U.S. patent application number 15/100720 was filed with the patent office on 2017-06-15 for work vehicle and method for obtaining tilt angle.
The applicant listed for this patent is KOMATSU LTD.. Invention is credited to Daiki ARIMATSU, Yuto FUJII, Katsuhiro IKEGAMI, Tsutomu IWAMURA, Masanobu SEKI.
Application Number | 20170167116 15/100720 |
Document ID | / |
Family ID | 55954516 |
Filed Date | 2017-06-15 |
United States Patent
Application |
20170167116 |
Kind Code |
A1 |
FUJII; Yuto ; et
al. |
June 15, 2017 |
WORK VEHICLE AND METHOD FOR OBTAINING TILT ANGLE
Abstract
A hydraulic excavator is provided with a tilt cylinder
disposition data creating unit and a bucket information computing
unit. The tilt cylinder disposition data creating unit creates tilt
cylinder disposition data which indicates that a disposition of a
tilt cylinder is either a first disposition in which a bucket is
rotated in the clockwise direction due to extension or a second
disposition in which the bucket is rotated in the clockwise
direction due to contraction, when viewing the bucket from a
vehicle body side. The bucket information computing unit obtains a
tilt angle of the bucket based on the stroke length on the basis of
the tilt cylinder disposition data.
Inventors: |
FUJII; Yuto; (Hirakata-shi,
Osaka, JP) ; IWAMURA; Tsutomu; (Yokohama-shi,
Kanagawa, JP) ; ARIMATSU; Daiki; (Hiratsuka-shi,
Kanagawa, JP) ; IKEGAMI; Katsuhiro; (Hiratsuka-shi,
Kanagawa, JP) ; SEKI; Masanobu; (Fujisawa-shi,
Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMATSU LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
55954516 |
Appl. No.: |
15/100720 |
Filed: |
December 9, 2015 |
PCT Filed: |
December 9, 2015 |
PCT NO: |
PCT/JP2015/084472 |
371 Date: |
June 1, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 3/425 20130101;
E02F 3/32 20130101; E02F 9/265 20130101; E02F 3/3681 20130101; E02F
9/264 20130101 |
International
Class: |
E02F 9/26 20060101
E02F009/26 |
Claims
1. A work vehicle comprising: a vehicle body; a work implement
having a bucket that is configured to rotate about a tilt axis; a
tilt cylinder configured to cause the bucket to rotate about the
tilt axis; a stroke length detecting unit configured to detect a
stroke length of the tilt cylinder; a tilt cylinder disposition
data creating unit configured to create tilt cylinder disposition
data which indicates whether a disposition of the tilt cylinder is
a first disposition or a second disposition when viewing the bucket
from the vehicle body side, the bucket disposed in the first
disposition being rotated in the clockwise direction due to
extension of the tilt cylinder, the bucket disposed in the second
disposition being rotated in the clockwise direction due to
contraction of the tilt cylinder; and a bucket information
computing unit configured to obtain a tilt angle of the bucket
based on the stroke length on the basis of the tilt cylinder
disposition data.
2. The work vehicle according to claim 1, further comprising a
display unit; and a display controller configured to cause a
selection screen for selecting the first disposition or the second
disposition to be displayed on the display unit, the tilt cylinder
disposition data creating unit creating the tilt cylinder
disposition data on the basis of a selection result from the
selection screen.
3. The work vehicle according to claim 2, wherein the display
controller is configured to cause a first pattern and a second
pattern to be displayed on the display unit as the first
disposition, when the bucket is disposed in the first pattern, a
first end part of the tilt cylinder coupled to the bucket is
positioned to the left of the tilt axis and a second end part
provided opposite the first end part of the tilt cylinder is
positioned below a coupling line that couples the tilt axis and the
first end part when viewing the bucket from the vehicle body side,
when the bucket is disposed in the second pattern, the first end
part is positioned to the right of the tilt axis and the second end
part is positioned above the coupling line when viewing the bucket
from the vehicle body side, the display controller is configured to
cause a third pattern and a fourth pattern to be displayed on the
display unit as the second position, when the bucket is disposed in
the third pattern, the first end part is positioned to the right of
the tilt axis and the second end part is positioned below the
coupling line when viewing the bucket from the vehicle body side,
and when the bucket is disposed in the fourth pattern, the first
end part is positioned to the left of the tilt axis and the second
end part is positioned above the coupling line when viewing the
bucket from the vehicle body side.
4. The work vehicle according to claim 1, wherein the bucket
information computing unit is configured to select one of a first
computing equation corresponding to the first disposition and a
second computing equation corresponding to the second disposition
on the basis of the tilt cylinder disposition data, the bucket
information computing unit is configured to use a selected
computing equation to obtain the tilt angle of the bucket based on
the stroke length.
5. The work vehicle according to claim 2, wherein the display
controller is configured to cause a bucket file which indicates the
tilt cylinder disposition data to be displayed on the display unit,
and the tilt cylinder disposition data creating unit is configured
to obtain the tilt cylinder disposition data on the basis of a
selection result of the bucket file.
6. A method for obtaining a tilt angle, the method comprising: a
step creating tilt cylinder disposition data which indicates
whether a disposition of a tilt cylinder is a first disposition or
a second disposition when viewing a bucket from the vehicle body
side, the bucket disposed in the first disposition being rotated in
the clockwise direction due to extension of the tilt cylinder, the
bucket disposed in the second disposition being rotated in the
clockwise direction due to contraction of the tilt cylinder, the
bucket being disposed at the front of a vehicle body; and a step
obtaining a tilt angle of the bucket based on a stroke length of
the tilt cylinder on the basis of the tilt cylinder disposition
data.
7. The work vehicle according to claim 2, wherein the bucket
information computing unit is configured to select one of a first
computing equation corresponding to the first disposition and a
second computing equation corresponding to the second disposition
on the basis of the tilt cylinder disposition data, the bucket
information computing unit is configured to use a selected
computing equation to obtain the tilt angle of the bucket based on
the stroke length.
8. The work vehicle according to claim 3, wherein the bucket
information computing unit is configured to select one of a first
computing equation corresponding to the first disposition and a
second computing equation corresponding to the second disposition
on the basis of the tilt cylinder disposition data, the bucket
information computing unit is configured to use a selected
computing equation to obtain the tilt angle of the bucket based on
the stroke length.
9. The work vehicle according to claim 3, wherein the display
controller is configured to cause a bucket file which indicates the
tilt cylinder disposition data to be displayed on the display unit,
and the tilt cylinder disposition data creating unit is configured
to obtain the tilt cylinder disposition data on the basis of a
selection result of the bucket file.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National stage application of
International Application No. PCT/JP2015/084472, filed on Dec. 9,
2015.
BACKGROUND
[0002] Field of the Invention
[0003] The present invention relates to a work vehicle and a method
for obtaining a tilt angle.
[0004] Background Information
[0005] A work vehicle provided with a tiltable bucket that is able
to rotate about the center of a tilt axis is known in the prior
art. A tiltable bucket is rotated by a tilt cylinder coupled to the
bucket.
[0006] In order to obtain a tilt angle, which is a rotation angle
of the bucket about the center of a tilt axis, a method for using
an inclination angle sensor for detecting the inclination angle of
the bucket is known (see Japanese Patent Laid-open No.
2014-55407).
SUMMARY
[0007] The inclination angle sensor includes a liquid-type
inclination angle sensor that detects the inclination angle on the
basis of a change in the liquid level in response to movement of
the bucket. It is difficult to obtain the tilt angle data, which
may not be detected accurately depending on the posture of the
bucket corresponding to the motions of the work implement, such as
the boom or the arm, when using the liquid-type inclination angle
sensor.
[0008] Accordingly, a method has been considered to detect the
stroke length of a tilt cylinder and calculate the tilt angle based
on the stroke length using the law of cosines. According to this
method, it is possible to detect the tilt angle with greater
accuracy without relying on the posture of the bucket. However,
because the tilt angle calculation method differs according to
whether the tilt cylinder is disposed so as to rotate the bucket in
the clockwise direction due to extension or whether the tilt
cylinder is disposed so as to rotate the bucket in the clockwise
direction due to contraction when viewing the bucket from the
vehicle body side, the method is complicated and requires the
operator to previously input the disposition of the tilt
cylinder.
[0009] An object of the present invention is to provide a work
vehicle and a method for obtaining a tilt angle in which the tilt
angle can be detected easily in consideration of the above
conditions.
[0010] A work vehicle according to a first aspect is equipped with
a vehicle body, a work implement, a tilt cylinder, a stroke length
detecting unit, a tilt cylinder disposition data creating unit, and
a bucket information computing unit. The work implement has a
bucket that is configured to rotate about a tilt axis. The tilt
cylinder is configured to cause the bucket to rotate about the tilt
axis. The stroke length detecting unit is configured to detect a
stroke length of the tilt cylinder. The tilt cylinder disposition
data creating unit is configured to create tilt cylinder
disposition data which indicates whether a disposition of the tilt
cylinder is a first disposition or a second disposition when
viewing the bucket from the vehicle body side. The bucket disposed
in the first disposition is rotated in the clockwise direction due
to extension. The bucket disposed in the second disposition is
rotated in the clockwise direction due to contraction. The bucket
information computing unit is configured to obtain a tilt angle of
the bucket based on the stroke length on the basis of the tilt
cylinder disposition data.
[0011] According to the work vehicle as in the first aspect, the
tilt angle can be obtained easily by using a suitable method for
calculating the tilt angle according to whether the tilt cylinder
is in the first disposition or the second disposition.
[0012] The work vehicle according to a second aspect is equipped
with a display unit and a display controller. The display
controller is configured to cause a selection screen for selecting
the first disposition or the second disposition to be displayed on
the display unit. The tilt cylinder disposition data creating unit
creates the tilt cylinder disposition data on the basis of the
selection results from the selection screen.
[0013] The work vehicle according to a third aspect is related to
the second aspect, and the display controller is configured to
cause a first pattern and a second pattern to be displayed on the
display unit as the first disposition. When the bucket is disposed
in the first pattern, a first end part of the tilt cylinder coupled
to the bucket is positioned to the left of the tilt axis and a
second end part provided opposite the first end part of the tilt
cylinder is positioned below a coupling line that couples the tilt
axis and the first end part when viewing the bucket from the
vehicle body side. When the bucket is disposed in the second
pattern, the first end part is positioned to the right of the tilt
axis and the second end part is positioned above the coupling line
when viewing the bucket from the vehicle body side. The display
controller is configured to cause a third pattern and a fourth
pattern to be displayed on the display unit as the second position.
When the bucket is disposed in the third pattern, the first end
part is positioned to the right of the tilt axis and the second end
part is positioned below the coupling line when viewing the bucket
from the vehicle body side. When the bucket is disposed in the
fourth pattern, the first end part is positioned to the left of the
tilt axis and the second end part is positioned above the coupling
line when viewing the bucket from the vehicle body side.
[0014] The work vehicle according to a fourth aspect is related to
any one of the first to third aspects, and the bucket information
computing unit is configured to select one of a first computing
equation corresponding to the first disposition and a second
computing equation corresponding to the second disposition on the
basis of the tilt cylinder disposition data. The bucket information
computing unit is configured to use a selected computing equation
to obtain the tilt angle of the bucket based on the stroke
length.
[0015] The work vehicle according to a fifth aspect is related to
the second or third aspect, and the display controller displays is
configured to cause a bucket file which indicates the tilt cylinder
disposition data to be displayed on the display unit. The tilt
cylinder disposition data creating unit is configured to obtain the
tilt cylinder disposition data on the basis of a selection result
of the bucket file.
[0016] A method for obtaining a tilt angle according to a sixth
aspect includes a step creating tilt cylinder disposition data
which indicates whether a disposition of a tilt cylinder is a first
disposition or a second disposition when viewing a bucket from the
vehicle body side, and a step obtaining a tilt angle of the bucket
based on a stroke length of the tilt cylinder on the basis of the
tilt cylinder disposition data. The bucket disposed in the first
disposition is rotated in the clockwise direction due to extension.
The bucket disposed in the second disposition is rotated in the
clockwise direction due to contraction. The bucket is disposed at
the front of a vehicle body.
[0017] According to aspects of the present invention, a work
vehicle and a method for obtaining a tilt angle can be provided in
which the tilt angle can be detected easily.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a perspective view of a hydraulic excavator.
[0019] FIG. 2 is a side cross-sectional view illustrating a
configuration of the vicinity of a tilt cylinder and a bucket.
[0020] FIG. 3 is a front view illustrating a configuration of the
vicinity of the tilt cylinder and the bucket as seen from the
vehicle body side.
[0021] FIG. 4 is a front view illustrating a configuration of the
vicinity of the tilt cylinder and the bucket as seen from the
vehicle body side.
[0022] FIG. 5 is a front view illustrating a configuration of the
vicinity of the tilt cylinder and the bucket as seen from the
vehicle body side.
[0023] FIG. 6 is a front view illustrating a configuration of the
vicinity of the tilt cylinder and the bucket as seen from the
vehicle body side.
[0024] FIG. 7 is a side view schematically illustrating the
hydraulic excavator.
[0025] FIG. 8 is a rear view schematically illustrating the
hydraulic excavator.
[0026] FIG. 9 is a plan view schematically illustrating the
hydraulic excavator.
[0027] FIG. 10 is a side view schematically illustrating the
bucket.
[0028] FIG. 11 is a front view schematically illustrating the
bucket.
[0029] FIG. 12 is a block diagram illustrating a functional
configuration of a control system.
[0030] FIG. 13 is a schematic view for explaining a method for
obtaining the tilt angle in which a bucket is in a reference
position.
[0031] FIG. 14 is a schematic view for explaining a method for
obtaining the tilt angle in which a bucket is in a tilted
position.
[0032] FIG. 15 illustrates selection screens of a first disposition
and a second disposition of the tilt cylinder as seen from the
vehicle body side.
[0033] FIG. 16 is a view illustrating a dimension input screen of a
display unit.
[0034] FIG. 17 is a flow diagram for explaining a method for
obtaining the tilt angle.
[0035] FIG. 18 is a view illustrating another dimension input
screen of the display unit.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
Overall Configuration of a Hydraulic Excavator CM
[0036] A configuration of a hydraulic excavator construction
machinery (CM) as an example of a work vehicle according to an
exemplary embodiment shall be explained in detail with reference to
the drawings. The positional relationships of the configurations
will be explained hereinbelow while referring to a global
coordinate system and a local coordinate system.
[0037] The global coordinate system is based on an origin Pg (see
FIG. 7) positioned in a work area and fixed on the Earth. The
global coordinate system is defined by a XgYgZg Cartesian
coordinate system. The Xg-axis direction is one direction in a
horizontal plane, the Yg-axis direction is a direction orthogonal
to the Xg-axis direction in the horizontal plane, and the Zg-axis
direction is a direction orthogonal to both the Xg-axis direction
and the Yg-axis direction. Therefore, the Xg axis is orthogonal to
the YgZg plane, the Yg axis is orthogonal to the XgZg plane, and
the Zg axis is orthogonal to the XgYg plane. The XgYg plane is
parallel to the horizontal plane and the Zg-axis direction is in
the vertical direction. Further, the respective rotational
directions around the Xg axis, the Yg axis, and the Zg axis are the
.theta.Xg direction, the .theta.Yg direction, and the .theta.Zg
direction.
[0038] The local coordinate system is based on an origin P0 (see
FIG. 7) fixed on a vehicle body 1 of the hydraulic excavator CM.
The origin P0 which is the reference position of the local
coordinate system is positioned on the center of revolution AX of a
revolving superstructure 3. The local coordinate system is defined
by a XYZ Cartesian coordinate system. The X-axis direction is one
direction in a predetermined horizontal plane, the Y-axis direction
is a direction orthogonal to the X-axis direction in the
predetermined horizontal plane, and the Z-axis direction is a
direction orthogonal both the X-axis direction and the Y-axis
direction. The X axis is orthogonal to the YZ plane, the Y axis is
orthogonal to the XZ plane, and the Z axis is orthogonal to the XY
plane. Further, the respective rotational directions around the X
axis, the Y axis, and the Z axis are the .theta.x direction, the
.theta.y direction, and the .theta.z direction.
[0039] FIG. 1 is a perspective view illustrating an overall
configuration of the hydraulic excavator CM. The hydraulic
excavator CM is equipped with the vehicle body 1 and working
equipment 2. The hydraulic excavator CM has mounted thereon a
control system 200 for executing excavation control.
[0040] In the following explanation, "front," "rear," "left" and
"right" are defined by the positional relationships when the
attachment position of the work implement 2 is in the forward
direction as seen from the vehicle body 1. The front-back direction
is the X-axis direction and the left-right direction is the Y-axis
direction. The left-right direction is the same as the width
direction of the vehicle (referred to below as "vehicle width
direction").
[0041] The vehicle body 1 has the revolving superstructure 3, a cab
4, and a travel device 5. The revolving superstructure 3 is
disposed on the travel device 5. The travel device 5 supports the
revolving superstructure 3. The revolving superstructure 3 is able
to rotate about the center of the axis of revolution AX. An
operating seat 4S on which the operator sits is provided inside the
cab 4. The operator operates the hydraulic excavator CM in the cab
4. The travel device 5 has a pair of crawler belts 5Cr. The pair of
crawler belts 5Cr rotate thereby allowing the hydraulic excavator
CM to travel.
[0042] The revolving superstructure 3 has an engine room 9 in which
an engine and a hydraulic pump and the like are housed, and a
counterweight provided in the rear part of the revolving
superstructure 3. A handrail 22 is provided in front of the engine
room 9 on the revolving superstructure 3.
[0043] The work implement 2 is connected to the revolving
superstructure 3. The work implement 2 includes a boom 6, an arm 7,
a bucket 8, a boom cylinder 10, an arm cylinder 11, a bucket
cylinder 12, and a tilt cylinder (bucket tilt cylinder) 30 (FIGS. 2
and 3).
[0044] The boom 6 is connected to the revolving superstructure 3
via a boom pin 13. The arm 7 is connected to the boom 6 via an arm
pin 14. The bucket 8 is connected to the arm 7 via a bucket pin 15
and a tilt pin 80. The boom cylinder 10 drives the boom 6. The arm
cylinder 11 drives the arm 7. The bucket cylinder 12 and the tilt
cylinder 30 drive the bucket 8. The proximal end of the boom 6 is
connected to the revolving superstructure 3. The distal end part of
the boom 6 is connected to the proximal end part of the arm 7. The
distal end part of the arm 7 is connected to the proximal end part
of the bucket 8. The boom cylinder 10, the arm cylinder 11, the
bucket cylinder 12, and the tilt cylinder 30 are all hydraulic
cylinders and are driven by hydraulic fluid.
[0045] The work implement 2 has a first stroke sensor 16, a second
stroke sensor 17, a third stroke sensor 18, and a fourth stroke
sensor 19 (FIG. 3). The first stroke sensor 16 is disposed on the
boom cylinder 10 and detects a stroke length of the boom cylinder
10 (hereinbelow referred to as "boom cylinder length"). The second
stroke sensor 17 is disposed on the arm cylinder 11 and detects a
stroke length of the arm cylinder 11 (hereinbelow referred to as
"arm cylinder length"). The third stroke sensor 18 is disposed on
the bucket cylinder 12 and detects a stroke length of the bucket
cylinder 12 (hereinbelow referred to as "bucket cylinder length").
The fourth stroke sensor 19 is disposed on the tilt cylinder 30 and
detects a stroke length of the tilt cylinder 30 (hereinbelow
referred to as "tilt cylinder length").
[0046] The fourth stroke sensor 19 is an example of a "stroke
length detecting unit" according to the present exemplary
embodiment. The bucket 8, the tilt cylinder 30, and the fourth
stroke sensor 19 configure the "bucket device" according to the
present embodiment.
[0047] The boom 6 is capable of rotating relative to the revolving
superstructure 3 about the center of a boom axis J1 which is a
rotating axis. The arm 7 is capable of rotating relative to the
boom 6 about the center of an arm axis J2 which is a rotating axis
parallel to the boom axis J1. The bucket 8 is capable for rotating
with respect to the arm 7 about the center of a bucket axis J3
which is a rotating axis parallel to the boom axis J1 and the arm
axis J2. The bucket 8 is capable of rotating relative to the arm 7
about the center of a tilt axis J4 which is a rotating axis
orthogonal to the bucket axis J3. The boom pin 13 has the boom axis
J1. The arm pin 14 has the arm axis J2. The bucket pin 15 has the
bucket axis J3. The tilt pin 80 has the tilt axis J4.
[0048] The boom axis J1, the arm axis J2, and the bucket axis J3
are all parallel to the Y axis. The tilt axis J4 is perpendicular
to the Y axis. The boom 6, the arm 7, and the bucket 8 are all
capable of rotating in the .theta.y direction.
Configuration of Bucket 8
[0049] A configuration of the bucket 8 will be explained next. FIG.
2 is a side cross-sectional view illustrating a configuration of
the vicinity of the tilt cylinder 30 and the bucket 8 as seen in
the radial direction perpendicular to the tilt axis J4. FIG. 3 is a
front view illustrating a configuration of the vicinity of the tilt
cylinder 30 and the bucket 8 as seen in an axial direction parallel
to the tilt axis J4.
[0050] The bucket 8 disposed at the reference position is depicted
in FIG. 2. FIG. 3 illustrates the bucket 8 as seen from the vehicle
body 1 side. The bucket 8 disposed in the reference position is
depicted with solid lines, and the bucket 8 tilted as far as left
and right tilt end positions is depicted with dashed lines in FIG.
3. The reference position of the bucket 8 refers to a position of
the bucket 8 while the upper edge or the lower edge of the bucket 8
is parallel to the horizontal plane when the tilt axis J4 is
assumed as being included on the horizontal plane. The tilt angle
of the bucket 8 is "0 degrees" at the reference position of the
bucket 8. The tilt end position signifies the position of the
bucket 8 when the bucket 8 is tilted as far as the greatest tilt
angle.
[0051] The bucket 8 is a tiltable bucket. The work implement 2 has
the bucket 8 which is capable of rotating relative to the arm 7
about the center of the bucket axis J3 and the center of the tilt
axis J4 which is orthogonal to the bucket axis J3. The bucket 8 is
supported by the arm 7 in a rotatable manner about the center of
the bucket axis J3 of the bucket pin 15. The bucket 8 is supported
by the arm 7 in a rotatable manner about the center of the tilt
axis J4 of the tilt pin 80.
[0052] The bucket 8 is connected to the distal end part of the arm
7 via a connecting member 90. The bucket pin 15 couples the arm 7
and the connecting member 90. The tilt pin 80 couples the
connecting member 90 and the bucket 8. The bucket 8 is connected in
a rotatable manner to the arm 7 via the connecting member 90.
[0053] The bucket 8 has a bottom plate 81, a back plate 82, an
upper plate 83, a left side plate 84, and a right side plate 85. An
opening section 86 of the bucket 8 is formed by the bottom plate
81, the upper plate 83, the left side plate 84, and the right side
plate 85.
[0054] The bucket 8 has a bracket 87 provided on an upper part of
the upper plate 83. The bracket 87 couples the connecting member 90
and the tilt pin 80.
[0055] The connecting member 90 has a plate member 91 and brackets
92 and 93. The bracket 92 is provided on the upper surface of the
plate member 91. The bracket 93 is provided on the lower surface of
the plate member 91. The bracket 92 couples the arm 7 and a
below-mentioned second link member 95. The bracket 93 is disposed
on an upper part of the bracket 87 and couples the tilt pin 80 and
the bracket 87.
[0056] The bucket pin 15 couples the bracket 92 of the connecting
member 90 and the distal end part of the arm 7. The tilt pin 80
couples the bracket 93 of the connecting member 90 and the bracket
87 of the bucket 8. As a result, the connecting member 90 and the
bucket 8 are capable of rotating about the center of the bucket
axis J3 relative to the arm 7, and the bucket 8 is capable of
rotating about the center of the tilt axis J4 relative to the
connecting member 90.
[0057] The work implement 2 has a first link member 94 and the
second link member 95. The first link member 94 is connected to the
arm 7 in a rotatable manner via a first link pin 94P. The second
link member 95 is connected to the bracket 92 in a rotatable manner
via a second link pin 95P.
[0058] The proximal end part of the first link member 94 is
connected to the arm 7 via the first link pin 94P. The proximal end
part of the second link member 95 is connected to the bracket 92
via the second link pin 95P. The distal end part of the first link
member 94 and the distal end part of the second link member 95 are
coupled to each other via a bucket cylinder top pin 96.
[0059] The distal end part of the bucket cylinder 12 is connected
to the distal end part of the first link member 94 and the distal
end part of the second link member 95 in a rotatable manner via the
bucket cylinder top pin 96. The connecting member 90 rotates about
the center of the bucket axis J3 with the bucket 8 due to the
extension and contraction of the bucket cylinder 12. The tilt axis
J4 of the tilt pin 80 rotates about the center of the bucket axis
J3 with the bucket 8 due to the rotation of the bucket 8 about the
center of the bucket axis J3.
[0060] The tilt cylinder 30 is coupled to the bucket 8 and the
connecting member 90 as illustrated in FIG. 3. The tilt cylinder 30
causes the bucket 8 to rotate about the center of the tilt axis J4.
A first end part 30A of the tilt cylinder 30 is coupled in a
rotatable manner to a bracket 88 provided on the bucket 8. The
first end part 30A is capable of rotating about the center of a
first cylinder rotating axis J5. The first end part 30A is the
distal end part of the cylinder body of the tilt cylinder 30. The
bracket 88 is disposed in a position away from the tilt axis J4 in
the vehicle width direction. The bracket 88 is disposed at an upper
end part of the bucket 8 in the vehicle width direction. A second
end part 30B of the tilt cylinder 30 is connected in a rotatable
manner to a bracket 97 provided on the connecting member 90. The
second end part 30B is capable of rotating about the center of a
second cylinder rotating axis J6. The bracket 97 is provided on the
lower surface of the plate member 91. The bracket 97 is formed in a
substantially triangular shape as seen in a front view.
[0061] In the present exemplary embodiment, the first end part 30A
of the tilt cylinder 30 is positioned below the tilt axis J4 when
viewing the bucket 8 from the vehicle body 1 side and when the
bucket 8 is disposed in the reference position. The first end part
30A is positioned between the tilt axis J4 and the bucket 8. The
first end part 30A is positioned on the same side as the bucket 8
relative to the horizontal plane (XgYg plane) passing through the
tilt axis J4.
[0062] The first end part 30A of the tilt cylinder 30 is positioned
away from the tilt axis J4 in the vehicle width direction when
viewing the bucket 8 from the side of the vehicle body 1 and when
the bucket 8 is disposed in the reference position. In the present
exemplary embodiment, the first end part 30A is positioned to the
left of the tilt axis J4. The first end part 30A is positioned on
the same side as the left side plate 84 relative to the vertical
plane (Z plane) passing through the tilt axis J4. The first end
part 30A is positioned between the left side plate 84 of the bucket
8 and the tilt axis J4.
[0063] Moreover, the second end part 30B of the tilt cylinder 30 is
spaced away from an axis coupling line W (example of a "coupling
line") that passes through the tilt axis J4 and the first cylinder
rotating axis J5 when viewing the bucket 8 from the vehicle body 1
side and when the bucket 8 is disposed in the reference position.
That is, the second end part 30B is not positioned on the axis
coupling line W. In the present exemplary embodiment, the second
end part 30B is positioned below the axis coupling line W. The
second end part 30B is positioned between the axis coupling line W
and the bucket 8. The second end part 30B is positioned on the same
side as the bucket 8 relative to the axis coupling line W. The
second end part 30B is positioned on the same side as the bucket 8
relative to a horizontal line.
[0064] In this way, the first end part 30A is positioned to the
left of the tilt axis J4 and the second end part 30B is positioned
below the axis coupling line W when viewing the bucket 8 from the
vehicle body 1 side. As a result, the tilt cylinder 30 rotates the
bucket 8 in the clockwise direction due to extension and rotates
the bucket 8 in the anticlockwise direction due to contraction. In
the present exemplary embodiment, the disposition of the tilt
cylinder 30 such that the bucket 8 is rotated in the clockwise
direction due to extension is referred to as a "first disposition
P1." In the present exemplary embodiment, the pattern when the
first end part 30A is positioned to the left of the tilt axis J4
and the second end part 30B is positioned below the axis coupling
line W is referred to as a "first pattern PT1."
[0065] Moreover, the "first disposition P1" of the tilt cylinder 30
includes the first end part 30A being positioned to the right of
the tilt axis J4 and the second end part 30B being positioned above
the axis coupling line W when viewing the bucket 8 from the vehicle
body 1 side as depicted by the tilt cylinder 30a in FIG. 4. In this
case as well, the tilt cylinder 30a is able to rotate the bucket 8
in the clockwise direction due to extension. In the present
exemplary embodiment, the pattern when the first end part 30A is
positioned to the right of the tilt axis J4 and the second end part
30B is positioned above the axis coupling line W is referred to as
a "second pattern PT2."
[0066] Meanwhile in the present exemplary embodiment, the
disposition of the tilt cylinder 30 such that the bucket 8 is
rotated in the clockwise direction due to contraction is referred
to as a "second disposition P2."
[0067] The "second disposition P2" of the tilt cylinder 30 includes
the first end part 30A being positioned to the right of the tilt
axis J4 and the second end part 30B being positioned below the axis
coupling line W when viewing the bucket 8 from the vehicle body 1
side as depicted by the tilt cylinder 30b in FIG. 5. In this case
as well, the tilt cylinder 30b is able to rotate the bucket 8 in
the clockwise direction due to contraction. In the present
exemplary embodiment, the pattern when the first end part 30A is
positioned to the right of the tilt axis J4 and the second end part
30B is positioned below the axis coupling line W is referred to as
a "third pattern PT3."
[0068] The "second disposition P2" of the tilt cylinder 30 includes
the first end part 30A being positioned to the left of the tilt
axis J4 and the second end part 30B being positioned above the axis
coupling line W when viewing the bucket 8 from the vehicle body 1
side as depicted by the tilt cylinder 30c in FIG. 6. In this case,
the tilt cylinder 30c is able to rotate the bucket 8 in the
clockwise direction due to contraction. In the present exemplary
embodiment, the pattern when the first end part 30A is positioned
to the left of the tilt axis J4 and the second end part 30B is
positioned above the axis coupling line W is referred to as a
"fourth pattern PT4."
Posture of the Hydraulic Excavator CM
[0069] FIG. 7 is a side view schematically illustrating the
hydraulic excavator. FIG. 8 is a rear view schematically
illustrating the hydraulic excavator. FIG. 9 is a plan view
schematically illustrating the hydraulic excavator.
[0070] In the following explanation, a boom length L1 is the
distance between the boom axis J1 and the arm axis J2, an arm
length L2 is the distance between the arm axis J2 and the bucket
axis J3, and a bucket length L3 is the distance between the bucket
axis J3 and a distal end part 8a of the bucket 8. The distal end
part 8a of the bucket 8 is the blade tip of the bucket 8.
[0071] The hydraulic excavator CM is provided with a position
detection device 20. The position detection device 20 detects
vehicle body position data P which indicates the current position
of the vehicle body 1, and vehicle body posture data Q which
indicates the posture of the vehicle body 1. The vehicle body
position data P includes information that indicates the current
position (Xg position, Yg position, and Zg position) of the vehicle
body 1 in the global coordinate system. The vehicle body posture
data Q includes position information of the revolving
superstructure 3 pertaining to the .theta.Xg direction, the
.theta.Yg direction, and the .theta.Zg direction.
[0072] The vehicle body posture data Q includes an inclination
angle (roll angle) .theta.1 (FIG. 8) in the left-right direction of
the revolving superstructure 3 relative to the horizontal plane
(XgXy plane), an inclination angle (pitch angle) .theta.2 (FIG. 7)
in the front-back direction of the revolving superstructure 3
relative to the horizontal plane, and an inclination angle (yaw
angle) .theta.3 (FIG. 9) formed by a reference azimuth (e.g.,
north) in the global coordinates and the azimuth in which the
revolving superstructure 3 (work implement 2) is facing.
[0073] The position detection device 20 has an antenna 21, a
position sensor 23, and an inclination sensor 24. The antenna 21 is
an antenna for detecting the current position of the vehicle body
1. The antenna 21 is an antenna for a global navigation satellite
system (GNSS). The antenna 21 outputs a signal corresponding to a
received radio wave (GNSS radio wave) to the position sensor
23.
[0074] The position sensor 23 includes a three-dimensional position
sensor and a global coordinate computing unit. The position sensor
23 detects an installation position Pr of the antenna 21 in the
global coordinate system. The global coordinate computing unit
calculates the vehicle body position data P indicating the current
position of the vehicle body 1, on the basis of the installation
position Pr of the antenna in the global coordinate system. The
global coordinate system is a three-dimensional coordinate system
based on a reference position Pg installed in the work area. As
illustrated in FIG. 7, the reference position Pg is a position at
the distal end of a reference marker set in the work area.
[0075] The inclination sensor 24 is provided on the revolving
superstructure 3. The inclination sensor 24 has an inertial
measurement unit (IMU). The position detection device 20 uses the
inclination sensor 24 to obtain the vehicle body posture data Q
which includes the roll angle .theta.1 and the pitch angle
.theta.2.
[0076] FIG. 10 is a side view schematically illustrating the bucket
8. FIG. 11 is a front view schematically illustrating the bucket
8.
[0077] In the following explanation, a tilt length L4 is the
distance between the bucket axis J3 and the tilt axis J4, and a
width L5 of the bucket 8 is the distance between the left side
plate 84 and the right side plate 85.
[0078] A tilt angle .delta. is a rotation angle of the bucket 8
about the center of the tilt axis and is a rotation angle of the
bucket 8 relative to the XY plane in the local coordinate system. A
method for obtaining the tilt angle .delta. is described below. A
tilt axis angle .epsilon. is an inclination angle of the tilt axis
J4 relative to the XY plane in the local coordinate system. The
inclination angle (tilt axis absolute angle) of the tilt axis J4
relative to the horizontal plane in the global coordinate system is
calculated by a belowmentioned sensor controller 32.
Configuration of Control System 200
[0079] FIG. 12 is a block diagram illustrating the functional
configuration of the control system 200 mounted on the hydraulic
excavator CM.
[0080] The control system 200 is provided with the position
detection device 20, an operating device 25, a work implement
controller 26, a pressure sensor 66, a control valve 27, a
directional control valve 64, a display controller 28, a display
unit 29, an input unit 36, and the sensor controller 32.
[0081] The display unit 29 is a monitor for example. A setting
screen of the bucket 8 and a below-mentioned target design terrain
and the like are displayed on the display unit 29. The display unit
29 includes a human machine interface (HMI) monitor as a guidance
monitor for computer-aided construction.
[0082] The input unit 36 receives an input operation from the
operator. A touch panel on the display unit 29 and the like may be
used as the input unit 36. The input unit 36 reports the contents
of the input operation by the operator to the display controller
28.
[0083] The operating device 25 is disposed in the cab 4. The
operating device 25 is operated by the operator. The operating
device 25 receives operations by the operator for driving the work
implement 2. The operating device 25 is a pilot hydraulic pressure
type of operating device. The operating device 25 has a first
operating lever 25R, a second operating lever 25L, and a third
operating lever 25P.
[0084] The first operating lever 25R is disposed on the right side
of the operator's seat 4S for example. The second operating lever
25L is disposed on the left side of the operator's seat 4S for
example. The third operating lever 25P is disposed on the first
operating lever 25R for example. The third operating lever 25P may
be disposed on the second operating lever 25L. The back and forth,
left and right motions of the first operating lever 25R and the
second operating lever 25L correspond to motions in two axes.
[0085] The boom 6 and the bucket 8 are operated by the first
operating lever 25R. A front-back direction operation of the first
operating lever 25R corresponds to an operation of the boom 6, and
up and down motions of the boom 6 are executed in response to the
front-back direction operations. The left-right direction operation
of the first operating lever 25R corresponds to an operation of the
bucket 8, and excavating and releasing motions of the bucket 8 are
executed in response to the left-right direction operations.
Rotation of the bucket 8 about the center of the bucket axis J3 is
operated by left-right direction operations of the first operating
lever 25R.
[0086] The arm 7 and the revolving superstructure 3 are operated by
the second operating lever 25L. An operation of the second
operating lever 25L in the front-back direction corresponds to an
operation of the arm 7, and releasing and excavating motions of the
arm 7 are executed in response to the front-back direction
operations. An operation of the second operating lever 25L in the
left-right direction corresponds to the turning of the revolving
superstructure 3 and left and right turning motions of the
revolving superstructure 3 are executed in response to the
left-right direction operations.
[0087] The tilt motion of the bucket 8 about the center of the tilt
axis J4 is operated with the third operating lever 25P.
[0088] Pilot hydraulic pressure of a pilot hydraulic pressure line
450 is adjusted in response to the operation amount of the
operating device 25 and as a result the directional control valve
64 is driven. The directional control valve 64 adjusts the amount
of hydraulic fluid supplied to the hydraulic cylinders (the boom
cylinder 10, the arm cylinder 11, the bucket cylinder 12, and the
tilt cylinder 30). A pressure sensor 66 for detecting the pilot
hydraulic pressure is disposed on the pilot hydraulic pressure line
450. The detection result of the pressure sensor 66 is outputted to
the work implement controller 26. The control valve 27 is an
electromagnetic proportional control valve. The control valve 27
adjusts the pilot hydraulic pressure on the basis of a control
signal from the work implement controller 26.
[0089] The sensor controller 32 has a work implement angle
computing unit 281A, a bucket information computing unit 282A, and
a tilt axis angle computing unit 283A.
[0090] The work implement angle computing unit 281A calculates a
rotation angle .alpha. of the boom 6 relative to the vertical
direction of the vehicle body 1 based on the boom cylinder length
obtained on the basis of the detection results from the first
stroke sensor 16. The work implement angle computing unit 281A
calculates a rotation angle .beta. of the arm 7 relative to the
boom 6 based on the arm cylinder length obtained on the basis of
the detection results from the second stroke sensor 17. The work
implement angle computing unit 281A calculates a rotation angle
.alpha. of the bucket 8 relative to the arm 7 based on the bucket
cylinder length obtained on the basis of the detection results from
the third stroke sensor 18.
[0091] The bucket information computing unit 282A calculates the
tilt angle .delta. of the bucket 8 relative to the XY plane in the
local coordinate system based on the tilt cylinder length obtained
on the basis of the detection results from the fourth stroke sensor
19.
[0092] FIGS. 13 and 14 are schematic views for explaining a method
for calculating the tilt angle .delta. carried out by the bucket
information computing unit 282A. The bucket 8 in the reference
position is depicted in FIG. 13 and a tilted bucket 8 is depicted
in FIG. 14.
[0093] The bucket information computing unit 282A obtains a length
M1 of a first line segment "a" linking the first end part 30A of
the tilt cylinder 30 and the tilt axis J4 from the display
controller 28. The length M1 of the first line segment "a" is the
straight line distance between the first cylinder rotating axis J5
and the tilt axis J4.
[0094] The bucket information computing unit 282A obtains a length
M2 of a second line segment "b" linking the second end part 30B of
the tilt cylinder 30 and the tilt axis J4 from the display
controller 28. The length M2 of the second line segment "b" is the
straight line distance between the second cylinder rotating axis J6
and the tilt axis J4.
[0095] The bucket information computing unit 282A obtains a
reference angle .omega.' (see FIG. 13) formed by the first line
segment "a" and the second line segment "b" when the bucket 8 is
disposed at the reference position from the display controller
28.
[0096] The bucket information computing unit 282A stores the length
M1 of the first line segment "a", the length M2 of the second line
segment "b", and the reference angle .omega.'.
[0097] The bucket information computing unit 282A calculates the
tilt cylinder length on the basis of the detection results from the
fourth stroke sensor 19. The bucket information computing unit 282A
uses the law of cosines to calculate a current inclination angle
.omega. (see FIG. 14) in a state of being tilted based on the
length M1 of the first line segment "a", the length M2 of the
second line segment "b", and the tilt cylinder length.
[0098] The bucket information computing unit 282A obtains "tilt
cylinder disposition data" which indicates whether the tilt
cylinder 30 is disposed in the first disposition P1 or the second
disposition P2, from the display controller 28. The first
disposition P1 signifies the dispositions of the tilt cylinder 30
and the tilt cylinder 30a that rotate the bucket 8 in the clockwise
direction due to extension as depicted in FIGS. 3 and 4. The second
disposition P2 signifies the dispositions of the tilt cylinder 30c
and the tilt cylinder 30c that rotate the bucket 8 in the clockwise
direction due to contraction as depicted in FIGS. 5 and 6.
[0099] The bucket information computing unit 282A selects one of a
following first computing equation Eq1 and a second computing
equation Eq2 on the basis of the tilt cylinder disposition
data.
.omega.-.omega.'=clockwise tilt angle .delta. First computing
equation Eq1:
.omega.-.omega.'=anticlockwise tilt angle .delta. Second computing
equation Eq2:
[0100] The first computing equation Eq1 is a computing equation
corresponding to the first disposition P1. The value derived by
subtracting the reference angle .omega.' from the inclination angle
.omega. in the first computing equation Eq1 is calculated as the
clockwise tilt angle. This is because the bucket 8 is rotated in
the clockwise direction due to the extension of the tilt cylinder
30 disposed in the first disposition P1.
[0101] The second computing equation Eq2 is a computing equation
corresponding to the second disposition P2. The value derived by
subtracting the reference angle .omega.' from the inclination angle
.omega. in the second computing equation Eq2 is calculated as the
anticlockwise tilt angle. This is because the bucket 8 is rotated
in the anticlockwise direction due to the extension of the tilt
cylinder 30 disposed in the second disposition P2.
[0102] The bucket information computing unit 282A refers to the
tilt cylinder disposition data and selects the first computing
equation Eq1 when it is detected that the tilt cylinder 30 is
disposed in the first disposition P1. The bucket information
computing unit 282A refers to the tilt cylinder disposition data
and selects the second computing equation Eq2 when it is detected
that the tilt cylinder 30 is disposed in the second disposition P2.
The bucket information computing unit 282A obtains the clockwise or
the anticlockwise tilt angle .delta. on the basis of the
inclination angle .omega. and the reference angle .omega.'. When
the bucket 8 is disposed in the reference position as illustrated
in FIG. 13, the tilt angle is "0 degrees" because the inclination
angle .omega. and the reference angle .omega.' match.
[0103] The bucket information computing unit 282A creates bucket
data R which indicates the shape and position of the bucket 8 in
the plane of motion of the work implement 2 on the basis of the
rotation angles .alpha. to .gamma. calculated by the work implement
angle computing unit 281A, the vehicle body posture data Q obtained
by the inclination sensor 24, and the tilt angle .delta..
[0104] The tilt axis angle computing unit 283A calculates the angle
(tilt axis absolute angle) of the tilt axis J4 relative to the
horizontal plane on the basis of the rotation angles .alpha. to
.gamma. and the vehicle body posture data Q. Specifically, the tilt
axis angle computing unit 283A calculates the angle (tilt axis
angle .epsilon.) of the tilt axis J4 in the local coordinate system
on the basis of the rotation angles .alpha. to .gamma. and
calculates the tilt axis absolute angle in the global coordinate
system on the basis of the tilt axis angle .epsilon. and the
vehicle body posture data Q.
[0105] The sensor controller 32 outputs the rotation angles .alpha.
to .gamma., the tilt axis angle .epsilon., the tilt axis absolute
angle, and the bucket data R to the display controller 28 and the
work implement controller 26.
[0106] The display controller 28 obtains the vehicle body position
data P and the vehicle body posture data Q from the position
detection device 20. The display controller 28 obtains the bucket
data R from the sensor controller 32. The display controller 28 has
a target design terrain obtaining unit 284A, a target design
terrain computing unit 284B, a display controller 284C, and a tilt
cylinder disposition data creating unit 284D.
[0107] The target design terrain obtaining unit 284A stores target
construction information (three-dimensional target design terrain
data S) which indicates a stereoscopic design terrain that is a
three-dimensional target design terrain of the excavation object.
The three-dimensional target design terrain data S includes
coordinate data and angle data of the target design terrain
required for creating target design terrain data T. However, the
three-dimensional target design terrain data S may be inputted to
the display controller 28 via a wireless communication device for
example, or may be inputted to the display controller 28 from an
external memory and the like.
[0108] The target design terrain computing unit 284B creates the
target design terrain data T which indicates the target design
terrain that is a two-dimensional target shape of an excavation
object in the plane of motion of the work implement 2, on the basis
of the vehicle body position data P, the vehicle body posture data
Q, the bucket data R, and the three-dimensional target design
terrain data S. The target design terrain computing unit 284B
outputs the target design terrain data T to the work implement
controller 26.
[0109] The target design terrain computing unit 284B is able to
calculate the position in the local coordinate when seen in the
global coordinate system on the basis of the vehicle body position
data P, the vehicle body posture data Q, and the bucket data R. The
target design terrain computing unit 284B converts the target
design terrain data T outputted to the work implement controller 26
to local coordinates but other computations are carried out in the
global coordinate system.
[0110] The display controller 284C causes the target design terrain
to be displayed on the display unit 29 on the basis of the target
design terrain data T created by the target design terrain
computing unit 284B. Moreover, the display controller 284C causes
the posture of the hydraulic excavator CM relative to the target
design terrain to be displayed on the display unit 29 on the basis
of the bucket data R.
[0111] The display controller 284C causes a selection screen for
selecting whether the tilt cylinder 30 is in the first disposition
P1 or the second disposition P2, on the display unit 29. FIG. 15 is
an example of the selection screen. FIG. 15 illustrates four forms
representing the tilt cylinder 30 (bottom right), a tilt cylinder
30a (upper left), a tilt cylinder 30b (lower left), and a tilt
cylinder 30c (upper right) depicted respectively in FIGS. 3 to 6.
The selection screen in FIG. 15 displays the tilt cylinder 30, the
tilt cylinder 30a, the tilt cylinder 30b, and the tilt cylinder 30c
as seen from the vehicle body 1 side in the same way as in FIGS. 3
to 6. The tilt cylinder 30 and the tilt cylinder 30a are examples
of the tilt cylinder in the first disposition P1, and the tilt
cylinder 30b and the tilt cylinder 30c are examples of the tilt
cylinder in the second disposition P2. The tilt cylinder 30 is an
example of the first pattern PT1, the tilt cylinder 30a is an
example of the second pattern PT2, the tilt cylinder 30b is an
example of the third pattern PT3, and the tilt cylinder 30c is an
example of the fourth pattern PT4.
[0112] As described above, while the computation of the tilt angle
by the bucket information computing unit 282A needs only
information about the tilt cylinder being disposed in the first
disposition P1 or the second disposition P2, due to the four
patterns PT1 to PT4 being displayed on the selection screen as
depicted in FIG. 15, the operator is able to easily select the
disposition that conforms to the actual shape of the tilt
cylinder.
[0113] The display controller 284C inserts a check mark in the
selected tilt cylinder when the input unit 36 receives a selection
operation by the operator. In the present exemplary embodiment, it
is assumed that the tilt cylinder 30 in the first pattern PT1 is
selected and thus the check mark is inserted into the tilt cylinder
30 as depicted in FIG. 15.
[0114] Further, the display controller 284C causes the display unit
29 to display a dimension input screen for the tilt cylinder 30
selected by the operator. FIG. 16 is an example of the dimension
input screen. FIG. 16 illustrates input fields for the length M1 of
the first line segment "a", the length M2 of the second line
segment "b", and the reference angle .omega.'. The display
controller 284C displays the values inputted by the operator in the
input fields.
[0115] The tilt cylinder disposition data creating unit 284D
creates tilt cylinder disposition data which indicates that the
disposition is the first disposition P1 when the selection of the
tilt cylinder of the first disposition P1 by the operator is
reported by the input unit 36.
[0116] The tilt cylinder disposition data creating unit 284D
creates tilt cylinder disposition data which indicates that the
disposition is the second disposition P2 when the selection of the
tilt cylinder of the second disposition P2 by the operator is
reported by the input unit 36.
[0117] In the present exemplary embodiment, the tilt cylinder
disposition data creating unit 284D creates the tilt cylinder
disposition data indicating that the disposition is the first
disposition P1 because it is assumed that the tilt cylinder 30 is
selected. The tilt cylinder disposition data creating unit 284D
transmits the created tilt cylinder disposition data to the bucket
information computing unit 282A of the sensor controller 32.
[0118] Further, the tilt cylinder disposition data creating unit
284D transmits, to the bucket information computing unit 282A, the
length M1 of the first line segment "a", the length M2 of the
second line segment "b", and the reference angle .omega.' inputted
with the input unit 36.
[0119] The work implement controller 26 has a work implement
control unit 26A and a storage unit 26C. The work implement control
unit 26A controls the motions of the work implement 2 by creating
control commands to the control valve 27 on the basis of the target
design terrain data T and the bucket data R obtained from the
display controller 28. The work implement control unit 26A
executes, for example, a limited excavation control for
automatically controlling at least a portion of the motions of the
work implement 2. Specifically, the work implement control unit 26A
determines a limit velocity in response to the distance of the
bucket 8 from the target design terrain, and controls the work
implement 2 so that the velocity in the direction of the work
implement 2 approaching the target design terrain is equal to or
less than the limit velocity. Consequently, the position of the
bucket 8 relative to the target design terrain is controlled and
the bucket 8 is suppressed from intruding into the target design
terrain. The work implement control unit 26A may automatically
control a portion of grading work for moving the bucket 8 along the
target design terrain.
[0120] Various types of programs and data required for the work
implement control unit 26A to control the motions of the work
implement are stored in the storage unit 26C.
Method for Obtaining Tilt Angle .delta.
[0121] A method for obtaining the tilt angle .delta. by the control
system 200 will be explained with reference to the drawings. FIG.
17 is a flow diagram for explaining a method for obtaining the tilt
angle .delta..
[0122] In step S1, the input unit 36 receives an operator operation
for selecting either the tilt cylinder of the first disposition P1
or the tilt cylinder of the second disposition P2.
[0123] In step S2, the input unit 36 reports whether the first
disposition P1 or the second disposition P2 is selected to the tilt
cylinder disposition data creating unit 284D.
[0124] In step S3, the tilt cylinder disposition data creating unit
284D creates the tilt cylinder disposition data indicating that the
disposition of the tilt cylinder 30 is the first disposition P1 or
the second disposition P2, and transmits the tilt cylinder
disposition data to the bucket information computing unit 282A.
[0125] In step S4, the bucket information computing unit 282A
calculates the tilt cylinder length of the tilt cylinder 30 on the
basis of the detection results from the fourth stroke sensor
19.
[0126] In step S5, the bucket information computing unit 282A uses
the law of cosines to calculate the inclination angle .omega. (see
FIG. 14) based on the length M1 of the first line segment "a", the
length M2 of the second line segment "b", and the tilt cylinder
length.
[0127] In step S6, the bucket information computing unit 282A
selects either the first computing equation Eq1 corresponding to
the first disposition P1 or the second computing equation Eq2
corresponding to the second disposition P2 on the basis of the tilt
cylinder disposition data.
[0128] In step S7, the bucket information computing unit 282A uses
the selected computing equation (the first computing equation Eq1
or the second computing equation Eq2) to obtain the tilt angle
.delta. by subtracting the reference angle .omega.' from the
inclination angle .omega..
[0129] The hydraulic excavator CM (example of the work vehicle) is
provided with the tilt cylinder disposition data creating unit 284D
and the bucket information computing unit 282A. The tilt cylinder
disposition data creating unit 284D creates the tilt cylinder
disposition data indicating that the disposition of the tilt
cylinder 30 is in the first disposition P1 in which the bucket 8
rotates in the clockwise direction due to extension or the second
disposition P2 in which the bucket 8 rotates in the clockwise
direction due to contraction when viewing the bucket 8 from the
vehicle body 1 side. The bucket information computing unit 282A
selects either the first computing equation Eq1 corresponding to
the first disposition P1 or the second computing equation Eq2
corresponding to the second disposition P2 on the basis of the tilt
cylinder disposition data, and uses the selected computing equation
to obtain the tilt angle .delta. of the bucket 8 based on the
stroke length.
[0130] In this way, the tilt angle .delta. can be obtained easily
by selecting the suitable computing equation according to whether
the disposition of the tilt cylinder 30 is the first disposition P1
or the second disposition P2.
Other Exemplary Embodiments
[0131] Although an exemplary embodiment of the present invention
has been described so far, the present invention is not limited to
the above exemplary embodiments and various modifications may be
made within the scope of the invention.
[0132] While the display controller 284C causes the selection
screen of the tilt cylinder in the first disposition P1 or the tilt
cylinder in the second disposition P2 to be displayed on the
display unit 29 in the above exemplary embodiment, the present
invention is not limited to this configuration. For example, the
display controller 284C may cause a bucket file which indicates
previously created tilt cylinder disposition data to be displayed
on the display unit 29 as illustrated in FIG. 18. In this case,
when a desired bucket file is selected by the operator via the
input unit 36, the tilt cylinder disposition data creating unit
284D refers to the selected bucket file and retrieves the tilt
cylinder disposition data included in the bucket file. The tilt
cylinder disposition data creating unit 284D then transmits the
retrieved tilt cylinder disposition data to the bucket information
computing unit 282A.
[0133] While the rotation angle .alpha. of the boom 6, the rotation
angle .beta. of the arm 7, and the rotation angle .alpha. of the
bucket 8 are detected by stroke sensors in the above exemplary
embodiment, the rotation angles may be detected by an angle
detecting instrument such as a rotary encoder and the like.
[0134] While the hydraulic excavator CM is provided with the cab 4
in the above exemplary embodiment, the cab 4 may be omitted.
[0135] While an example of the hydraulic excavator CM is used as
the work vehicle, the above exemplary embodiments may also be
applied to another work vehicle such as a bulldozer or a wheel
loader.
[0136] The present invention is useful in the field of work
vehicles because the tilt angle can be obtained easily according to
the present invention.
* * * * *