction machine control system and method of controlling construction machine.
This patent application is currently assigned to Komatsu Ltd.. The applicant listed for this patent is KOMATSU LTD.. Invention is credited to Masashi Ichihara, Yoshiki Kami, Jin Kitajima, Toru Matsuyama, Takeo Yamada.
Application Number | 20160040398 14/782937 |
Document ID | / |
Family ID | 54071959 |
Filed Date | 2016-02-11 |
United States Patent
Application |
20160040398 |
Kind Code |
A1 |
Kitajima; Jin ; et
al. |
February 11, 2016 |
CONSTRUCTION MACHINE CONTROL SYSTEM AND METHOD OF CONTROLLING
CONSTRUCTION MACHINE
Abstract
A control method includes: detecting an attitude of a work
machine including a boom, an arm, and a bucket; operating an
operating device to drive a movable member including the arm and
the bucket; detecting an amount of operation of the operating
device; generating position data of a cutting edge of the bucket
based on the detected attitude; acquiring a target shape of an
excavation object to be excavated by the work machine and
calculating a distance between the cutting edge and the target
shape based on the position data and the target shape; setting a
limited amount of operation limiting a speed of the movable member
based on the detected amount of operation; and outputting a signal
to a valve that adjusts an amount of operating oil supplied to a
hydraulic cylinder driving the work machine so that the movable
member is driven with the limited amount of operation.
Inventors: |
Kitajima; Jin; (Naka-gun,
JP) ; Kami; Yoshiki; (Hadano-shi, JP) ;
Yamada; Takeo; (Komatsu-shi, JP) ; Matsuyama;
Toru; (Naka-gun, JP) ; Ichihara; Masashi;
(Hiratsuka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMATSU LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
Komatsu Ltd.
Tokyo
JP
|
Family ID: |
54071959 |
Appl. No.: |
14/782937 |
Filed: |
June 2, 2015 |
PCT Filed: |
June 2, 2015 |
PCT NO: |
PCT/JP2015/065958 |
371 Date: |
October 7, 2015 |
Current U.S.
Class: |
701/50 |
Current CPC
Class: |
E02F 3/32 20130101; E02F
3/435 20130101; E02F 9/2228 20130101; E02F 9/262 20130101; E02F
9/2296 20130101; E02F 9/2285 20130101; E02F 9/265 20130101; E02F
9/22 20130101 |
International
Class: |
E02F 9/26 20060101
E02F009/26; E02F 9/22 20060101 E02F009/22; E02F 3/43 20060101
E02F003/43 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2014 |
JP |
PCT/JP2014/064650 |
Claims
1. A construction machine control system comprising: a detector
that detects an attitude of a work machine that includes a boom, an
arm, and a bucket; an operating device that is operated to drive a
movable member that includes at least one of the arm and the
bucket; a detection device that detects an amount of operation of
the operating device; a control valve that adjusts an amount of
operating oil supplied to a hydraulic cylinder that drives the work
machine; a bucket position data generating unit that generates
cutting edge position data indicating a position of a cutting edge
of the bucket based on a detection result of the detector; a
distance acquiring unit that acquires a target excavation landform
indicating a target shape of an excavation object to be excavated
by the work machine and calculates a distance between the cutting
edge of the bucket and the target excavation landform based on the
cutting edge position data and the target excavation landform; a
limit value setting unit that sets a limited amount of operation
for limiting a speed of the movable member based on a detection
result of the detection device; and a movable member control unit
that outputs a control signal to the control valve so that the
movable member is driven with the limited amount of operation.
2. The construction machine control system according to claim 1,
wherein the limit value setting unit sets the limited amount of
operation so that the larger the distance, the larger the limited
amount of operation.
3. The construction machine control system according to claim 1,
further comprising: a timer that starts time measurement based on
the detection result of the detection device, wherein the limit
value setting unit sets the limited amount of operation so that the
longer a time elapsed from a start time of the time measurement of
the timer, the larger the limited amount of operation.
4. The construction machine control system according to claim 3,
wherein the movable member control unit outputs a control signal so
that the movable member is driven with the limited amount of
operation in a predetermined period from the start time of the time
measurement of the timer.
5. The construction machine control system according to claim 4,
wherein the start time of the time measurement of the timer
includes at least one of a start time of an operation of the
operating device, time at which a detection value of the detection
device exceeds a threshold value, and a time at which an amount of
increase per unit time of the detection value of the detection
device exceeds an allowable value.
6. The construction machine control system according to claim 4,
wherein the driving based on the limited amount of operation is
disabled when the predetermined period has elapsed from the start
time of the time measurement.
7. The construction machine control system according to claim 3,
wherein the limited amount of operation in a first half of the
predetermined period is smaller than the limited amount of
operation in a second half.
8. The construction machine control system according to claim 1,
further comprising: a boom limiting unit that determines a speed
limit according to the distance and limits a speed of the boom so
that a speed at which the work machine approaches the target
excavation landform is equal to or smaller than the speed limit;
and a hydraulic system that includes a first hydraulic actuator for
driving the boom, a second hydraulic actuator for driving the
movable member, and the control valve that adjusts an amount of
operating oil supplied to the second hydraulic actuator, wherein in
an excavation operation of the bucket, the hydraulic system is
operated so that the boom is raised and the arm is lowered, and the
arm is driven with the limited amount of operation when the arm is
lowered.
9. The construction machine control system according to claim 8,
wherein the hydraulic system includes: a hydraulic pump that
supplies operating oil; and a pump control unit that controls the
hydraulic pump so that the operating oil is supplied with a first
largest discharge capacity from the hydraulic pump in a first
operation mode and the operating oil is supplied with a second
largest discharge capacity smaller than the first largest discharge
capacity from the hydraulic pump in a second operation mode, and
the limited amount of operation in the second operation mode is
smaller than the limited amount of operation in the first operation
mode.
10. The construction machine control system according to claim 1,
wherein the movable member is replaceable, and the limited amount
of operation when the movable member of a first weight is connected
to the boom is smaller than the limited amount of operation when
the movable member of a second weight smaller than the first weight
is connected.
11. The construction machine control system according to claim 1,
wherein the output of the control signal is started so that the
movable member is driven with the limited amount of operation when
an amount of increase per unit time of the detection value of the
detection device exceeds an allowable value, and the amount of
increase includes a difference between the amount of operation of
the operating device and a processing amount generated by low-pass
filtering of the amount of operation.
12. The construction machine control system according to claim 1,
wherein the construction machine includes a vehicle body that
supports the boom, and the limited amount of operation when the
work machine is driven so that a distance between the bucket and a
reference position of the vehicle body is a first distance is
smaller than the limited amount of operation when the work machine
is driven so that the distance between the bucket and the reference
position is a second distance shorter than the first distance.
13. The construction machine control system according to claim 1,
wherein the output of the control signal is started so that the
movable member is driven with the limited amount of operation when
an amount of increase per unit time of the detection value of the
detection device exceeds an allowable value, and the amount of
increase includes a difference between the amount of operation of
the operating device and a processing amount generated by low-pass
filtering of the amount of operation.
14. A method of controlling a construction machine, comprising:
detecting, by a detector, an attitude of a work machine that
includes a boom, an arm, and a bucket; operating an operating
device to drive a movable member that includes at least one of the
arm and the bucket; detecting, by a detection device, an amount of
operation of the operating device; generating cutting edge position
data indicating a position of a cutting edge of the bucket based on
a detection result of the detector; acquiring a target excavation
landform indicating a target shape of an excavation object to be
excavated by the work machine and calculating a distance between
the cutting edge of the bucket and the target excavation landform
based on the cutting edge position data and the target excavation
landform; setting a limited amount of operation for limiting a
speed of the movable member based on a detection result of the
detection device; and outputting a control signal to a control
valve that adjusts an amount of operating oil supplied to a
hydraulic cylinder that drives the work machine so that the movable
member is driven with the limited amount of operation.
Description
FIELD
[0001] The present invention relates to a construction machine
control system and a method of controlling construction
machine.
BACKGROUND
[0002] A construction machine like an excavator includes a work
machine that includes a boom, an arm, and a bucket and an operating
device that an operator operates to drive the work machine. As a
method of controlling a construction machine, limited excavation
control in which a bucket is moved based on a target excavation
landform indicating a target shape of an excavation object is known
as disclosed in Patent Literatures 1 and 2.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Patent Application Laid-open
No. 2013-217138
[0004] Patent Literature 2: Japanese Patent Application Laid-open
No. 2006-265954
SUMMARY
Technical Problem
[0005] In the excavation process using the work machine of the
construction machine, there is a possibility that a cutting edge of
the bucket falls at the start of excavation. An example of the
cause of the falling of a cutting edge is a delay in generation of
pressure in relation to an operation command generated from the
operating device. When excavation starts near a target excavation
landform, the bucket may exceed the target excavation landform and
the excavation accuracy may decrease.
[0006] An object of some aspects of the present invention is to
provide a construction machine control system, a construction
machine, and a method of controlling the construction machine
capable of suppressing falling of a cutting edge.
Solution to Problem
[0007] According to a first embodiment of the invention, there is
provided a construction machine control system comprising: a
detector that detects an attitude of a work machine that includes a
boom, an arm, and a bucket; an operating device that is operated to
drive a movable member that includes at least one of the arm and
the bucket; a detection device that detects an amount of operation
of the operating device; a control valve that adjusts an amount of
operating oil supplied to a hydraulic cylinder that drives the work
machine; a bucket position data generating unit that generates
cutting edge position data indicating a position of a cutting edge
of the bucket based on a detection result of the detector; a
distance acquiring unit that acquires a target excavation landform
indicating a target shape of an excavation object to be excavated
by the work machine and calculates a distance between the cutting
edge of the bucket and the target excavation landform based on the
cutting edge position data and the target excavation landform; a
limit value setting unit that sets a limited amount of operation
for limiting a speed of the movable member based on a detection
result of the detection device; and a movable member control unit
that outputs a control signal to the control valve so that the
movable member is driven with the limited amount of operation.
[0008] In the first embodiment of the present invention, it is
preferable that the limit value setting unit sets the limited
amount of operation so that the larger the distance, the larger the
limited amount of operation.
[0009] In the first embodiment of the present invention, it is
preferable that the construction machine control system further
comprises: a timer that starts time measurement based on the
detection result of the detection device, wherein the limit value
setting unit sets the limited amount of operation so that the
longer a time elapsed from a start time of the time measurement of
the timer, the larger the limited amount of operation.
[0010] In the first embodiment of the present invention, it is
preferable that the movable member control unit outputs a control
signal so that the movable member is driven with the limited amount
of operation in a predetermined period from the start time of the
time measurement of the timer.
[0011] In the first embodiment of the present invention, it is
preferable that the start time of the time measurement of the timer
includes at least one of a start time of an operation of the
operating device, time at which a detection value of the detection
device exceeds a threshold value, and a time at which an amount of
increase per unit time of the detection value of the detection
device exceeds an allowable value.
[0012] In the first embodiment of the present invention, it is
preferable that the driving based on the limited amount of
operation is disabled when the predetermined period has elapsed
from the start time of the time measurement.
[0013] In the first embodiment of the present invention, it is
preferable that the limited amount of operation in a first half of
the predetermined period is smaller than the limited amount of
operation in a second half.
[0014] In the first embodiment of the present invention, it is
preferable that the construction machine control system further
comprises: a boom limiting unit that determines a speed limit
according to the distance and limits a speed of the boom so that a
speed at which the work machine approaches the target excavation
landform is equal to or smaller than the speed limit; and a
hydraulic system that includes a first hydraulic actuator for
driving the boom, a second hydraulic actuator for driving the
movable member, and the control valve that adjusts an amount of
operating oil supplied to the second hydraulic actuator, wherein in
an excavation operation of the bucket, the hydraulic system is
operated so that the boom is raised and the arm is lowered, and the
arm is driven with the limited amount of operation when the arm is
lowered.
[0015] In the first embodiment of the present invention, it is
preferable that the hydraulic system includes: a hydraulic pump
that supplies operating oil; and a pump control unit that controls
the hydraulic pump so that the operating oil is supplied with a
first largest discharge capacity from the hydraulic pump in a first
operation mode and the operating oil is supplied with a second
largest discharge capacity smaller than the first largest discharge
capacity from the hydraulic pump in a second operation mode, and
the limited amount of operation in the second operation mode is
smaller than the limited amount of operation in the first operation
mode.
[0016] In the first embodiment of the present invention, it is
preferable that the movable member is replaceable, and the limited
amount of operation when the movable member of a first weight is
connected to the boom is smaller than the limited amount of
operation when the movable member of a second weight smaller than
the first weight is connected.
[0017] In the first embodiment of the present invention, it is
preferable that the output of the control signal is started so that
the movable member is driven with the limited amount of operation
when an amount of increase per unit time of the detection value of
the detection device exceeds an allowable value, and the amount of
increase includes a difference between the amount of operation of
the operating device and a processing amount generated by low-pass
filtering of the amount of operation.
[0018] In the first embodiment of the present invention, it is
preferable that the construction machine includes a vehicle body
that supports the boom, and the limited amount of operation when
the work machine is driven so that a distance between the bucket
and a reference position of the vehicle body is a first distance is
smaller than the limited amount of operation when the work machine
is driven so that the distance between the bucket and the reference
position is a second distance shorter than the first distance.
[0019] In the first embodiment of the present invention, it is
preferable that the output of the control signal is started so that
the movable member is driven with the limited amount of operation
when an amount of increase per unit time of the detection value of
the detection device exceeds an allowable value, and the amount of
increase includes a difference between the amount of operation of
the operating device and a processing amount generated by low-pass
filtering of the amount of operation.
[0020] According to a second embodiment of the invention, there is
provided a method of controlling a construction machine,
comprising: detecting, by a detector, an attitude of a work machine
that includes a boom, an arm, and a bucket; operating an operating
device to drive a movable member that includes at least one of the
arm and the bucket; detecting, by a detection device, an amount of
operation of the operating device; generating cutting edge position
data indicating a position of a cutting edge of the bucket based on
a detection result of the detector; acquiring a target excavation
landform indicating a target shape of an excavation object to be
excavated by the work machine and calculating a distance between
the cutting edge of the bucket and the target excavation landform
based on the cutting edge position data and the target excavation
landform; setting a limited amount of operation for limiting a
speed of the movable member based on a detection result of the
detection device; and outputting a control signal to a control
valve that adjusts an amount of operating oil supplied to a
hydraulic cylinder that drives the work machine so that the movable
member is driven with the limited amount of operation.
Advantageous Effects of Invention
[0021] According to the aspects of the present invention, a
decrease in excavation accuracy is suppressed.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a perspective view illustrating an example of a
construction machine.
[0023] FIG. 2 is a side view schematically illustrating an example
of the construction machine.
[0024] FIG. 3 is a rear view schematically illustrating an example
of the construction machine.
[0025] FIG. 4A is a block diagram illustrating an example of a
control system.
[0026] FIG. 4B is a block diagram illustrating an example of a
control system.
[0027] FIG. 5 is a schematic view illustrating an example of target
construction information.
[0028] FIG. 6 is a flowchart illustrating an example of limited
excavation control.
[0029] FIG. 7 is a diagram for describing an example of limited
excavation control.
[0030] FIG. 8 is a diagram for describing an example of limited
excavation control.
[0031] FIG. 9 is a diagram for describing an example of limited
excavation control.
[0032] FIG. 10 is a diagram for describing an example of limited
excavation control.
[0033] FIG. 11 is a diagram for describing an example of limited
excavation control.
[0034] FIG. 12 is a diagram for describing an example of limited
excavation control.
[0035] FIG. 13 is a diagram for describing an example of limited
excavation control.
[0036] FIG. 14 is a diagram for describing an example of limited
excavation control.
[0037] FIG. 15 is a diagram illustrating an example of a hydraulic
cylinder.
[0038] FIG. 16 is a diagram illustrating an example of a cylinder
stroke sensor.
[0039] FIG. 17 is a diagram illustrating an example of a control
system.
[0040] FIG. 18 is a diagram illustrating an example of a control
system.
[0041] FIG. 19 is a schematic diagram illustrating an example of an
operation of a construction machine.
[0042] FIG. 20 is a functional block diagram illustrating an
example of a control system.
[0043] FIG. 21 is a flowchart illustrating an example of a method
of controlling the construction machine.
[0044] FIG. 22 is a diagram for describing an example of a method
of controlling the construction machine.
[0045] FIG. 23 is a diagram for describing an example of a method
of controlling the construction machine.
[0046] FIG. 24 is a diagram for describing an example of a method
of controlling the construction machine.
[0047] FIG. 25 is a functional block diagram illustrating an
example of a control system.
[0048] FIG. 26 is a diagram for describing an example of a method
of controlling the construction machine.
[0049] FIG. 27 is a diagram for describing an example of a method
of controlling the construction machine.
[0050] FIG. 28 is a diagram for describing an example of a method
of controlling the construction machine.
[0051] FIG. 29 is a diagram for describing an example of a method
of controlling the construction machine.
[0052] FIG. 30 is a functional block diagram illustrating an
example of a control system.
[0053] FIG. 31 is a diagram for describing an example of a method
of controlling the construction machine.
[0054] FIG. 32 is a diagram for describing an example of a method
of controlling the construction machine.
[0055] FIG. 33 is a flowchart illustrating an example of a method
of controlling the construction machine.
[0056] FIG. 34 is a diagram for describing an example of a method
of controlling the construction machine.
[0057] FIG. 35 is a diagram for describing an example of a method
of controlling the construction machine.
[0058] FIG. 36 is a diagram for describing an example of a method
of controlling the construction machine.
[0059] FIG. 37 is a diagram for describing an example of a method
of controlling the construction machine.
[0060] FIG. 38 is a functional block diagram illustrating an
example of a control system.
[0061] FIG. 39 is a flowchart illustrating an example of a method
of controlling the construction machine.
[0062] FIG. 40 is a diagram for describing an example of a method
of controlling the construction machine.
[0063] FIG. 41 is a diagram for describing an example of a method
of controlling the construction machine.
[0064] FIG. 42 is a diagram for describing an example of a method
of controlling the construction machine.
[0065] FIG. 43 is a functional block diagram illustrating an
example of a control system.
[0066] FIG. 44 is a schematic diagram illustrating an example of an
operation of the construction machine.
[0067] FIG. 45 is a diagram for describing an example of a method
of controlling the construction machine.
[0068] FIG. 46 is a diagram for describing an example of a method
of controlling the construction machine.
[0069] FIG. 47 is a diagram for describing an example of a method
of controlling the construction machine.
[0070] FIG. 48 is a functional block diagram illustrating an
example of a control system.
[0071] FIG. 49 is a diagram for describing an example of a method
of controlling the construction machine.
[0072] FIG. 50 is a flowchart illustrating an example of a method
of controlling the construction machine.
DESCRIPTION OF EMBODIMENTS
[0073] Hereinafter, embodiments according to the present invention
are described with reference to the drawings, and the present
invention is not limited thereto. Constituent components of the
respective embodiments described hereinafter may be appropriately
combined with each other. Moreover, some constituent components may
be not used.
[0074] [Overall Structure of Excavator]
[0075] FIG. 1 is a perspective view illustrating an example of a
construction machine 100 according to the present embodiment. In
the present embodiment, an example in which the construction
machine 100 is an excavator 100 that includes a work machine 2
operating with hydraulic pressure.
[0076] As illustrated in FIG. 1, the excavator 100 includes a
vehicle body 1 and the work machine 2. As will be described later,
a control system 200 that executes excavation control is mounted on
the excavator 100.
[0077] The vehicle body 1 includes a revolving structure 3, a cab
4, and a traveling device 5. The revolving structure 3 is disposed
on the traveling device 5. The traveling device 5 supports the
revolving structure 3. The revolving structure 3 may be referred to
as an upper revolving structure 3. The traveling device 5 may be
referred to as a lower traveling structure 5. The revolving
structure 3 can revolve about a revolution axis AX. A driver's seat
4S on which an operator sits is provided in the cab 4. The operator
operates the excavator 100 in the cab 4. The traveling device 5
includes a pair of crawler belts 5Cr. With rotation of the crawler
belts 5Cr, the excavator 100 travels. The traveling device 5 may
include wheels (tires).
[0078] In the present embodiment, a positional relation of
respective portions is described based on the driver's seat 4S. A
front-rear direction is defined based on the driver's seat 4S. A
left-right direction is defined based on the driver's seat 4S. A
direction in which the driver's seat 4S faces the front is defined
as a front direction and a direction opposite to the front
direction is defined as a rear direction. The right and left sides
in a lateral direction when the driver's seat 4S faces the front
are defined as right and left directions, respectively.
[0079] The revolving structure 3 includes an engine room 9 in which
an engine is stored and a counterweight provided at the rear
portion of the revolving structure 3. A handrail 19 is provided in
a portion of the revolving structure 3 on the front side of the
engine room 9. An engine, a hydraulic pump, and the like are
disposed in the engine room 9.
[0080] The work machine 2 is supported by the revolving structure
3. The work machine 2 includes a boom 6 connected to the revolving
structure 3, an arm 7 connected to the boom 6, a bucket 8 connected
to the arm 7, a boom cylinder 10 driving the boom 6, an arm
cylinder 11 driving the arm 7, and a bucket cylinder 12 driving the
bucket 8. The boom cylinder 10, the arm cylinder 11, and the bucket
cylinder 12 are hydraulic cylinders driven by operating oil.
[0081] A base end of the boom 6 is connected to the revolving
structure 3 with a boom pin 13 interposed. A base end of the arm 7
is connected to a distal end of the boom 6 with an arm pin 14
interposed. The bucket 8 is connected to a distal end of the arm 7
with a bucket pin 15 interposed. The boom 6 can rotate about the
boom pin 13. The arm 7 can rotate about the arm pin 14. The bucket
8 can rotate about the bucket pin 15. The arm 7 and the bucket 8
are movable members that can move on the distal end side of the
boom 6.
[0082] FIG. 2 is a side view schematically illustrating the
excavator 100 according to the present embodiment. FIG. 3 is a rear
view schematically illustrating the excavator 100 according to the
present embodiment. As illustrated in FIG. 2, the length L1 of the
boom 6 is the distance between the boom pin 13 and the arm pin 14.
The length L2 of the arm 7 is the distance between the arm pin 14
and the bucket pin 15. The length L3 of the bucket 8 is the
distance between the bucket pin 15 and a distal end 8a of the
bucket 8. In the present embodiment, the bucket 8 has a plurality
of teeth. In the following description, the distal ends 8a of the
bucket 8 will be appropriately referred to as cutting edges 8a.
[0083] The bucket 8 may not have teeth. The distal end of the
bucket 8 may be formed of a straight steel plate.
[0084] As illustrated in FIG. 2, the excavator 100 includes a first
cylinder stroke sensor 16 disposed in the boom cylinder 10, a
second cylinder stroke sensor 17 disposed in the arm cylinder 11,
and a third cylinder stroke sensor 18 disposed in the bucket
cylinder 12. A stroke length of the boom cylinder 10 is obtained
based on a detection result of the first cylinder stroke sensor 16.
A stroke length of the arm cylinder 11 is obtained based on a
detection result of the second cylinder stroke sensor 17. A stroke
length of the bucket cylinder 12 is obtained based on a detection
result of the third cylinder stroke sensor 18.
[0085] In the following description, the stroke length of the boom
cylinder 10 will be appropriately referred to as a boom cylinder
length, the stroke length of the arm cylinder 11 will be
appropriately referred to as an arm cylinder length, and the stroke
length of the bucket cylinder 12 will be appropriately referred to
as a bucket cylinder length. Moreover, in the following
description, the boom cylinder length, the arm cylinder length, and
the bucket cylinder length will be appropriately collectively
referred to as cylinder length data L.
[0086] The excavator 100 includes a position detection device 20
that can detect the position of the excavator 100. The position
detection device 20 includes an antenna 21, a global coordinate
calculating unit 23, and an inertial measurement unit (IMU) 24.
[0087] The antenna 21 is a global navigation satellite systems
(GNSS) antenna. The antenna 21 is a real time kinematic-global
navigation satellite systems (RTK-GNSS) antenna. The antenna 21 is
provided in the revolving structure 3. In the present embodiment,
the antenna 21 is provided in the handrail 19 of the revolving
structure 3. The antenna 21 may be provided in a rear direction of
the engine room 9. For example, the antenna 21 may be provided in
the counterweight of the revolving structure 3. The antenna 21
outputs a signal corresponding to a received radio wave (GNSS radio
wave) to the global coordinate calculating unit 23.
[0088] The global coordinate calculating unit 23 detects an
installed position P1 of the antenna 21 in a global coordinate
system. The global coordinate system is a 3-dimensional coordinate
system based on a reference position Pr set in a work area. As
illustrated in FIG. 2, in the present embodiment, the reference
position Pr is the position of a distal end of a reference post set
in a work area.
[0089] The global coordinate system is a coordinate system based on
the origin Pr (see FIG. 2) fixed on the earth. A local coordinate
system is a coordinate system based on the origin P2 (see FIG. 2)
fixed to the vehicle body 1 of the construction machine 100. The
local coordinate system may be referred to as a vehicle body
coordinate system.
[0090] In FIG. 2 and other figures, the global coordinate system is
represented by an XgYgZg orthogonal coordinate system. A reference
position (origin) Pr of the global coordinate system is positioned
in a work area. A direction within a horizontal plane is defined as
an Xg-axis direction, a direction orthogonal to the Xg-axis
direction within the horizontal plane is defined as a Yg-axis
direction, and a direction orthogonal to the Xg-axis direction and
the Yg-axis direction is defined as a Zg-axis direction. Moreover,
rotational (tilt) directions about the Xg, Yg, and Zg-axes are
defined as .theta.Xg, .theta.Yg, and .theta.Zg-directions,
respectively. The Xg-axis is orthogonal to a YgZg plane. The
Yg-axis is orthogonal to an XgZg plane. The Zg-axis is orthogonal
to an XgYg plane. The XgYg plane is parallel to the horizontal
plane. The Zg-axis direction is a vertical direction.
[0091] In FIG. 2 and other figures, the local coordinate system is
represented by an XYZ orthogonal coordinate system. The reference
position (origin) P2 of the local coordinate system is positioned
at the revolution center AX of the revolving structure 3. A
direction within a certain plane is defined as an X-axis direction,
a direction orthogonal to the X-axis direction within the plane is
defined as a Y-axis direction, and a direction orthogonal to the
X-axis direction and the Y-axis direction is defined as a Z-axis
direction. Moreover, rotational (tilt) directions about the X, Y,
and Z-axes are defined as .theta.X, .theta.Y, and
.theta.Z-directions, respectively. The X-axis is orthogonal to the
YZ plane. The Y-axis is orthogonal to the XZ plane. The Z-axis is
orthogonal to the XY plane.
[0092] In the present embodiment, the antenna 21 includes a first
antenna 21A and a second antenna 21B provided in the revolving
structure 3 so as to be separated in a vehicle width direction. The
first antenna 21A and the second antenna 21B detect installed
positions P1a and P1b, respectively, and output the same to the
global coordinate calculating unit 23.
[0093] The global coordinate calculating unit 23 acquires reference
position data P represented by a global coordinate. In the present
embodiment, the reference position data P is data indicating the
reference position P2 positioned at the revolution axis (revolution
center) AX of the revolving structure 3. The reference position
data P may be data indicating the installed position P1. In the
present embodiment, the global coordinate calculating unit 23
generates revolving structure direction data Q based on two
installed positions P1a and P1b. The revolving structure direction
data Q is determined based on an angle between a reference
direction (for example, the north) of the global coordinate and a
line determined by the installed positions P1a and P1b. The
revolving structure direction data Q indicates a direction in which
the revolving structure 3 (the work machine 2) faces. The global
coordinate calculating unit 23 outputs the reference position data
P and the revolving structure direction data Q to a display
controller 28 (described later).
[0094] The IMU 24 is provided in the revolving structure 3. In the
present embodiment, the IMU 24 is disposed under the cab 4. A
high-rigidity frame is disposed in a portion of the revolving
structure 3 under the cab 4. The IMU 24 is disposed on the frame.
The IMU 24 may be disposed on a lateral side (right or left side)
of the revolution axis AX (the reference position P2) of the
revolving structure 3. The IMU 24 detects a tilt angle .theta.4 in
the left-to-right direction of the vehicle body 1 and a tilt angle
.theta.5 in the front-rear direction of the vehicle body 1 in
relation to the global coordinate.
[0095] [Configuration of Control System]
[0096] Next, an overview of the control system 200 according to the
present embodiment will be described. FIG. 4A is a block diagram
illustrating a functional configuration of the control system 200
according to the present embodiment.
[0097] The control system 200 controls an excavation process of
using the work machine 2. The control of excavation process
includes limited excavation control. As illustrated in FIG. 4A, the
control system 200 includes the first cylinder stroke sensor 16,
the second cylinder stroke sensor 17, the third cylinder stroke
sensor 18, the antenna 21, the global coordinate calculating unit
23, the IMU 24, an operating device 25, a work machine controller
26, pressure sensors 66 and 67, a control valve 27, a direction
control valve 64, the display controller 28, a display unit 29, a
sensor controller 30, and a man machine interface 32 that sets an
operation mode.
[0098] The operating device 25 is disposed in the cab 4. The
operating device 25 is operated by an operator. The operating
device 25 receives an operator operation that drives the work
machine 2. In the present embodiment, the operating device 25 is a
pilot hydraulic-type operating device.
[0099] In the following description, oil supplied to hydraulic
cylinders (the boom cylinder 10, the arm cylinder 11, and the
bucket cylinder 12) in order to operate the hydraulic cylinders
will be appropriately referred to as operating oil. In the present
embodiment, the amount of operating oil supplied to the hydraulic
cylinder is adjusted by the direction control valve 64. The
direction control valve 64 operates with oil supplied. In the
following description, oil supplied to the direction control valve
64 in order to operate the direction control valve 64 will be
appropriately referred to as pilot oil. Moreover, the pressure of
pilot oil will be appropriately referred to as pilot pressure.
[0100] The operating oil and the pilot oil may be delivered from
the same hydraulic pump. For example, a portion of the operating
oil delivered from the hydraulic pump is decompressed and the
decompressed operating oil may be used as the pilot oil. Moreover,
a hydraulic pump (main hydraulic pump) that delivers operating oil
and a hydraulic pump (pilot hydraulic pump) that delivers pilot oil
may be different hydraulic pumps.
[0101] The operating device 25 includes a first operating lever 25R
and a second operating lever 25L. The first operating lever 25R is
disposed on the right side of the driver's seat 4S, for example.
The second operating lever 25L is disposed on the left side of the
driver's seat 4S, for example. In the first and second operating
levers 25R and 25L, the front-rear and left-right movements
correspond to 2-axis operations.
[0102] The boom 6 and the bucket 8 are operated by the first
operating lever 25R. The operation in the front-rear direction of
the first operating lever 25R corresponds to an operation of the
boom 6, and a lowering operation and a raising operation of the
boom 6 are executed according to the operation in the front-rear
direction. The operation in the left-right direction of the first
operating lever 25R corresponds to an operation of the bucket 8,
and an excavating operation and a releasing operation of the bucket
8 are executed according to the operation in the left-right
direction.
[0103] The arm 7 and the revolving structure 3 are operated by the
second operating lever 25L. The operation in the front-rear
direction of the second operating lever 25L corresponds to an
operation of the arm 7, and a raising operation and a lowering
operation of the arm 7 are executed according to the operation in
the front-rear direction. The operation in the left-right direction
of the second operating lever 25L corresponds to revolving of the
revolving structure 3, and a right revolving operation and a left
revolving operation of the revolving structure 3 are executed
according to the operation in the left-right direction.
[0104] In the present embodiment, the raising operation of the boom
6 corresponds to a dumping operation. The lowering operation of the
boom 6 corresponds to an excavating operation. The lowering
operation of the arm 7 corresponds to an excavating operation. The
raising operation of the arm 7 corresponds to a dumping operation.
The lowering operation of the bucket 8 corresponds to an excavating
operation. The lowering operation of the arm 7 may be referred to
as a bending operation. The raising operation of the arm 7 may be
referred to as an extending operation.
[0105] The pilot oil which has been delivered from the hydraulic
pump and decompressed to pilot pressure by the pressure-reducing
valve is supplied to the operating device 25. The pilot pressure is
adjusted by the amount of operation of the operating device 25, and
the direction control valve 64 via which operating oil supplied to
the hydraulic cylinders (the boom cylinder 10, the arm cylinder 11,
and the bucket cylinder 12) is driven with the pilot pressure. The
pressure sensors 66 and 67 are disposed in pilot pressure lines
450. The pressure sensors 66 and 67 detect the pilot pressure. The
detection results of the pressure sensors 66 and 67 are output to
the work machine controller 26.
[0106] The first operating lever 25R is operated in the front-rear
direction in order to drive the boom 6. The direction control valve
64 via which the operating oil supplied to the boom cylinder 10 for
driving the boom 6 is driven according to an amount of operation
(amount of boom operation) of the first operating lever 25R in the
front-rear direction. Moreover, the pressure generated in the
sensor 66 during this lever operation is referred to an amount of
boom lever operation MB.
[0107] The first operating lever 25R is operated in the left-right
direction in order to drive the bucket 8. The direction control
valve 64 via which the operating oil supplied to the bucket
cylinder 12 for driving the bucket 8 is driven according to the
amount of operation (amount of bucket operation) of the first
operating lever 25R in the left-right direction. Moreover, the
pressure generated in the sensor 66 during this lever operation is
referred to as an amount of bucket lever operation MT.
[0108] The second operating lever 25L is operated in the front-rear
direction in order to drive the arm 7. The direction control valve
64 via which the operating oil supplied to the arm cylinder 11 for
driving the arm 7 is driven according to an amount of operation
(amount of arm operation) of the second operating lever 25L in the
front-rear direction. Moreover, the pressure generated in the
sensor 66 during this lever operation is referred to as an amount
of arm lever operation MA.
[0109] The second operating lever 25L is operated in the left-right
direction in order to drive the revolving structure 3. The
direction control valve 64 via which the operating oil supplied to
a hydraulic actuator for driving the revolving structure 3 is
driven according to the amount of operation of the second operating
lever 25L in the left-right direction.
[0110] The operation in the left-right direction of the first
operating lever 25R may correspond to the operation of the boom 6,
and the operation in the front-rear direction may correspond to the
operation of the bucket 8. The operation in the left-right
direction of the second operating lever 25L may correspond to the
operation of the arm 7, and the operation in the front-rear
direction may correspond to the operation of the revolving
structure 3.
[0111] The control valve 27 operates in order to adjust the amount
of operating oil supplied to the hydraulic cylinders (the boom
cylinder 10, the arm cylinder 11, and the bucket cylinder 12). The
control valve 27 operates based on a control signal from the work
machine controller 26.
[0112] The sensor controller 30 calculates a boom cylinder length
based on a detection result of the first cylinder stroke sensor 16.
The first cylinder stroke sensor 16 outputs a phase shift pulse
associated with the revolving operation to the sensor controller
30. The sensor controller 30 calculates the boom cylinder length
based on the phase shift pulse output from the first cylinder
stroke sensor 16. Similarly, the sensor controller 30 calculates an
arm cylinder length based on a detection result of the second
cylinder stroke sensor 17. The sensor controller 30 calculates a
bucket cylinder length based on a detection result of the third
cylinder stroke sensor 18.
[0113] The sensor controller 30 calculates an attitude angle
.theta.1 of the boom 6 with respect to the vertical direction of
the revolving structure 3 from the boom cylinder length acquired
based on the detection result of the first cylinder stroke sensor
16. The sensor controller 30 calculates an attitude angle .theta.2
of the arm 7 with respect to the boom 6 from the arm cylinder
length acquired based on the detection result of the second
cylinder stroke sensor 17. The sensor controller 30 calculates an
attitude angle .theta.3 of the cutting edge 8a of the bucket 8 with
respect to the arm 7 from the bucket cylinder length acquired based
on the detection result of the third cylinder stroke sensor 18. The
first, second, and third cylinder stroke sensors 16, 17, and 18
function as a detector that detects the attitude of the work
machine 2. The attitude of the work machine 2 includes at least one
of the attitude angle .theta.1 of the boom 6, the attitude angle
.theta.2 of the arm 7, and the attitude angle .theta.3 of the
cutting edge 8a of the bucket 8.
[0114] The attitude angle .theta.1 of the boom 6, the attitude
angle .theta.2 of the arm 7, and the attitude angle .theta.3 of the
bucket 8 may not be detected by the cylinder stroke sensors. The
attitude angle .theta.1 of the boom 6 may be detected by an angle
detector such as a rotary encoder. The angle detector detects a
bending angle of the boom 6 with respect to the revolving structure
3 to detect the attitude angle .theta.1. Similarly, the attitude
angle .theta.2 of the arm 7 may be detected by an angle detector
attached to the arm 7. The attitude angle .theta.3 of the bucket 8
may be detected by an angle detector attached to the bucket 8.
[0115] FIG. 4B is a block diagram illustrating the work machine
controller 26, the display controller 28, and the sensor controller
30. The sensor controller 30 acquires a cylinder length data L from
the detection results of the first, second, and third cylinder
stroke sensors 16, 17, and 18. The sensor controller 30 outputs the
data of the tilt angle .theta.4 and the data of the tilt angle
.theta.5 of the vehicle body 1 output from the IMU 24. The sensor
controller 30 outputs the data of the attitude angles .theta.1 to
.theta.3 and the data of the tilt angle .theta.5 of the respective
work machines to the display controller 28 and the work machine
controller 26, respectively.
[0116] As described above, in the present embodiment, the detection
results of the cylinder stroke sensors (16, 17, and 18) and the
detection result of the IMU 24 are output to the sensor controller
30, and the sensor controller 30 performs a predetermined
calculating process. In the present embodiment, the functions of
the sensor controller 30 may be performed by the work machine
controller 26. For example, the detection results of the cylinder
stroke sensors (16, 17, and 18) may be output to the work machine
controller 26, and the work machine controller 26 may calculate the
cylinder lengths (the boom cylinder length, the arm cylinder
length, and the bucket cylinder length) based on the detection
results of the cylinder stroke sensors (16, 17, and 18). The
detection result of the IMU 24 may be output to the work machine
controller 26.
[0117] The display controller 28 includes a target construction
information storage unit 28A, a bucket position data generating
unit 28B, and a target excavation landform data generating unit
28C. The display controller 28 acquires the reference position data
P and the revolving structure direction data Q from the global
coordinate calculating unit 23. The display controller 28 acquires
cylinder attitude data .theta.1 to .theta.3 from the sensor
controller 30.
[0118] The bucket position data generating unit 28B generates
bucket position data indicating a 3-dimensional position of the
bucket 8 based on the reference position data P, the revolving
structure direction data Q, and the cylinder attitude data .theta.1
to .theta.3. In the present embodiment, the bucket position data is
cutting edge position data S indicating a 3-dimensional position of
the cutting edge 8a.
[0119] The target excavation landform data generating unit 28C
generates a target excavation landform U indicating a target shape
of an excavation object using the cutting edge position data S and
target construction information T (described later) stored in the
target construction information storage unit 28A. Moreover, the
display controller 28 displays the target excavation landform U on
the display unit 29 based on the target excavation landform U. The
display unit 29 is a monitor, for example, and displays various
types of information of the excavator 100. In the present
embodiment, the display unit 29 includes a human machine interface
(HMI) monitor as a guidance monitor for information-oriented
construction.
[0120] The display controller 28 can calculate the local coordinate
position when seen in the global coordinate system based on the
detection result of the position detection device 20. The local
coordinate system is a 3-dimensional coordinate system based on the
excavator 100. The reference position of the local coordinate
system is the reference position P2 positioned at the revolution
axis AX of the revolving structure 3, for example.
[0121] The target construction information storage unit 28A stores
target construction information (3-dimensional designed landform
data) T indicating a 3-dimensional designed landform which is a
target shape of a work area. The target construction information T
includes coordinate data and angle data required in order to
generate the target excavation landform (designed landform data) U
indicating a designed landform which is a target shape of an
excavation object. The target construction information T may be
supplied to the display controller 28 via a radio communication
device, for example. The target construction information T may be
transmitted from a connection-type recording device such as a
memory.
[0122] The target excavation landform data generating unit 28C
calculates the position P3 of the bucket cutting edge 8a in the
global coordinate system in relation to the reference position P2
of the global coordinate system from the attitude angle .theta.1 of
the boom 6, the attitude angle .theta.2 of the arm 7, the attitude
angle .theta.3 of the bucket 8, the length L1 of the boom 6, the
length L2 of the arm 7, the length L3 of the bucket 8, and the
position information of the boom pin 13. The target excavation
landform data generating unit 28C acquires a nodal line E between
the 3-dimensional designed landform and a working plane MP of the
work machine 2 defined in the front-rear direction of the revolving
structure 3 as illustrated in FIG. 5 as a candidate line of the
target excavation landform U based on the target construction
information T and the cutting edge position data 8a. The target
excavation landform data generating unit 28C sets a point of the
candidate line of the target excavation landform U located
immediately below the bucket cutting edge 8a as a reference point
AP of the target excavation landform U. The target excavation
landform data generating unit 28C determines a single or a
plurality of inflection points appearing before and after the
reference point AP of the target excavation landform U and lines
appearing before and after the inflection points as the target
excavation landform U which serves as an excavation object. The
target excavation landform data generating unit 28C generates the
target excavation landform U indicating a designed landform which
is a target shape of the excavation object. A relative distance d
between the target excavation landform U and the cutting edge 8a is
acquired based on the target excavation landform U and the bucket
cutting edge 8a.
[0123] The target excavation landform data generating unit 28C
outputs the target excavation landform U, the bucket cutting edge
8a, and the distance between the target excavation landform U and
the bucket cutting edge 8a to the display unit 29. The display unit
29 displays a positional relation between the target excavation
landform and the bucket 8 as an image and displays the distance d
between the target excavation landform U and the bucket cutting
edge 8a. Moreover, the target excavation landform data generating
unit 28C outputs the calculated target excavation landform U to the
work machine controller 26.
[0124] The man machine interface 32 includes an input unit and a
display unit. The display unit includes a monitor such as a flat
panel display. The input unit of the man machine interface 32
includes operation buttons arranged around the display unit of the
man machine interface 32. The input unit of the man machine
interface 32 may include a touch panel. The man machine interface
32 may be referred to a multi-monitor 32. The input unit of the man
machine interface 32 is operated by an operator. A command signal
generated according to operations on the input unit is output to
the work machine controller 26. The work machine controller 26
controls the display unit of the man machine interface 32 to
display predetermined information on the display unit.
[0125] [Limited Excavation Control]
[0126] Next, an example of limited excavation control according to
the present embodiment will be described. The work machine
controller 26 includes a target speed determining unit 52 that
determines a target speed of the bucket 8 determined according to
the amount of operation of the operating device 25, a distance
acquiring unit 53, a speed limit determining unit 54, a work
machine control unit 57, and an arm control unit 263. The work
machine controller 26 derives the position P3 of the cutting edge
8a in the local coordinate system from the attitude angles
.theta.1, .theta.2, and .theta.3, the position information of the
boom pin 13, the angle .theta.5 output from the IMU 24, the
detection result of the position detection device 20, and the
position information of the antenna 21 with the aid of the sensor
controller 30. The work machine controller 26 acquires the cutting
edge position information independently from the display controller
28.
[0127] The target speed determining unit 52 acquires the tilt angle
.theta.5 in the front-rear direction of the vehicle body 1 and the
amounts of operation MB, MA, and MT acquired from the sensor 66 as
Vc_bm, Vc_am, and Vc_bk corresponding to the lever operation for
driving the respective work machines of the boom 6, the arm 7, and
the bucket 8. The distance acquiring unit 53 acquires the target
excavation landform U from the display controller 28. The distance
acquiring unit 53 calculates the distance d between the cutting
edge 8a of the bucket 8 and the target excavation landform U in the
direction vertical to the target excavation landform U based on the
cutting edge position data P3 and the target excavation landform U.
The speed limit determining unit 54 limits the movement of the boom
6 based on the distance d and the target speed. The work machine
control unit 57 determines an intervention command CBI on an
intervention valve 27C with respect to a speed limit Vc_bm_lmt. An
intervention speed of the boom 6 is output according to the above
commands, whereby the work machine controller 28 executes limited
excavation control (intervention control).
[0128] The arm control unit 263 acquires the amount of operation MA
of the arm 7 from the target speed determining unit 52. When it is
determined that it is necessary to limit the operation on the arm
7, which will be described later, a speed limit Vc_am_lmt is output
to the work machine control unit 57. The work machine control unit
57 outputs a deceleration command CA to the control valve 27 (27A
and 27B) according to the speed limit Vc_am_lmt. The limitation
determination of the arm control unit 263 will be described in
detail later.
[0129] Hereinafter, an example of limited excavation control
according to the present embodiment will be described with
reference to the flowchart of FIG. 6 and the schematic diagrams of
FIGS. 7 to 14. FIG. 6 is a flowchart illustrating an example of
limited excavation control according to the present embodiment.
[0130] As described above, the target excavation landform U is set
(step SA1). After the target excavation landform U is set, the work
machine controller 26 determines the target speed Vc of the work
machine 2 (step SA2). The target speed Vc of the work machine 2
includes a boom target speed Vc_bm, an arm target speed Vc_am, and
a bucket target speed Vc_bkt. The boom target speed Vc_bm is the
speed of the cutting edge 8a when the boom cylinder 10 only is
driven. The arm target speed Vc_am is the speed of the cutting edge
8a when the arm cylinder 11 only is driven. The bucket target speed
Vc_bkt is the speed of the cutting edge 8a when the bucket cylinder
12 only is driven. The boom target speed Vc_bm is calculated based
on the amount of boom operation. The arm target speed Vc_am is
calculated based on the amount of arm operation. The bucket target
speed Vc_bkt is calculated based on the amount of bucket
operation.
[0131] Target speed information that defines the relation between
the amount of boom operation and the boom target speed Vc_bm is
stored in a storage unit 264 of the work machine controller 26. The
work machine controller 26 determines the boom target speed Vc_bm
corresponding to the amount of boom operation based on the target
speed information. The target speed information is a map in which
the magnitude of the boom target speed Vc_bm corresponding to the
amount of boom operation, for example, is described. The target
speed information may be in the form of a table, a numerical
expression, or the like. The target speed information includes
information that defines the relation between the amount of arm
operation and the arm target speed Vc_am. The target speed
information includes information that defines the relation between
the amount of bucket operation and the bucket target speed Vc_bkt.
The work machine controller 26 determines the arm target speed
Vc_am corresponding to the amount of arm operation based on the
target speed information. The work machine controller 26 determines
the bucket target speed Vc_bkt corresponding to the amount of
bucket operation based on the target speed information.
[0132] As illustrated in FIG. 7, the work machine controller 26
converts the boom target speed Vc_bm into a speed component
(vertical speed component) Vcy_bm in the direction vertical to the
surface of the target excavation landform U and a speed component
(horizontal speed component) Vcx_bm in the direction parallel to
the surface of the target excavation landform U (step SA3).
[0133] The work machine controller 26 calculates an inclination of
the vertical axis (the revolution axis AX of the revolving
structure 3) of the local coordinate system with respect to the
vertical axis of the global coordinate system and an inclination in
the vertical direction of the surface of the target excavation
landform U with respect to the vertical axis of the global
coordinate system from the reference position data P, the target
excavation landform U, and the like. The work machine controller 26
calculates an angle .beta.1 indicating the inclination between the
vertical axis of the local coordinate system and the vertical
direction of the surface of the target excavation landform U from
these inclinations.
[0134] As illustrated in FIG. 8, the work machine controller 26
converts the boom target speed Vc_bm into a speed component VL1_bm
in the vertical axis direction of the local coordinate system and a
speed component VL2_bm in the horizontal axis direction according
to the theorem of trigonometric function from an angle .beta.2
between the vertical axis of the local coordinate system and the
direction of the boom target speed Vc_bm.
[0135] As illustrated in FIG. 9, the work machine controller 26
converts the speed component VL1_bm in the vertical axis direction
of the local coordinate system and the speed component VL2_bm in
the horizontal axis direction into a vertical speed component
Vcy_bm and a horizontal speed component Vcx_bm with respect to the
target excavation landform U according to the theorem of
trigonometric function from the inclination .beta.1 between the
vertical axis of the local coordinate system and the vertical
direction of the surface of the target excavation landform U.
Similarly, the work machine controller 26 converts the arm target
speed Vc_am into a vertical speed component Vcy_am and a horizontal
speed component Vcx_am in the vertical axis direction of the local
coordinate system. The work machine controller 26 converts the
bucket target speed Vc_bkt into a vertical speed component Vcy_bkt
and a horizontal speed component Vcx_bkt in the vertical axis
direction of the local coordinate system.
[0136] As illustrated in FIG. 10, the work machine controller 26
acquires the distance d between the cutting edge 8a of the bucket 8
and the target excavation landform U (step SA4). The work machine
controller 26 calculates the shortest distance d between the
surface of the target excavation landform U and the cutting edge 8a
of the bucket 8 from the position information of the cutting edge
8a, the target excavation landform U, and the like. In the present
embodiment, the limited excavation control is executed based on the
shortest distance d between the surface of the target excavation
landform U and the cutting edge 8a of the bucket 8.
[0137] The work machine controller 26 calculates an overall speed
limit Vcy_lmt of the work machine 2 based on the distance d between
the surface of the target excavation landform U and the cutting
edge 8a of the bucket 8 (step SA5). The overall speed limit Vcy_lmt
of the work machine 2 is an allowable moving speed of the cutting
edge 8a in the direction in which the cutting edge 8a of the bucket
8 approaches the target excavation landform U. Speed limit
information that defines the relation between the distance d and
the speed limit Vcy_lmt is stored in the storage unit 264 of the
work machine controller 26.
[0138] FIG. 11 illustrates an example of the speed limit
information according to the present embodiment. In the present
embodiment, the horizontal axis is the distance d and the vertical
axis is the speed limit Vcy_lmt. The distance d has a positive
value when the cutting edge 8a is positioned on the outer side of
the surface of the target excavation landform U (that is, on the
side close to the work machine 2 of the excavator 100), and the
distance d has a negative value when the cutting edge 8a is
positioned on the inner side of the surface of the target
excavation landform U (that is, on the inner side of the excavation
object than the target excavation landform U). As illustrated in
FIG. 10, the distance d has a positive value when the cutting edge
8a is positioned above the surface of the target excavation
landform U. The distance d has a negative value when the cutting
edge 8a is positioned under the surface of the target excavation
landform U. Moreover, the distance d has a positive value when the
cutting edge 8a is positioned at such a position that the cutting
edge 8a does not dig into the target excavation landform U. The
distance d has a negative value when the cutting edge 8a is
positioned at such a position that the cutting edge 8a digs into
the target excavation landform U. The distance d is 0 when the
cutting edge 8a is positioned on the target excavation landform U
(that is, when the cutting edge 8a is in contact with the target
excavation landform U).
[0139] In the present embodiment, the speed has a positive value
when the cutting edge 8a moves from the inner side of the target
excavation landform U toward the outer side, and the speed has a
negative value when the cutting edge 8a moves from the outer side
of the target excavation landform U toward the inner side. That is,
the speed has a positive value when the cutting edge 8a moves
toward the upper side of the target excavation landform U, and the
speed has a negative value when the cutting edge 8a moves toward
the lower side of the target excavation landform U.
[0140] In the speed limit information, an inclination of the speed
limit Vcy_lmt when the distance d is between d1 and d2 is smaller
than an inclination when the distance d is equal to or larger than
d1 or equal to or smaller than d2. d1 is larger than 0. d2 is
smaller than 0. In operations near the surface of the target
excavation landform U, in order to set the speed limit more
accurately, the inclination when the distance d is between d1 and
d2 is smaller than the inclination when the distance d is equal to
or larger than d1 or equal to or smaller than d2. The speed limit
Vcy_lmt has a negative value when the distance d is equal to or
larger than d1, and the larger the distance d, the smaller the
speed limit Vcy_lmt. That is, when the distance d is equal to or
larger than d1, the farther the cutting edge 8a above the target
excavation landform U from the surface of the target excavation
landform U, the larger the speed of moving toward the lower side of
the target excavation landform U and the larger the absolute value
of the speed limit Vcy_lmt. When the distance d is equal to or
smaller than 0, the speed limit Vcy_lmt has a positive value, and
the smaller the distance d, the larger the speed limit Vcy_lmt.
That is, when the distance d of the cutting edge 8a of the bucket 8
from the target excavation landform U is equal to or smaller than
0, the farther the cutting edge 8a on the lower side of the target
excavation landform U from the target excavation landform U, the
larger the speed of moving toward the upper side of the target
excavation landform U, and the larger the absolute value of the
speed limit Vcy_lmt.
[0141] When the distance d is equal to or larger than a
predetermined value dth1, the speed limit Vcy_lmt is Vmin. The
predetermined value dth1 is a positive value and is larger than d1.
Vmin is smaller than a smallest value of the target speed. That is,
when the distance d is equal to or larger than the predetermined
value dth1, the operation of the work machine 2 is not limited.
Thus, when the cutting edge 8a is separated greatly from the target
excavation landform U on the upper side of the target excavation
landform U, the operation of the work machine 2 is not limited
(that is, the limited excavation control is not performed). When
the distance d is smaller than the predetermined value dth1, the
operation of the work machine 2 is limited. When the distance d is
smaller than the predetermined value dth1, the operation of the
boom 6 is limited.
[0142] The work machine controller 26 calculates a vertical speed
component (limited vertical speed component) Vcy_bm_lmt of the
speed limit of the boom 6 from the overall speed limit Vcy_lmt of
the work machine 2, the arm target speed Vc_am, and the bucket
target speed Vc_bkt (step SA6).
[0143] As illustrated in FIG. 12, the work machine controller 26
calculates the limited vertical speed component Vcy_bm_lmt of the
boom 6 by subtracting the vertical speed component Vcy_am of the
arm target speed and the vertical speed component Vcy_bkt of the
bucket target speed from the overall speed limit Vcy_lmt of the
work machine 2.
[0144] As illustrated in FIG. 13, the work machine controller 26
converts the limited vertical speed component Vcy_bm_lmt of the
boom 6 into a speed limit (boom speed limit) Vc_bm_lmt of the boom
6 (step SA7). The work machine controller 26 obtains a relation
between a direction vertical to the surface of the target
excavation landform U and the direction of the boom speed limit
Vc_bm_lmt from a rotation angle .alpha. of the boom 6, a rotation
angle .beta. of the arm 7, a rotation angle of the bucket 8,
vehicle body position data P, the target excavation landform U, and
the like and converts the limited vertical speed component
Vcy_bm_lmt of the boom 6 into a boom speed limit Vc_bm_lmt. This
calculation is performed in a reverse order to that of the
calculation of calculating the vertical speed component Vcy_bm in
the direction vertical to the surface of the target excavation
landform U from the boom target speed Vc_bm. After that, a cylinder
speed corresponding to a boom intervention amount is determined,
and a release command corresponding to the cylinder speed is output
to the intervention valve 27C described later.
[0145] The pilot pressure based on the lever operation is filled in
an oil passage 451B and the pilot pressure based on boom
intervention is filled in an oil passage 502. A shuttle valve 51
(described later) selects the larger pressure (step SA8).
[0146] For example, when no intervention is performed on the boom
6, and the magnitude of the boom speed limit Vc_bm_lmt in the
downward direction of the boom 6 is smaller than the magnitude of
the boom target speed Vc_bm in the downward direction, limiting
conditions are not satisfied. Moreover, when the boom 6 is raised
by performing intervention on the boom 6, and the magnitude of the
boom speed limit Vc_bm_lmt in the upward direction of the boom 6 is
larger than the magnitude of the boom target speed Vc_bm in the
upward direction, the limiting conditions are satisfied.
[0147] The work machine controller 26 controls the work machine 2.
When controlling the boom 6, the work machine controller 26
controls the boom cylinder 10 by transmitting a boom command signal
to the intervention valve 27C. The boom command signal has a
current value corresponding to a boom command speed.
[0148] When the limiting conditions are not satisfied, the shuttle
valve 51 selects the supply of operating oil from the oil passage
451B, and a normal operation is performed (step SA9). The work
machine controller 26 operates the boom cylinder 10, the arm
cylinder 11, and the bucket cylinder 12 according to the amount of
boom operation, the amount of arm operation, and the amount of
bucket operation, respectively. The boom cylinder 10 operates at
the boom target speed Vc_bm. The arm cylinder 11 operates at the
arm target speed Vc_am. The bucket cylinder 12 operates at the
bucket target speed Vcb_kt.
[0149] When the limiting conditions are satisfied, the shuttle
valve 51 selects the supply of operating oil from an oil passage
502, and the limited excavation control is executed (step
SA10).
[0150] The limited vertical speed component Vcy_bm_lmt of the boom
6 is calculated by subtracting the vertical speed component Vcy_am
of the arm target speed and the vertical speed component Vcy_bkt of
the bucket target speed from the overall speed limit Vcy_lmt of the
work machine 2. Thus, when the overall speed limit Vcy_lmt of the
work machine 2 is smaller than the sum of the vertical speed
component Vcy_am of the arm target speed and the vertical speed
component Vcy_bkt of the bucket target speed, the limited vertical
speed component Vcy_bm_lmt of the boom 6 has a negative value, in
which case the boom is raised.
[0151] In this case, the work machine controller 27 lowers the boom
6 at a speed lower than the boom target speed Vc_bm. Thus, it is
possible to prevent the bucket 8 from digging into the target
excavation landform U while suppressing the sense of incongruity
the operator might feel.
[0152] When the overall speed limit Vcy_lmt of the work machine 2
is larger than the sum of the vertical speed component Vcy_am of
the arm target speed and the vertical speed component Vcy_bkt of
the bucket target speed, the limited vertical speed component
Vcy_bm_lmt of the boom 6 has a positive value. Thus, the boom speed
limit Vc_bm_lmt has a positive value. In this case, even when the
operating device 25 is operated in a direction where the boom 6 is
lowered, the work machine controller 26 raises the boom 6. Thus, it
is possible to quickly suppress expansion of a digging area of the
target excavation landform U.
[0153] When the cutting edge 8a is positioned above the target
excavation landform U, the closer the cutting edge 8a approaches
the target excavation landform U, the smaller the absolute value of
the limited vertical speed component Vcy_bm_lmt of the boom 6, and
the smaller the absolute value of the speed component (limited
horizontal speed component) Vcx_bm_lmt of the speed limit of the
boom 6 in the direction parallel to the surface of the target
excavation landform U. Thus, when the cutting edge 8a is positioned
above the target excavation landform U, the closer the cutting edge
8a approaches the target excavation landform U, the more the speed
of the boom 6 in the direction vertical to the surface of the
target excavation landform U and the speed of the boom 6 in the
direction parallel to the surface of the target excavation landform
U are decelerated. When the left operating lever 25L and the right
operating lever 25R are operated simultaneously by the operator of
the excavator 100, the boom 6, the arm 7, and the bucket 8 are
operated simultaneously. In this case, the above-described control
when target speeds Vc_bm, Vc_am, and Vc_bkt of the boom 6, the arm
7, and the bucket 8 are input will be described below.
[0154] FIG. 14 illustrates an example of a change in the speed
limit of the boom 6 when the distance d between the target
excavation landform U and the cutting edge 8a of the bucket 8 is
smaller than the predetermined value dth1 and the cutting edge 8a
of the bucket 8 moves from the position Pn1 to the position Pn2.
The distance between the cutting edge 8a and the target excavation
landform U at the position Pn2 is smaller than the distance between
the cutting edge 8a and the target excavation landform U at the
position Pn1. Due to this, the limited vertical speed component
Vcy_bm_lmt2 of the boom 6 at the position Pn2 is smaller than the
limited vertical speed component Vcy_bm_lmt1 of the boom 6 at the
position Pn1. Thus, the boom speed limit Vc_bm_lmt2 at the position
Pn2 is smaller than the boom speed limit Vc_bm_lmt1 at the position
Pn1. Moreover, the limited horizontal speed component Vcx_bm_lmt2
of the boom 6 at the position Pn2 is smaller than the limited
horizontal speed component Vcx_bm_lmt1 of the boom 6 at the
position Pn1. However, in this case, the arm target speed Vc_am and
the bucket target speed Vc_bkt are not limited. Due to this, the
vertical speed component Vcy_am and the horizontal speed component
Vcx_am of the arm target speed and the vertical speed component
Vcy_bkt and the horizontal speed component Vcx_bkt of the bucket
target speed are not limited.
[0155] As described above, since no limitation is applied to the
arm 7, a change in the amount of arm operation corresponding to the
operator's intention to excavate is reflected as a change in the
speed of the cutting edge 8a of the bucket 8. Thus, the present
embodiment can suppress the sense of incongruity during the
excavation operation of the operator while suppressing expansion of
a digging area of the target excavation landform U.
[0156] In this manner, in the present embodiment, the work machine
controller 26 limits the speed of the boom 6 based on the target
excavation landform U indicating the designed landform which is a
target shape of an excavation object and the cutting edge position
data S indicating the position of the cutting edge 8a of the bucket
8 so that a relative speed at which the bucket 8 approaches the
target excavation landform U decreases according to the distance d
between the target excavation landform U and the cutting edge 8a of
the bucket 8. The work machine controller 26 determines the speed
limit according to the distance d between the target excavation
landform U and the cutting edge 8a of the bucket 8 based on the
target excavation landform U indicating the designed landform which
is a target shape of an excavation object and the cutting edge
position data S indicating the position of the cutting edge 8a of
the bucket 8 and controls the work machine 2 so that the speed in
the direction in which the work machine 2 approaches the target
excavation landform U is equal to or smaller than the speed limit.
In this way, limited excavation control on the cutting edge 8a is
executed, and the position of the cutting edge 8a in relation to
the target excavation landform U is controlled.
[0157] In the following description, outputting a control signal to
the control valve 27 connected to the boom cylinder 10 to control
the position of the boom 6 so that digging of the cutting edge 8a
into the target excavation landform U is suppressed is referred to
as intervention control.
[0158] The intervention control is executed when the relative speed
of the cutting edge 8a in the vertical direction in relation to the
target excavation landform U is larger than the speed limit. The
intervention control is not executed when the relative speed of the
cutting edge 8a is smaller than the speed limit. The fact that the
relative speed of the cutting edge 8a is smaller than the speed
limit includes the fact that the bucket 8 moves in relation to the
target excavation landform U so that the bucket 8 is separated from
the target excavation landform U.
[0159] Moreover, the work machine controller 26 controls the arm 7
and the bucket 8. When an arm speed limit command is output from an
arm control unit described later, the work machine controller 26
transmits an arm command signal CA to the control valve 27 (27A and
27B) to thereby limit the supply of pilot pressure that drives the
arm cylinder 11. With limited supply of the pilot pressure, the
driving of the arm cylinder 11 is limited. The arm command signal
CA has a current value corresponding to an arm command speed. The
work machine controller 26 transmits a bucket command signal to the
control valve 27 to thereby control the bucket cylinder 12
similarly to the arm cylinder 11. The bucket command signal has a
current value corresponding to a bucket command speed.
[0160] [Cylinder Stroke Sensor]
[0161] Next, the cylinder stroke sensor 16 will be described with
reference to FIGS. 15 and 16. In the following description, the
cylinder stroke sensor 16 attached to the boom cylinder 10 is
described. The cylinder stroke sensor 17 and the like attached to
the arm cylinder 11 have the same configuration as the cylinder
stroke sensor 16.
[0162] The cylinder stroke sensor 16 is attached to the boom
cylinder 10. The cylinder stroke sensor 16 measures the stroke of a
piston. As illustrated in FIG. 15, the boom cylinder 10 includes a
cylinder tube 10X and a cylinder rod 10Y configured to move within
the cylinder tube 10X in relation to the cylinder tube 10X. A
piston 10V is slidably provided in the cylinder tube 10X. The
cylinder rod 10Y is attached to the piston 10V. The cylinder rod
10Y is slidably provided in a cylinder head 10W. A chamber formed
by the cylinder head 10W, the piston 10V, and a cylinder inner wall
is a rod-side oil chamber 40B. An oil chamber on the opposite side
of the rod-side oil chamber 40B with the piston 10V interposed is a
cab-side oil chamber 40A. A seal member is provided in the cylinder
head 10W so as to seal the gap between the cylinder head 10W and
the cylinder rod 10Y so that dust or the like does not enter into
the rod-side oil chamber 40B.
[0163] The cylinder rod 10Y retracts when operating oil is supplied
to the rod-side oil chamber 40B and the operating oil is discharged
from the cab-side oil chamber 40A. Moreover, the cylinder rod 10Y
extends when operating oil is discharged from the rod-side oil
chamber 40B and the operating oil is supplied to the cab-side oil
chamber 40A. That is, the cylinder rod 10Y moves linearly in the
left-right direction in the figure.
[0164] A case 164 that covers the cylinder stroke sensor 16 and
accommodates the cylinder stroke sensor 16 is provided outside the
rod-side oil chamber 40B at the proximity of the cylinder head 10W.
The case 164 is fixed to the cylinder head 10W by being fastened to
the cylinder head 10W by bolts or the like.
[0165] The cylinder stroke sensor 16 includes a rotation roller
161, a rotation center shaft 162, and a rotation sensor portion
163. The rotation roller 161 has a surface in contact with the
surface of the cylinder rod 10Y and is provided so as to rotate
according to linear movement of the cylinder rod 10Y. That is,
linear movement of the cylinder rod 10Y is converted into
rotational movement by the rotation roller 161. The rotation center
shaft 162 is disposed to be orthogonal to the direction of linear
movement of the cylinder rod 10Y.
[0166] The rotation sensor portion 163 is configured to detect the
amount of rotation (rotation angle) of the rotation roller 161 as
an electrical signal. The electrical signal indicating the amount
of rotation (rotation angle) of the rotation roller 161 detected by
the rotation sensor portion 163 is output to the sensor controller
30 via an electrical signal line. The sensor controller 30 converts
the electrical signal into the position (stroke position) of the
cylinder rod 10Y of the boom cylinder 10.
[0167] As illustrated in FIG. 16, the rotation sensor portion 163
includes a magnet 163a and a hall IC 163b. The magnet 163a which is
a detecting medium is attached to the rotation roller 161 so as to
rotate integrally with the rotation roller 161. The magnet 163a
rotates with rotation of the rotation roller 161 around the
rotation center shaft 162. The magnet 163a is configured such that
the N pole and the S pole alternate according to the rotation angle
of the rotation roller 161. The magnet 163a is configured such that
magnetic force (magnetic flux density) detected by the hall IC 163b
changes periodically every rotation of the rotation roller 161.
[0168] The hall IC 163b is a magnetic force sensor that detects the
magnetic force (magnetic flux density) generated by the magnet 163a
as an electrical signal. The hall IC 163b is provided along the
axial direction of the rotation center shaft 162 at a position
separated by a predetermined distance from the magnet 163a.
[0169] The electrical signal (phase shift pulse) detected by the
hall IC 163b is output to the sensor controller 30. The sensor
controller 30 converts the electrical signal from the hall IC 163b
into an amount of rotation of the rotation roller 161 (that is, a
displacement amount (boom cylinder length) of the cylinder rod 10Y
of the boom cylinder 10).
[0170] Here, referring to FIG. 16, a relation between the rotation
angle of the rotation roller 161 and the electrical signal
(voltage) detected by the hall IC 163b will be described. When the
rotation roller 161 rotates and the magnet 163a rotates with the
rotation, the magnetic force (magnetic flux density) that passes
through the hall IC 163b changes periodically according to the
rotation angle and the electrical signal (voltage) which is the
sensor output changes periodically. The rotation angle of the
rotation roller 161 can be measured from the magnitude of the
voltage output from the hall IC 163b.
[0171] Moreover, by counting the number of repetitions of each
cycle of the electrical signal (voltage) output from the hall IC
163b, it is possible to measure the number of rotations of the
rotation roller 161. Moreover, the displacement amount (boom
cylinder length) of the cylinder rod 10Y of the boom cylinder 10 is
calculated based on the rotation angle of the rotation roller 161
and the number of rotations of the rotation roller 161.
[0172] Moreover, the sensor controller 30 can calculate the moving
speed (cylinder speed) of the cylinder rod 10Y based on the
rotation angle of the rotation roller 161 and the number of
rotations of the rotation roller 161.
[0173] [Hydraulic Cylinder]
[0174] Next, the hydraulic cylinder according to the present
embodiment will be described. The boom cylinder 10, the arm
cylinder 11, and the bucket cylinder 12 are hydraulic cylinders. In
the following description, the boom cylinder 10, the arm cylinder
11, and the bucket cylinder 12 will be appropriately collectively
referred to as a hydraulic cylinder 60.
[0175] FIG. 17 is a schematic diagram illustrating an example of
the control system 200 according to the present embodiment. FIG. 18
is an enlarged view of a portion of FIG. 17.
[0176] As illustrated in FIGS. 17 and 18, a hydraulic system 300
includes the hydraulic cylinder 60 including the boom cylinder 10,
the arm cylinder 11, and the bucket cylinder 12 and a revolving
motor 63 that allows the revolving structure 3 to revolve. The
hydraulic cylinder 60 operates with operating oil supplied from a
main hydraulic pump. The revolving motor 63 is a hydraulic motor
and operates with operating oil supplied from a main hydraulic
pump.
[0177] In the present embodiment, the direction control valve 64
that controls the direction in which operating oil flows is
provided. The operating oil supplied from the main hydraulic pump
is supplied to the hydraulic cylinder 60 via the direction control
valve 64. The direction control valve 64 is a spool-type valve in
which a rod-shaped spool is moved to change the flowing direction
of operating oil. When the spool moves in an axial direction, the
supply of operating oil to the cab-side oil chamber 40A (the oil
passage 48) and the supply of operating oil to the rod-side oil
chamber 40B (the oil passage 47) are switched. Moreover, when the
spool moves in the axial direction, the amount (the amount of
supply per unit time) of operating oil supplied to the hydraulic
cylinder 60 is adjusted. When the amount of operating oil supplied
to the hydraulic cylinder 60 is adjusted, the cylinder speed is
adjusted.
[0178] A spool stroke sensor 65 that detects a moving distance
(spool stroke) of the spool is provided in the direction control
valve 64. Although not illustrated in the figure, the detection
signal of the spool stroke sensor 65 is output to the work machine
controller 26.
[0179] The driving of the direction control valve 64 is adjusted by
the operating device 25. In the present embodiment, the operating
device 25 is a pilot hydraulic-type operating device. Pilot oil
which has been delivered from the main hydraulic pump and
decompressed by the pressure-reducing valve is supplied to the
operating device 25. Pilot oil which has been delivered from a
pilot hydraulic pump different from the main hydraulic pump may be
supplied to the operating device 25. The operating device 25
includes a pilot pressure adjustment valve. The pilot pressure is
adjusted based on the amount of operation of the operating device
25. The direction control valve 64 is driven with the pilot
pressure. When the pilot pressure is adjusted by the operating
device 25, the movement amount and the moving speed of the spool in
the axial direction are adjusted.
[0180] The direction control valve 64 is provided in each of the
boom cylinder 10, the arm cylinder 11, the bucket cylinder 12, and
the revolving motor 63. In the following description, the direction
control valve 64 connected to the boom cylinder 10 will be
appropriately referred to as a direction control valve 640. The
direction control valve 64 connected to the arm cylinder 11 will be
appropriately referred to as a direction control valve 641. The
direction control valve 64 connected to the bucket cylinder 12 will
be appropriately referred to as a direction control valve 642.
[0181] The operating device 25 and the direction control valve 64
are connected by the pilot pressure lines 450. In the present
embodiment, the control valve 27, the pressure sensor 66, and the
pressure sensor 67 are disposed in the pilot pressure lines
450.
[0182] In the following description, among the pilot pressure lines
450, a pilot pressure line 450 between the operating device 25 and
the control valve 27 will be appropriately referred to as an oil
passage 451, and a pilot pressure line 450 between the control
valve 27 and the direction control valve 64 will be appropriately
referred to as an oil passage 452.
[0183] The oil passage 451 includes an oil passage 451A that
connects an oil passage 452A and the operating device 25 and an oil
passage 451B that connects an oil passage 452B and the operating
device 25. The oil passages 451A and 452A are connected to the
direction control valve. The oil passage 452 is connected to the
direction control valve 64. The pilot oil is supplied to the
direction control valve 64 through the oil passage 452. The
direction control valve 64 includes a first pressure receiving
chamber and a second pressure receiving chamber. The oil passage
452 includes the oil passage 452A connected to the first pressure
receiving chamber and the oil passage 452B connected to the second
pressure receiving chamber.
[0184] When pilot oil is supplied to the first pressure receiving
chamber of the direction control valve 64 through the oil passage
452A, the spool moves with the pilot pressure, and the operating
oil is supplied to the rod-side oil chamber 40B via the direction
control valve 64. The amount of operating oil supplied to the
rod-side hydraulic chamber 40B is adjusted according to the amount
of operation (spool movement amount) of the operating device
25.
[0185] When pilot oil is supplied to the second pressure receiving
chamber of the direction control valve 64 through the oil passage
452B, the spool moves with the pilot pressure, and the operating
oil is supplied to the cab-side oil chamber 40A via the direction
control valve 64. The amount of operating oil supplied to the
cab-side oil chamber 40A is adjusted according to the amount of
operation (spool movement amount) of the operating device 25.
[0186] That is, when pilot oil of which the pilot pressure is
adjusted by the operating device 25 is supplied to the direction
control valve 64, the spool moves to one side in the axial
direction. When pilot oil of which the pilot pressure is adjusted
by the operating device 25 is supplied to the direction control
valve 64, the spool moves to the other side in the axial direction.
In this way, the position of the spool in the axial direction is
adjusted.
[0187] In the following description, the oil passage 452A connected
to the direction control valve 640 via which operating oil is
supplied to the boom cylinder 10 will be appropriately referred to
as an oil passage 4520A, and the oil passage 452B connected to the
direction control valve 640 will be appropriately referred to as an
oil passage 4520B. The oil passage 452A connected to the direction
control valve 641 via which operating oil is supplied to the arm
cylinder 11 will be appropriately referred to as an oil passage
4521A, and the oil passage 452B connected to the direction control
valve 641 will be appropriately referred to as an oil passage
4521B. The oil passage 452A connected to the direction control
valve 642 via which operating oil is supplied to the bucket
cylinder 12 will be appropriately referred to as an oil passage
4522A, and the oil passage 452B connected to the direction control
valve 642 will be appropriately referred to as an oil passage
4522B.
[0188] In the following description, the oil passage 451A connected
to the oil passage 4520A will be appropriately referred to as an
oil passage 4510A, and the oil passage 451B connected to the oil
passage 4520B will be appropriately referred to as an oil passage
4510B. The oil passage 451A connected to the oil passage 4521A will
be appropriately referred to as an oil passage 4511A, and the oil
passage 451B connected to the oil passage 4521B will be
appropriately referred to as an oil passage 4511B. The oil passage
451A connected to the oil passage 4522A will be appropriately
referred to as an oil passage 4512A, and the oil passage 451B
connected to the oil passage 4522B will be appropriately referred
to as an oil passage 4512B.
[0189] As described above, according to the operation of the
operating device 25, the boom 6 executes two operations of the
lowering operation and the raising operation. When the operating
device 25 is operated so that the raising operation of the boom 6
is executed, pilot oil is supplied to the direction control valve
640 connected to the boom cylinder 10 through the oil passages
4510B and 4520B. The direction control valve 640 operates based on
pilot pressure. In this way, operating oil is supplied from the
main hydraulic pump to the boom cylinder 10, and the boom cylinder
10 is extended. The raising operation of the boom 6 is executed
according to extension of the boom cylinder. When the operating
device 25 is operated so that the lowering operation of the boom 6
is executed, pilot oil is supplied to the direction control valve
640 connected to the boom cylinder 10 through the oil passages
4510A and 4520A. The direction control valve 640 operates based on
pilot pressure. In this way, operating oil is supplied from the
main hydraulic pump to the boom cylinder 10, and the boom cylinder
10 is retracted. The lowering operation of the boom 6 is executed
according to retraction of the boom cylinder.
[0190] Moreover, according to the operation of the operating device
25, the arm 7 executes two operations of the lowering operation and
the raising operation. When the operating device 25 is operated so
that the lowering operation of the arm 7 is executed, pilot oil is
supplied to the direction control valve 641 connected to the arm
cylinder 11 through the oil passages 4511B and 4521B. The direction
control valve 641 operates based on pilot pressure. In this way,
operating oil is supplied from the main hydraulic pump to the arm
cylinder 11, and the arm cylinder 11 is extended. The lowering
operation of the arm 7 is executed according to extension of the
arm cylinder 11. When the operating device 25 is operated so that
the raising operation of the arm 7 is executed, pilot oil is
supplied to the direction control valve 641 connected to the arm
cylinder 11 through the oil passages 4511A and 4521A. The direction
control valve 641 operates based on pilot pressure. In this way,
operating oil is supplied from the main hydraulic pump to the arm
cylinder 11, and the arm cylinder 11 is retracted. The raising
operation of the arm 7 is executed according to retraction of the
arm cylinder 11.
[0191] Moreover, according to the operation of the operating device
25, the bucket 8 executes two operations of the lowering operation
and the raising operation. When the operating device 25 is operated
so that the lowering operation of the bucket 8 is executed, pilot
oil is supplied to the direction control valve 642 connected to the
bucket cylinder 12 through the oil passages 4512B and 4522B. The
direction control valve 642 operates based on pilot pressure. In
this way, operating oil is supplied from the main hydraulic pump to
the bucket cylinder 12, and the bucket cylinder 12 is extended. The
lowering operation of the bucket 8 is executed according to
extension of the bucket cylinder 12. When the operating device 25
is operated so that the raising operation of the bucket 8 is
executed, pilot oil is supplied to the direction control valve 642
connected to the bucket cylinder 12 through the oil passages 4512A
and 4522A. The direction control valve 642 operates based on pilot
pressure. In this way, operating oil is supplied from the main
hydraulic pump to the bucket cylinder 12, and the bucket cylinder
12 is retracted. The raising operation of the bucket 8 is executed
according to retraction of the bucket cylinder 12.
[0192] Moreover, according to the operation of the operating device
25, the revolving structure 3 executes two operations of the right
revolving operation and the left revolving operation. When the
operating device 25 is operated so that the right revolving
operation of the revolving structure 3 is executed, operating oil
is supplied to the revolving motor 63. When the operating device 25
is operated so that the left revolving operation of the revolving
structure 3 is executed, the operating oil is supplied to the
revolving motor 63.
[0193] The control valve 27 adjusts pilot pressure based on a
control signal (EPC current) from the work machine controller 26.
The control valve 27 is an electromagnetic proportional control
valve and is controlled based on a control signal from the work
machine controller 26. The control valve 27 includes a control
valve 27A that can adjust the pilot pressure of pilot oil supplied
to the first pressure receiving chamber of the direction control
valve 64 to adjust the amount of operating oil supplied to the
rod-side oil chamber 40B via the direction control valve 64 and a
control valve 27B that can adjust the pilot pressure of pilot oil
supplied to the second pressure receiving chamber of the direction
control valve 64 to adjust the amount of operating oil supplied to
the cab-side oil chamber 40A via the direction control valve
64.
[0194] The pressure sensors 66 and 67 that detect the pilot
pressure are provided on both sides of the control valve 27. In the
present embodiment, the pressure sensor 66 is disposed in the oil
passage 451 between the operating device 25 and the control valve
27. The pressure sensor 67 is disposed in the oil passage 452
between the control valve 27 and the direction control valve 64.
The pressure sensor 66 can detect the pilot pressure before being
adjusted by the control valve 27. The pressure sensor 67 can detect
the pilot pressure adjusted by the control valve 27. Although not
illustrated in the figure, the detection results of the pressure
sensors 66 and 67 are output to the work machine controller 26.
[0195] In the following description, the control valves 27 capable
of adjusting the pilot pressure of pilot oil to the direction
control valve 640 via which operating oil is supplied to the boom
cylinder 10 will be appropriately referred to as control valves
270. Moreover, among the control valves 270, one set of control
valves (corresponding to control valves 27A) will be appropriately
referred to as control valves 270A, and the other set of control
valves (corresponding to control valves 27B) will be appropriately
referred to as control valves 270B. The control valves 27 capable
of adjusting the pilot pressure of pilot oil to the direction
control valve 641 via which operating oil is supplied to the arm
cylinder 11 will be appropriately referred to as control valves
271. Moreover, among the control valves 271, one set of control
valves (corresponding to control valves 27A) will be appropriately
referred to as control valves 271A, and the other set of control
valves (corresponding to control valves 27B) will be appropriately
referred to as control valves 271B. The control valves 27 capable
of adjusting the pilot pressure of pilot oil to the direction
control valve 642 via which operating oil is supplied to the bucket
cylinder 12 will be appropriately referred to as control valves
272. Moreover, among the control valves 272, one set of control
valves (corresponding to control valves 27A) will be appropriately
referred to as control valves 272A, and the other set of control
valves (corresponding to control valves 27B) will be appropriately
referred to as control valves 272B.
[0196] In the following description, the pressure sensor 66 that
detects the pilot pressure of the oil passage 451 connected to the
direction control valve 640 via which operating oil is supplied to
the boom cylinder 10 will be appropriately referred to as a
pressure sensor 660, and the pressure sensor 67 that detects the
pilot pressure of the oil passage 452 connected to the direction
control valve 640 will be appropriately referred to as a pressure
sensor 670. Moreover, the pressure sensor 660 disposed in the oil
passage 4510A will be appropriately referred to as a pressure
sensor 660A, and the pressure sensor 660 disposed in the oil
passage 4510B will be appropriately referred to as a pressure
sensor 660B. Moreover, the pressure sensor 670 disposed in the oil
passage 4520A will be appropriately referred to as a pressure
sensor 670A, and the pressure sensor 670 disposed in the oil
passage 4520B will be appropriately referred to as a pressure
sensor 670B.
[0197] In the following description, the pressure sensor 66 that
detects the pilot pressure of the oil passage 451 connected to the
direction control valve 641 via which operating oil is supplied to
the arm cylinder 11 will be appropriately referred to as a pressure
sensor 661, and the pressure sensor 67 that detects the pilot
pressure of the oil passage 452 connected to the direction control
valve 641 will be appropriately referred to as a pressure sensor
671. Moreover, the pressure sensor 661 disposed in the oil passage
4511A will be appropriately referred to as a pressure sensor 661A,
and the pressure sensor 661 disposed in the oil passage 4511B will
be appropriately referred to as a pressure sensor 661B. Moreover,
the pressure sensor 671 disposed in the oil passage 4521A will be
appropriately referred to as a pressure sensor 671A, and the
pressure sensor 671 disposed in the oil passage 4521B will be
appropriately referred to as a pressure sensor 671B.
[0198] In the following description, the pressure sensor 66 that
detects the pilot pressure of the oil passage 451 connected to the
direction control valve 642 via which operating oil is supplied to
the bucket cylinder 12 will be appropriately referred to as a
pressure sensor 662, and the pressure sensor 67 that detects the
pilot pressure of the oil passage 452 connected to the direction
control valve 642 will be appropriately referred to as a pressure
sensor 672. Moreover, the pressure sensor 661 disposed in the oil
passage 4512A will be appropriately referred to as a pressure
sensor 661A, and the pressure sensor 661 disposed in the oil
passage 4512B will be appropriately referred to as a pressure
sensor 661B. Moreover, the pressure sensor 672 disposed in the oil
passage 4522A will be appropriately referred to as a pressure
sensor 672A, and the pressure sensor 672 disposed in the oil
passage 4522B will be appropriately referred to as a pressure
sensor 672B.
[0199] When limited excavation control is not performed and the
operation of each work machine is not limited, the work machine
controller 26 controls the control valve 27 to open the pilot
pressure line 450. When the pilot pressure line 450 is open, the
pilot pressure of the oil passage 451 becomes the same as the pilot
pressure of the oil passage 452. In the open state of the pilot
pressure line 450, the pilot pressure is adjusted based on the
amount of operation of the operating device 25.
[0200] When limited excavation control is performed and the work
machine 2 is controlled by the work machine controller 26, the work
machine controller 26 outputs a control signal to the control valve
27. The oil passage 451 has a predetermined pressure due to the
action of a pilot relief valve, for example. When the control
signal is output from the work machine controller 26 to the control
valve 27, the control valve 27 operates based on the control
signal. The operating oil of the oil passage 451 is supplied to the
oil passage 452 via the control valve 27. The pressure of the
operating oil of the oil passage 452 is adjusted (reduced) by the
control valve 27. The pressure of the operating oil of the oil
passage 452 acts on the direction control valve 64. As a result,
the direction control valve 64 operates based on the pilot pressure
controlled by the control valve 27. In the present embodiment, the
pressure sensor 66 detects the pilot pressure before being adjusted
by the control valve 27. The pressure sensor 67 detects the pilot
pressure after being adjusted by the control valve 27.
[0201] When the operating oil of which the pressure is adjusted by
the control valve 27A is supplied to the direction control valve
64, the spool moves to one side in the axial direction. When the
operating oil of which the pressure is adjusted by the control
valve 27B is supplied to the direction control valve 64, the spool
moves to the other side in the axial direction. In this way, the
position of the spool in the axial direction is adjusted.
[0202] For example, the work machine controller 26 can adjust the
pilot pressure to the direction control valve 640 connected to the
boom cylinder 10 by outputting a control signal to at least one of
the control valves 270A and 270B.
[0203] Moreover, the work machine controller 26 can adjust the
pilot pressure to the direction control valve 641 connected to the
arm cylinder 11 by outputting a control signal to at least one of
the control valves 271A and 271B.
[0204] Moreover, the work machine controller 26 can adjust the
pilot pressure to the direction control valve 642 connected to the
bucket cylinder 12 by outputting a control signal to at least one
of the control valves 272A and 272B.
[0205] The work machine controller 26 limits the speed of the boom
6 based on the target excavation landform U indicating the designed
landform which is a target shape of an excavation object and the
bucket position data (cutting edge position data S) indicating the
position of the bucket 8 so that a speed at which the bucket 8
approaches the target excavation landform U decreases according to
the distance d between the target excavation landform U and the
bucket 8. The work machine controller 26 includes a boom
intervention unit that outputs a control signal for limiting the
speed of the boom 6. In the present embodiment, when the work
machine 2 is driven based on the operation of the operating device
25, the movement of the boom 6 is controlled (intervened) based on
the control signal output from the boom intervention unit of the
work machine controller 26 so that the cutting edge 8a of the
bucket 8 does not dig into the target excavation landform U. When
the bucket 8 performs excavation, the raising operation of the boom
6 is executed by the work machine controller 26 so that the cutting
edge 8a does not dig into the target excavation landform U.
[0206] In the present embodiment, the oil passage 502 is connected
to the control valve 27C that operates based on an intervention
control signal output from the work machine controller 26 in order
to perform intervention control. The oil passage 501 is connected
to the control valve 27C so as to supply pilot oil to the direction
control valve 640 connected to the boom cylinder 10. The oil
passage 502 is connected to the control valve 27C and the shuttle
valve 51 and is connected to the oil passage 4520B connected to the
direction control valve 640 via the shuttle valve 51.
[0207] The shuttle valve 51 has two inlet ports and one outlet
port. One inlet port is connected to the oil passage 502. The other
inlet port is connected to the oil passage 4510B. The outlet port
is connected to the oil passage 4520B. The shuttle valve 51
connects an oil passage having a higher pilot pressure among the
oil passages 502 and 4510B to the oil passage 4520B. For example,
when the pilot pressure of the oil passage 502 is higher than the
pilot pressure of the oil passage 4510B, the shuttle valve 51
operates so that the oil passages 502 and 4520B are connected and
the oil passages 4510B and 4520B are not connected. In this way,
the pilot oil of the oil passage 502 is supplied to the oil passage
4520B via the shuttle valve 51. When the pilot pressure of the oil
passage 4510B is higher than the pilot pressure of the oil passage
502, the shuttle valve 51 operates so that the oil passages 4510B
and 4520B are connected and the oil passages 502 and 4520B are not
connected. In this way, the pilot oil of the oil passage 4510B is
supplied to the oil passage 4520B via the shuttle valve 51.
[0208] A pressure sensor 68 that detects the pilot pressure of the
pilot oil of the oil passage 501 is provided in the oil passage
501. The pilot oil before passing through the control valve 27C
flows in the oil passage 501. The pilot oil having passed through
the control valve 27C flows in the oil passage 502. The control
valve 27C is controlled based on the control signal output from the
work machine controller 26 in order to execute intervention
control.
[0209] When intervention control is not executed, the work machine
controller 26 does not output a control signal to the control valve
27 so that the direction control valve 64 is driven based on the
pilot pressure adjusted by the operation of the operating device
25. For example, the work machine controller 26 opens the control
valve 270B to its full width and closes the control valve 27C and
the oil passage 501 so that the direction control valve 640 is
driven based on the pilot pressure adjusted by the operation of the
operating device 25.
[0210] When intervention control is executed, the work machine
controller 26 controls the respective control valves 27 so that the
direction control valve 64 is driven based on the pilot pressure
adjusted by the control valve 27C. For example, when intervention
control of limiting the movement of the boom 6 is executed, the
work machine controller 26 controls the control valve 27C so that
the pilot pressure adjusted by the control valve 27C is higher than
the pilot pressure adjusted by the operating device 25. In this
way, the pilot oil from the control valve 27C is supplied to the
direction control valve 640 via the shuttle valve 51.
[0211] When the boom 6 is raised at a high speed by the operating
device 25 so that the bucket 8 does not dig into the target
excavation landform U, the intervention control is not executed.
When the operating device 25 is operated so that the boom 6 is
raised at a high speed and the pilot pressure is adjusted based on
the amount of operation, the pilot pressure adjusted by the
operation of the operating device 25 becomes higher than the pilot
pressure adjusted by the control valve 27C. In this way, the pilot
oil having the pilot pressure adjusted by the operation of the
operating device 25 is supplied to the direction control valve 640
via the shuttle valve 51.
[0212] Here, when the work machine controller 26 determines that it
is necessary to limit the excavation of the arm 7, the work machine
controller 26 outputs a command so that the amount of oil supplied
to the control valve 271B decreases. In this way, the supply of
pilot pressure to the oil passage 4521B according to the lever
operation on the arm cylinder 11 is limited.
Control of Arm
First Embodiment
[0213] FIG. 19 is a diagram schematically illustrating an example
of the operation of the work machine 2 when limited excavation
control (boom intervention control) is performed. As described
above, the hydraulic system 300 includes the boom cylinder 10 for
driving the boom 6, the arm cylinder 11 for driving the arm 7, and
the bucket cylinder 12 for driving the bucket 8.
[0214] As illustrated in FIG. 19, during the excavation operation
of the bucket 8, the hydraulic system 300 operates so that the boom
6 is raised and the arm 7 is lowered. In the excavation operation,
intervention control including the raising operation of the boom 6
is executed so that the bucket 8 does not dig into the target
excavation landform U.
[0215] In the boom intervention control, there is a possibility
that the boom 6 is not moved at a high speed but is moved slower
than the movement of the arm 7 and the bucket 8. In the excavation
operation, since the arm 7 is lowered, the arm 7 can move at a
higher speed than the boom 6 due to the action of gravity (its own
weight). With the intervention control on the boom 6, the boom 6 is
raised. Moreover, load corresponding to the weight of the arm 7 and
the weight of the bucket 8 is applied to the arm cylinder 11,
whereas load corresponding to the weight of the boom 6, the weight
of the arm 7, and the weight of the bucket 8 is applied to the boom
cylinder 10. That is, the load applied to the boom cylinder 10 is
larger than the weight applied to the arm cylinder 11. The boom
cylinder 10 needs to operate while resisting against the load. As a
result, it may be difficult for the boom 6 to be moved
appropriately (raised) in synchronization with the movement of the
arm 7 so that the bucket 8 is suppressed from digging into the
target excavation landform U. Moreover, the boom 6 is driven by the
hydraulic cylinder (the boom cylinder) 10. Due to this, it may be
difficult for the boom 6 to satisfactorily follow the movement of
the arm 7. As a result, the bucket 8 may dig into the target
excavation landform U and the excavation accuracy may decrease.
[0216] In the present embodiment, in the boom intervention control
including the raising operation of the boom 6, the work machine
controller 26 performs limitation control on the arm 7 so that the
arm 7 moves in synchronization with the movement of the boom 6 by
taking a difference in the operating conditions (raising operation
or lowering operation) of the boom 6 and the arm 7 and a difference
in the load conditions of the boom cylinder 10 and the arm cylinder
11 during the excavation operation into consideration.
[0217] FIG. 20 is a functional block diagram illustrating an
example of the control system 200 according to the present
embodiment. As illustrated in FIG. 20, the control system 200
includes the operating device 25 operated in order to drive the arm
7, a detection device 70 that detects the amount of operation MA
(hereinafter simply M) of the operating device 25, and the work
machine controller 26. The work machine controller 26 includes a
timer 261 that starts time measurement based on the detection
result of the detection device 70, a limit value setting unit 262
that sets a limited amount of operation Mr for limiting the speed
of the arm 7 in association with the time elapsed from the start
time of the time measurement of the timer 261, the arm control unit
263 that generates a control signal N so that the arm 7 is driven
with the limited amount of operation Mr in a predetermined period
from the start of the time measurement of the timer 261 and outputs
an arm speed limit Vc_am_lmt based on the control signal N, and the
storage unit 264.
[0218] In the present embodiment, the detection device 70 includes
the pressure sensor 66 (661B). The detection device 70 detects the
amount of operation M of the operating device 25 by detecting the
pilot pressure adjusted by the operating device 25.
[0219] When the operating device 25 is operated at a high speed
(abruptly) by the operator in order to lower the arm 7, the work
machine controller 26 limits the amount of operation (amount of arm
operation) M of the operating device 25 and drives the arm 7 with
the limited amount of operation Mr so that a delay in the raising
intervention speed of the boom 6 in relation to the lowering speed
of the arm 7 does not occur. That is, in the present embodiment, in
the boom intervention control, the arm 7 is driven with the limited
amount of operation Mr in at least a portion of the period where
the boom 6 is raised and the arm 7 is lowered. Due to this, even
when the operating device 25 is operated at a high speed by the
operator in order to drive the arm 7, since the arm 7 moves at a
limited speed (low speed), the occurrence of a following delay of
the boom 6 in which the raising intervention speed of the boom 6 is
delayed in relation the lowering speed of the arm 7 is
suppressed.
[0220] The limited amount of operation Mr is a value that can
suppress a following delay of the boom 6 even when the arm 7 is
operated with the limited amount of operation Mr. The limited
amount of operation Mr is obtained in advance through experiments
or simulations and is stored in a memory (storage unit) of the work
machine controller 26.
[0221] In the present embodiment, the work machine controller 26
compares the amount of arm operation M detected by the detection
device 70 with the limited amount of operation Mr. The amount of
arm operation M detected by the detection device 70 and the limited
amount of operation Mr from the limit value setting unit 262 are
output to the arm control unit 263. The arm control unit 263
includes a comparing unit. The comparing unit of the arm control
unit 263 compares the amount of arm operation M with the limited
amount of operation Mr.
[0222] The arm control unit 263 selects the smaller amount of
operation among the amount of arm operation M and the limited
amount of operation Mr based on a comparison result between the
amount of arm operation M and the limited amount of operation Mr.
The arm control unit 263 outputs an arm speed limit Vc_am_lmt to
the work machine control unit 57 so that the arm 7 is driven with
the selected amount of operation among the amount of arm operation
M and the limited amount of operation Mr.
[0223] In the following description, control of limiting the
operation (speed) of the arm 7 so that a delay in the raising
intervention speed of the boom 6 in relation to the lowering speed
of the arm 7 does not occur will be appropriately referred to as
arm speed limitation control. Moreover, the selected amount of
operation (the smaller amount of operation) among the amount of arm
operation M and the limited amount of operation Mr will be
appropriately referred to as an amount of operation Mf.
[0224] FIG. 21 is a flowchart for describing an example of the
operation of the control system 200 according to the present
embodiment. FIGS. 22, 23, and 24 are timing charts for describing
an example of the operation of the control system 200 according to
the present embodiment.
[0225] In the excavation operation, the operating device 25 is
operated by the operator (step SB1). The operator operates the
operating device 25 in order to drive the arm 7. The operating
device 25 is operated so that the arm 7 is lowered.
[0226] Intervention control on the boom 6 starts so that the bucket
8 does not dig into the target excavation landform U (step SB2). In
the intervention control, the speed of the boom 8 is limited based
on the target excavation landform U indicating the target shape of
an excavation object and the cutting edge position data S
indicating the position of the cutting edge 8a of the bucket 8 so
that the speed at which the bucket 8 approaches the target
excavation landform U decreases according to the distance d between
the target excavation landform U and the bucket 8. The intervention
control includes the raising operation of the boom 6. With the
intervention control on the boom 6, the boom 6 is raised.
[0227] The amount of operation M of the operating device 25 is
detected by the detection device 70 (step SB3). The detection
device 70 includes the pressure sensor 66 and detects the amount of
operation M of the operating device 25 by detecting the pilot
pressure adjusted by the operating device 25. In the present
embodiment, at least the pilot pressure (the pilot pressure of the
oil passage 451) to the direction control valve 641 is detected by
the pressure sensor 661.
[0228] The detection value of the detection device 70 (the pressure
sensor 661) is output to the timer 261. The timer 261 starts time
measurement based on the detection result of the detection device
70 (step SB4). In FIGS. 22, 23, and 24, time t0 is the start time
of the time measurement of the timer 261.
[0229] In FIG. 20 of the present embodiment, the timer 261 starts
the time measurement when the operating device 25 starts operating
in order to drive the arm 7. That is, time t0 is the start time of
the operation of the operating device 25. The start time of the
time measurement of the timer 261 may be the time at which the
detection value of the detection device 70 exceeds a threshold
value. The threshold value may be the value of the limited amount
of operation Mr. The start time of the time measurement of the
timer 261 may be the time at which the amount (change rate) of
increase per unit time of the detection value of the detection
device 70 exceeds an allowable value.
[0230] The limit value setting unit 262 sets the limited amount of
operation Mr for limiting the speed (lowering speed) of the arm 7
in association with the time elapsed from the start time t0 of the
time measurement of the timer 261 (step SB5). The limited amount of
operation Mr is a value that can suppress the occurrence of a
following delay of the boom 6 even when the arm 7 is operated with
the limited amount of operation Mr. The limited amount of operation
Mr is obtained in advance through experiments or simulations. The
limited amount of operation Mr is set in association with the time
elapsed from the start time t0 of the time measurement of the timer
261. In the following description, data indicating the limited
amount of operation Mr set in association with time will be
appropriately referred to as a limit pattern.
[0231] FIG. 22 illustrates a relation between the time elapsed from
the start time t0 and the amount of operation M of the arm 7 by the
operating device 25. FIG. 23 illustrates a relation between the
time elapsed from the start time t0 and the limited amount of
operation Mr set by the limit value setting unit 262. That is, FIG.
23 illustrates a limit pattern. FIG. 24 illustrates a relation
between the time elapsed from the start time t0 and the amount of
operation Mf of the arm 7. As described above, the start time t0 is
the start time of the time measurement of the timer 261. In FIGS.
22, 23, and 24, the horizontal axis is time (elapsed time). In FIG.
22, the vertical axis is the amount of operation M of the arm 7 and
the count value of the timer 261. In FIG. 23, the vertical axis is
the limited amount of operation Mr and the count value of the timer
261. In FIG. 24, the vertical axis is the amount of operation Mf of
the arm 7 and the count value of the timer 261.
[0232] In FIG. 22, the relation between the time elapsed from the
start time t0 and the amount of operation M of the arm 7 by the
operating device 25 is indicated by line S1. In FIG. 23, the
relation (limit pattern) between the time elapsed from the start
time t0 and the limited amount of operation Mr is indicated by line
S2. In FIG. 24, the relation (limit pattern) between the time
elapsed from the start time t0 and the amount of operation Mf is
indicated by line Sc. Line Lt indicates the count value of the
timer 261. In FIG. 23, the line S2 is depicted by a solid line and
the line S1 is depicted by a dot line.
[0233] In the present embodiment, the amounts of operation (M, Mr,
and Mf) of the arm 7 are associated with the pilot pressure acting
on the direction control valve 641 connected to the arm cylinder
11. In the present embodiment, the unit of the amounts of operation
(M, Mr, and Mf) of the arm 7 is mega Pascal (MPa). The pilot
pressure corresponding to the amount of operation M is adjusted by
the operating device 25. The pilot pressure corresponding to the
limited amount of operation Mr is adjusted by the control valve 271
that is controlled by the arm control unit 263.
[0234] The amount of operation M corresponds to the detection value
of the pressure sensor 661 that detects the pilot pressure acting
on the direction control valve 640 connected to the arm cylinder
11. The pressure sensor 661 outputs the detection value of the
pilot pressure corresponding to the amount of operation M of the
operating device 25 for driving the arm cylinder 11.
[0235] The limited amount of operation Mr corresponds to a target
value (limit value) of the pilot pressure acting on the direction
control valve 640 connected to the arm cylinder 11. The correlation
between the pilot pressure and the limited amount of operation Mr
is obtained in advance and is stored in the storage unit 264 of the
work machine controller 26. During the arm speed limitation
control, the arm control unit 263 determines the limited amount of
operation Mr so that the target pilot pressure acts on the
direction control valve 641 and generates a control signal N so
that the pilot pressure corresponding to the limited amount of
operation Mr is obtained.
[0236] The amount of operation Mf corresponds to the detection
value of the pressure sensor 671 that detects the pilot pressure
acting on the direction control valve 640 connected to the arm
cylinder 11. As described above, the amount of operation Mf is the
smaller amount of operation among the amount of operation M and the
limited amount of operation Mr. When the amount of operation M is
smaller than the limited amount of operation Mr, the arm control
unit 263 does not generate the control signal N. When the amount of
operation M is smaller than the limited amount of operation Mr, the
control valve 271 is open to its full width and the pilot pressure
based on the amount of operation M acts on the direction control
valve 641. When the amount of operation M is larger than the
limited amount of operation Mr, the arm control unit 263 generates
the control signal N to the control valve 271 so that the arm speed
limitation control is executed based on the limited amount of
operation Mr. When the amount of operation M is larger than the
limited amount of operation Mr, the pilot pressure based on the
limited amount of operation Mr, adjusted by the control valve 271
acts on the direction control valve 641.
[0237] FIG. 22 illustrates an example of the profile of the amount
of operation M. The profile of the amount of operation M is
indicated by line S1. As illustrated in FIG. 22, at time to, the
operating device 25 is operated by the operator in order to drive
the arm 7. The timer 261 starts time measurement. In the present
embodiment, as an example, as indicated by the line S1 of FIG. 22,
a case where the operating device 25 is operated by the operator so
that the amount of operation M increases abruptly from 0 to value
M3 will be considered. The amount of operation M maintains the
value M3 for a certain period after reaching the value M3 and then
decreases until it reaches 0. When the arm speed limitation control
is not executed, the amount of operation M (Mf) has a profile
indicated by the line S1 of FIG. 22. In this case, a delay in the
raising intervention speed of the boom 6 in relation to the
lowering speed of the arm 7 may occur.
[0238] FIG. 23 illustrates an example of the profile of the limited
amount of operation Mr. The profile of the limited amount of
operation Mr is indicated by line S2. As described above, the
limited amount of operation Mr is an amount of operation that is
determined in advance so that a delay in the raising intervention
speed of the boom 6 does not occur. Here, when the amount of
operation M exceeds a value N1, the value M1 is set as a lower
limit threshold value so that the limited amount of operation Mr is
generated. The limited amount of operation Mr is smaller than the
amount of operation M. In the present embodiment, in a
predetermined period Ts where the time measurement is performed by
the timer 261, the driving of the arm 7 is controlled so that the
arm 7 is not operated with the amount of operation M larger than
the limited amount of operation Mr. In the present embodiment, the
predetermined period Ts is a period between the time t0 and the
time t1.
[0239] As illustrated in FIG. 23, since the amount of operation M
exceeds the value M1 at the time t0 at which the operator performs
operations, the limited amount of operation Mr increases up to a
value M2 from 0. That is, in a period near the start time to, the
limited amount of operation Mr has the value M2. The value M2 is
smaller than a value M3. The limited amount of operation Mr
maintains the value M2 for a certain period after reaching the
value M2, and increases gradually and reaches the value M3 at the
ending time t1. After that, the limited amount of operation Mr
decreases until it reaches 0 at the time at which the amount of
operation M based on the operation of the operator is smaller than
the value M1 after maintaining the value M3. In this manner, in the
predetermined period Ts between the time t0 and the time t1, the
limited amount of operation Mr is set to be smaller than the amount
of operation M. The value at the time t0 which is the starting
point of the limit pattern S2 illustrated in FIG. 23 is M2 and the
value at the time t1 which is the ending point of the limit pattern
S2 is M3. In the period later than the time t1, the limited amount
of operation Mr is the same as the amount of operation M. In this
manner, in the present embodiment, the limited amount of operation
Mr in the first half of the predetermined period Ts is smaller than
the limited amount of operation Mr in the second half of the
predetermined period Ts.
[0240] In the present embodiment, the arm control unit 263 compares
the amount of operation M with the limited amount of operation Mr,
selects the smaller amount of operation, and generates the control
signal N based on the selected amount of operation Mf. In the
present embodiment, as described with reference to FIGS. 22 and 23,
in the predetermined period Ts between the time t0 and the time t1,
the limited amount of operation Mr is smaller than the amount of
operation M. Thus, in the predetermined period between the time t0
and the time t1, the arm control unit 263 generates the control
signal N so that the arm 7 is driven based on the limited amount of
operation Mr.
[0241] In the period later than the time t1, the limited amount of
operation Mr is set to the value M3. In the present embodiment, in
the period later than the time t1, the limited amount of operation
Mr is the same as the amount of operation M. In the present
embodiment, the arm control unit 263 compares the amount of
operation M with the limited amount of operation Mr and selects the
amount of operation M. In the present embodiment, at the time t1,
the arm speed limitation control ends. That is, in the present
embodiment, the driving (arm speed limitation control) of the arm 7
based on the limited amount of operation Mr starts at the start
time t0 of the time measurement of the timer 261 and ends at the
ending time t1 after the elapse of the predetermined period Ts from
the start time t0. After the elapse of the predetermined period Ts
from the start time t0 of the time measurement of the timer 261,
the driving based on the limited amount of operation Mr is
disabled.
[0242] FIG. 24 illustrates an example of the profile of the amount
of operation Mf. The profile of the amount of operation Mf is
indicated by the line Sc. As illustrated in FIG. 24, in the
predetermined period Ts between the time t0 and the time t1, the
arm 7 is operated with the pilot pressure adjusted according to the
limited amount of operation Mr as indicated by the line Sc. After
the elapse of the predetermined period Ts, the arm 7 is operated
with the pilot pressure adjusted according to the amount of
operation M as indicated by the line Sc.
[0243] That is, in the present embodiment, the profile of the
amount of operation Mf of the arm 7 is determined so as to change
along the line Sc of FIG. 24. Specifically, the operation of the
operating device 25 starts at the time t0, and the amount of
operation Mf increases abruptly from 0 to the value M2 and
maintains the value M2 for a certain period. After that, the amount
of operation Mf increases gradually and reaches the value M3 at the
time t1. The amount of operation Mf maintains the value M3 for a
certain period after the time t1 and then decreases to 0.
[0244] The arm control unit 263 generates the control signal N so
that the arm 7 is driven with the limited amount of operation Mr in
the predetermined period Ts from the start time t0 of the time
measurement of the timer 261 (step SB6). That is, the arm control
unit 263 generates the control signal N for driving the arm 7 so
that the arm 7 is driven according to the profile of the limited
amount of operation Mr in the predetermined period Ts.
[0245] The arm control unit 263 generates the control signal N so
that the arm 7 is driven with the limited amount of operation Mr in
the predetermined period Ts and stops generating the control signal
N so that the arm 7 is driven with the amount of operation M after
the elapse of the predetermined period Ts where the driving based
on the limited amount of operation Mr is disabled. That is, the arm
control unit 263 generates the control signal N so that the arm 7
moves at a low speed in the predetermined period Ts and the arm 7
moves at a high speed after the elapse of the predetermined period
Ts.
[0246] The arm speed limit Vc_am lmt is output based on the control
signal N generated by the arm control unit 263, and the arm
operation command CA based on the arm speed limit Vc_am_lmt is
output to the control valve 27 connected to the arm cylinder 11.
The control valve 27 adjusts (limits) the pilot pressure based on
the control signal N so that the amount of operating oil supplied
to the arm cylinder 11 is adjusted (limited). When the amount of
operating oil supplied to the arm cylinder 11 is limited, the
cylinder speed is adjusted and the speed of the arm 7 is limited.
The arm control unit 263 suppresses the speed (lowering speed) of
the arm 7 in the lowering operation of the arm 7. In the present
embodiment, although the speed of the arm 7 is limited in the
predetermined period Ts, it is possible to suppress a decrease in
the excavation accuracy even when the predetermined period Ts is
not provided.
[0247] [Effects]
[0248] As described above, according to the present embodiment, the
control system 200 of the construction machine 100 that includes
the work machine 2 including the boom 6, the arm 7, and the bucket
8 includes: the first, second, and third cylinder stroke sensors
16, 17, and 18 that function as a detector that detects the
attitude of the work machine 2; the operating device 25 that is
operated in order to drive a movable member that includes at least
one of the arm 7 and the bucket 8; the detection device 70 that
detects the amount of operation M of the operating device 25; the
control valve 27 that adjusts the amount of operating oil supplied
to the hydraulic cylinders 10, 11, and 12 driven by the work
machine 2; and the work machine controller 26 that functions as a
control device that acquires the detection result of the detection
device 70 and outputs a control signal to the control valve 27.
[0249] The work machine controller 26 includes: the bucket position
data generating unit 28B that generates cutting edge position data
(bucket position data) S indicating the 3-dimensional position of
the bucket 8 based on the cylinder attitude data .theta.1,
.theta.2, and .theta.3 which is the detection results of the first,
second, and third cylinder stroke sensors 16, 17, and 18; the
distance acquiring unit 53 that acquires the target excavation
landform U indicating the target shape of the excavation object to
be excavated by the work machine 2 and calculates the distance d
between the cutting edge 8a of the bucket 8 and the target
excavation landform U based on the cutting edge position data S and
the target excavation landform U; the timer 261 that starts time
measurement based on the detection result of the detection device
70; the limit value setting unit 262 that sets the limited amount
of operation Mr for limiting the speed of the movable member based
on the time elapsed from the start time of the time measurement of
the timer 261; and the movable member control unit 263 that outputs
the control signal N to the control valve 271 based on the
detection result of the detection device 70 so that the arm 7 is
driven with the limited amount of operation Mr when the operation
of the operating device 25 is started to raise the boom 6 and lower
the arm 7 in the excavation operation of the bucket 8.
[0250] Due to this, even when a delay in generation of pressure in
relation to the operation command generated by the operating device
25 occurs, falling of the bucket 8 is suppressed and the bucket 8
is suppressed from exceeding the target excavation landform U.
Thus, the decrease in excavation accuracy is suppressed.
[0251] Moreover, in the present embodiment, an excavation operation
is determined and the operation of the arm 7 at the start of
excavation is limited. Since the time at which the operation of the
arm 7 is limited is limited to the start time of excavation, the
decrease in the amount of work performed by the construction
machine 100 is suppressed. Due to this, the control system 200 can
suppress the decrease in the amount of work performed by the
construction machine 100 and the falling of the cutting edge
8a.
[0252] Moreover, in the present embodiment, the limit value setting
unit 262 sets the limited amount of operation Mr so that the longer
the time elapsed from the start time of the time measurement of the
timer 261, the larger the limited amount of operation Mr (that is,
the longer the elapsed time, the more the limitation on the
operation of the arm 7 is mitigated). Since the operation of the
arm 7 is sufficiently limited at the start of excavation, and after
that, the limitation of the operation of the arm 7 is mitigated
gradually, the cutting edge 8a can be moved along the target
excavation landform U.
[0253] As described above, according to the present embodiment,
since the speed of the arm 7 is limited in the intervention control
(limited excavation control) of the boom 6, a delay in the raising
intervention speed of the boom 6 in relation to the excavation
operation of the arm 7 is suppressed. Thus, a decrease in the
excavation accuracy is suppressed.
[0254] Further, in the present embodiment, the timer 261 performs
time measurement, and the driving of the arm 7 is limited for the
predetermined period Ts only from the start time t0 of the time
measurement of the timer 261. Due to this, a decrease in the
excavation accuracy is suppressed without complicating the control.
Moreover, since the arm 7 is driven based on the operation of the
operator after the elapse of the predetermined period Ts, a
decrease in the workability is suppressed.
[0255] In the present embodiment, the start time (the start time of
limiting the driving of the arm 7) t0 of the time measurement of
the timer 261 includes at least one of a start time of the
operation of the operating device 25, the time at which the
detection value of the detection device 70 exceeds the threshold
value, and the time at which the amount of increase per unit time
of the detection value of the detection device 70 exceeds an
allowable value. In this way, it is possible to smoothly limit the
driving of the arm 7 in a period where a delay in the raising
intervention speed of the boom 6 in relation to the excavation
operation of the arm 7 is likely to occur.
[0256] In the present embodiment, the driving based on the limited
amount of operation Mr is disabled after the elapse of the
predetermined period Ts from the start time t0 of the time
measurement of the timer 261. In this way, it is possible to
perform a normal operation based on the amount of arm operation M
of the operating device 25.
[0257] In the present embodiment, the limited amount of operation
Mr in the first half of the predetermined period Ts is smaller than
the limited amount of operation Mr in the second half. In the first
half of the predetermined period Ts, the limitation on the arm 7 is
strengthened, whereby the occurrence of a following delay of the
boom 6 is suppressed. In the second half of the predetermined
period Ts, the limitation on the arm 7 is weakened, whereby a
decrease in the operation efficiency is suppressed.
[0258] In the present embodiment, the arm 7 is driven with the
limited amount of operation Mr in at least a portion of the period
where the boom 6 is raised and the arm 7 is lowered. Due to this,
even when the operating device 25 is operated at a high speed by
the operator in order to drive the arm 7, since the arm 7 moves at
a limited speed (low speed), a delay in the raising intervention
speed of the boom 6 in relation the excavation operation of the arm
7 is suppressed.
[0259] In the present embodiment, in the arm speed limitation
control, it is possible to adjust the pilot pressure according to
the control signal N to accurately adjust the amount of operating
oil supplied to the arm cylinder 11 at a high speed.
[0260] In the present embodiment, in the boom intervention control,
the movement of the arm 7 is limited in order to suppress a
following delay of the boom 6. In the boom intervention control,
the movement of the bucket 8 may be limited. That is, in the
above-described embodiment, the operating device 25 may be operated
in order to drive the bucket 8, an amount of operation of the
operating device 25 may be detected by the detection device 70 (the
pressure sensor 662), the time measurement of the timer 261 may
start based on the detection result of the detection device 70, the
limited amount of operation for limiting the speed of the bucket 8
may be set in association with the time elapsed from the start time
of the time measurement of the timer 261, a bucket control unit may
be provided so that the bucket 8 is driven with a limited control
amount in a predetermined period from the start time of the time
measurement of the timer 261, and a control signal may be output
from the bucket control unit. The same is true for the following
embodiments.
[0261] In the intervention control, the movement of both the arm 7
and the bucket 8 may be limited. The same is true for the following
embodiments.
Second Embodiment
[0262] Next, a second embodiment of control of the arm 7 (or the
bucket 8) will be described. In the following description, the same
or equivalent portions as those of the above-described embodiment
will be denoted by the same reference numerals, and description
thereof will be simplified or omitted.
[0263] FIG. 25 is a schematic diagram illustrating an example of a
control system 200 according to the present embodiment. FIGS. 26,
27, and 28 are timing charts for describing an example of the
operation of the control system 200 according to the present
embodiment.
[0264] As illustrated in FIG. 25, the control system 200 includes a
variable capacitance hydraulic pump (main hydraulic pump) 41 that
supplies operating oil, a direction control valve 641 (64) to which
the operating oil from the hydraulic pump 41 is supplied, an arm
cylinder 11 that is driven with the operating oil supplied from the
hydraulic pump 41 via the direction control valve 641, a pump
controller (pump control unit) 49 that controls the hydraulic pump
41, a mode setting unit 26M, and a work machine controller 26. The
pump controller 49 is connected to the work machine controller 26.
The pump controller 49 outputs a control signal to a pump swash
plate control device 41C to control a pump swash plate of the
hydraulic pump 41.
[0265] The work machine controller 26 is connected to a man machine
interface 32. The man machine interface 32 includes the mode
setting unit 26M. The mode setting unit 26M sets an operation mode
of the excavator 100 based on the operation of the operator. In the
present embodiment, the mode setting unit 26M stores information on
a first operation mode and information on a second operation mode.
The mode setting unit may be provided with a switch or the like
separately.
[0266] In the present embodiment, the control system 200 controls
the excavator 100 in the first and second operation modes. The
first operation mode is an operation efficiency priority mode
(P-mode). The second operation mode is a fuel-saving mode (economy
mode). In the second operation mode, the supply of operating oil is
limited so that a largest discharge capacity of operating oil from
the hydraulic pump 41, which is a second largest discharge
capacity, is smaller than a largest discharge capacity of operating
oil from the hydraulic pump 41 which is a first largest discharge
capacity in the first operation mode.
[0267] In the present embodiment, both a limited amount of
operation (the limited amount of operation for the first operation
mode) Mr in the first operation mode and a limited amount of
operation (the limited amount of operation for the second operation
mode) Mr in the second operation mode are determined in advance and
are stored in the storage unit 264 (not illustrated in FIG. 25) of
the work machine controller 26. When controlling the excavator 100
in the first operation mode, the work machine controller 26
performs arm speed limitation control using the limited amount of
operation Mr in the first operation mode. When controlling the
excavator 100 in the second operation mode, the work machine
controller 26 performs arm speed limitation control using the
limited amount of operation Mr in the second operation mode.
[0268] FIG. 26 illustrates a relation between the time elapsed from
the start time t0 in the first operation mode (P-mode) and the
limited amount of operation Mr set by the limit value setting unit
262. A profile of the limited amount of operation Mr in the first
operation mode is indicated by line S2. FIG. 26 also illustrates a
relation between the time elapsed from the start time t0 and the
amount of operation M of the arm 7 by the operating device 25. A
profile of the amount of operation M is indicated by line S1. In
FIG. 26, the horizontal axis is time (elapsed time) and the
vertical axis is the amount of operation (M, Mr) of the arm 7 and
the count value of the timer 261.
[0269] FIG. 27 illustrates a relation between the time elapsed from
the start time t0 in the second operation mode (economy mode) and
the limited amount of operation Mr set by the limit value setting
unit 262. A profile of the limited amount of operation Mr in the
second operation mode is indicated by line S3. FIG. 27 also
illustrates the profile of the limited amount of operation Mr in
the first operation mode by line S2. In FIG. 27, the horizontal
axis is time (elapsed time) and the vertical axis is the amount of
operation (Mr) of the arm 7 and the count value of the timer
261.
[0270] FIG. 28 illustrates a relation between the time elapsed from
the start time t0 in the second operation mode and the amount of
operation Mf of the arm 7 as an example. In FIG. 28, the horizontal
axis is time (elapsed time) and the vertical axis is the amount of
operation (Mf) of the arm 7 and the count value of the timer
261.
[0271] Similarly to the above-described embodiment, as indicated by
the line S1 in FIG. 26, a case where the operating device 25 is
operated by the operator so that the amount of operation M
increases abruptly from 0 to value M3 will be considered. The
amount of operation M maintains the value M3 for a certain period
after reaching the value M3 and then decreases until it reaches 0.
When the arm speed limitation control is not executed, the amount
of operation M (Mf) has a profile indicated by the line S1 of FIG.
26. In this case, a delay in the raising intervention speed of the
boom 6 in relation to the excavation operation of the arm 7 may
occur.
[0272] The line S2 of FIG. 26 illustrates an example of the profile
of the limited amount of operation Mr in the first operation mode.
The profile (limit pattern) of the limited amount of operation Mr
in the first operation mode illustrated in FIG. 26 is equal to the
profile of the limited amount of operation Mr described with
reference to FIG. 23. Description of the profile of the limited
amount of operation Mr in the first operation mode will be
omitted.
[0273] FIG. 27 illustrates an example of the profile of the limited
amount of operation Mr in the second operation mode. The profile of
the limited amount of operation Mr in the second operation mode is
indicated by line S3. Similarly to the limited amount of operation
Mr in the first operation mode, the limited amount of operation Mr
in the second operation mode is an amount of operation that is
determined in advance so that a following delay of the boom 6 does
not occur. The limited amount of operation Mr in the second
operation mode is smaller than the limited amount of operation Mr
and the amount of operation M in the first operation mode.
[0274] In the first operation mode, in a predetermined period Ts
where the time measurement is performed by the timer 261, the
driving of the arm 7 is controlled so that the arm 7 is not
operated with the amount of operation M larger than the limited
amount of operation Mr indicated by the line S2.
[0275] In the second operation mode, in a predetermined period Ts
where the time measurement is performed by the timer 261, the
driving of the arm 7 is controlled so that the arm 7 is not
operated with the amount of operation M larger than the limited
amount of operation Mr indicated by the line S3.
[0276] The predetermined period Ts is a period between the time t0
and the time t1.
[0277] As illustrated in FIG. 27, the limited amount of operation
Mr in the second operation mode is 0 at time t0 and increases from
0 to a value M2u. The value M2u is larger than 0 and is smaller
than the value M2. That is, in a period near the start time t0, the
limited amount of operation Mr in the second operation mode has the
value M2u. The limited amount of operation Mr in the second
operation mode maintains the value M2u for a certain period after
reaching the value M2u, and increases gradually and reaches the
value M3 at the ending time t1. After that, the limited amount of
operation Mr decreases until it reaches 0 after maintaining the
value M3. In this manner, in the predetermined period Ts between
the time t0 and the time t1, the limited amount of operation Mr in
the second operation mode is set to be smaller than the limited
amount of operation Mr and the amount of operation M in the first
operation mode. The value at the time t0 which is the starting
point of the limit pattern S3 illustrated in FIG. 27 is M2u and the
value at the time t1 which is the ending point of the limit pattern
S2 is M3. In the period later than the time t1, the limited amount
of operation Mr in the second operation mode is the same as the
amount of operation M. Similarly to the first operation mode, in
the second operation mode, the limited amount of operation Mr in
the first half of the predetermined period Ts is smaller than the
limited amount of operation Mr in the second half of the
predetermined period Ts.
[0278] In the present embodiment, the arm control unit 263 compares
the amount of operation M with the limited amount of operation Mr,
selects the smaller amount of operation, and generates the control
signal N based on the selected amount of operation Mf. In the
present embodiment, in the predetermined period Ts between the time
t0 and the time t1, the limited amount of operation Mr is smaller
than the amount of operation M. Thus, in the predetermined period
between the time t0 and the time t1, the arm control unit 263
generates the control signal N so that the arm 7 is driven based on
the limited amount of operation Mr.
[0279] In the present embodiment, in the first operation mode, the
arm control unit 263 outputs the control signal N to the control
valve 271 so that the arm 7 is driven based on the limited amount
of operation Mr for the first operation mode as indicated by the
line S2 of FIG. 26. In the second operation mode, the arm control
unit 263 generates the control signal N so that the arm 7 is driven
based on the limited amount of operation Mr for the second
operation mode indicated by the line S3 of FIG. 27.
[0280] In the period later than the time t1, the limited amount of
operation Mr in the second operation mode is set to the value M3.
In the period later than the time t1, the limited amount of
operation Mr in the second operation mode is the same as the amount
of operation M. Similarly to the above-described embodiment, the
arm control unit 263 compares the amount of operation M with the
limited amount of operation Mr and selects the amount of operation
M. In the present embodiment, at the time t1, the arm speed
limitation control ends. That is, in the present embodiment, the
driving (arm speed limitation control) of the arm 7 based on the
limited amount of operation Mr starts at the start time t0 of the
time measurement of the timer 261 and ends at the ending time t1
after the elapse of the predetermined period Ts from the start time
t0. After the elapse of the predetermined period Ts from the start
time t0 of the time measurement of the timer 261, the driving based
on the limited amount of operation Mr is disabled.
[0281] FIG. 28 illustrates an example of the profile of the amount
of operation Mf in the second operation mode. The profile of the
amount of operation Mf in the second operation mode is indicated by
the line Sc. As illustrated in FIG. 28, in the predetermined period
Ts between the time t0 and the time t1, the arm 7 is operated with
the pilot pressure adjusted according to the limited amount of
operation Mr for the second operation mode as indicated by the line
Sc. After the elapse of the predetermined period Ts, the arm 7 is
operated with the pilot pressure adjusted according to the amount
of operation M as indicated by the line Sc.
[0282] That is, in the present embodiment, the profile of the
amount of operation Mf of the arm 7 is determined so as to change
along the line Sc of FIG. 28. Specifically, the operation of the
operating device 25 starts at the time t0, and the amount of
operation Mf increases abruptly from 0 to the value M2u and
maintains the value M2u for a certain period. After that, the
amount of operation Mf increases gradually and reaches the value M3
at the time t1. The amount of operation Mf maintains the value M3
for a certain period after the time t1 and then decreases to 0.
[0283] The arm control unit 263 generates the control signal N so
that the arm 7 is driven with the limited amount of operation Mr
for the second operation mode in the predetermined period Ts from
the start time t0 of the time measurement of the timer 261.
[0284] The arm control unit 263 generates the control signal N so
that the arm 7 is driven with the limited amount of operation Mr
for the second operation mode in the predetermined period Ts and
stops generating the control signal N so that the arm 7 is driven
with the amount of operation M after the elapse of the
predetermined period Ts where the driving based on the limited
amount of operation Mr for the second operation mode is disabled.
In this way, in the present embodiment, the arm 7 moves at a low
speed in the predetermined period Ts and the arm 7 moves at a high
speed after the elapse of the predetermined period Ts.
[0285] [Effects]
[0286] As described above, in the present embodiment, the limited
amount of operation Mr in the second operation mode is smaller than
the limited amount of operation Mr in the first operation mode.
[0287] The second operation mode is advantageous over the first
operation mode in terms of fuel efficiency. On the other hand, in
the second operation mode, the amount of operating oil supplied to
the hydraulic cylinder 60 decreases. Thus, in the second operation
mode, it is more difficult for the boom 6 and the arm 7 to move at
a high speed than the first operation mode. Moreover, the
possibility of the occurrence of a delay in the raising
intervention speed of the boom 6 increases.
[0288] In the present embodiment, the limited amount of operation
Mr in the second operation mode is smaller than the limited amount
of operation Mr in the first operation mode. That is, in the second
operation mode, the movement of the arm 7 is limited more strictly
than the first operation mode. Due to this, the occurrence of a
delay in the raising intervention speed of the boom is suppressed.
Thus, a decrease in the excavation accuracy is suppressed.
Third Embodiment
[0289] Next, a third embodiment of the control of the arm 7 (or the
bucket 8) will be described. In the following description, the same
or equivalent portions as those of the above-described embodiments
will be denoted by the same reference numerals, and description
thereof will be simplified or omitted.
[0290] In the present embodiment illustrated in FIG. 25, the bucket
8 is replaceable. Various buckets 8 are connected to the distal end
of the arm 7.
[0291] In a state where the bucket 8 of a first weight is connected
to the distal end of the arm 7, such a limit pattern indicated by
the line S3 as described with reference to FIG. 27, for example, is
set. Specifically, when the type of a bucket is selected, the
display controller 26 transmits the selected type to the work
machine controller 26. The work machine controller 26 selects a
limit pattern corresponding to the type of the bucket. In a state
where the bucket 8 of a second weight smaller than the first weight
is connected to the distal end of the arm 7, such a limit pattern
indicated by the line S2 as described with reference to FIG. 26 is
set. That is, the limited amount of operation Mr when the bucket 8
of the first weight is connected to the boom 6 with the arm 7
interposed is smaller than the limited amount of operation Mr when
the bucket 8 of the second weight smaller than the first weight is
connected to the boom 6 with the arm 7 interposed.
[0292] When a heavy bucket 8 is connected to the boom 6 with the
arm 7 interposed, the possibility of the occurrence of a following
delay of the boom 6 increases. On the other hand, if the movement
of the arm 7 is limited excessively when a light bucket 8 is
connected to the boom 6 with the arm 7 interposed, the workability
decreases.
[0293] [Effects]
[0294] As described above, in the present embodiment, the limited
amount of operation Mr when the bucket 8 of the first weight is
connected is smaller than the limited amount of operation Mr when
the bucket 8 of the second weight is connected. Due to this, it is
possible to suppress the occurrence of a following delay of the
boom 6 while suppressing a decrease in the workability.
Fourth Embodiment
[0295] Next, a fourth embodiment of the control of the arm 7 (or
the bucket 8) will be described. In the following description, the
same or equivalent portions as those of the above-described
embodiments will be denoted by the same reference numerals, and
description thereof will be simplified or omitted.
[0296] In the present embodiment, an example in which an amount of
increase per unit time of the detection value of the detection
device 70 exceeds an allowable value during the operation of the
operating device 25 will be described.
[0297] FIG. 29 is a diagram illustrating an example of the amount
of operation M and the limited amount of operation Mr. Similarly to
the above-described embodiment, the amount of operation M of the
operating device 25 is derived from the detection result of the
detection device 70 (the pressure sensor 661). The amount of
operation M derived from the detection result of the detection
device 70 is compared with the limited amount of operation Mr
(limit pattern) stored in the storage unit 264. When the amount of
operation M is smaller than the limited amount of operation Mr, the
arm 7 is operated based on the amount of operation M of the
operating device 25.
[0298] In a state where the operating device 25 is operated so that
the amount of operation M does not exceed the limited amount of
operation Mr, as illustrated in FIG. 29, the operating device 25
may be operated abruptly so that the amount of operation M
increases abruptly to exceed the limited amount of operation Mr. In
this case, even when the amount of operation M is compared with the
limited amount of operation Mr and the speed of the arm 7 is
limited based on the limited amount of operation Mr, the speed of
the arm 7 may not be limited sufficiently.
[0299] Thus, in the present embodiment, when the amount of
operation M increases abruptly during the operation of the
operating device 25, the work machine controller 26 starts
(restarts) the time measurement of the timer 261 and changes a
portion of the limited amount of operation Mr to perform the arm
speed limitation control.
[0300] In the present embodiment, the fact that the amount of
operation M increases abruptly includes the fact that the amount of
increase per unit time of the amount of operation M exceeds an
allowable value. In the present embodiment, the amount of operation
M is derived from the detection result of the detection device 70.
The fact that the amount of operation M increases abruptly includes
the fact that the amount of increase per unit time of the detection
value of the detection device 70 (the pressure sensor 661) exceeds
an allowable value.
[0301] In the present embodiment, when the amount of increase per
unit time of the detection value of the detection device 70 exceeds
the allowable value, the work machine controller 26 restarts the
time measurement of the timer 261 and changes a portion of the
limited amount of operation Mr to perform the arm speed limitation
control.
[0302] In the present embodiment, the amount of increase of the
detection value of the detection device 70 (the pressure sensor
661) is a difference (deviation) between the amount of operation M
of the operating device 25 detected by the detection device 70 and
a processing amount R generated from the amount of operation M by a
low-pass filtering process.
[0303] FIG. 30 is a diagram illustrating an example of the control
system 200 according to the present embodiment. As illustrated in
FIG. 30, a detection value (the amount of operation M of the
operating device 25) of the detection device 70 is output to the
work machine controller 26. Moreover, the detection value of the
detection device 70 is output to a filtering device 71. The
filtering device 71 can execute a first-order low-pass filtering
process. The filtering device 71 performs a first-order low-pass
filtering process on the detection value of the detection device 70
and generates a processing amount R. The work machine controller 26
calculates a deviation between the amount of operation M and the
processing amount R.
[0304] FIG. 31 is a schematic view illustrating a relation between
the amount of operation M and the processing amount R when the
operating device 25 is operated abruptly (at a high speed). As
illustrated in FIG. 31, when the operating device 25 is operated
abruptly and the amount of operation M increases in a stepwise
manner, the deviation between the amount of operation M and the
processing amount R is large.
[0305] FIG. 32 is a schematic view illustrating a relation between
the amount of operation M and the processing amount R when the
operating device 25 is operated smoothly (at a low speed). As
illustrated in FIG. 32, when the operating device 25 is operated
smoothly and the amount of operation M increases smoothly, the
deviation between the amount of operation M and the processing
amount R is small.
[0306] In the present embodiment, when the operating device 25 is
operated in order to drive the arm 7 to perform an excavation
operation and a deviation between the amount of operation M and the
processing amount R exceeds an allowable value during the operation
of the operating device 25, the time measurement of the timer 261
starts (restarts).
[0307] FIG. 33 is a flowchart illustrating an example of the
operation of the control system 200 according to the present
embodiment. FIGS. 34, 35, and 36 are timing charts for describing
an example of the operation of the control system 200 according to
the present embodiment. In FIGS. 34, 35, and 36, the horizontal
axis is time and the vertical axis is the amount of operation (M,
Mr, and Mf) of the arm 7 and the count value of the timer.
[0308] Similarly to the above-described embodiment, when the
operating device 25 starts operating the arm 7, the time
measurement of the timer 261 starts (step SC1). When the arm 7 is
lowered in order for the bucket 8 to perform an excavation
operation, boom intervention control including the raising
operation of the boom 6 is executed according to the distance d
between the target designed landform U and the cutting edge 8a
(step SC2).
[0309] The amount of operation M of the operating device 25 for
driving the arm 7 is detected by the detection device 70 (the
pressure sensor 661) (step SC3).
[0310] Similarly to the above-described embodiment, the detection
result of the amount of operation M is output to the comparing unit
of the arm control unit 263. Moreover, information on the limited
amount of operation Mr is output from the limit value setting unit
262 to the comparing unit of the arm control unit 263. The arm
control unit 263 compares the amount of operation M with the
limited amount of operation Mr according to the above-described
embodiment (step SC4).
[0311] When it is determined in step SC4 that the amount of
operation M is larger than the limited amount of operation Mr (that
is, Yes in step SC4), the arm control unit 263 selects the limited
amount of operation Mr and uses the same as the amount of operation
Mf. The arm control unit 263 generates the control signal N based
on the selected limited amount of operation Mr. In this way, the
arm speed limitation control is performed based on the limited
amount of operation Mr (step SC5).
[0312] When it is determined in step SC4 that the amount of
operation M is equal to or smaller than the limited amount of
operation Mr (that is, No in step SC4), the arm control unit 263
selects the amount of operation M and uses the same as the amount
of operation Mf. The arm control unit 263 does not generate the
control signal N. The arm 7 is driven with the pilot pressure
adjusted based on the amount of operation M of the operating device
25 (step SC6).
[0313] FIG. 34 illustrates an example of the profile of the amount
of operation M according to the present embodiment. The profile of
the amount of operation M is indicated by line S1. As illustrated
in FIG. 34, at time to, the operating device 25 is operated by the
operator in order to drive the arm 7. The timer 261 starts time
measurement. In the present embodiment, as an example, as indicated
by the line S1 of FIG. 34, a case where the operating device 25 is
operated by the operator so that the amount of operation M
increases from 0 to value M1u will be considered.
[0314] The value M1u is smaller than a lower limit value M1 of the
amount of operation generated by the limited amount of operation Mr
and the value M2 of the limited amount of operation Mr. The amount
of operation M maintains the value M1u for a certain period after
reaching the value M1u. In the present embodiment, in a period
between time t0 and time t0n, the amount of operation M maintains
the value M1u.
[0315] In FIG. 34, the profile of the limited amount of operation
Mr is indicated by line S2. The limited amount of operation Mr
indicated by the line S2 is the same as the limited amount of
operation Mr described with reference to FIG. 23 or the like.
Detailed description of the limited amount of operation Mr
indicated by the line S2 will not be provided.
[0316] At the time t0, the limited amount of operation Mr indicated
by the line S2 has the value M2. In the period between the time t0
and the time t0n, the limited amount of operation Mr is equal to or
larger than the value M2. That is, in the example illustrated in
FIG. 34, in the period between the time t0 and the time t0n, the
amount of operation M does not exceed the limited amount of
operation Mr indicated by the line S2. Thus, the arm 7 is driven
based on the amount of operation M of the operating device 25.
[0317] In a state where the operating device 25 is operated so that
the amount of operation M does not exceed the limited amount of
operation Mr indicated by the line S2 and the arm 7 is driven based
on the amount of operation M, the operating device 25 may be
operated abruptly so that the amount of operation M increases
abruptly as indicated by the line S1 of FIG. 34 to exceed the
limited amount of operation Mr indicated by the line S2.
[0318] In the present embodiment, as illustrated in FIG. 34, at the
time t0n during the operation of the operating device 25, the
operating device 25 is operated abruptly and the amount of
operation M increases abruptly. As illustrated in FIG. 34, in the
present embodiment, at the time t0n, the amount of operation M
increases abruptly from the value M1u to the value M3v. The value
M3v is larger than the value M3.
[0319] As described above, in the present embodiment, the amount of
increase of the detection value of the detection device 70 (the
pressure sensor 661) is a difference (deviation) between the amount
of operation M of the operating device 25 detected by the detection
device 70 and the processing amount R generated from the amount of
operation M by a low-pass filtering process. When the amount of
operation M increases abruptly, a change in the amount of operation
M is detected by the detection device 70 (step SC7). The detection
result of the detection device 70 is output to a determining unit
of the work machine controller 26. The determining unit of the work
machine controller 26 determines whether a deviation between the
amount of operation M and the processing amount R exceeds an
allowable value (step SC8).
[0320] When it is determined in step SC8 that the deviation is
equal to or smaller than the allowable value (that is, No in step
SC8), the flow returns to step SC4 and the work machine controller
26 compares the increased amount of operation M with the limited
amount of operation Mr and executes the above-described
process.
[0321] When it is determined in step SC8 that the deviation exceeds
the allowable value (that is, Yes in step SC8), the work machine
controller 26 resets the time measurement from the time t0 and
starts (restarts) the time measurement of the timer 261 (step
SC9).
[0322] Moreover, the limit value setting unit 262 resets the time
measurement, resets the limited amount of operation Mr indicated by
the line S2, and sets (resets) the limited amount of operation Mr
in association with the time elapsed from the start time t0n of the
time measurement of the timer 261.
[0323] FIG. 35 illustrates an example of the profile of the reset
limited amount of operation Mr. The profile of the reset limited
amount of operation Mr is indicated by line S4. The limited amount
of operation Mr is an amount of operation that is determined in
advance so that the following delay of the boom 6 does not occur.
The limited amount of operation Mr is smaller than the amount of
operation M indicated by the line S1 of FIG. 34.
[0324] The time measurement of the timer 261 restarts at the time
t0n, the driving of the arm 7 is controlled so that the arm 7 is
not operated with the amount of operation M larger than the limited
amount of operation Mr in a predetermined period Tu where the timer
261 performs time measurement. In the present embodiment, the
predetermined period Tu is a period between the time t0n and the
time t3.
[0325] As illustrated in FIG. 35, at the time t0n, the limited
amount of operation Mr has a value M2. The value M2 is smaller than
a value M3v. The limited amount of operation Mr set to the value M2
at the time t0n maintains the value M2 for a certain period, and
increases gradually and reaches the value M3 at the time t2. After
that, the limited amount of operation Mr decreases until it reaches
0 after maintaining the value M3 until the time t3. In this manner,
in the predetermined period Tu between the time t0n and the time
t3, the limited amount of operation Mr is set to be smaller than
the amount of operation M. The value at the time t0n which is the
starting point of the limit pattern S4 illustrated in FIG. 35 is
M2, the value immediately before the time t3 which is the ending
point of the limit pattern S4 is M3, and the value at the time t3
is 0.
[0326] In this manner, in the present embodiment, the limited
amount of operation Mr in the first half of the predetermined
period Tu is smaller than the limited amount of operation Mr in the
second half of the predetermined period Tu.
[0327] The arm control unit 263 compares the amount of operation M
with the reset limited amount of operation Mr (step SC10).
[0328] When it is determined in step SC10 that the amount of
operation M is equal to or smaller than the limited amount of
operation Mr (that is, step SC10:No), the arm control unit 263
selects the amount of operation M and uses the same as the amount
of operation Mf. The arm control unit 263 does not generate the
control signal N. The arm 7 is driven with the pilot pressure
adjusted based on the amount of operation M of the operating device
25 (step SC11).
[0329] When it is determined in step SC10 that the amount of
operation M is larger than the limited amount of operation Mr (that
is, Yes in step SC10), the arm control unit 263 selects the reset
limited amount of operation Mr indicated by the line S4 and uses
the same as the amount of operation Mf. The arm control unit 263
generates the control signal N based on the selected limited amount
of operation Mr. In this way, the arm speed limitation control is
performed based on the limited amount of operation Mr (step
SC12).
[0330] In the present embodiment, as illustrated in FIGS. 34 and
35, the amount of operation M is larger than the limited amount of
operation Mr indicated by the line S4. Thus, the arm control unit
263 performs arm speed limitation control based on the limited
amount of operation Mr.
[0331] FIG. 36 illustrates an example of the profile of the amount
of operation Mf according to the present embodiment. The profile of
the amount of operation Mf is indicated by line Sc. As illustrated
in FIG. 36, in a predetermined period Ts between the time t0 and
the time t10, the arm 7 is operated with the pilot pressure
adjusted according to the amount of operation M as indicated by the
line Sc. That is, the amount of operation Mf increases from 0 to
the value M1u at the time t0 and increases from the value M1u to
the value M2 at the time t0n after maintaining the value M1u until
the time t0n. After that, the amount of operation Mf maintains the
value M2 for a predetermined period, increases gradually to reach
the value M3 at the time t2, and maintains the value M3 until the
time t3.
[0332] [Effects]
[0333] As described above, according to the present embodiment,
when the amount of operation M of the operating device 25 increases
abruptly during the operation of the operating device 25, the time
measurement of the timer 261 is reset and restarted, and the limit
pattern S4 in which the value at the starting point (time t0n) is
M2 is set (reset). Thus, the arm 7 is controlled smoothly and a
decrease in the excavation accuracy is suppressed.
[0334] For example, if the movement of the arm 7 is limited based
on the limit pattern S2 that is set in advance without resetting
the limit pattern S4, the amount of operation (the profile Sc) may
increase abruptly to the value M3 based on the limit pattern S2ni
at the time t0n. As a result, the speed of the arm 7 may increase
abruptly, the intervention speed of the boom 6 may be slower than
the raising speed of the arm 7, and the excavation accuracy may
decrease.
[0335] According to the present embodiment, when the operating
device 25 is operated abruptly so that the amount of operation M
increases abruptly during the operation of the operating device 25,
the time measurement of the timer 261 is reset to restart the time
measurement, and a portion of the limit pattern S2 is changed to
set a new limit pattern S4. Thus, it is possible to move the arm 7
smoothly and to suppress a decrease in the excavation accuracy.
Fifth Embodiment
[0336] Next, a fifth embodiment of the control of the arm 7 (or the
bucket 8) will be described. In the following description, the same
or equivalent portions as those of the above-described embodiments
will be denoted by the same reference numerals, and description
thereof will be simplified or omitted.
[0337] In the present embodiment, an example in which the operating
device 25 is operated so that the amount of operation M decreases
in the predetermined period Ts from the start time of the time
measurement of the timer 261 will be described.
[0338] FIG. 37 is a diagram illustrating an example of the amount
of operation M and the limited amount of operation Mr. As described
above, when the amount of operation M derived from the detection
value of the detection device 70 exceeds the limited amount of
operation Mr, the arm 7 is operated based on the limited amount of
operation Mr. As illustrated in FIG. 37, in a period where the
limited amount of operation Mr increases, the operating device 25
may be operated so that the amount of operation M decreases. When
the amount of operation M is larger than the limited amount of
operation Mr, even if the operating device 25 is operated so that
the amount of operation M decreases, the arm 7 is driven so as to
be accelerated. In this case, the operator may feel a sense of
incongruity.
[0339] Thus, in the present embodiment, in the predetermined period
Ts from the start time t0 of the time measurement of the timer 261,
when the operating device 25 is operated so that the amount of
operation M decreases, the work machine controller 26 determines
that the amount of operation has decreased and maintains the
limited amount of operation Mr to a certain value from the decrease
start time tg. When the operating device 25 is operated so that the
amount of operation M decreases, since the limited amount of
operation Mr is maintained to a certain value, it is possible to
suppress the sense of incongruity that the operator might feel.
[0340] FIG. 38 is a functional block diagram illustrating an
example of the control system 200 according to the present
embodiment. FIG. 39 is a flowchart for describing an example of the
operation of the control system 200 according to the present
embodiment. FIGS. 40, 41, and 42 are timing charts for describing
an example of the operation of the control system 200 according to
the present embodiment. In FIGS. 40, 41, and 42, the horizontal
axis is time and the vertical axis is the amount of operation (M,
Mr, and Mf) of the arm 7 and the count value of the timer.
[0341] As illustrated in FIG. 38, in the present embodiment, the
arm control unit 263 has a comparing unit 263A. The comparing unit
263A compares the amount of operation M with the limited amount of
operation Mr according to the above-described embodiment.
[0342] Similarly to the above-described embodiment, when the
operating device 25 starts operating the arm 7, the time
measurement of the timer 261 starts (step SD1). When the arm 7 is
lowered in order for the bucket 8 to perform an excavation
operation, boom intervention control including the raising
operation of the boom 6 is executed according to the distance d
between the target designed landform U and the cutting edge 8a
(step SD2).
[0343] The amount of operation M of the operating device 25 for
driving the arm 7 is detected by the detection device 70 (the
pressure sensor 661) (step SD3).
[0344] Similarly to the above-described embodiment, the detection
result of the amount of operation M is output to the comparing unit
263A of the arm control unit 263. Moreover, information on the
limited amount of operation Mr is output from the limit value
setting unit 262 to the comparing unit 263A of the arm control unit
263. The arm control unit 263 compares the amount of operation M
with the limited amount of operation Mr according to the
above-described embodiment (step SD4).
[0345] When it is determined in step SD4 that the amount of
operation M is larger than the limited amount of operation Mr (that
is, Yes in step SD4), the arm control unit 263 selects the limited
amount of operation Mr and uses the same as the amount of operation
Mf. The arm control unit 263 generates the control signal N based
on the selected limited amount of operation Mr. In this way, the
arm speed limitation control is performed based on the limited
amount of operation Mr (step SD5).
[0346] When it is determined in step SD4 that the amount of
operation M is equal to or smaller than the limited amount of
operation Mr (that is, No in step SD4), the arm control unit 263
selects the amount of operation M and uses the same as the amount
of operation Mf. The arm control unit 263 does not generate the
control signal N. The arm 7 is driven with the pilot pressure
adjusted based on the amount of operation M of the operating device
25 (step SD6).
[0347] FIG. 40 illustrates an example of the profile of the amount
of operation M according to the present embodiment. The profile of
the amount of operation M is indicated by line S1. As illustrated
in FIG. 40, at time to, the operating device 25 is operated by the
operator in order to drive the arm 7. The timer 261 starts time
measurement. In the present embodiment, as an example, as indicated
by the line S1 of FIG. 40, a case where the operating device 25 is
operated by the operator so that the amount of operation M
increases from 0 to value M3v will be considered.
[0348] The value M3v is larger than the lower limit value M1 of the
amount of operation generated by the limited amount of operation
Mr, the value M2 of the limited amount of operation, and the value
M3 of the largest amount of operation. The amount of operation M
maintains the value M3v for a certain period after reaching the
value M3v. In the present embodiment, in a period between time t0
and time tg, the amount of operation M maintains the value M3v. The
time tg is the time occurring after the predetermined period Ts has
elapsed from the start time to.
[0349] In FIG. 40, the profile of the limited amount of operation
Mr is indicated by line S2. The limited amount of operation Mr
indicated by the line S2 is the same as the limited amount of
operation Mr described with reference to FIG. 23 or the like.
Detailed description of the limited amount of operation Mr
indicated by the line S2 will not be provided.
[0350] At the time t0, the limited amount of operation Mr indicated
by the line S2 has the value M2. In the period between the time t0
and the time ta, the limited amount of operation Mr is smaller than
the value M3v of the amount of operation M. That is, in the example
illustrated in FIG. 40, in the period between the time t0 and the
time ta, the amount of operation M exceeds the limited amount of
operation Mr indicated by the line S2. Thus, the arm 7 is driven
based on the limited amount of operation Mr.
[0351] At the time tg in the predetermined period Ts, the operating
device 25 is operated so that the amount of operation M decreases.
That is, in a state where the arm 7 is driven based on the limited
amount of operation Mr, the operating device 25 may be operated
abruptly so that the amount of operation M decreases abruptly at
the time tg as indicated by the line S1 of FIG. 40 and becomes
smaller than the limited amount of operation Mr indicated by the
line S2 at the time ta.
[0352] In the present embodiment, as illustrated in FIG. 40, at the
time tg, the operating device 25 is operated abruptly and the
amount of operation M decreases abruptly. As illustrated in FIG.
40, in the present embodiment, the amount of operation M decreases
abruptly from the value M3v to the value M1v. The value M1v of the
amount of operation M is larger than the value M1 and is smaller
than the value M2 of the limited amount of operation Mr.
[0353] When the amount of operation M decreases (falls) abruptly,
the change in the amount of operation M is detected by the
detection device 70 (step SD7). The detection result of the
detection device 70 is output to a determining unit 262A of the
limit value setting unit 262. The determining unit 262A determines
whether a decrease rate (the amount of decrease per unit time) of
the amount of operation M exceeds an allowable value (step
SD8).
[0354] When it is determined in step SD8 that the decrease rate is
equal to or smaller than the allowable value (that is, No in step
SD8), the flow returns to step SD4 and the work machine controller
26 compares the decreased amount of operation M with the limited
amount of operation Mr and executes the above-described
process.
[0355] When it is determined in step SD8 that the decrease rate of
the amount of operation M exceeds the allowable value (that is, Yes
in step SD8), the limit value setting unit 262 of the work machine
controller 26 maintains the limited amount of operation Mr at the
decrease start time tg to a certain value M4 (step SD9). The
limited amount of operation Mr is maintained to the value M4 from
the time tg as indicated by line S2a of FIG. 40. The arm 7 is
driven based on the changed limit pattern S2a. In this way, it is
possible to suppress the sense of incongruity that the operator
might feel.
[0356] When the operating device 25 is operated so that the amount
of operation M decreases, the amount of operation M becomes smaller
than the limited amount of operation Mr (the value M4). The arm
control unit 263 compares the amount of operation M with the reset
limited amount of operation Mr indicated by the line S2a (step
SD10).
[0357] When it is determined in step SD10 that the amount of
operation M is equal to or smaller than the limited amount of
operation Mr (that is, No in step SD10), the arm control unit 263
selects the amount of operation M and uses the same as the amount
of operation Mf. The arm control unit 263 does not generate the
control signal N. The arm 7 is driven with the pilot pressure
adjusted based on the amount of operation M of the operating device
25 (step SD11).
[0358] When it is determined in step SD10 that the amount of
operation M is larger than the limited amount of operation Mr (that
is, Yes in step SD10), the arm control unit 263 selects the limited
amount of operation Mr and uses the same as the amount of operation
Mf. The arm control unit 263 generates the control signal N based
on the selected limited amount of operation Mr. In this way, the
arm speed limitation control is performed based on the limited
amount of operation Mr (step SD12).
[0359] The amount of operation M indicated by the line S1 of FIG.
40 increases abruptly at time tb. When the amount of operation M
increases abruptly, the time measurement of the timer 261 restarts
and the limit pattern S4a is reset according to the embodiment
described with reference to FIGS. 29 to 36. FIG. 41 illustrates an
example of the reset limit pattern S4a.
[0360] FIG. 42 illustrates an example of the profile of the amount
of operation Mf according to the present embodiment. The profile of
the amount of operation Mf is indicated by line Sc. As illustrated
in FIG. 42, in the period Ts between the time t0 and the time ta,
the arm 7 is operated with the pilot pressure adjusted according to
the limited amount of operation Mr as indicated by the line Sc. In
the period later than the time ta, the arm 7 is operated with the
pilot pressure adjusted according to the amount of operation M. In
the period later than the time tb, the arm 7 is operated with the
pilot pressure adjusted according to the limited amount of
operation Mr.
[0361] [Effects]
[0362] As described above, according to the present embodiment,
when the arm 7 is driven based on the limit pattern S2, the arm 7
is moved so as to be accelerated, and the operating device 25 is
operated so as to be decelerated, a portion of the limit pattern S2
is changed to obtain the limit pattern S2a so that the limited
amount of operation Mr is maintained to a certain value without
being increased. Thus, it is possible to suppress the sense of
incongruity that the operator might feel.
Sixth Embodiment
[0363] Next, a sixth embodiment of the control of the arm 7 (or the
bucket 8) will be described. In the following description, the same
or equivalent portions as those of the above-described embodiments
will be denoted by the same reference numerals, and description
thereof will be simplified or omitted.
[0364] FIG. 43 is a functional block diagram of the control system
200 according to the present embodiment. As illustrated in FIG. 43,
in the present embodiment, the work machine controller 26 has a
distance determining unit 262B.
[0365] FIG. 44 is a schematic view illustrating an example of the
excavator 100 according to the present embodiment. As illustrated
in FIG. 44, the excavator 100 includes the vehicle body 1 and the
work machine 2. The vehicle body 1 supports the boom 6. When the
work machine 2 is driven, the distance x between the reference
position P2 of the vehicle body 1 and the position P3 of the
cutting edge 8a of the bucket 8 changes. The distance x may be the
distance between the position of the boom pin and the position of
the cutting edge 8a and may be the distance between the installed
position P1 and the cutting edge 8a.
[0366] In the present embodiment, the distance x between the
reference position P2 and the position P3 is calculated from the
attitude angles .theta.1 to .theta.3 of the work machines output
from the sensor controller 30, and the limited amount of operation
Mr when the work machine 2 is driven so that the distance x between
the reference position P2 and the position P3 is a first distance
is smaller than the limited amount of operation Mr when the work
machine 2 is driven so that the distance x between the reference
position P2 and the position P3 is a second distance shorter than
the first distance.
[0367] FIG. 45 is a timing chart for describing an example of the
operation of the control system 200 according to the present
embodiment. In FIG. 45, the horizontal axis is time and the
vertical axis is the amount of operation M (limited amount of
operation Mr) of the arm 7 and the count value of the timer.
[0368] As illustrated in FIG. 45, when the distance x is a first
distance, such a limit pattern as indicated by the line S2 is set.
When the distance x is a second distance, such a limit pattern as
indicated by the line S5 is set. The limited amount of operation Mr
of the limit pattern indicated by the line S2 is smaller than the
limited amount of operation Mr of the limit pattern indicated by
the line S5.
[0369] FIG. 46 illustrates an example of the profile of the amount
of operation Mf determined based on the limit pattern S2. FIG. 47
illustrates an example of the profile of the amount of operation Mf
determined based on the limit pattern S5.
[0370] The longer the distance x, the larger the moment of the work
machine 2, and the higher the possibility of the occurrence of a
following delay of the boom 6. In the present embodiment, the
limited amount of operation Mr when the distance x is the first
distance which is long is smaller than the limited amount of
operation Mr when the distance x is the second distance which is
short. That is, in the first distance state, the movement of the
arm 7 is limited more strictly than in the second distance state.
In this way, the occurrence of the following delay of the boom 6 is
suppressed. Thus, a decrease in the excavation accuracy is
suppressed.
[0371] [Effects]
[0372] As described above, according to the present embodiment, the
limited amount of operation Mr when the work machine 2 is driven so
that the distance between the reference position of the vehicle
body 1 and the bucket 8 is the first distance is smaller than the
limited amount of operation Mr when the work machine 2 is driven so
that the distance between the reference position of the vehicle
body 1 and the bucket 8 is the second distance shorter than the
first distance. Thus, it is possible to suppress a decrease in the
excavation accuracy while suppressing a decrease in the operation
efficiency.
Seventh Embodiment
[0373] Next, a seventh embodiment of control of the arm 7 (or the
bucket 8) will be described. In the following description, the same
or equivalent portions as those of the above-described embodiments
will be denoted by the same reference numerals, and description
thereof will be simplified or omitted.
[0374] FIG. 48 is a functional block diagram illustrating an
example of a control system 200 according to the present
embodiment. Similarly to the above-described embodiment, the
control system 200 includes a display controller 28, a work machine
controller 26, an operating device 25 that is operated to drive a
movable member that includes at least one of the arm 7 and the
bucket 8, and a detection device 70 that detects the amount of
operation M of the operating device 25.
[0375] The display controller 28 includes a target construction
information storage unit 28A, a bucket position data generating
unit 28B, and a target excavation landform data generating unit
28C. The bucket position data generating unit 28B generates cutting
edge position data S indicating the 3-dimensional position of the
bucket 8 based on the attitude angles .theta.1, .theta.2, and
.theta.3 of the boom 6, the arm 7, and the bucket 8 which are the
detection results of the first, second, and third cylinder stroke
sensors 16, 17, and 18.
[0376] The target excavation landform data generating unit 28C
generates the target excavation landform U indicating the target
shape of the excavation object to be excavated by the work machine
2 based on the target construction information T output from the
target construction information storage unit 28A and the cutting
edge position data S output from the bucket position data
generating unit 28B.
[0377] The work machine controller 26 includes: a distance
acquiring unit 53 that acquires the target excavation landform U
from the target excavation landform data generating unit 28C and
calculates the distance d between the cutting edge 8a of the bucket
8 and the target excavation landform U based on the cutting edge
position data S and the target excavation landform U; a timer 261
that starts time measurement based on the detection result of the
detection device 70; a limit value setting unit 262 that sets the
limited amount of operation Mr for limiting the speed of the arm 7
based on the distance d calculated by the distance acquiring unit
53; an arm control unit 263 that outputs a control signal N to the
control valve 27 based on the detection result of the detection
device 70 so that the arm 7 is driven with the limited amount of
operation Mr when the operation of the operating device 25 is
started to raise the boom 6 and lower the arm 7 in the excavation
operation of the bucket 8; and a storage unit 264.
[0378] In the present embodiment, the limit value setting unit 262
sets the limited amount of operation Mr so that the larger the
distance d, the larger the limited amount of operation Mr. That is,
the limit value setting unit 262 sets the limited amount of
operation Mr so that the larger the distance d, the more the
limitation on the operation of the arm 7 is mitigated.
[0379] FIG. 49 is a diagram schematically illustrating an example
of data stored in the storage unit 264. As illustrated in FIG. 49,
an offset amount of the limited amount of operation Mr in relation
to the distance d for mitigating the limited amount of operation Mr
is stored in the storage unit 264. The offset amount increases
proportionally to the distance d when the distance d is between 0
and a predetermined value d1. The offset amount is constant when
the distance d is larger than the predetermined value d1. The arm
control unit 263 adds the offset amount to the limited amount of
operation Mr.
[0380] FIG. 50 is a flowchart for describing an example of the
operation of the control system 200 according to the present
embodiment. In the excavation operation, the operating device 25 is
operated by the operator (step SE1). The operator operates the
operating device 25 in order to drive the arm 7. The operating
device 25 is operated so that the arm 7 is lowered.
[0381] The detection device 70 detects the amount of operation M of
the operating device 25 (step SE2). The detection device 70
includes the pressure sensor 66 and detects the amount of operation
M of the operating device 25 by detecting the pilot pressure
adjusted by the operating device 25.
[0382] The detection value of the detection device 70 is output to
the timer 261. The timer 261 starts time measurement based on the
detection result of the detection device 70 (step SE3).
[0383] The bucket position data generating unit 28B generates the
cutting edge position data S indicating the 3-dimensional position
of the bucket 8 based on the cylinder attitude data .theta.1,
.theta.2, and .theta.3 which is the detection results of the first,
second, and third cylinder stroke sensors 16, 17, and 18 (step
SE4).
[0384] The distance acquiring unit 53 calculates the distance d
between the cutting edge 8a of the bucket 8 and the target
excavation landform U based on the cutting edge position data S and
the target excavation landform U (step SE5).
[0385] The arm control unit 263 sets the limited amount of
operation Mr corresponding to the distance d based on the distance
d calculated in step SE5 and the relation between the distance d
and the offset amount of the limited amount of operation Mr, stored
in the storage unit 264, described with reference to FIG. 49 (step
SE6). Specifically, the arm control unit 263 adds the offset amount
of the limited amount of operation Mr to the amount of operation M
detected by the detection device 70.
[0386] The arm control unit 263 compares the amount of operation M
and the limited amount of operation Mr to which the offset amount
is added to select the smaller amount of operation and generates
the control signal N based on the selected amount of operation Mf.
The generated control signal N is output to the control valve 27
(step ES7). As described above, in the present embodiment, the
operation of the arm 7 is limited when the distance d is small and
the limitation on the operation of the arm 7 is mitigated when the
distance d is large. Moreover, the operation of the arm 7 is not
limited when the distance d is larger than the predetermined value
d1, and the arm 7 operates based on the amount of operation M of
the operating device 25.
[0387] [Effects]
[0388] As described above, according to the present embodiment, the
operation of the arm 7 at the start of excavation is limited. Since
the time at which the operation of the arm 7 is limited is limited
to the start time of excavation, the decrease in the amount of work
performed by the construction machine 100 is suppressed.
[0389] Moreover, in the present embodiment, the limit value setting
unit 262 sets the limited amount of operation Mr so that the larger
the distance d, the larger the limited amount of operation Mr (that
is, the larger the distance d, the more the limitation on the
operation of the arm 7 is mitigated). Since the operation of the
arm 7 is sufficiently limited when the distance d is small and the
limitation on the operation of the arm 7 is mitigated when the
distance d is large, the cutting edge 8a can be moved along the
target excavation landform U while suppressing the decrease in the
amount of work performed.
[0390] Moreover, according to the present embodiment, since the
operation of the arm 7 is limited and the limitation is mitigated
according to the distance d, it is possible to suppress the
decrease in the amount of work performed by the construction
machine 100 and the falling of the cutting edge 8a.
[0391] While the embodiments of the present invention have been
described, the present invention is not limited to the embodiments
and various changes can be made without departing from the spirit
of the present invention.
[0392] For example, in the above-described embodiments, the
operating device 25 is a pilot hydraulic-type operating device. The
operating device 25 may be an electric lever-type operating device.
For example, an operating lever detecting unit that detects an
amount of operation of the operating lever of the operating device
25 with the aid of a potentiometer or the like and outputs a
detection value corresponding to the amount of operation to the
work machine controller 26 may be provided. The work machine
controller 26 may output a control signal to the direction control
valve 64 based on the detection result of the operating lever
detecting unit to adjust the amount of operating oil supplied to
the hydraulic cylinder. The control according to the present
invention may be performed by other controllers such as the sensor
controller 30 as well as a work machine controller 226.
[0393] In the above-described embodiments, although an excavator
has been described as an example of the construction machine, the
construction machine is not limited to the excavator, and the
present invention may be applied to other types of construction
machine.
[0394] The position of the excavator CM in the global coordinate
system may be acquired by other position measurement means without
being limited to GNSS. Thus, the distance d between the designed
landform and the cutting edge 8a may be acquired by other position
measurement means without being limited to GNSS.
REFERENCE SIGNS LIST
[0395] 1 VEHICLE BODY [0396] 2 WORK MACHINE [0397] 3 REVOLVING
STRUCTURE [0398] 4 CAB [0399] 5 TRAVELING DEVICE [0400] 5Cr CRAWLER
BELT [0401] 6 BOOM [0402] 7 ARM [0403] 8 BUCKET [0404] 9 ENGINE
ROOM [0405] 10 BOOM CYLINDER [0406] 11 ARM CYLINDER [0407] 12
BUCKET CYLINDER [0408] 13 BOOM PIN [0409] 14 ARM PIN [0410] 15
BUCKET PIN [0411] 16 FIRST CYLINDER STROKE SENSOR [0412] 17 SECOND
CYLINDER STROKE SENSOR [0413] 18 THIRD CYLINDER STROKE SENSOR
[0414] 19 HANDRAIL [0415] 20 POSITION DETECTION DEVICE [0416] 21
ANTENNA [0417] 23 GLOBAL COORDINATE CALCULATING UNIT [0418] 24 IMU
[0419] 25 OPERATING DEVICE [0420] 25L SECOND OPERATING LEVER [0421]
25R FIRST OPERATING LEVER [0422] 26 WORK MACHINE CONTROLLER [0423]
27 CONTROL VALVE [0424] 28 DISPLAY CONTROLLER [0425] 29 DISPLAY
UNIT [0426] 31 BOOM OPERATION OUTPUT UNIT [0427] 32 BUCKET
OPERATION OUTPUT UNIT [0428] 33 ARM OPERATION OUTPUT UNIT [0429] 34
REVOLVING OPERATION OUTPUT UNIT [0430] 40A CAB-SIDE OIL CHAMBER
[0431] 40B ROD-SIDE OIL CHAMBER [0432] 41 HYDRAULIC PUMP [0433] 41A
SWASH PLATE [0434] 45 DISCHARGE OIL PASSAGE [0435] 47 OIL PASSAGE
[0436] 48 OIL PASSAGE [0437] 49 PUMP CONTROLLER [0438] 50 OIL
PASSAGE [0439] 51 SHUTTLE VALVE [0440] 60 HYDRAULIC CYLINDER [0441]
63 REVOLVING MOTOR [0442] 64 DIRECTION CONTROL VALVE [0443] 65
SPOOL STROKE SENSOR [0444] 66 PRESSURE SENSOR [0445] 67 PRESSURE
SENSOR [0446] 70 DETECTION DEVICE [0447] 71 FILTERING DEVICE [0448]
100 CONSTRUCTION MACHINE (EXCAVATOR) [0449] 161 ROTATION ROLLER
[0450] 162 ROTATION CENTER SHAFT [0451] 163 ROTATION SENSOR PORTION
[0452] 164 CASE [0453] 200 CONTROL SYSTEM [0454] 300 HYDRAULIC
SYSTEM [0455] AX REVOLUTION AXIS [0456] Q REVOLVING STRUCTURE
DIRECTION DATA [0457] S CUTTING EDGE POSITION DATA [0458] T TARGET
CONSTRUCTION INFORMATION [0459] U TARGET EXCAVATION LANDFORM
* * * * *