US 20080028883A1

(19) United States

(12) Patent Application Publication (10) Pub. No.: US 2008/0028883 A1
Inada et al. (43) Pub. Date: Feb. 7, 2008
(54) ROBOT ARM STRUCTURE (30) Foreign Application Priority Data
(75) Inventors: Takahiro Inada, Kakodawa-shi (JP); Jul. 20, 2004 (JP)...................................... 2004-211921
Yuji Maeguchi, Kobe-shi (JP); Isao Jul. 20, 2004 (JP)...................................... 2004-211923
Kato, Nishinomiya-shi (JP); Tadashi Publication Classification
Isomura, Kobe-shi (JP)
Correspondence Address: (51) Int. Cl.
B25, 9/06 (2006.01)
OLIFF & BERRIDGE, PLC B25, 9/16 (2006.01)
P.O. BOX 320850
(52) U.S. Cl. ................... 74/490.05; 318/.568.11:901/28;
ALEXANDRIA, VA 22320-4850 (US) 901/19
(73) Assignee: KAWASAKI UKOGYO (57) ABSTRACT
KABUSHIK KAISHA KOBE-SHI
(JP) A robot arm structure for a carrying robot is capable of
carrying a load in a wide range under restrictions on robot
(21) Appl. No.: 11/632,795 arm motions. A second arm 38 is joined to an upper link 35.
a third arm 39 is joined to the second arm 38, and a fourth
(22) PCT Filed: Jul. 20, 2005 arm 40 is joined to the third arm 39. A holding unit mounted
on the fourth arm 40 can be moved in a wide range through
(86). PCT No.: PCT/UP05/13313 the angular displacement of the second arm 38 to the fourth
arm 40 even in a state where a first arm 36 is maintained at
S 371(c)(1), a predetermined position relative to a bed 33. Thus a load
(2), (4) Date: Mar. 2, 2007 can be moved in a wide range.
Patent Application Publication Feb. 7, 2008 Sheet 1 of 28 US 2008/0028883 A1

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Patent Application Publication Feb. 7, 2008 Sheet 2 of 28 US 2008/0028883 A1
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Patent Application Publication Feb. 7, 2008 Sheet 10 of 28 US 2008/0028883 A1

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Patent Application Publication Feb. 7, 2008 Sheet 16 of 28 US 2008/0028883 A1

START

RECEIVE A LOAD

CARRY THE LOAD

HORIZONTALLY INA
DOWNSTREAM
CARRYING DIRECTION

TRANSFER THE LOAD MOVE THE TABLE a6

TO THE DOWNSTREAM HORIZONTALLY IN THE
CARRYING ROBOT UPSTREAM CARRYING
DIRECTION

DOES THE
CARRYING OPERATION
NEED TO BE
CONTINUED2

a5

FIG. 22
Patent Application Publication Feb. 7, 2008 Sheet 17 of 28 US 2008/0028883 A1

(2)

(3)

(4)

(6)

(7)
Patent Application Publication Feb. 7, 2008 Sheet 18 of 28 US 2008/0028883 A1
Patent Application Publication Feb. 7, 2008 Sheet 19 of 28 US 2008/0028883 A1

START bO

MAINTAIN THE RESPECTIVE POSITIONS

OF THE FIRST AND SECOND ARMS AND-b1
DISPLACE THE THIRD AND FOURTH
ARMS COORONATELY

DISPLACE THE FIRST TO FOURTH b2

ARMS COORDINATELY

STOP AND HOLD THE TABLE AT b3

A MACHINING STATION

DISPLACE THE FIRST TO FOURTH b4

ARMS COORDINATELY

MANTAIN THE RESPECTIVE POSITIONS

OF THE FIRSTAND'SECONDARMS AND-b5
DISPLACE THE THIRD AND FOURTH
ARMS COORDNATELY

END b6

FIG. 25.
Patent Application Publication Feb. 7, 2008 Sheet 20 of 28 US 2008/0028883 A1

FIG. 26
Patent Application Publication Feb. 7, 2008 Sheet 21 of 28 US 2008/0028883 A1
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Patent Application Publication Feb. 7, 2008 Sheet 26 of 28 US 2008/0028883 A1

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Patent Application Publication Feb. 7, 2008 Sheet 27 of 28 US 2008/0028883 A1
Patent Application Publication Feb. 7, 2008 Sheet 28 of 28 US 2008/0028883 A1
20A
US 2008/0028883 A1 Feb. 7, 2008

ROBOT ARM STRUCTURE on expanding a carrying region in which the load 21 can be
carried. More concretely, there is a possibility that the upper
CROSS REFERENCE TO RELATED links 3 and 8 collide with the second lower link 7, the first
APPLICATIONS arm 4 and the first auxiliary link 5 interfere with each other
and the second arm 9 and the second auxiliary link 10
0001. This application is based upon and claims the interfere with each other.
benefit of priority from the prior Japanese Patent Application
Nos. 2004-211921 and 2004-211923, the entire contents of 0009. The carrying robot 20 drives the joints of a quadric
which are incorporated herein by reference. crank mechanism to carry the load 21. Therefore, the car
rying robot 20 has a large carrying capacity for carrying the
TECHNICAL FIELD load 21 of a large mass. However, the quadric crank mecha
nism is a complicated mechanism and the carrying robot 20
0002 The present invention relates to an arm structure including the quadric crank mechanism is inevitably large.
for an articulated robot and, more particularly, to an arm 0010 FIGS. 36 and 37 show a carrying robot 20A
structure for a carrying robot capable of carrying a load obtained by omitting the second parallel linkage 11 of the
along a predetermined carrying route.
known carrying robot 20. FIG. 36 shows a state after the
BACKGROUND ART load 21 has been carried to a position at the longest distance
from the first lower link 2 by the carrying robot 20A. FIG.
0003. A carrying robot is installed in a production plant 37 shows a state after the load 21 has been carried to a
for producing automobiles and Such to carry a vehicle body, position above the first lower link 2, namely, a state in a
namely, a load. The body carried to a predetermined position reference position.
is processed by a processing robot. A plurality of known 0011. The carrying robot 20A does not has any mecha
carrying robots are arranged on a carrying route. The car nism corresponding to the second linkage 11 of the carrying
rying robot on the upstream side in the upstream direction robot 20. Therefore, second arm 9 and the third arm 17 can
X2 with respect to a carrying direction carries a body and be extended straight. Thus the carrying robot 20A can carry
transfers the same to the carrying robot on the downstream the load 21 further downstream with respect to the carrying
side in the downstream carrying direction X1. Thus the body direction than the carrying robot 20.
is transferred from one to another of the successively
arranged carrying robots to carry the body along the carrying 0012 FIG. 38 is a view of assistance in explaining the
route (refer to, for example, JP 2003-231075A). movement of the load 21 in a state where the respective
0004 FIG. 33 is a front elevation of a known carrying positions of the first arm 4 and the second arm 9 are fixed.
robot 20. The carrying robot 20 drives the joints of parallel In some cases, the first arm 4 and the second arm 9 of the
carrying robot 20A are held at predetermined angles 01 and
linkages 6 and 11 to carry a load 21. The carrying robot 20 02 to a vertical, respectively, for purposes including that of
is designed to hold the load 21 at a processing station while avoiding the interference of the carrying robot 20A with
the load 21 is being processed. other carrying robots. When the first arm 4 and the second
0005 The known carrying robot 20 has the two parallel arm 9 are held at the predetermined angles 01 and 02 to a
linkages 6 and 11. The first parallel linkage 6 has a first vertical, respectively, as shown in FIG. 38, the third arm 17
lower link 2, a first upper link 3, a first arm 4 and a first can move in a narrow range and hence it is difficult to carry
auxiliary link 5. The first arm 4 and the first auxiliary link 5 the load 21 to a desired position.
link together the first lower link 2 and the first upper link 3.
DISCLOSURE OF THE INVENTION
0006 The second linkage 11 has a second lower link 7,
a second upper link 8 fixed to the first upper link 3, a second 0013. Accordingly, it is an object of the present invention
arm 9 and a second auxiliary link 10. The second arm 9 and to provide a carrying arm structure for a carrying robot
the second auxiliary link 10 link together the second lower capable of carrying a load in a wide range even in a state
link 7 and the second upper link 8. A third arm 17 is joined where movements of the arm are limited.
to the second lower link 7 so as to turn for angular displace 0014) Another object of the present invention is to pro
ment on the third arm 17. A holding device for holding the vide a small robot having a large carrying capacity.
load 21 is attached to the free end of the third arm 17.
0007. The carrying robot 20 includes a first driving unit 0015 To achieve the object, a robot arm structure in a
for turning the first arm 4 relative to the first lower link 2. first aspect of the present invention includes: a bed installed
a second driving unit for turning the second arm 9 relative on a predetermined reference plane; a lower link disposed on
to the second upper link 8, and a third driving unit for the bed; an upper link disposed above the lower link; a first
turning the third arm 17 relative to the second lower link 7. arm joining the lower link and the upper link so as to be
capable of being displaced relative to the upper link and the
0008 FIGS. 34 and 35 are schematic front elevations of lower link; an auxiliary link joining the lower link and the
the known carrying robot 20. FIG. 34 shows a state where upper link so as to be capable of being displaced relative to
the carrying robot 20 has carried the load 21 to a position at the upper link and the lower link; a second arm having a first
the longest distance from the first lower link 2. FIG. 35 end and a second end, the first end being joined to the upper
shows a state where the carrying robot 20 has carried the link, the second arm being capable of being displaced
load 21 to a position above the first lower link 2 and is in a relative to the upper link; a third arm having a first end and
reference position. The carrying robot 20 needs to turn the a second end, the second end of the third arm being joined
arms of the two parallel linkages 6 and 11 so that the arms to the second end of the second arm, the third arm being
may not interfere with each other, which places a restriction capable of being displaced relative to the second arm; and a
US 2008/0028883 A1 Feb. 7, 2008

fourth arm having a first end and a second end, the first end 0024 Preferably, the arm position maintaining means
of the fourth arm being joined to the second end of the third comes into contact with the arm with the second end of the
arm, the fourth arm being capable of being displaced relative arm distanced horizontally from the base to apply a part of
to the third arm, the fourth arm being equipped with holding force necessary for counterbalancing gravitational force
means for holding a load to be carried; acting on the arm.
0016 wherein the lower link, the upper link, the first arm, 0025. According to the present invention, when the arm
and the auxiliary link form a quadric crank mechanism, and position maintaining means applies force to the arm, the arm
the first end of the fourth arm is below the first end of the driving means capable of exerting of a low driving force can
third arm when the first to fourth arms are respectively maintain the arm in a position.
vertically extended so as to set the robot arm in a reference 0026 Preferably, the arm position maintaining means
position. includes a contact member with which the arm comes into
0017 Preferably, in the state that the robot arm is set in contact, a holding member for holding the contact member
the reference position, the first to the fourth arms are So as to be displaced in predetermined opposite first and
distanced vertically from the reference plane respectively by second displacing directions, and a reactive force producing
distances not shorter than a limit height He at which the member for exerting a reactive force proportional to a
robot arm is at the nearest possible distance from the displacement with which the contact member is displaced in
reference plane. the displacing direction by the arm.
0018 Preferably, the second arm has a length Y2 not 0027 According to the present invention, the contact
member is displaced in the first displacing direction by force
greater than a value equal to (H-Hc), where H is the vertical exerted thereon by the arm when the arm comes into contact
distance of the first end of the second arm from the reference with the contact member. The contact member exerts a
plane when the robot arm is set in a specific position in reactive force corresponding to a displacement from a
which the first arm is inclined at a predetermined angle to the natural state thereof in the first displacing direction, i.e., a
lower link, and He is the limit height He. reactive force acting in the second displacing direction, on
0019 Preferably, the length Y2 of the second arm is not the arm. The force exerted by the contact member on the arm
shorter than a value equal to (He--Y3-H), where Hc is the increases with the increase of the displacement of the
limit height, Y3 is the length of the third arm and H is the contact member in the displacing direction. The driving
vertical distance of the first end of the second arm from the force of the arm driving means and the reactive force exerted
reference plane when the robot arm is set in the specific by the contact member act on the arm in the second
position. displacing direction, while the gravitational force acts in the
first displacing direction. Thus the forces balance out each
0020 Preferably, the robot arm structure further includes other to maintain the arm in the position.
an arm position maintaining means for exerting a force
necessary for maintaining a position of the secondarm to the 0028. The contact member is movable in the displacing
second arm. directions and the force acting on the arm changes with the
change of the displacement in the displacing directions.
0021. A robot in a second aspect of the present invention Accordingly, the forces acting on the arm can balance out
to achieve the object includes: a base; an arm having a first each other even if the weight of the load changes and hence
end and a second end, the first end being joined to the base, the flexibility of the robot can be improved. Since the
the arm being capable of being displaced relative to the base; contact member can be displaced in the displacing direc
arm driving means for driving the arm to displace the arm tions, an allowable range in which the arm can come into
relative to the base; and arm position maintaining means for contact with the contact member is wide and hence a
exerting a part of a force necessary for maintaining the arm position where the arm comes into contact with the contact
in a position to the arm by coming into contact with the arm member does not need to be accurately taught to the robot.
in a state where the second end of the arm is distanced from
the base in a predetermined direction. 0029 Preferably, the robot includes: a bed; a lower link
disposed on the bed; an upper link disposed above the lower
0022. According to the present invention, the arm can be link, the upper link forming the base to which the first end
moved along a predetermined route by displacing the arm by of the arm is joined; a first arm joining the lower link and the
the arm driving means. The second end of the arm distanced upper link so as to be capable of being displaced relative to
in a predetermined direction from the base is in contact with the upper link and the lower link; an auxiliary link joining
the arm position maintaining means. Exertion of force on the the lower link and the upper link so as to be capable of being
arm by the arm position maintaining means reduces driving displaced relative to the upper link and the lower link; a
force necessary for maintaining the arm in a position by the second arm having a first end and a second end so as to form
driving means. The rigidity of the arm may be low and the the arm, the first end of the second arm being joined to the
construction of the arm does not need to be as complicated upper link, the second arm being capable of being displaced
as that of the known arm. relative to the upper link; first arm driving means for driving
the first arm to displace the first arm relative to the lower
0023 The arm driving means exerts driving force con link; and second arm driving means for driving the second
tinuously on the arm even in a state where the arm position arm to displace the second arm relative to the upper link:
maintaining means exerts force on the arm. Thus a control wherein the arm position maintaining means comes in
method of controlling the arm driving means does not need contact with the second arm in a state where the second end
to be changed before and after the contact of the arm with of the second arm is distanced horizontally from the upper
the arm position maintaining means. link.
US 2008/0028883 A1 Feb. 7, 2008

0030. According to the present invention, the upper link, 0037 Preferably, a force exerted by the arm position
the lower link, the first arm and the auxiliary link form a maintaining means on the arm is lower than the maximum
quadric crank mechanism, namely, a hybrid linkage. Thus driving force of the arm driving means.
the first arm driving means may have a low driving force as 0038 According to the present invention, a downward
compared with that of a robot not employing a quadric crank force acting on the arm decreases upon the transfer of the
mechanism and employing a direct-acting mechanism, load from the robot to another robot. Then, if the arm
namely, a robot employing a serial linkage. When the second position maintaining means is still exerting a force on the
end of the second arm is distanced horizontally from the arm, the force exerted by the arm position maintaining
upper link by displacing the second arm relative to the upper means on the arm exceeds the force exerted by the arm on
link, the arm position maintaining means exerts force to the arm position maintaining means. According to the
extend the second arm upward. Thus the secondarm driving present invention, the force exerted by the arm position
means may be a driving means having a low driving force. maintaining means on the arm is lower than the maximum
0031) Preferably, the robot further includes a third arm driving force of the arm driving means. Therefore, even if
connected to the second arm and capable of being displaced the force exerted by the arm position maintaining means on
relative to the second arm, a fourth arm connected to the the arm exceeds the force exerted by the arm on the arm
third arm and capable of being displaced relative to the third position maintaining means, the arm can be restrained from
being displaced upward. The robot can exercise the same
arm, third arm driving means for driving the third arm to effect even if the force is exerted on the arm in a direction
displace the third arm relative to the second arm, and fourth other than a vertical direction.
arm driving means for driving the fourth arm to displace the
fourth arm relative to the third arm; wherein the third and the 0039 Preferably, the arm position maintaining means is
fourth arms can be displaced in a state where the second arm capable of adjusting the force exerted on the arm.
is in contact with the arm position maintaining means. 0040 According to the present invention, the robot can
0032. According to the present invention, the free end of flexibly deal with the change of the weight of the load to be
the fourth arm can be horizontally distanced from the base carried by adjusting the force exerted on the arm by the arm
by coordinately displacing the third and the fourth arms in position maintaining means. Thus the robot has improved
a state where the second arm is in contact with the arm flexibility.
position maintaining means. The first arm is a component of 0041) Preferably, the outer surface of at least either of the
the quadric crank mechanism. Therefore, the first and the contact part of the arm position maintaining means with
second driving means are required to produce low driving which the arm comes into contact and a contact part of the
forces, respectively, even in a state where the free end of the arm that comes into contact with the position maintaining
fourth arm is horizontally distanced from the base. The free means is a curved Surface.
end of the fourth arm can be optionally moved to a position
horizontally distanced from the second arm. 0042. According to the present invention, the arm and the
arm position maintaining means can be brought into point
0033 Preferably, the robot further includes a position contact or line contact with each other. In some cases, the
adjusting member movably disposed on the fourth arm, the arm comes into contact with the arm position maintaining
position adjusting member being equipped with holding means after moving in a direction oblique to a direction in
means for holding a load to be carried; and position adjust which the force exerted by the arm position maintaining
ing member driving means for driving the position adjusting means acts, and the arm slides on the arm position main
member to displace the position adjusting member relative taining means to the predetermined contact position. Since
to the fourth arm. the arm and the arm position maintaining means are in point
contact or line contact with each other, the arm can Smoothly
0034. According to the present invention, the load can be slide to the contact position after the arm has come into
held in a fixed position by displacing the position adjusting contact with the arm position maintaining means. Thus the
member by the position adjusting member driving means abrasion of the contact parts of the arm and the arm position
even if the fourth arm is displaced. Thus the load can be held maintaining means can be reduced.
in the fixed position while the load is being carried.
0043 Preferably, the arm position maintaining means
0035) Preferably, the arm position maintaining means is includes a contact member with which the arm comes into
joined to the bed. contact, a holding member for holding the contact member
0036). According to the present invention, special align So as to be displaceable in predetermined directions, and a
ment operation for aligning the arm position maintaining reactive force producing member for producing a reactive
means and the arm, which is necessary when the arm force proportional to a displacement by which the contact
position maintaining means is distanced from the bed, is member is displaced in a displacing direction, and the
unnecessary because the arm position maintaining means is contact member is held via a sliding bearing on the holding
member.
connected to the bed. A contact position where the arm
comes into contact with the arm position maintaining means 0044 According to the present invention, the sliding
can be determined beforehand and hence the contact posi bearing ensures the Smooth movement of the contact mem
tion does not need to be determined at the installation site of ber in the displacing direction even if a force acts on the
the robot. The arm is light as compared with an arm contact member in a direction intersecting the displacing
combined with arm position maintaining means because the direction. In some cases, the arm comes into contact with the
arm position maintaining means is distanced from the arm arm position maintaining means after moving in a direction
and hence the load on the arm driving means can be reduced. oblique to a direction in which the force exerted by the arm
US 2008/0028883 A1 Feb. 7, 2008

position maintaining means acts, and the arm slides on the predetermined position in a predetermined position relative
arm position maintaining means to the predetermined con to the bed. Consequently, the load can be moved in a wide
tact position. In Such a case, the contact member can range.
Smoothly move in the displacing direction. Consequently, 0054 When a plurality of robots are installed in an
the contact member can be displaced in the displacing narrow space, the second to fourth arms of the robot, in some
direction regardless of the direction in which the arm cases, interfere with other robots unless the first arm is held
advances toward the arm position maintaining means. in a predetermined angular position. The load can be moved
0045 Preferably, the contact member has a damping in a desired posture to a desired position even in Such a case
property with respect to a movement. by displacing the second to fourth arms. For example, the
0046 According to the present invention, the movement load can be carried to a desired position by displacing the
third and fourth arms even in a state where the second arm
damping property of the contact member can prevent the is held in a position by the arm position maintaining means.
sudden displacement of the contact member. Thus the vibra In this case, power necessary for maintaining the respective
tion of the contact member can be suppressed when the force positions of the first and second arms can be reduced by
acting on the contact member changes due to the collision of Supporting the second arm by the arm position maintaining
the contact member and the arm and due to the separation of CaS.
the arm from the contact member.
0047 Preferably, the robot is a carrying robot capable of 0055 According to the present invention, it is possible to
holding a load and of carrying the load in horizontal direc avoid the respective heights of the arms being not higher
tions. than the limit height He in a state where the arms are
extended vertically in the reference position. Thus the car
0.048. The robot according to the present invention is a rying robot can hold the load in the reference position. The
carrying robot. The carrying robot holds the load by the arm arms extend vertically when the arms are maintained in the
and carries the load from an upstream position to a down reference position, and hence power needed by the driving
stream position along a carrying route. The robot according means to maintain the position can be reduced. When the
to the present invention can move the arm to a position reference position is a standby position in which the robot is
horizontally apart from the base. Such as the bed, and can kept in readiness, standby power consumed by the driving
horizontally carry the load in a low position. means during the standby time can be reduced.
0049. To achieve the object, an arm position assisting 0056 According to the present invention, the second arm
structure in a third aspect of the present invention intended has a length Y2 not greater than a value equal to (H-Hc),
to realize the arm position maintaining means employed in where H is the vertical distance of the first end of the second
any one of the foregoing robots. arm from the reference plane when the robot arm structure
0050. According to the present invention, the robot is is set in the specific position in which the first arm is inclined
provided with the arm position assisting structure realizing at a predetermined angle to the lower link, and He is the limit
the arm position maintaining means. Thus the robot can be height He. Thus the reduction of the height of the second
realized by using the arm driving means having a low arm below the limit height He can be prevented even in a
driving force and the arm having a low rigidity, and hence state where the first arm is set in a position to set the robot
the robot arm structure is simplified and the robot can be arm structure in the specific position. Thus the second arm
formed in a small size. can be turned through an optional angle relative to the first
arm in a state where the first arm is set in a position to set
0051. The arm driving means exerts a driving force on the robot arm structure in the specific position. For example,
the arm even in a state where a force is exerted on the arm. in a state where the second and third arms are displaced to
Therefore, the control of the arm is not complicated. For maintain the fourth arm in an optional position, the fourth
example, when the contact member of the arm position arm can be moved in the carrying direction without reducing
assisting structure with which the arm comes into contact is the respective heights of the arms to the limit height. Thus
displaceable, part of the force for maintaining the position of the load held on the fourth arm can be carried without
the arm can be applied to the arm even if the force acting on changing the position thereof.
the arm varies and even if the position of the arm is not 0057 According to the present invention, the robot arm
accurately taught.
structure is designed such that the length Y2 of the second
0.052 In the robot arm structure in the first aspect of the arm is not shorter than a value equal to (HC+Y3-H), where
present invention for the carrying robot, the lower link, the Hc is the limit height, Y3 is the length of the third arm and
upper link, the first arm and the auxiliary link form the H is the vertical distance of the first end of the second arm
quadric crank mechanism. Therefore, the first arm can be from the reference plane when the robot arm structure is set
driven for displacement by driving means having a low in the specific position. Thus the reduction of the respective
power even when the load is placed at a position distanced heights of the second and third arms below the limit height
from the bed. Thus the load can be surely carried to a remote Hc can be prevented even in a state where the first arm is set
position. to set the robot arm structure in the specific position. The
0053. The second arm is connected to the upper link, the fourth arm can be moved in the carrying direction with the
third arm is connected to the second arm and the fourth arm fourth arm Surely maintained in an optional position.
is connected to the third arm. Therefore, the holding means 0058 According to the present invention, the position of
mounted on the fourth arm can be moved in a wide range by the second arm can be maintained, even if the load is heavy,
making the second to fourth arms move for angular dis by the arm position maintaining means for maintaining the
placement even in a state where the first arm is held at a position of the second arm and power to be produced by the
US 2008/0028883 A1 Feb. 7, 2008

driving means for driving the first and second arms can be Small space because the load can be moved in a low position.
reduced. Since the robot arm structure has the second, third If the load is to be machined by another machining robot
and fourth arms, the load can be displaced even in a state while the load is being moved, the height of the machining
where the position of the second arm is maintained by the robot may be low and the machining robot does not need to
arm position maintaining means. be built in a large size.
0059. The robot in the second aspect of the present 0066. According to the present invention, when the
invention employs the driving means having a low driving fourth arm is displaced due to the displacement of the
force as arm driving means and can maintain the position of position adjusting member, the load can be held in a fixed
the arm having low rigidity; that is, the arm driving means position. Thus the load can be moved with the load held in
is small and hence the robot is small. The construction of the the fixed position. Thus the operability can be improved
arm does not need as complicated as that of the known arm. when the robot is used for carrying and machining.
Complicated control of the arm driving means is unneces 0067. According to the present invention, aligning opera
sary. Consequently, the robot having a large carrying capac tion for aligning the arm position maintaining means and the
ity can be built in simple, Small construction. bed, which is necessary when the arm position maintaining
0060 According to the present invention, the position of means and the bed are separate, is not necessary because the
the arm can be maintained by the arm driving means having arm position maintaining means is connected to the bed.
a low driving force even when a high gravitational force acts Thus the arm contact position where the arm comes into
on the arm. When the robot of the present invention is, for contact with the arm position maintaining means is set
example, a carrying robot, the position of the load can be beforehand and hence the contact position does not need to
maintained at a position horizontally distanced from the bed be determined at the installation site of the robot. The arm
even if the load is heavy. When the robot of the present is light as compared with an arm combined with arm
invention is, for example, a machining robot, the position of position maintaining means because the arm position main
the robot can be maintained at an optional position even if taining means is distanced from the arm and hence the load
a machining unit is large. on the arm driving means can be reduced.
0061 According to the present invention, the contact 0068 According to the present invention, the force
member can be displaced in displacing directions, such as exerted on the arm by the arm position maintaining means
vertical directions. Therefore, the position of the arm can be is lower than the driving force of the arm driving means.
maintained when the robot is required to carry loads respec Therefore, the position of the arm can be maintained even if
tively having different weights and the robot has improved a force acting in a displacing direction, Such as a downward
flexibility. The arm can be brought into contact with the arm direction, changes. Therefore, the vibration of the arm can
even if the contact position where the arm is expected to be suppressed and the efficiency of operations by the robot
come into contact with the contact member is not accurately for carrying and machining can be improved.
taught. Therefore, teaching work for teaching the robot a 0069. According to the present invention, the robot can
moving path along which the arm is to be moved can be deal with change in the weight of the load through the
simplified. The reactive force producing means is, for adjustment of the force exerted on the arm by the arm
example, a coil spring. position maintaining means, which improves the flexibility
0062 According to the present invention, the robot has of the robot.
the quadric crank mechanism and the arm position main 0070 According to the present invention, the outer sur
taining means. Therefore, the driving means having a low face of at least either of the arm position maintaining means
driving force can be used as the first and second arm driving and the arm is a curved surface. Therefore, the arm can make
means. The driving means can be built in Small sizes, the arm position maintaining means slide Smoothly to the
respectively, and hence the robot can be built in a small size. predetermined contact position. Thus the arm can be accu
The free end of the second arm can be horizontally distanced rately moved to the contact position and the arm position
from the bed and hence the horizontal moving range is wide. maintaining means can Surely exert force on the arm.
0063. According to the present invention, the force is 0071 According to the present invention, the action of a
exerted on the second arm by the arm position maintaining jerking force on the contact member is Suppressed by the
means and the robot has the quadric crank mechanism. sliding bearing even if the arm is brought into contact with
Therefore, the first and second arm driving means may be the contact member by moving the arm from a position apart
driving means respectively having low driving forces even
in a state where the free end of the fourth arm is horizontally from the contact member in a direction intersecting the
distanced from the base. The first and second arms may be displacing direction of the contact member, and the contact
low-rigidity arms. member can be Smoothly displaced in the displacing direc
tion. Thus the arm position maintaining means can Surely
0064. The fourth arm can be horizontally moved with the exert force on the arm. Preferably, sliding bearings are
free end thereof held low relative to the bed by coordinately placed on the opposite sides, respectively, of the holding
moving the third and fourth arms in a state where force is member with respect to a contact member displacing direc
exerted on the second arm by the arm position maintaining tion to move the contact member more smoothly when force
means. Preferably, the third arm is connected to a free end is exerted on the contact member in a direction intersecting
of the second arm to move the free end of the fourth arm the displacing direction.
farther in the horizontal direction.
0072 According to the present invention, the contact
0065. When the load is held, for example, on the free end member is prevented from Sudden displacement because the
of the fourth arm for carrying, the load can be carried in a contact member has a movement damping property. The
US 2008/0028883 A1 Feb. 7, 2008

vibration of the contact member can be prevented. Thus the in positions, respectively, and a third arm 39 and a fourth
arm is prevented from coming into contact with the vibrating arm 40 are displaced coordinately:
contact member, and the arm or the contact member is
prevented from being damaged. The arm can be prevented 0.086 FIG. 11 is a sectional view of the second arm 38
from being shocked by the sudden displacement of the and a contact member 62 included in the arm position
contact member. The arm can be prevented from vibrating maintaining means 60 and in contact with the second arm
upon the transfer of a load held by arm to another robot in 38:
a state where force is exerted on the arm by the arm position 0087 FIG. 12 is a sectional view of assistance in explain
maintaining means. ing a state where a second end 38b of the second arm 38 is
0073. The robot according to the present invention is a obliquely approaching the arm position maintaining means
carrying robot that holds a load and carries the same from an 60;
upstream position to a downstream position with respect to 0088 FIG. 13 is a sectional view of assistance in explain
a carrying direction. Since the arm of the robot can be moved ing a state where a second end 38b of a second arm 38 is
to a position horizontally distanced from the bed, the load obliquely approaching an arm position maintaining means
can be carried in a low position in horizontal directions. 60 in a first comparative example:
Thus the load can be carried in a small space. If the load is
to be machined by another machining robot while the load 0089 FIG. 14 is a sectional view of assistance in explain
is being moved, the height of the machining robot may be ing a state where a second end 38b of a second arm 38 is
low. obliquely approaching an arm position maintaining means
60 in a second comparative example:
0074 The robot provided with the arm position assisting
structure in the third aspect of the present invention can be 0090 FIG. 15 is an enlarged view of a second arm before
built in a small size. The arm driving means having a low coming into contact with an arm position maintaining
driving force is inexpensive. means,
0075. The arm position maintaining means exerts an 0091 FIG. 16 is an enlarged view of the second arm
auxiliary force for maintaining the position of the arm to the before coming into contact with the arm position maintain
arm in a state where the arm driving means exerts driving ing means in the second comparative example:
force on the arm. Therefore, the arm driving means does not 0092 FIG. 17 is a front elevation of the carrying robot 30
need to be controlled by a complicated control operation. in a reference position;
When the arm position maintaining means is displaceable in
displacing directions, such as vertical directions, the arm can 0093 FIG. 18 is a side elevation of the carrying robot 30
be brought into contact with the arm position maintaining in a reference position;
means even if the force acting on the arm changes and even
if the position of the arm is not taught accurately. 0094 FIG. 19 is a plan view of a table 50:
BRIEF DESCRIPTION OF THE DRAWINGS
0.095 FIG. 20 is a front elevation of two carrying robots
30A and 30B in a state where a load 31 is being transferred
0.076 FIG. 1 is a schematic front elevation of a carrying from one of the carrying robots 30a and 30B to the other;
robot 30 in a first embodiment according to the present 0096 FIG. 21 is a plan view of the two carrying robots
invention; 30A and 30B during load transfer operation;
0077 FIG. 2 is a front elevation of the carrying robot 30 0097 FIG. 22 is a flow chart of a carrying procedure to
set in a reference position; be carried out by the carrying robot 30 to carry the load;
0078 FIG. 3 is a view of the carrying robot 30 in a 0098 FIG. 23 is a diagrammatic view of assistance in
working position; explaining a load receiving operation for receiving the load
0079 FIG. 4 is a view showing positional changes of a 31 and a load transfer operation for transferring the load 31
fourth arm in a state where a second arm 38 is supported by of the carrying robot;
an arm position maintaining means 60:
0099 FIG. 24 is a front elevation of assistance in explain
0080 FIG. 5 is a front elevation of the carrying robot 30: ing some of operations of the carrying robot 30;
0081 FIG. 6 is a front elevation of the carrying robot 30 0100 FIG. 25 is a flow chart of a control procedure to be
in a carrying operation for carrying a load 31; carried out by control means 55 in step a2 of the carrying
0082 FIG. 7 is a front elevation of the carrying robot 30 procedure shown in FIG. 22;
of assistance in explaining an arm structure included in the 0101 FIG. 26 is a front elevation of assistance in explain
carrying robot 30: ing some of operations of the carrying robot 30;
0.083 FIG. 8 is a sectional view of the arm position 0102 FIG. 27 is a view of assistance in explaining
maintaining means 60: operations of a carrying robot 300 in a second embodiment
0084 FIG. 9 is a schematic plan view of the carrying according to the present invention;
robot 30 of assistance in explaining force to be exerted on a 0.103 FIG. 28 is a view of assistance in comparatively
second arm 38: explaining maximum load carrying ranges when a second
0085 FIG. 10 is a front elevation of the carrying robot 30 arm 38 is long and when the second arm 38 is short,
in a state where a first arm 36 and the secondarm 38 are held respectively;
US 2008/0028883 A1 Feb. 7, 2008

0104 FIG. 29 is a view showing a state where the second plurality of arms 36 and 38 to 40 to displace the same. The
arm 38 is moved toward a bed when the second arm 38 is arms and the links 34 to 40 are a lower link34, an upper link
excessively short; 35, a first arm 36, an auxiliary link 37, a second arm 38, a
0105 FIG.30 is a view showing the relation between the third arm 39 and a fourth arm 40. The arm driving means 42
second arm 38 and a third arm 39: to 45 are first arm driving means 42 for driving the first arm
36 for displacement, second arm driving means 43 for
0106 FIG. 31 is a view of assistance in explaining the driving the second arm 38 for displacement, third arm
operation of the carrying robot 300 in the second embodi driving means 44 for driving the third arm 39 for displace
ment, ment, and fourth arm driving means 45 for driving the fourth
0107 FIG. 32 is a view comparatively showing positions arm 40 for displacement.
near bases that can be reached by the carrying robots 30 and 0118. The second arm 38 has a first end 38a and a second
300 embodying the present invention and a known carrying end 38b joined to the upper link 35 and the a first end 39a
robot 20A: of the third arm 39, respectively. The third arm 39 has a
second end 39b connected to a first end 4.0a of the fourth arm
0108 FIG. 33 is a front elevation of a known carrying 40. The adjacent ones of the second arm 38 to the fourth arm
robot 20: 40 are joined together so as to be turnable relative to each
0109 FIG. 34 is a front elevation of the known carrying other for angular displacement.
robot 20, in which a load 21 is distanced the longest possible 0119) The carrying robot 30 is provided with a position
distance apart from a lower link 2; adjusting member 41, and a position adjusting member
0110 FIG. 35 is a front elevation of the known carrying driving means 46 (FIG. 5) for driving the position adjusting
robot 20, in which the load 21 is supported above the lower member 41 to hold the load 31 in a desired position. The
link 2; position adjusting member 41 is joined to the second end
40b of the fourth arm 40. A table 50, namely, a holding
0111 FIG. 36 is a front elevation of the carrying robot means for holding the load 31, is attached to the position
20A, in which a load 21 is distanced the longest possible adjusting member 41.
distance apart from the lower link 2 in a carrying direction; 0120 FIG. 2 is a front elevation of the carrying robot 30
0112 FIG. 37 is a front elevation of the carrying robot set in a reference position. When the carrying robot 30 is set
20A, in which a load 21 is held above the lower link 2; and in the reference position, the arms 36 to 40 extend vertically
and the first end 4.0a of the fourth arm 40 is below the first
0113 FIG. 38 is a view of assistance in explaining the end 39a of the third arm 39. The arms 37 to 40 are formed
movement of the load 21 in a state where the respective So as to be respectively at heights not lower than a limit
positions of a first arm 4 and a second arm 9 are fixed. height He, namely, a lower limit height from the floor
BEST MODE FOR CARRYING OUT THE Surface, namely, the reference plane, when the carrying
INVENTION robot 30 is set in the reference position. The first end 38a of
the second arm 38 is at a predetermined reference height H0
0114 Carrying robots in preferred embodiments accord from the floor surface. Each arm is set at a height not lower
ing to the present invention will be described with reference than the reference height He, namely, a lower limit height
to FIGS 1 to 30. from the reference surface when the carrying robot 30 is set
in the reference position. A value (Y2+Y3), namely, the sum
0115 FIG. 1 is a schematic front elevation of a carrying of the respective lengths Y2 and Y3 of the second arm 38
robot 30 in a first embodiment according to the present and the third arm 39 is not greater than a value (H0-Hc),
invention. A plurality of carrying robots 30 like that shown namely, a value obtained by subtracting the limit height He
in FIG. 1 are arranged to move a load 31 along a predeter from the distance H0 between the first end 38a of the second
mined carrying route. The carrying robot 30 receives the arm 38 and the floor surface. The limit height He is depen
load 31 from the carrying robot 30 on the upstream side in dent on the respective shapes of the links, and dimensions of
the upstream direction X2 with respect to a carrying direc motors and reduction gears.
tion and transfers the load 31 to the carrying robot 30 on the
downstream side in the downstream carrying direction X1. 0121 FIG. 3 is view showing the change of the position
Thus the load 31 is carried along the carrying route. The load of the carrying robot30. As shown in FIG. 3(1), the carrying
31 is a heavy object, such as a body of an automobile. While robot 30 includes an arm position maintaining means 60 for
the carrying robots 30 carry the load 31 successively, exerting a part of force necessary for maintaining the posi
machining robots installed at machining stations machine tion of the second arm 38 on the second arm 38. As shown
the load 31. in FIG. 3(2), the arm position maintaining means 60 Sup
ports the joint of the second end 38b of the second arm 38
0116 Each of the carrying robots 30 includes a bed 33 and the first end 39a of the third arm when the first arm 36
fixedly installed at the site, arms supported on the bed 33 so is maintained at a predetermined first angle 01 and the
as to be turned for angular displacement, and arm driving second arm 38 is maintained at a predetermined second
means for turning the arms for angular displacement. The angle 02. The first angle 01 is the inclination of the axis of
arm driving means of the carrying robot 30 move the arms the first arm 36 to an imaginary vertical line. The second
to move the load 31 connected to the arm along the carrying angle 02 is the inclination of the axis of the second arm 38
rOute. to an imaginary vertical line. The arm position maintaining
0117 More specifically, the carrying robot 30 includes means 60 is realized by an elastic member.
the bed 33, the plurality of arms and links 34 to 40, and arm 0.122 FIG. 4 shows the change of the position of the
driving means 42 to 45 (FIG. 5) for individually driving the fourth arm 40 in a state where the second arm 38 is
US 2008/0028883 A1 Feb. 7, 2008

Supported by the arm position maintaining means 60. As 35. The first arm 36 can turn through angular displacement
shown in FIGS. 4(1) to 4(4), the load can be moved through about a first axis J1 on the lower link 34 and about a second
the angular displacement of the third arm 39 and the fourth axis J2 on the upper link 35.
arm 40 with the position of the second arm 38 maintained by 0129. The first axis J1 is horizontal and parallel to
the arm position maintaining means 60. transverse directions Y perpendicular to the carrying direc
0123. In this embodiment, the lower link 34, the upper tions X. The first axis 31 passes the joint of the lower link
link 35, the first arm 36 and the auxiliary link 37 form a 34 and the first arm 36. The second axis J2 is parallel to the
quadric crank mechanism. Therefore, Adriving means hav first axis J1 and passes the joint of the upper link 35 and the
ing a small power can drive the first arm 36 for displacement first arm 36. First arm driving means 43 drives the first arm
even if the load 31 is placed apart from the bed 33. Thus the 36 for angular displacement about the first axis J1.
load can be more Surely carried to a distant position. 0.130. The auxiliary link 37 connects a second end 34b on
0.124. The second arm 38 is joined to the first arm 36, the the side of the other carrying direction of the lower link 34
third arm 39 is joined to the second arm 38, and the fourth and a second end 35b on the side of the other carrying
arm 40 is joined to the third arm 39. Thus holding means direction of the upper link 35. The auxiliary link 37 has a
mounted on the fourth arm 40 can be moved in a wide range first end 37 joined to the second end 34b of the lower link
through the angular displacement of the second arm 38, the 34 and a second end 37b joined to the second end 35b of the
third arm 39 and the fourth arm 40 even in a state where the upper link35. The auxiliary link 37 can be turned for angular
first arm 36 is maintained in a predetermined position displacement about a third axis J3 on the lower link 34. The
relative to the bed 33. Thus the load held by the holding auxiliary link 37 can be turned for angular displacement
means can be moved in a wide range. about a fourth axis J4 on the upper link 35.
0125 When a plurality of robots are installed in an 0131) The third axis 33 is parallel to the first axis J1 and
narrow space and the carrying robot 30 interferes with other passes the joint of the lower link34 and the auxiliary link37.
robots unless the first arm 36 is maintained at a predeter The fourth axis J4 is parallel to the first axis J1 and passes
mined angle, this embodiment can move the load in a the joint of the upper link 35 and the auxiliary link 37.
desired position to a desired place by displacing the second 0132) The second arm 38 to the fourth arm 40 are
arm 38, the third arm 39 and the fourth arm 40. The load can connected Successively to form a direct-acting linkage,
be moved to a desired position by displacing the third arm namely, a serial linkage. More concretely, a first end 38a of
39 and the fourth arm 40 even when the second arm 38 is
Supported and maintained in a position by the arm position the second arm 38 is joined to a middle part 35c with respect
maintaining means 60. Power needed by a driving means for to the carrying directions of the upper link 35. The second
arm 38 can be turned for angular displacement about a fifth
driving the first arm 36 and the second arm 38 can be axis J5 on the upper link 35. The fifth axis J5 is parallel to
reduced by supporting the second arm 38 by the arm position the first axis J1 and passes the joint of the upper link 35 and
maintaining means 60. the second arm 38. The second arm driving means 43 drives
0126 FIG. 5 is a front elevation of the carrying robot 30 the second arm 38 for angular displacement about the fifth
and FIG. 6 is a front elevation of the carrying robot 30 in a axis 35.
carrying operation for carrying the load 31. The bed 33 is 0133) The third arm 39 has a first end 39a joined to the
fixed to the floor 32 of a carrying site in a production plant second end 38b of the second arm 38. The third arm 39 can
or the like. The lower link 34 is integrated into the bed 33. be turned for angular displacement about a sixth axis J6 on
The upper link 35 is spaced in an upward direction Z1 from the second arm 38. The sixth axis 36 is parallel to the first
the lower link 34. The lower link 34 and the upper link 35 axis 31 and passes the joint of the second arm 38 and the
are parallel to each other. In this embodiment, the lower link third arm 39. The third arm driving means 44 drives the third
34 and the upper link 35 are horizontal. The first arm 36 and arm 39 for angular displacement about the sixth axis J6.
the auxiliary link 37 connect the lower link 34 and the upper
link35. The upper link 35 connected to the lower link34 by 0.134. The fourth arm 40 has a first end 4.0a joined to the
the first arm 36 and the auxiliary link 37 can be displaced second end 39b of the second arm 39. The fourth arm 40 can
through angles relative to the lower link 34. be turned for angular displacement about a seventh axis 37
0127. In the carrying robot 30, the lower link 34, the on the third arm 39. The seventh axis 37 is parallel to the first
upper link35, the first arm 35 and the auxiliary link 37 form axis J1 and passes the joint of the third arm 39 and the fourth
a quadric crank mechanism, namely, a hybrid linkage. The arm 40. The fourth arm driving means 45 drives the fourth
upper link 35 maintained parallel to the lower link 34 can arm 40 for angular displacement about the seventh axis 37.
move in carrying directions X relative to the bed 33. The 0.135 The position adjusting member 41 is joined to the
load 31 is carried in the carrying direction X. In this second end of the fourth arm 40. The position adjusting
embodiment, the carrying directions X are horizontal direc member 41 can be turned about an eighth axis J8 on the
tions. fourth arm 40. The eighth axis J8 is parallel to the first axis
J1 and passes the joint of the fourth arm 40 and the position
0128. The first arm 36 connects a first end 34a on the side adjusting member 41. The position adjusting member driv
of one of the carrying directions of the lower link 34 and a ing means 46 drives the position adjusting member 41 for
first end 35a on one of the carrying directions of the upper angular displacement about the eighth axis J8.
link 35. The first arm 36 has a first end 36a joined to a first
end 35a on the side of one of the carrying directions of the 0.136 The holding means is mounted on the position
lower link34, and a second end 36b joined to a first end 35a adjusting member 41. Desirably, the holding means is
on the side of one of the carrying directions of the upper link capable of detachably holding the load 31. In this embodi
US 2008/0028883 A1 Feb. 7, 2008

ment, the holding means is a table 50. The load 31 is 0142 FIG. 7 is a front elevation of the carrying robot 30
supported on the table 50. The table 50 may be provided showing the arrangement of the arms of the carrying robot
with a holding mechanism for detachably holding the load 30. A first distance L1 between the first axis J1 and the third
31. The position of the position adjusting member 41 about axis J3 and a second distance L2 between the second axis 32
the carrying directions X, the transverse directions Yand the and the fourth axis J4 are equal. A third distance L3 between
vertical directions Z is manually adjustable. Thus the posi the first axis J1 and the second axis J2 and a fourth distance
tion of the table 50 can be minutely adjusted and the load 31 L4 between the third axis J3 and the fourth axis J4 are equal.
supported on the table 50 can be stably carried. Thus the lower link34, the upper link35, the first arm 36 and
0137) The table 50 held at a desired height can be the auxiliary link 37 form a shape substantially resembling
horizontally moved by individually driving the first arm 36, a parallelogram
the second arm 38, the third arm 39 and the fourth arm 40 0.143 A fifth distance L5 between the second axis J2 and
for displacement. In this embodiment, the table 50 held in a the fifth axis J5 and a sixth distance L6 between the fourth
desired position at a desired height can be horizontally axis L4 and the fifth axis J5 are approximately equal. A
moved by coordinately individually driving the first arm 36, seventh distance L7 between the fifth axis J5 and the six axis
the second arm 38, the third arm 39, the fourth arm 40 and J6 and an eighth distance L8 between the sixth axis J6 and
the position adjusting member 41. the seventh axis J7 are approximately equal. The sum of the
0.138. The carrying robot 30 includes control means 55. seventh distance L7 and the eighth distance L8 is approxi
The control means 55 controls the first arm driving means mately equal to a ninth distance L9 between the seventh axis
42, the second arm driving means 43, the third arm driving J7 and the eighth axis 38. The ninth distance L9 and the third
means 44, the fourth arm driving means 45 and the position distance L3 are approximately equal. The adjacent links and
adjusting member driving means 46. The driving means 42 the arms are pivotally joined. The arms are pivotally joined.
to 46 are, for example, servomotors, and the control means 0144). As shown in FIG. 7, the second end 38b of the
55 is, for example, a robot controller. The robot controller second arm 38 horizontally spaced apart from the fifth axis
adjusts currents Supplied to the servomotors. The control J5 comes into contact with the arm position maintaining
means 55 calculates currents to be supplied to the servomo means 60 (61) from above the arm position maintaining
tors, and Supplies the calculated currents to the servomotors means 60 (61). The arm position maintaining means 60 (61)
to carry the load 31 along a predetermined carrying route. exerts a part of force necessary for maintaining the position
0.139. The control means 55 is provided with a storage of the second arm 38 on the second arm 38. In this
unit for storing predetermined programs, an arithmetic unit embodiment, the arm position maintaining means 60 (61)
for carrying out the programs stored in the storage unit, an exerts an upward force on the second end 38b of the second
output unit for sending out drive signals determined by the arm 2 in a state where the load 31 is held on the table 50.
arithmetic operations performed by the arithmetic unit to the 0145 As mentioned above, the arm position maintaining
driving means 42 to 46, and an input unit for receiving means 60 and 61 are fixedly disposed on the side in the
instructions provided by the operator and angular displace downstream carrying direction X1 and on the side of the
ment data provided by the driving means. The storage unit upstream carrying direction X2, respectively, with respect to
is a memory. The arithmetic unit is an arithmetic circuit, the bed 33. Since the arm position maintaining means 60 and
such as a CPU.
61 are the same in construction, only the arm position
0140. The control means 55 controls the arm driving maintaining means 60 on the downstream side in the down
means 42 to 45 for coordinated operations to move the table stream carrying direction X1 with respect to the bed 33 will
50 horizontally. The position adjusting member driving be described and the description of the arm position main
means 46 is operated coordinately to move the table 50 taining means 61 will be omitted.
horizontally with the load 31 held in a fixed position.
0141. The carrying robot 30 is provided with arm posi 0146 FIG. 8 is a sectional view of the arm position
tion maintaining means 60 and 61 to maintain the position maintaining means 60. The arm position maintaining means
of the second arm 38. The arm position maintaining means 60 exerts a part of force necessary for maintaining the
60 and 61 come into contact with the second end 38b of the position of the second arm 38 on the second arm 38. The
second arm 38 and exerts a part of force necessary for second arm 38 can be maintained in a desired position
maintaining the position of the second arm 38 on the second against gravitational force by forces exerted thereon by the
arm 38. The arm position maintaining means 60 and 61 are second arm driving means 43 and the arm position main
on the side in the downstream carrying direction X1 and on taining means 60.
the side in the upstream carrying direction X2, respectively, 0147 The arm position maintaining means 60 is provided
with respect to the bed 33. The second end 38b of the second with a contact member 62, a holding member 63 and a
arm 38 comes into contact with the arm position maintaining reactive force producing member 64. The contact member
means 60 on the side in the downstream carrying direction 62 can be moved in predetermined displacing directions,
X1 when the second end 38b of the second arm 38 is moved namely, vertical directions Z in the embodiment. The second
in the downstream carrying direction X1 and receives an arm 38 comes into contact with the contact member 62. The
upward force from the arm position maintaining means 60. holding member 63 holds the contact member 62 so as to be
The second end 38b of the second arm 38 comes into contact movable in vertical directions Z. The reactive force produc
with the arm position maintaining means 61 on the side of ing member 64 exerts a reactive force corresponding to a
the upstream carrying direction X2 when the second arm displacement of the contact member 62 from a natural state
38b of the second arm 38 is moved in the upstream carrying thereof in the vertical direction Z on the contact member 62.
direction X2 and receives an upward force from the arm More concretely, when the second end 38b of the second
position maintaining means 61. arm 38 comes into contact with the contact member 62 and
US 2008/0028883 A1 Feb. 7, 2008

displaces the contact member 62 in the vertically downward 72 have axes aligned with the reference axis 100. The outer
direction Z2, the reactive force producing member 64 exerts tube 70 is cylindrical. The inner tube 71 is disposed inside
a force corresponding to the displacement of the contact the outer tube 70. The bottom wall 69 is joined to the lower
member 62 through the contact member 62 on the second ends of the outer tube 70 and the inner tube 71. The bottom
arm 38. wall 69 is continuous with the inside surface of the outer
tube 70 and the outside Surface of the inner tube 71. The
0148. The arm position maintaining means 60 has a bottom wall 69 has an annular shape. The inner tube 71 has
predetermined reference axis 100 parallel to directions in an axial size shorter than that of the outer tube 70.
which the contact member 62 is displaced. The contact
member 62, the holding member 63 and the reactive force 0154) The flange 72 projects radially outward from the
producing member 64 are coaxial and are aligned with the upper end of the outer tube 70. The inside surface of the
reference axis 100. In the following description, a direction outer tube 70 faces the circumference of the flange 66 of the
in which the contact member 62 exerts a reactive force on contact member 62. The inside diameter of the outer tube 70
the second arm 38 is called an upward direction 101 and a and the diameter of the flange 66 are approximately equal to
direction in which the second arm 38 exerts force on the each other. In this embodiment, a sealing member 99 is
contact member 62 is called a downward direction 102. attached to the flange 66 to seal a gap between the outer tube
014.9 The holding member 63 is formed in a cylindrical 70 and the flange 66. The inside surface of the inner tube 71
faces the surface of the lower stem 68 of the contact member
shape having an axis aligned with the reference axis 100. A 62. The inside diameter of the inner tube 71 and the diameter
part of the contact member 62 projects from the holding of the lower stem 68 are approximately equal to each other.
member 63 and the other part of the same extends in a space The lower stem 68 extends in a space surrounded by the
in the holding member 63. The contact member 63 has a inner tube 71.
flange 66, an upper stem 67 projecting from the holding
member 63, a lower stem 68 and a contact head 81. The 0.155) A cover 80 is fastened to the flange 72. The cover
flange 66, the upper stem 67, the lower stem 68 and the 80 is a ring having an axis aligned with the reference axis
contact head 81 are aligned with the reference axis 100 when 100. The cover 80 covers the upper open end of the outer
the contact member 62 is held by the holding member 63. tube 70. The cover 80 is provided with an opening through
0150. The flange 66 is a circular plate having a circum which the upper stem 67 extends. The diameter of the
ference contiguous with the inner circumference 65 of the opening of the cover 80 is approximately equal to the
holding member 63. The upper stem 67 extends in the diameter of the upper stem 67 and smaller than the respec
upward direction 101 from the flange 66. The upper stem 67 tive diameters of the flange 66 and the contact head 81. The
is cylindrical and has a diameter smaller than that of the cover 80 is fastened to the flange 72 and the upper stem 67
flange 66. When the flange 66 is placed in the holding is passed through the opening of the cover 80. Thus the
member 63, the upper stem 67 projects from the holding contact member 62 is restrained from separating from the
member 63. The lower stem 68 extends in the downward holding member 63. The holding member 63 and the cover
direction 102 from the flange 66. The lower stem 68 is 80 are detachably fastened together with screws 83 or bolts.
cylindrical and has a diameter Smaller than that of the flange The upper stem 67 of the contact member 62 is extended
66. through the opening of the cover 80 and the lower stem 68
of the contact member 62 is inserted into the inner tube 71.
0151. The contact head 81 is on the upper end of the The contact member 62 is movable in the vertical directions
upper stem 67. The second arm 38 comes into contact with Z.
the contact head 81. The contact head 81 is formed in a
circular plate of a diameter greater than that of the upper 0156 The reactive force producing member 64 is, for
stem 67. The contact head 81 has an upward convex, curved example, a compression coil spring 64. The compression
position maintaining contact surface 85. The second arm 38 coil spring 64 is contained in the outer tube 70 and has an
comes into contact with the position maintaining contact axis aligned with the reference axis 100. The compression
surface 85. The position maintaining contact surface 85 has coil spring 64 has a lower end 64b seated on the bottom wall
a top point 85a on the reference axis 100. The position 69 and an upper end 64a pressed against the flange 66. The
maintaining contact surface 85 is a curved surface or a compression coil spring Surrounds the lower stem 68
spherical Surface. entirely. The compression coil spring 64 is compressed in
the holding member 63. Thus the compressed compression
0152. A contact part 81a forming the position maintain coil spring 64 exerts an upward force in the upward direction
ing contact Surface 85 is made of a synthetic resin having a 101 on the flange 66. The flange 66 pushed by the com
shock absorbing property and exerting a low frictional pression coil spring 64 comes into contact with the cover 80
resistance on the second arm 38, Such as nylon 6. Thus to restrain the contact member 62 from separating from the
shocks of the impact of the second arm 38 on the contact holding member 63.
head 81 can be absorbed. Further more, the second arm 38 0157. In a natural state, the flange 66 is pressed against
can Smoothly slide on the position maintaining contact
surface 85. The contact part 81a is fastened to the other part the cover 80 by the compression coil spring 64 and the
of the contact head 81 with bolts and is detachable. The worn contact member exerts force on the cover 80 in the upward
direction Z1. When the second arm 38 comes into contact
out contact part 81a can be replaced with a new contact part with the contact member 62 and exerts a downward force on
81a.
the contact member 62, the contact member 62 is displaced
0153. The holding member 63 has an outer tube 70, a downward against the resilience of the compression coil
bottom wall 69, an inner tube 71 and a flange 72. The outer spring 64. When the contact member 62 is thus displaced
tube 70, the bottom wall 69, the inner tube 71 and the flange downward, the contact member 62 exerts an upward force
US 2008/0028883 A1 Feb. 7, 2008

equal to the product of a displacement X in the downward 6-nylon. The upper shock absorbing members 88 are
direction 102 and the spring constant k of the compression arranged at equal angular intervals about the reference axis
coil spring 64 on the second arm 38. 100. The flange 66 collides against the upper shock absorb
0158. In this embodiment, the force to be exerted by the ing members 88 when the downward force exerted on the
contact member 62 on the second arm 38 is changeable. For contact member 62 by the second arm 38 is removed. The
example, a spacer, namely, a space adjusting member, may shock absorbing members 88 can attenuate noise and shocks
be interposed between the flange 72 and the cover 80. The resulting from the collision of the flange 66 against the shock
spacer increases the axial distance between the holding absorbing members 88.
member 63 and the cover 80 in a natural state and thus the 0.163 A plurality of lower shock absorbing members 89
pressure exerted by the compression coil spring 64 on the are attached to parts facing the contact head 81 of the contact
contact member 62 can be adjusted. The force exerted on the member 62 of the cover 80. The lower shock absorbing
second arm 38 by the contact member 62 may be adjusted members 89 are made of a synthetic resin, such as 6-nylon
by a method that adjusts the position of the bottom wall 69 and are arranged at equal angular intervals about the refer
relative to the cover 80. For example, it is possible to cope ence axis 100. It is possible that the contact head 81 collides
with the change of the load 31 by changing the force exerted against the cover 80 when a downward force is exerted on
by the compression coil spring 64 on the contact member 62 the contact member 62. In this embodiment, the contact head
according to the weight of the load 31, which improves the 81 collides against the lower shock absorbing members 89.
flexibility of the carrying robot. The lower shock absorbing members 89 can absorb noise
0159. A support means 82 for supporting the arm position and shocks resulting from the collision.
maintaining means 60 is connected to the bed 33. The arm 0.164 Preferably, the contact member 62 has a damping
position maintaining means 60 is detachably fastened to the ability. The damping ability can prevent the Sudden displace
support means 82 with screws 84 or bolts. The arm position ment of the contact member 62 in the displacing direction
maintaining means 60 fastened to the Support means 82 is when force is exerted on the contact member 62. Thus
held at a predetermined position at a distance in the carrying vibrations can be suppressed when the contact member 62
direction X from the bed 33. Therefore, the positional collides against the holding member 63. Since the interior
relation between the arm position maintaining means 60 and space of the holding member 63 is sealed by the sealing
the robot does not need to be adjusted at the operating site members 87 and 73, it is preferable to form a through hole
where the carrying robot is used and hence teaching work 75 in the flange 66 so that an upper space extending over the
can be curtailed. flange 66 and a lower space extending under the flange 66
can communicate with each other by means of the through
0160 Abearing 86 and a sealing member 87 are disposed hole 75. When the through hole 75 is formed in a proper size,
between the cover 80 and the upper stem 67. More con the flow of air between the upper space extending over the
cretely, the sliding bearing 86 and the sealing member 87 are flange 66 and the lower space extending under the flange 66
fitted in the opening of the cover 80 such that the sealing through the through hole 75 can be properly restricted. Thus
member 87 is disposed above the sliding bearing 86. A a damping function can be exercised by a simple mecha
bearing 74 and a sealing member 73 are disposed between nism. The damping function prevents the Sudden movement
the inner tube 71 and the lower stem 68. More concretely, of the contact member 62. Other mechanism having a
the sliding bearing 74 and the sealing member 73 are fitted damping function may be used. The damping function can
in the inner tube 71 such that the sealing member 73 is suppress the vibration of the contact member 62 when the
disposed below the sliding bearing 74. The sliding bearings force exerted on the contact member 62 changes.
86 and 74 employed in this embodiment contain a lubricant
and can bear heavy load. The sliding bearings 86 and 74 do 0.165. When the load 31 is heavy, a compression coil
not need lubrication. The sealing members 87 and 73 spring having a large spring constant k is used as the reactive
prevent the entry of dust in the holding member 63. The force producing member 64 to bear the heavy weight of the
sealing members 87 and 73 are, for example, oil seals. The load 31. In this embodiment, impact applied to the cover 80
interior space of the holding member 63 is sealed by the by the flange 66 of the contact member 62 on the cover 80
sealing members 87 and 73. can be damped by the damping function of the contact
member 62 even if the second arm 38 is distanced for a short
0161 Thus the contact member 62 is supported in the two time from the contact member 62. The lower shock absorb
sliding bearings 86 and 74 arranged in the direction of ing members 89 can further reduces the impact.
displacement of the contact member 62 on the holding 0166 FIG. 9 is a schematic plan view of the carrying
member 63. The sliding bearings 86 and 74 ensure the robot 30 of assistance in explaining force to be exerted on
smooth displacement of the contact member 62 even if the the second arm 38. When the table 50 holding the load 31 is
second arm 38 comes into contact with contact member 62
from an oblique direction 120 inclined to the reference axis moved to a position horizontally spaced from the fifth axis
100. Thus the exertion of a resistive force against the 35, the gravity produces a first torque M1 acting on the
displacement of the contact member in the displacing direc second arm 38 about the fifth axis J5. The first torque M1
exercises an effort to move the second end 38b of the second
tion by the holding member 63 can be suppressed. There arm 38 downward. Suppose that the arms are light as
fore, an upward force can be Surely exerted on the second compared with the load 31. Then, the first torque M1 is equal
arm 38 even if the second arm 38 comes into contact with
the contact member 62 from the oblique direction 120. to FXL10, where F is the weight of the load 31 and L10 is
the horizontal distance between the fifth axis J5 and the
0162 Upper shock absorbing members 88 are attached to eighth axis J8. Thus the first torque M1 increases with the
parts facing the flange 66 of the cover 80. The upper shock increase of the distance between the table 50 and the fifth
absorbing members 88 are made of a synthetic resin, such as axis J5 and with the increase of the weight of the load 31.
US 2008/0028883 A1 Feb. 7, 2008

0167. When the second arm 38 comes into contact with 0.172. The contact head 81 of the arm position maintain
the contact member 62 of the arm position maintaining ing means 60 of this embodiment is movable in the vertical
means 60 and displaces the contact member 62 downward, directions Z. Therefore, the arm position maintaining means
the arm position maintaining means 60 applies a second 60 can apply a force for maintaining the position of the
torque M2 to the second arm 38. The second torque M2 second arm 38 to the second arm even if a taught contact
exercises an effort to move the second end 38b of the second point where the second arm 38 is expected to come into
arm 38 upward. The second torque M2=-kx-L11, where k contact with the contact head 81 is slightly off in the vertical
is the spring constant of the compression coil spring 64, X is direction Z. Thus the allowable range for a position where
a deflection from an axial length of the compression coil the second arm 38 comes into contact with the arm position
spring 64 in an natural state where any force is not acting on maintaining means 60 is wide and a teaching operation for
the compression coil spring 64 caused by the second arm 38, teaching the second arm 38 is simple.
and L11 is the horizontal distance between the fifth axis J5
and a point in contact with the contact member 62 on the 0173 The second arm driving means 43 applies a driving
second arm 38. The direction of action of the second torque force continuously to the second arm 38 while a force is
M2 is opposite that of the first torque M1. applied to the second arm 38 by the arm position maintain
ing means 60. Therefore, a control method of controlling the
0168 Since the arm position maintaining means 60 second arm driving means 43 does not need to be greatly
applies the second torque M2 to the second arm 38, the changed before and after the second arm 38 comes into
second arm driving means 43 can maintain the position of contact with the arm position maintaining means 60 and the
the second arm 38 by only a force necessary to produce a first arm driving means 42 and the secondarm driving means
third torque M3=M1-M2. If the carrying robot 30 is not 43 can be easily controlled.
provided with the arm position maintaining means 60, the
second arm driving means 43 needs to produce a force 0.174 FIG. 10 is a front elevation of the carrying robot 30
necessary for producing a torque that can balance the first in a state where the first arm 36 and the second arm 38 are
torque M1. This force is higher than a force needed to be held in positions, respectively, and the third arm 39 and the
produced by the second arm driving means 43 when the fourth arm 40 are displaced coordinately. In this embodi
carrying robot 30 is provided with the arm position main ment, the third arm 39 and the fourth arm 40 are connected
taining means 60. to the second arm 38. The third arm 39 and the fourth arm
40 can be coordinately operated for displacement relative to
0169. Thus, in this embodiment provided with the arm the second arm 38 and the third arm 39, respectively.
position maintaining means 60, the position of the second
arm 38 can be maintained by the second arm driving means 0175 Thus, the table 50 at an optional height H can be
43 having a small driving force in a state where the load 31 horizontally displaced as shown in FIG. 10 with the second
is horizontally moved. The position of the secondarm 38 can arm 38 kept in contact with the contact member 62 of the
be maintained even if the second arm 38 has a low rigidity. arm position maintaining means 60. The table 50 holding the
Similarly, the arm position maintaining means 60 enables load 31 can carry the load 31 long distance in the horizontal
the first arm driving means 42 having a low driving force to direction because the arm position maintaining means 60
maintain the position of the first arm 36 even if the first arm applies an upward force to the second arm 38.
36 has a low rigidity.
0176 FIG. 11 is a sectional view of the second arm 38
0170 When the load 31 is transferred from the carrying and the contact member 62 included in the arm position
robot 30 to the carrying robot 30 on the downstream side in maintaining means 60 and in contact with the second arm
the downstream carrying direction X1, the first torque M1 is 38. The second arm 38 has flat contact surfaces 90 that come
removed from the second arm 38. Then, the second arm into contact with the contact member 62. Each of the contact
driving means 43 is required to apply a downward force to surfaces 90 is perpendicular to a radius 110 crossing the
the second arm 38 to press the second end 38b of the second sixth axis J6 and perpendicular to the sixth axis J6. The
arm 38 downward against the second torque M2. If the force contact surface 90 is finished in a smooth surface so that the
applied by the second torque M2 to the second arm 38 is contact surface 90 can slide smoothly along the position
higher than the driving force of the second arm driving maintaining contact surface 85 of the contact member 62.
means 43, the position of the second arm 38 cannot be The contact surface 90 is formed such that the radius 110 is
maintained and the second arm 38 vibrates. Therefore, it is aligned with the reference axis 100 on the arm position
desirable to determine the spring constant k and the deflec maintaining means 60 when the second arm 38 comes into
tion X of the compression coil spring 64, and the horizontal contact with the contact member 62.
distance L11 between the fifth axis 35 and a point in contact
with the contact member 62 on the second arm 38 so that the 0177. The second arm 38 comes into contact with either
force producing the second torque M2 is lower than the of the arm position maintaining means 60 on the down
maximum driving force of the second arm driving means 43. stream side in the downstream carrying direction X1 and the
arm position maintaining means 61 on the upstream side in
0171 Such a condition applies similarly to the first arm the upstream carrying direction X2. The contact surfaces 90
driving means 42. The respective weights of the arms and are formed so as to correspond to the arm position main
the weight of the carrying robot 30 are neglected in the taining means 60 and 61, respectively.
foregoing description. Practically, it is preferable to take the
weight of the carrying robot into consideration in determin 0.178 FIG. 12 is a sectional view of assistance in explain
ing the spring constant k and the deflection X of the com ing a state where a second end 38b of the second arm 38 is
pression coil spring 64, and the horizontal distance L11 obliquely approaching the arm position maintaining means
between the fifth axis J5 and a point in contact with the 60. FIG. 13 is a sectional view of assistance in explaining a
contact member 62 on the second arm 38. state where a second end 38b of a second arm 38 is obliquely
US 2008/0028883 A1 Feb. 7, 2008

approaching the arm position maintaining means 60 in a first 0.184 When the position maintaining contact surface 85
comparative example. FIG. 14 is a sectional view of assis is curved and does not have any sharp edges as shown in
tance in explaining a state where a second end 38b of a FIG. 15, the second arm 38 can be smoothly moved to a
second arm 38 is obliquely approaching an arm position predetermined position after the contact surface 90 has come
maintaining means 60 in a second comparative example. into contact with the position maintaining contact Surface
0179. In some cases, the second end 38b of the second 85. On the other hand, when the position maintaining
arm 38 approaches the contact member 62 from the oblique contact surface 85 is flat as shown in FIG. 16, it is possible
direction 120 inclined to the reference axis 100 on the arm that the contact surface 90 of the second arm 38 comes into
position maintaining means 60 to curtail carrying time. In contact with the edge 95 of the position maintaining contact
surface 85. If the contact surface 90 comes into contact with
Such a case, the flat contact Surface 90 comes into contact the edge 95 of the position maintaining contact surface 85.
with a point near the top point 85a of the position main the second arm 38 and the arm position maintaining means
taining contact surface 85 as shown in FIG. 12. As the 60 vibrate, and the position maintaining contact surface 85
second arm 38 is further displaced, the contact surface 90 in may possibly be damaged. Impact on the second arm 38 and
point or line contact with the point near the top point 85a the arm position maintaining means 60 can be reduced by
slides and the radius 110 is aligned with the reference axis curving the position maintaining contact Surface 85 as
100 on the arm position maintaining means 60. shown in FIG. 15. Consequently, carrying speed can be
0180. If the contact surface 90 is a spherical surface, the increased to curtail carrying time.
contact surface 90 comes into contact with a point 85b apart
from the top point 85a of the position maintaining contact 0185 FIGS. 17 and 18 are a front elevation and a side
surface 85 as shown in FIG. 13. As the second arm 38 is elevation, respectively, of the carrying robot 30 in a refer
further displaced, the second end 38b of the second arm 38 ence position. When the carrying robot 30 is set in the
pushes the contact member 62 horizontally. In Such a case it reference position, the axes J5 to J7 are on a vertical
is possible that the contact member 62 cannot be smoothly imaginary line 29 bisecting a line extending between the first
displaced in the displacing direction. axis J1 and the third axis J3 as shown in FIG. 17.

0181. If the position maintaining contact surface 85 is a 0186. As shown in FIG. 18, the lower link 34 rises in the
flat surface, the contact surface 90 of the second arm 38 upward direction Z1 from the bed 33. Suppose that the
slides in flat contact with the position maintaining contact transverse directions Y are perpendicular to both the carry
surface 85 as shown in FIG. 14. A moving route for the ing directions X and the vertical directions Z. Then, the first
second arm 38 needs to be accurately taught to keep the arm 36 and the auxiliary link 37 are on the side in the
contact surface 90 of the second arm 38 parallel to the transverse direction Y1 of the lower link34, the second arm
position maintaining contact Surface 85, which requires 38 is on the side in the transverse direction Y2 of the first
difficult teaching work. arm 36, the third arm 39 is on the side in the transverse
direction Y2 of the second arm 36, and the fourth arm 40 is
0182. In this embodiment, the position maintaining con on the side in the transverse direction Y2 of the third arm 39.
tact surface 85 is curved and the contact surface 90 of the In this embodiment, the width L1, namely, a dimension in
second arm 38 is flat as shown in FIG. 12. Therefore, the the transverse direction, of the lower link 34 is approxi
horizontal force that acts on the contact member 62 and the mately equal to the width L2, namely, a dimension in the
impact exerted on the contact member by the second arm 38 transverse direction, of the second arm 38. The lower link34
when the contact surface 90 comes into contact with the is disposed between the first arm 36 and the third arm 39.
contact surface 85 are less than those exerted on the contact Since the third arm 39 and the fourth arm 40 are displaced
member 62 in the comparative example 1. Consequently, the in the transverse direction Y relative to the second arm 38,
life of the arm position maintaining means 60 can be the third arm 39 and the fourth arm 40 can be displaced even
extended. Teaching work for teaching a moving route for the in a state where the second arm 38 is in contact with the arm
second arm 38 in this embodiment is simpler than that in the position maintaining means 60.
comparative example 2. It is possible that the second arm 38
comes into contact with the contact member 62 at a contact 0187 FIG. 19 is a plan view of a table 50. The table 50
position of the desired contact position when the load 31 is substantially U-shaped. The table 50 has a pair of arms 51
carried by the carrying robot 30 is heavy. The allowable and 52 extending in the transverse direction Y when the table
range for the contact position is wide and an upward force 50 is mounted on the position adjusting member 41, and a
can be surely applied to the second arm 38. connecting member 53 connecting the corresponding end of
the arms 51 and 52. The table 50 defines a space 54 opening
0183 FIG. 15 is an enlarged view of the second arm in the transverse direction Y1 and the vertical directions Z.
before coming into contact with the arm position maintain The position adjusting member 41 is joined to a middle part
ing means and FIG. 16 is an enlarged view of the second arm of the connecting member 53 of the table 50. The position
before coming into contact with the arm position maintain adjusting member 41 may be provided with a holding
ing means in the second comparative example. The second mechanism for holding the load 31. The control means 55
arm 38 in this embodiment is moved in coordination with the
first arm 36 such that the inclination of the contact surface
controls the holding mechanism to hold the load 31 and to
release the load 31.
90 of the second arm 38 to a horizontal plane decreases
gradually and the contact surface 90 becomes parallel to the 0188 FIG. 20 is a front elevation of two carrying robots
horizontal plane as the second arm 38 moves in the carrying 30A and 30B in a state where a load 31 is being transferred
direction X. In FIGS. 15 and 16, two-dot chain lines 90A, from one of the carrying robots 30A and 30B to the other and
90B and 90C typically indicate the contact surface 90 FIG. 21 is a plan view of the two carrying robots 30A and
approaching the contact head 81. 30B during load transfer operation. The two carrying robots
US 2008/0028883 A1 Feb. 7, 2008

30A and 30B are identical with the foregoing carrying robot in the upstream carrying direction X2 and a downstream
30. The carrying robot 30A is on the upstream side in the carrying robot 30B provided with a table 50B is on the down
upstream carrying direction X2 and the carrying robot 30B stream side in the downstream carrying direction X1. A
is on the downstream side in the downstream carrying moving route for the table 50A on the upstream side in the
direction X1 upstream carrying direction X2 is indicted by two-dot chain
0189 The plurality of carrying robots 30A and 30B are lines 102 and a moving route for the table 50B on the
used when the carrying route extends beyond the limit of a downstream side in the downstream carrying direction X1 is
carrying range in which the carrying robot 30 can carry the indicted by chain lines 103.
load 31. The carrying robots 30A and 30B are arranged 0196. A transfer position where the carrying robot 30A on
along the carrying route at an interval. The upstream carry the upstream side in the upstream carrying direction X2
ing robot 30A in the direction X2 carries the load 31 in the transfers the load 31 and a receiving position where the
downstream carrying direction X1 and transfers the load 31 carrying robot 30B on the downstream side in the down
to the downstream carrying robot 30B, and then the down stream carrying direction X1 receives the load 31 are sub
stream carrying robot 30B carries the load 31 in the down stantially at the same position 101.
stream carrying direction X1. 0.197 As shown in FIGS. 23(1) to 23(4), the upstream
0.190 FIG. 22 is a flow chart of a carrying procedure to carrying robot 30A moves the table 50A holding the load 31
be carried out by the carrying robot 30 to carry the load 31. horizontally in the downstream carrying direction X1 to the
The control means 55 of the carrying robot 30 controls the transfer position 101. As shown in FIGS. 23(5) and 23 (6),
driving means 42 to 46 to move the table 50 without the upstream robot 30A moves the table 50A downward
changing the position of the table 50. A carrying instruction from the transfer position 101 to a posttransfer position 104.
is given to the control means 55 in step ato, and then the The posttransfer position 104 is on the downstream side of
control means 55 starts a carrying operation in step a1. the transfer position 101 in the downstream carrying direc
tion X1. As shown in FIG. 23(7), the upstream carrying
0191 In step a1, the controller 55 controls the driving robot 30A moves the table 50A horizontally from the
means 42 to 46 to move the table 50 to a receiving position posttransfer position in the upstream carrying direction X2.
on the upstream side in the upstream carrying direction X2. 0198 As shown in FIGS. 23(1) and 23(2), the down
Upon the arrival of the table 50 at the receiving position, the stream carrying robot 30B maintains the table 50B in a state
table 50 receives the load 31 from the carrying robot on the for receiving the load 31 thereon and moves the table 50B
upstream side in the upstream carrying direction X2 and horizontally in the upstream carrying direction X2 to a
holds the load 31. Then, step a2 is executed. prereceiving position 105. In this embodiment, the prere
0192 In step a2, the load 31 is maintained at a predeter ceiving position 105 is on the upstream side of the receiving
mined height and is carried in the downstream carrying position 101 in the upstream carrying direction X2. As
direction X1. If the load 31 needs to be machined by a shown in FIGS. 23(3) and 23(4), the downstream carrying
machining robot during being carried, the load 31 is stopped robot 30B moves the table 50B upward from the prereceiv
at a machining station, the machining robot machines the ing position 105 to the receiving position 101. As shown in
load 31, and then the carrying operation is resumed to carry FIGS. 23(5) to 23(7), the downstream carrying robot 30B
the load 31 in the downstream carrying direction X1 after the moves the table 50B horizontally from the receiving position
completion of machining. After the table 50 has been moved 101 in the downstream carrying direction X1.
in the downstream carrying direction X1 to a transfer 0199 The tables 50A and 50B are formed so as to be able
position, the control means 55 executes step a3. to support the load 31 thereon. The tables 50A and 50B can
0193 In step a3, the table 50 releases the load 31, and the be simultaneously positioned at the transfer position 101 and
carrying robot transfers the load 31 to the carrying robot on at the receiving position 101, respectively. During the
the downstream side in the downstream carrying direction receiving operation and the transfer operation, the upstream
X1. Then, step a4 is executed. A query is made in step a4 to table 50A is moved horizontally toward the transfer position
see whether or not the carrying operation is to be continued. 101 and, at the same time, the downstream table 50B is
If the response in step a4 is affirmative, a load receiving moved to the prereceiving position 105 as shown in FIG.
operation is carried out to receive another load 31 from the 23(1).
upstream side in the direction X2. Concretely, step af is 0200. After the down stream table 50B has arrived at the
executed. In step a6, the table 50 is moved horizontally in prereceiving position 105 as shown in FIG. 23(2), the down
the upstream carrying direction X2 and the carrying proce stream table 50B is moved to the receiving position 101 as
dure returns to step a1. shown in FIG. 23(3). The upstream table 50A is moved to
the transfer position 101 and the downstream table 50B is
0194 The control means 55 thus controls the driving moved to the receiving position 101 so that the tables 50A
means 42 to 46 to carry loads 31 successively from the and 50B may not interfere with each other. Then, the
upstream side in the upstream carrying direction X2 to the upstream table 50A releases the load 31 and the downstream
downstream side in the downstream carrying direction X1. table 50B is set ready to chuck the load 31.
0.195 FIG. 23 is a diagrammatic view of assistance in 0201 As shown in FIG. 23(4), after the upstream table
explaining a load receiving operation for receiving the load 50A and the down Stream table SOB have been moved to the
31 and a load transfer operation for transferring the load 31 transfer position 101 and the receiving position 101, respec
of the carrying robot. Steps of the load receiving operation tively, the respective support surfaces of the tables 50a and
and the load transfer operation are carried out in order of 50B are flush with each other. Thus the load 31 is supported
FIG. 23(1) to FIG. 23(7). In FIG. 23, an upstream carrying on both the upstream table 50A and the down stream table
robot 30A provided with a table 50A is on the upstream side SOB.
US 2008/0028883 A1 Feb. 7, 2008

0202 Then, as shown in FIG. 23(5), the upstream table 0208 FIG. 25 is a flow chart of a control procedure to be
50A is lowered to the posttransfer position 104. Conse carried out by the control means 55 in step a2 of the carrying
quently, the load 31 is transferred from the upstream table procedure shown in FIG. 22. The carrying robot 30 receives
50A to the downstream table 50B. Then the downstream the load 31 with an upward force applied to the second arm
table 50B chucks the load 31. 38 by the arm position maintaining means 60 in step b0.
0203 Subsequently, as shown in FIGS. 23(6) and 23(7), Then, step b1 is executed.
the downstream robot 30B moves the downstream table 50B 0209. In step b1, the third arm 39 and the fourth arm 40
horizontally in the downstream carrying direction X1. The are displaced coordinately with the position of the second
upstream robot 30A moves the upstream table 50A to the arm 38 maintained to move the table 50 horizontally in the
posttransfer position 104, and then moves the upstream table downstream carrying direction X1. Upon the arrival of the
50A horizontally from the posttransfer position 104 in the table 50 at a predetermined position near the bed 33, step b2
upstream carrying direction X2. The load 31 is thus trans is executed. When the table 50 is at this predetermined
ferred and received by the transfer operation and the receiv position near the bed 33, the position of the second arm 38
ing operation. During the transfer operation for transferring can be maintained without the assistance of the arm position
the load 31 and the receiving operation for receiving the load maintaining means 60.
31, the arm position maintaining means 60 applies an 0210. In step b2, the control means 55 displaces the first
upward force to the second arm 38 to maintain the respective arm 36, the second arm 38, the third arm 39 and the fourth
positions of the first and the second arm, and the third arm arm 40 coordinately so as to move the table 50 horizontally
39 and the fourth arm 40 are displaced. Thus the load 31 can in the downstream carrying direction X1. The position of the
be transferred from one to the other table at a position carrying robot 30 changes via the reference position to a
remote from the bed 33 by using the second arm driving position in which the second arm 38 is moved in the
means having a low driving force. Waiting time can be downstream carrying direction X1 beyond the bed 33. If the
reduced by the cooperative operation of the upstream and load 31 needs to be machined by a machining device during
downstream robots.
being carried, the table 50 is stopped at a machining station.
0204 FIG. 24 is a front elevation of assistance in explain Then, step b3 is executed.
ing some of operations of the carrying robot30. The carrying 0211. In step b3, the carrying robot 30 is kept stationary
robot 30 carries out steps of a table moving operation in until the machining device completes a machining opera
order of FIGS. 24(1) to 24(6). FIG. 24 shows steps of an tion. Step b4 is executed after the machining operation has
operation of the carrying robot 30 holding the load 31 in the been completed. In step b4, the control means 55 displaces
reference position to carry the load 31 to the transfer position the arms 36,38, 39 and 40 coordinately to move the table 50
101.
horizontally in the downstream carrying direction X1. Step
0205 The control means 55 carries out a control opera b5 is executed after the table 50 has arrived at a predeter
tion to make the carrying robot 30 in the reference position mined position beyond the bed 33 in the downstream
move the table 50 horizontally in the downstream carrying carrying direction X1. It is difficult to maintain the position
direction X1 without changing the position of the table 50. of the second arm 38 without the assistance of the arm
The control means 55 controls the driving means 42 to 46 to position maintaining means 60 when the table 50 is at the
displace the first to fourth arms such that the table 50 is predetermined position beyond the bed 33 in the down
moved horizontally in the downstream carrying direction X1 stream carrying direction X1. When the table 50 is at the
without changing its position. predetermined position beyond the bed 33 in the down
stream carrying direction X1, the secondarm 38 is in contact
0206 While the table 50 is being moved in the down with the arm position maintaining means 60 and the arm
stream carrying direction X1, the control means 55 controls position maintaining means 60 applies an upward force to
the driving means 42 to 46 so that the second arm 38 may the second arm 38.
come into contact with the arm position maintaining means
60. When the second arm 38 is brought into contact with the 0212. In step b5, the third arm 39 and the fourth arm 40
arm position maintaining means 60 as shown in FIG. 24(4), are displaced coordinately with the respective positions of
the first arm driving means 42 and the second arm driving the first arm 36 and the second arm 38 maintained to move
means 43 are controlled so as to maintain the respective the table 50 horizontally in the downstream carrying direc
positions of the first arm 36 and the second arm 38. In this tion X1 to the transfer position 101. Then, the control
state, the arm position maintaining means 60 applies an procedure goes to step b6. In step b6, the moving operation
upward force to the second arm 38. for moving the second arm 38 in the downstream carrying
direction X1 is ended.
0207. The arm position maintaining means 60 thus
applies an upward force to the second arm 38 and the third 0213 FIG. 26 is a front elevation of assistance in explain
arm 39 and the fourth arm 40 are displaced relative to the ing some of operations of the carrying robot30. The carrying
second arm 38 to move the table further in the downward robot 30 carries out steps of a table moving operation in
carrying direction X1 as shown in FIG. 24(5). The control order of FIGS. 26(1) to 26(5). FIG. 26 shows a table moving
means 55 carries out control operations to move the table in operation for moving the table in the upstream direction X2
the downstream carrying direction X1 to the transfer posi after the load 31 has been transferred to the carrying robot
tion 101 as shown in FIG. 24.(6). The control means 55 on the downstream side in the downstream carrying direc
reverses the foregoing procedure to move the table from the tion X1 and the table 50 has been moved beyond the transfer
receiving position on the upstream side in the upstream position 101 in the downstream carrying direction X1.
carrying direction X2 to a position where the carrying robot 0214) As shown in FIG. 26(1), the table 50 is lowered for
30 is set in the reference position. a transfer motion to transfer the load 31 to the carrying robot
US 2008/0028883 A1 Feb. 7, 2008

on the downstream side in the downstream carrying direc invention is applied to a machining robot, the machining
tion X1 as shown in FIG. 26. After the load 31 has been robot can be maintained in a desired position even if the
transferred to the carrying robot on the downstream side in machining robot is provided with a large machining head.
the downstream carrying direction X1, the control means 55
displaces the third arm 39 and the fourth arm 49 to lower the 0220. The contact member 62 can be displaced in the
table 50 from the transfer position 101 to the posttransfer displacing direction. The force applied to the second arm 38
position 104 as shown in FIG. 26(2). Then, the table 50 is by the contact member 62 changes with the displacement X
moved horizontally in the upstream carrying direction X2. of the contact member 62. The posture of the second arm 38
can be maintained flexibly even if the weight of an end
0215. The first arm 36 and the second arm 38 are dis effector attached to the second arm 38 or the weight of the
placed during the movement of the table 50 in the upstream load 31 is changed. Since the contact member 62 can be
carrying direction X2. The second arm driving means 43 can displaced in the displacing direction, the second arm 38 can
displace the second arm 38 even if the arm position main come into contact with the contact member 62 even if a
taining means 60 does not apply force to maintain the position where the second arm 38 comes into contact with
position of the second arm 38 to the second arm 38 because the contact member 62 is not accurately taught.
the table 50 has been unloaded. Thus, as shown in FIGS.
26(3) to 26(5), the first arm 36, the second arm 38, the third 0221) The upper link 35, the lower link 34, the first arm
arm 39 and the fourth arm 40 are displaced to move the table 46 and the auxiliary link 37 form a quadric crank mecha
50 in the upstream carrying direction X2. The control means nism. The second arm driving means 43, as compared with
55 reverses the foregoing procedure to move the table 50 to that of a robot provided with a direct-acting linkage and not
the preparatory receiving position on the upstream side in provided with a quadric crank mechanism, may be driving
the upstream carrying direction X2. The arms 36, 38.39 and means having a small driving capacity. When the load 31 is
40 may be coordinately displaced during the movement of moved horizontally, the displacement of the second arm 38,
the table 50, provided that the second arm 38 is in contact as compared with that of a robot provided with a direct
with the contact member 62 of the arm position maintaining acting linkage, may be Small because the second arm 38 is
means 60 and the arm position maintaining means 60 applies displaced relative to the upper link35. When the second arm
an upward force to the second arm 38 when the table 50 driving means 43 is a motor, the rotating speed of the motor
arrives at the posttransfer position 104 and at the preparatory may be low.
receiving position 105.
0222. The third arm 39 and the fourth arm 40 enables
0216) The arm position maintaining means 60 is in con moving the load 31 in a low position. Therefore, the carrying
tact with the second arm 38 and applies a part of force robot can carry the load in a small space. If the load 31 is to
necessary for maintaining the position of the second arm 38 be machined by another machining robot while the load 31
to the second arm 38 when the second end 38b of the second is being moved, the height of the machining robot may be
arm 38 is horizontally spaced apart from the upper link 35. low and the machining robot does not need to be built in a
Therefore, the driving force of the second arm driving means large size. The table 50, namely, an end effector, can be
43 for maintaining the position of the second arm 38 may be maintained in a fixed position by displacing the position
low; that is, the position of the second arm 38 can be adjusting member 41 in coordination with the displacement
maintained even if the second arm driving means 43 is of the arms. Consequently, the ease of working can be
driving means having a small driving capacity, and the improved when the robots carry and machine the load. Since
second arm 38 may be an arm having a low rigidity. the arm position maintaining means 60 is joined to the bed
Similarly, the first arm driving means 42 may be driving 33, the carrying robot can be installed in a short time, which
means having a small driving capacity and the first arm 36 improves convenience.
may be an arm having a low rigidity.
0223 The maximum force applied by the arm position
0217 Thus the first arm driving means 42 and the second maintaining means 60 to the second arm 38 is lower than the
arm driving means 43 are Small and hence the carrying robot driving force of the second arm driving means 43. Therefore,
30 can be formed in a small size. The arm structure does not
need to be as complicated as known arm structure to the position of the second arm 38 can be maintained regard
maintain the position of the arm. Thus the carrying robot is less of the variation of a force acting in one of opposite
simple in construction and Small in size and has a large load directions on the second arm 38, for example, a downward
force. Thus the vibration of the second arm 38 can be
capacity. controlled and the working performance of the robot can be
0218. The second arm driving means 43 exerts driving improved.
force continuously to the second arm 38 even in a state 0224. The downward force acting on the second arm 38
where the arm position maintaining means 60 exerts force drops upon the transfer of the load 31 from the carrying
on the second arm 38. Thus the control method of control
ling the second arm driving means 43 does not need to be robot 30 to another robot. In such a case, the force exerted
changed before and after the contact of the second arm 38 on the second arm 38 by the arm position maintaining means
with the arm position maintaining means 60, and the control 60 may exceed the force exerted on the arm position
method is simple. Consequently, programs to be stored in maintaining means 60 by the second arm 38 if the arm
the control means 55 can be easily prepared. position maintaining means 60 exerts force on the second
arm 38. The force that can be exerted on the second arm 38
0219. Since the arm position maintaining means 60 by the arm position maintaining means 60 is lower than the
applies an upward force to the second arm 38, the load 31 driving force of the second arm driving means 43. Thus the
can be carried to a position horizontally spaced apart from driving force of the second arm driving means 43 restrains
the bed 33 even if the load 31 is heavy. When the present the second arm 38 from moving upward even if the force
US 2008/0028883 A1 Feb. 7, 2008

exerted on the second arm 38 by the contact member 62 0231. Although the arm position maintaining means 60
exceeds the force exerted on the contact member 62 by the of this embodiment exerts an upward force on the second
second arm 38. arm 38, the arm position maintaining means 60 may exert
0225. The change of the weight of the load 31 can be position maintaining force on the arm other than the second
dealt with and the flexibility of the carrying robot can be arm 38. The base in the second arm 38 is the upper link.
improved by adjusting the force that can be exerted on the When the arm position maintaining means 60 exerts force on
second arm 38 by the arm position maintaining means 6. The the arm other than the second arm 38, the arm on the side of
contact surface 90 of the second arm 38 is flat, the position the bed with respect to the arm on which force is exerted is
a base.
maintaining contact Surface 85 is curved, and the contact
surface 90 and the position maintaining contact surface 85 0232 Although the compression coil spring is used in the
are in point contact or line contact with each other. There foregoing embodiment as the reactive force producing mem
fore, the possibility that force acts on the arm position ber 64, the reactive force producing member 64 may be any
maintaining means 60 in a direction other than the displac means other than the compression coil spring, such as a
ing direction of the arm position maintaining means 60 can pneumatic spring, a rubber member, an pneumatic cylinder
be reduced. or a hydraulic cylinder. The compression coil spring as the
0226. The sliding bearings 86 and 74 suppress the action reactive force producing member is simple and does not
need any power. Although the foregoing embodiment has
of a deflecting force on the contact member 62 and hence the been described as applied to carrying the load 31 along the
contact member 62 is displaced in the displacing direction. carrying route by receiving and transferring the load 31 by
Thus the contact member 62 can be displaced in the dis the plurality of carrying robots, the single carrying robot 31
placing direction regardless of directions in which the sec may be used for carrying the load 31. A synthetic resin plate
ond arm 38 approaches the contact member 62, and hence may be attached to the second arm to improve the shock
the arm position maintaining means 60 can Surely exert a absorbing property and sliding property of the second arm.
reactive force on the second arm 38.
0233 FIG. 27 is a view of assistance explaining opera
0227. The contact member 62 has a movement damping tions of a carrying robot 300 in a second embodiment
property. The damping property of the contact member 62 according to the present invention. The carrying robot 300 is
can prevent the sudden displacement of the second arm 38. similar in construction to the carrying robot 30 shown in
For example, when the load 31 held by the second arm 38 FIG. 1, except that the carrying robot 300 is not provided
is transferred to another robot while the arm position main with any means corresponding to the arm position main
taining means 60 is exerting force on the second arm 38, the taining means 60. In FIG. 27, parts like or corresponding to
weight of the load 31 is removed. In such a case, the upward those of the carrying robot 30 shown in FIG. 1 are desig
force exerted on the second arm 38 by the arm position nated by the same reference characters and the description
maintaining means 60 may exceed the force exerted on the thereof will be omitted.
arm position maintaining means 60 by the second arm 0234. The carrying robot 300 has a first arm 36 inclined
driving means 43 for a moment. Even under Such a condi at a predetermined angle to a lower link 33; that is, the first
tion, the contact member 62 can be restrained from sudden arm 36 is inclined at a predetermined angle 01 to a vertical
movement. Thus the second arm 38 can be restrained from
being displaced upward by the arm position maintaining imaginary line and is in a predetermined specific position. A
means 60 even immediately after the transfer of the load 31 second arm 38 has a first end 38a at a height H from a
and the second arm 38 can be restrained from vibrating. The reference plane when the first arm 36 is in the predetermined
spring constant k of the compression coil spring may be specific position. The first arm 36, the second arm 38, a third
large and hence the load can be moved to a position arm 39 and a fourth arm 40 have lengths Y1, Y2, Y3 and Y4,
horizontally remote from the bed 33 even if the load 31 has respectively. The length of each arm is the distance between
a large weight. the opposite joints of the arm and the adjacent arms.
0235. The length Y2 of the second arm is not greater than
0228 If the load 31 is large, it is difficult to attenuate the a first set value (H-Hc), where H is a vertical specific
vibration of the arm holding the load 31. Causes of vibra distance of a first end 38a of the second arm 38 from the
tions of the second arm 38 can be reduced and the load 31 reference plane when the first arm 36 is set in the specific
can be stably carried by the movement damping property of position and HC is a limit height He, namely, a lower limit
the contact member 62. The vibration of the contact member height from the reference plane for the arms of the carrying
62 can be controlled and the second arm can be prevented robot 300.
from coming into contact with the vibrating contact member 0236. In FIG. 27, the length Y2 of the second arm 38 is
62.
equal to the first set value (H-Hc). When the first arm 36 is
0229. The foregoing embodiment specifically described set in the predetermined specific position as shown in FIG.
above is only an example and many changes can be made 2, the lower limit position of a second end 38b of the second
therein without departing from the scope of the present arm 38 is not below the limit height He. Similarly to the state
invention. For example, although the invention has been shown in FIG. 2, a value (Y2+Y3), where Y2 is the length
described as applied to the carrying robot, the present of the second arm 38 and Y3 is the length of the third arm
invention is applicable to robots other than the carrying 39, is not greater than a value (H0-Hc), where H0 is the
robot, Such as machining robots. height of the first end 38a of the second arm 38 from the
0230. Any restrictions are not placed on the arm structure floor surface and He is the limit height, in a reference
of the robot. The arm position maintaining means 60 may position.
exert force on the second arm 38 in any direction other than 0237 As shown in FIGS. 27(1) to 27(4), the fourth arm
the upward direction. 40 can be horizontally moved without changing the position
US 2008/0028883 A1 Feb. 7, 2008

of the fourth arm 40 and without lowering the arms 37 to 40 and the second set conditions, the fourth arm 40 can be
below the limit height He. Even in the reference position, the moved toward the bed without causing a state shown in FIG.
load can be held without reducing the respective height of 29. More concretely, the fourth arm 40 can be moved toward
the arms below the limit height He. The carrying robot 20A the bed as shown in FIG. 31.
in a comparative example shown in FIG. 36 can move the
load from the remotest position toward the bed if the specific 0244 As shown in FIG.30(3), the length Y4 of the fourth
height H is high. However, the arms are lowered below the arm 40 is expressed by: Y4=H1-HO-(Y2+Y3)}, where H1
limit height if the specific height H is low. This embodiment is the height of a first end 4.0a of the fourth arm 40 from the
having the second arm 38 to the fourth arm 40 can move the floor surface. The length Y4 of the fourth arm 40 is not
load even if the specific height H is low; that is, the load can greater than (H1-Hc), where H1 is the height of the first end
be carried in a low posture. The carrying robot shown in 4.0a of the fourth arm 40 and He is the limit height, obtained
FIG. 27 can carry the load in a wide range in a state where by rearranging the expression.
the first arm 36 is fixed in an angular position and the robot
is maintained in a low posture. Thus a return cycle can be 0245. The sizes of the arms of the carrying robot 300
rapidly completed and cycle time can be curtailed. shown in FIG. 27 will be given by way of example. The
0238 FIG. 28 is a view of assistance in comparatively respective lengths Y2, Y3 and Y4 of the second arm 38, the
explaining maximum load carrying ranges when a second third arm 39 and the fourth arm 40 are 405 mm, 405 mm and
arm 38 is long and when the second arm 38 is short, 800 mm, respectively. In the reference position, the height
H1 of the Second end 40b of the fourth arm 40 is 1010 mm.
respectively. Under first and second set conditions men
tioned hereunder, as shown in FIG. 28, in a state where the In the reference position, the height H0 of the first end 38a
posture of the second arm 38 is fixed, the load held on the of the third arm 38 is 1020 mm. The limit height He is 210
extremity of the fourth arm 40 can be carried to a position mm. The height H of the first end 38a of the second arm 38
farther than a position to which the load can be carried when from the reference plane in the reference position is 620 mm.
the length Y2 is long by a predetermined distance AL when
the length Y2 is short. 0246 These sizes of the arms meet the first and the
second set conditions. More concretely, the value (Y2+Y3),
0239 FIG. 29 is a view showing a state where the second where Y2 is the length of the second arm 38 and Y3 is the
arm 38 is moved toward a bed when the second arm 38 is length of the third arm 39, is 810 mm, and the value
excessively short. In some cases, the third arm 39 is long as (H0-Hc), where H0 is the height of the first end 38a of the
shown in FIG. 29 when the second arm 38 is excessively second arm 38 from the floor surface in the reference
short. It is possible in such are state that the third arm 39 is position and He is the limit height, is not greater than 810
lowered below the limit height He and a space in which the .
load can be moved is narrowed when the first arm 36 is
maintained in the specific position and the fourth arm 40 is 0247 The value (Y3-Y2), where Y3 is the length of the
moved without changing the position thereof. third arm 39 and Y2 is the length of the second arm 38, is
0240 FIG. 30 is a view showing the relation between the Zero and not greater than the value (H-Hc)=410 mm, where
second arm 38 and the third arm 39. Under a first set H is the height of the first end 38a of the second arm from
condition, a value (Y2+Y3), where Y2 is the length of the the reference plane in the specific position and HC is the limit
second arm 38 and Y3 is the length of the third arm 39, is height.
not greater than a value (H0-Hc), where H0 is the height of 0248. The length Y2 of the second arm 38 is 405 mm and
the first end 38a of the second arm 38 from the floor surface
and HC is the limit height, in the reference position as shown is not smaller than half the value (H0-Hc)=200 mm, where
H0 is the height of the first end 38a of the second arm 38
in FIG. 30(1). from the floor surface in the reference position and He is the
0241 Under a second set condition, a value (Y3-Y2). limit height. The length Y2 of the second arm 38 is 405 mm
where Y2 is the length of the second arm 38 and Y3 is the and is not greater than the value (H-Hc)=410 mm, where H
length of the third arm 39, is not greater than a value is the height of the first end 38a of the second arm 38 in the
(H-Hc), where H is the height of the first end 38a of the reference position from the reference plane and HC is the
second arm 38 from the reference plane and He is the limit limit height.
height, in the reference position as shown in FIG. 30(2). In 0249. The length Y4 of the fourth arm 40 is 800 mm
other words, the length Y2 of the second arm 38 is not equal to H1-H0-(Y2+Y3)}=800 mm. Thus the carrying
smaller than the remainder (HC+Y3-H) of subtraction of the robot 300 meets all the foregoing conditions.
height H of the first end 38a of the second arm 38 in the
specific position from a value (HC+Y3), where Hc is the 0250 FIG. 32 is a view comparatively showing positions
limit height and Y3 is the length of the third arm 39. near bases that can be reached by the carrying robots 30 and
0242 Under the first and the second set condition, the 300 embodying the present invention. FIGS. 32(1), 32(2)
length Y2 of the second arm 38 is not smaller than half a and 3203) show the carrying robot shown in FIG. 1, the
value (H0-H), where H0 is the height of the first end 38a of carrying robot 300 shown in FIG. 27 and the carrying robot
the second arm 38 from the floor surface in the reference 20A in a comparative example shown in FIG. 36, respec
position and H is the height of the first end 38a of the second tively. Suppose that sizes of the corresponding parts of the
arm from the reference plane in the specific position. carrying robots 30, 300 and 20A are the same, the second
arm 38 is maintained in a horizontal position, and the height
0243 When the respective lengths of the second arm 38 H11 of the load is not lower than the height H of the first end
and the third arm 39 are determined so as to meet the first 38a of the second arm 38 in the specific position.
US 2008/0028883 A1 Feb. 7, 2008

0251 When the carrying robot of the present invention a second arm having a first end and a second end, the first
shown in FIG. 1 meets a condition expressed by: end being joined to the upper link, the second arm
being capable of being displaced relative to the upper
link;
HO - Ho - LA- (1)
a third arm having a first end and a second end, the first
witHo - He) - (H-Hc)? - volar - (H-Hc)? end of the third arm being joined to the second end of
2 the second arm, the third arm being capable of being
displaced relative to the second arm; and
0252 the load is at the shortest possible distance from the a fourth arm having a first end and a second end, the first
carrying robot as shown in FIG. 32(1). In this state, a end of the fourth arm being joined to the second end of
horizontal distance AX3 between a reference position on the the third arm, the fourth arm being capable of being
bed and the second end 40b of the fourth arm 40 is expressed displaced relative to the third arm, the fourth arm being
by Expression (2). equipped with holding means for holding a load to be
carried;
wherein the lower link, the upper link, the first arm, and
0253) The carrying robot 300 of the present invention the auxiliary link form a quadric crank mechanism, and
shown in FIG. 27 cannot move the load further toward the the first end of the fourth arm is below the first end of
carrying robot when (H0-H)/2<Y2<H-Hc. In this state, a the third arm when the first to fourth arms are respec
horizontal distance AX2 between the reference position on tively vertically extended so as to set the robot arm
the bed and the second end 40b of the fourth arm is structure in a reference position.
expressed by Expression (3). 2. The robot arm structure for a carrying robot according
to claim 1, wherein the first to fourth arms are distanced
vertically from the reference plane respectively by distances
not shorter than a limit height He at which the robot arm
0254 The carrying robot 20A in the comparative structure is at a nearest possible distance from the reference
example shown in FIG. 36 cannot move the load further plane when the robot arm structure is set in the reference
toward the robot in a position shown in FIG. 32(3). In this position.
state, a horizontal distance AX1 between a reference position 3. The robot arm structure for a carrying robot according
on the bed and the second end 40b of the fourth arm 40 is to claim 2, wherein the second arm has a length Y2 not
expressed by Expression (4). greater than a value equal to (H-Hc), where H is a vertical
distance of the first end of the second arm from the reference
plane when the robot arm structure is set in a specific
position in which the first arm is inclined at a predetermined
0255 Under the foregoing conditions, AX2<AX3<AX1. angle to the lower link, and He is the limit height He.
The carrying robots 30 and 300 of the present invention can 4. The robot arm structure for a carrying robot according
move the load closer thereto than the carrying robot 20A in to claim 3, wherein the length Y2 of the second arm is not
the comparative example. Thus the carrying robot of the shorter than a value equal to (He--Y3-H), where Hc is the
present invention can carry the load in a low position with limit height, Y3 is a length of the third arm and H is the
the first arm 36 disposed at a predetermined position without vertical distance of the first end of the second arm from the
changing the position of the fourth arm 40. In the reference reference plane when the robot arm structure is set in the
position, the arms 36 and 38 to 40 are not lowered below the specific position.
limit height He. 5. The robot arm structure for a carrying robot according
to claim 1, further comprising arm position maintaining
0256 Although the preferred embodiments of the present means for exerting a force necessary for maintaining the
invention have been described specifically with a certain second arm in a position to the second arm.
degree of particularity, obviously many changes are possible 6. (canceled)
therein. It is therefore to be understood that the present 7. (canceled)
invention may be practiced otherwise than as specifically 8. (canceled)
described herein without departing from the scope and spirit 9. A robot comprising:
thereof.
a base;
1. A robot arm structure for a carrying robot, comprising:
an arm having a first end and a second end, the first end
a bed installed on a predetermined reference plane; being joined to the base, the arm being displaceable
a lower link disposed on the bed; relative to the base;
an upper link disposed above the lower link: arm driving means for driving the arm to displace the arm
relative to the base;
a first arm joining the lower link and the upper link so as arm position maintaining means for exerting a part of a
to be capable of being displaced relative to the upper force necessary for maintaining the arm in a position to
link and the lower link;
the arm by coming into contact with the arm in a state
an auxiliary link joining the lower link and the upper link where the second end of the arm is distanced from the
so as to be capable of being displaced relative to the base in a predetermined direction, the arm position
upper link and the lower link: maintaining means including a contact member with
US 2008/0028883 A1 Feb. 7, 2008
20

which the arm comes into contact, a holding member third arm driving means for driving the third arm to
for movably holding the contact member so as to be displace the third arm relative to the second arm; and
displaceable in a predetermined displacing direction,
and a reactive force producing member for exerting a fourth arm driving means for driving the fourth arm to
reactive force proportional to a displacement by which displace the fourth arm relative to the third arm;
the contact member is displaced in the displacing wherein the third arm and the fourth arm are movably
direction by the arm to the contact member, the contact displaced in a state where the second arm is in contact
member coming into contact with the arm, in a state with the arm position maintaining means.
where the second end of the arm is distanced horizon
tally from the base, to apply a part of force necessary 11. The robot according to claim 10, further comprising:
for counterbalancing a gravitational force acting on the a position adjusting member movably disposed on the
arm to the arm; fourth arm, the position adjusting member being
a bed; equipped with holding means for holding a load to be
carried; and
a lower link disposed on the bed;
position adjusting member driving means for driving the
an upper link disposed above the lower link, the upper position adjusting member to displace the position
link forming the base to which the first end of the arm adjusting member relative to the fourth arm.
is joined; 12. The robot according to claim 9, wherein the arm
a first arm joining the lower link and the upper link so as position maintaining means is joined to the bed.
to be displaceable relative to the upper link and the 13. The robot according to claim 9, wherein a force
lower link; exerted by the arm position maintaining means on the arm
an auxiliary link joining the lower link and the upper link is lower than a maximum driving force of the arm driving
CaS.
so as to be displaceable relative to the upper link and
the lower link; 14. The robot according to claim 9, wherein the arm
position maintaining means is capable of adjusting a force
a second arm having a first end and a second end, the exerted on the arm.
second arm forming the arm, the first end of the second 15. The robot according to claim 9, wherein an outer
arm being joined to the upper link, the second arm surface of at least either of a contact part of the arm position
being displaceable relative to the upper link: maintaining means with which the arm comes into contact
first arm driving means for driving the first arm to displace and a contact part of the arm that comes into contact with the
the first arm relative to the lower link; and position maintaining means is a curved surface.
second arm driving means for driving the second arm to 16. The robot according to claim 9, wherein the contact
displace the second arm relative to the upper link; member is held via a sliding bearing on the holding member.
wherein the contact member of the arm position main 17. The robot according to claim 16, wherein the contact
member has a damping property with respect to a move
taining means comes in contact with the second end of ment.
the second arm in a state where the second end of the
second arm is distanced horizontally from the upper 18. The robot according to claim 9, wherein the robot is
link. a carrying robot for carrying a load in a horizontal direction
10. The robot according to claim 9, further comprising: with holding the load.
19. An arm position assisting structure serving as the arm
a third arm joined to the second arm so as to be displace position maintaining means of the robot according to claim
able relative to the second arm; 9.
a fourth arm joined to the third arm so as to be displace
able relative to the third arm;