Note: Descriptions are shown in the official language in which they were submitted.
~ t7
This invention concerns an industrial robot.
In a case where sealing, coatiny, welding or like
other working is applied to a work piece using a so-called
teaching-playback type robot, those portions of the work piece
to be applied with the working have to be situated accurately
¦ upon a playback operation where a teachi.ng operation was
executed.
However, in the case where each of work pieces is
' transported successively by a belt conveyor and applied with
10 1, sealing, coating, welding or like other working during the
transportation, the operation for situating all of the work
! pieces, relative to the robot manipulator, accurately where the
teaching operation was executed is time consuming and difficult. ¦
In addition, even if each of the work pieces can be situated
accurately relative to the robot manipulator at the position
where the teaching operation was executed, it still leaves
some undissolved problem, since the portions to be worked of
each of the work pieces, that is, the positions of the portions
l to which working is to be applied actually are somewhat varied
20 11 even for the work pieces of an identical formO This problem
I¦ itself can substantially be solved in a robot having a detection
I device provided to the manipulator for detecting the portions
i to be worked and adapted to perform playback operation while
.~ applying positional correction which is performed by rotating
or swinging a sealing nozzle, spray nozzle or welding torch
based on a detection signal from the detection device to bring
.
-1-
..
3~
the top end thereof to the portions to be worked. However,
if the position control for the top end of the nozzle or
torch to the portions to be worked i5 effected by a large
amount of operation for the positional correction, it may
some time fail to obtain satisfactory sealing, coating or
welding with respect to the resolution and the response of
the detection device.
An object of this invention is to provide an industrial
robot capable of performing satisfactory working even when
the positions where the work pieces are situated upon play-
back operation and/or positions of the portions of the
workpieces to be worked differ from each other.
According to the present invention, there is provided
an industrial robot comprising a memory means for storing
a working program, a manipulator means provided with a
tool means at the top end thereof, said manipulator means
being adapted to position said tool means relative to a
work piece in accordance with the working program stored
in said memory means, a detection means provided on said
manipulator means for detecting the portion of a work
piece to be worked, a correcting means for correcting the
position of said tool means relative to said portion to
be worked based on detection signals from said detection
means and a conveying means for conveying said manipulator
means based on the detection signals of said detection
means concerning a reference position of said work piece
so as to set said tool means to the reference position.
Certain preferred embodiments of the invention are
illustrated by the attached drawings in which:
Fig. 1 is a side view for a preferred embodiment of
this invention,
,3~3t~
Fig. 2 is a plan view for the embodiment shown in
Fig. l;
Fig. 3 and Figc 4 are perspective views for the
detaîls of a wrist and its relevant portions,
Fig. 5 and Fig~ 6 are explanatory views for the images
of slit received by a television camera, and
Fig. 7 is a block dia~ram for explaining the operation
of the embodiment shown in Fig. lo
In the drawings, a multi-joint type robot main body or
manipulator 1 comprises a platform 2 and a movable arm 3.
The movable arm 3 comprises a turn table 4 pivotal to the
platform 2 in the direction of an arrow A, a support post
5 pivotal to the table 4 in the direction of an arrow B,
an arm 6 pivotal to the support post 5 in the direction
of an arrow C and a freely bendable wrist 7 of a so-called
flexible type. The manipula~or 1 of such a constitution
has been described specifically in U.S. Patent No.
4,420,812 and No. 4,385,358 and the details of the wrist
7 are described in DE-OS 3,202,076.
A bracket 9 is secured to a cylindrical top end
of the wrist 7 and another bracket 12 is provided
by way of a connecting member 10 to the bracket 9
pivotally around an axial line 11. To the bracket
12, are secured a slit light source 16 for project-
ing a slit image 15 to 2 surface 14 of a work piece
.~
3 7
. , .
1 '
13 to be worked, a television camera 17 using semi-conductor
image sensors or the like for receiving the slit image 15 on
ij the surface 14 and a tool 18. A rotatable shaft 19 positioned
on the axial line 11 for supporting the bracket 12 pivotally
to the bracket 9 is secured at its middle portion to the
~ television camera 17 and pivotally supported at its both ends
¦j on side projections 20 and 21 of the bracket 9. A sec-tor gear
¦¦ 22 is secured to one end of the rotatable shaft 19 and the
gear 22 meshes with a gear 23, which is secured to an output
10 1 shaft of a reduction gear 24. The gear 24 is connected to a
motor 25 of a good responsivity, such as a coreless motor,
secured to the bracket 9. In response to the operation of
the motor 25 as a correcting device, the slit light source 16,
the television camera 17 and the tool 18 are integrally displaced
rotationally around the axial line 11 in the direction of an
arrow H.
A light-receiving optical axis 26 o~ the television
camera 17 as the detection device is aligned with the axial
~ center line for the cylindrical top end 8 of the wrist 7 and
1¦ in perpendicular to ~he rotational axial line 11. An optical
axis 27 of the slit light source 26 intersects obliquely the
op-tical axis 26 and the rotational axial line 11. The tool
18 comprises a sealing nozzle 31 which is in slight contact
at its top end 28 with the surface 14 and supplies sealer
material 30 from the top end 28 to a portion 2~ of the wor~
piece 13 to be sealed, a nozzle holder 32 which resiliently
'i .
i .
. ' ,
j - 4 ~
,~ supports the nozzle 31 displacea~ly in the direction along i
¦¦ the sealing direction shown ~y an arrow D and in the direction
crossing this direction and a member 33 for securing tne nozzle
'l holder 32 to the bracket 12. The nozzle holder 32 can absorb
the vertical error at the top end 28 upon playback operation.
The nozzle 31 is in a plane including the axial lines 26 a.nd
27, and the top end 28 of the nozzle 31 situates at the crossing
point between the axial lines 26 and 27. The platform 2 is
jl carried on a conveying device 34 comprising an endless chain
conveyor and the manipulator 1 is conveyed by the running of the i
chain of the conveying device 34 in the direction of an arrow
F perpendicular to the direction of an arrow E in which the
work piece 13 is conveyed by a conveying device 35. The
conveying device 34 is carried on a conveying device 36 also
comprising an endless chain conveyor and the conveying device
34, thus, the manipulator 1 is conveyed by the running of the
chain of the conveying device 36 in the direction shown by
an arrow G in parallel with the di.rection E, The conveying
device 35 comprises, for example, an endless belt conveyor
and conveys the works pieces 13 successively in the direction E.
As described later, a control device 37 comprising
a microcomputer or the like stores the positional information
I¦ for the arm 3 of the manipulator 1 into a memory unit 38 as the
! teaching data in accordance with a control program previously .
stored in the memory unit 38 upon teaching operation and reads
¦ out the teaching data stored in the memory unit 38 also in
ll l
i1 ''.
~l ~ 5
,. 1.
!
accordance with the control program and operates the arm 3
of the manipulator 1 based on the ~eaching data ~hus read
out upon playback operation. The control device 37 also
controls the operations of the conveying devices 34 and
36 and the conveying device 35 based on the signal from
a detector 39 that optically or magnetically detects the
approach of the work pieces 13, the signal from an image
processing device 40 and the control program stored in the
memory device 38. Details for the teaching and playback
operations on the manipulator 1 are described in U.S.
Patent Nos. 4,420,812 and 4,385,358 referred to above.
The image processing device 40 compares the images re-
ceived by the television camera 17 with reference images
previously stored in a memory unit 41 and outputs a
control signal based on the result of the comparison
to the control device 37 and to the motor 25. Details
for the image processing device 40 are disclosed in
GB 2,088,095A.
The operation of a multi-joint type robot 50 having
thus been constituted is to be explained next. Upon
teaching operation, running of the conveying device 35
is stopped and the work piece 13 is situated at a pre-
determined p~sition on the belt of the conveying device
35. Then, the manipulator 1 is manually moved to the
work piece 13 thus set stationary while bringing the top
end 28 to the start point 51 for the sealing, setting
the axial line 11 in parallel with the sealed line 29
as the portion to be worked, crossing the axial line 26
-- 6 --
c ~37
in perpendicular to the worked surface 14 and positioning the
crossing point between the axial lines 26 and 27 to the start
point 51. Thereafter, the top end 28 is displaced along the
sealed line 29 to the end point 52 for the sealing while
maintaining the positional relations as stated above. Each of
the positions for -the arm 3 while the top end 28 is being
displaced from the start point 51 to the end point 52 are
successively stored as the teaching data, that is, a working
program into the memory unit 38 under the control of the control
device 37. Each of the positions for the arm 3 can be detected,
for example, by a potentiometer provided to each of the joints
of the arm 3. Upon playback operation, the conveying device 37
is moved by the conveying device 36 in the direction opposite
to the direction E and set to the initial position at the
rightmost end in Fig. 2 under the control of the control device
37. Then, when the conveying device 35 is run by the operation
start signal from the control device 37~ the work pieces 13
are successively conveyed in the direction E. When the
positional relation between the initial work piece 13 being
conveyed and the conveying device 34 attains the same positional
relation which has been set upon teaching operation, the
teaching data stored in the memory device 38 axe read out based
on the signal from the detector 39 that detects the above
situation optically or magnetically under the control of the
control device 37, whereby the manipulator 1 is operated so
that the top end 28 is set to the start point 51 by the teaching
' i ~
'. - 7 - ~
I
., ,
data and, while on the other hand, the conveying device 36 is
i! I
jl operated under the control of the control device 37 in such
a way that the manipulator 1 is moved in the same direction as
1~ the moving direction of the work piece 13 in the direction E in
¦l a synchronized manner. That is, the manipulator 1 and the work
¦I pieces 13 are moved in the direction E at the same speed. Then,
when the top end 28 is situated to the start point 51, the
image processing device 40 of the robot 50 inspects the images
Il of the slit 15 received by the television camera 17. If the
10 I light source 16, the television camera 17, the tool 18 and the
sealed portion 29 of the work piece 13 are in the same positional
relation as that for the teaching operation, the camera 17
receives slit images 53 as a detection signal. While on the
¦ other hand, if the light source 16, the camera 17, the tool 18
Il and the sealed portion 29 of the work piece 13 are in the
¦~ different positional relation from that for the teaching
¦~ operation, the camera 17 receiVes~ for example, slit images 54
as the detection signal. In the lmages 55 of the images 54
~ corresponding to the slit 15, the distance 58 in the direction
il F between the position 56 for the bent portion resulted at the
step of the sealed portion 29 and the central position 57 for
~I the image 54 represents the deviation in the direction F
il between the top end 28 and the portion 29 to be sealed. In
'I a case where the images 53 are obtained in the television
!!
!I camera 17, the control device 37 of the robot 50 directly
l! actuates the arm 3 to move the top end 28 in the direction D
., .
il
1 1,
- 8
., .
based on the indication signal from the image processing device
40 in such a way that the sealing working may be performed on
the sealed portion 29 from the start point 51 to the end point
52 based on the teaching data. In a case if the images 5~ are
obtained in the television camera 17, the image processing
device 40 outputs an indication signal based on the distance 58
to the control device 37 of the robot 50 and the control device
37 actuates the conveying device 34 to move the manipulator 1
in the direction F based on the indication signal from the image ¦
processing device 40 until the images 53 are obtained. When
the images 53 are obtained as the result of the movement of
the manupulator 1 in the direction F, the robot 50 starts the
sealing for the sealed portion 29 in the same manner as described
above. During sealing for the sealed portion 2~ from the start
point 51 to the end point 52 in accordance with the teaching
data, the image processing device 40 monitors the slit images
obtained from the television camera 17. If the slit images 54
are received in the course of the sealing due to the displace- !
ment of the sealed portion 29, the device 40 actuates the
reversible motor 25 to rotate the light source 16, the camera 17
and the tool 18 around the axial line 11 in the direction H so
that the slit image 53 can be obtained and positions the top
end 28 to the sealed position 29. The distance 58 can be
detected by comparing the received images 54 with the image 53
which are previously stored as reference images in the form of
digital signals in the memory unit 41. When the sealing for
., .
'I .
Il _ g
i! I
., .
1,
I I ,
the sealed portion 29 has been completed based on the teaching
data, the control device 37 causes the conveying device 36 to
stop the movement of the manipulator 1 in the direction E and,
in turn, moves the manipulator 1 in the direction opposite to
the direction E by the conveying device 36 to set the manipulator
1 to the initial position. When the manipulator 1 is set to
the initial position, the robot 50 repeats the sealing in the
same way to the next work piece 13 to be conveyed.
In this embodiment, explanations have been made for
the displacement, in the direction F, of the portion to be worked
such as the sealed portion 29 which extends in the same direction
as the conveying direction E. In another case where the sealed
portion 29 extends, for example, in the direction F, the optical
source 16 is disposed so that the slit images 15 are formed on
the surface 14 in perpendicular to the direction F and the
moving speed of the manipulator 1 in the direction E may be
adjusted properly by the conveying device 36 based on the slit
images, whereby the top end 28 can accurately be set to the
start point for the working with respect to the displacement
of the sealed portion 29 either in the direction E or in the
opposite direction. In the latter case, by mounting the bracket
9 to the wrist 7 so that the axial line 11 is in parallel with
the sealed portion 29, the top end 28 can accurately track the
portion from the start point to the end point to be sealed in
the same manner as in the previous embodiment even if the
portion to be sealed deviates in the direction E or in the
.
-- 1 0
1~ 1
ll !
li
opposite direction. The portion to be worked is not necessarily
restricted only to the linear portion as described above but it
may be a curved por~ion. In this case, a detection device
capable of detecting such curved portion is mounted at ~he top
end of the wrist 7 and both of the conveying de~ices 34 and 36
are operated based on the detection signal from the detection
device. At first, the top end 28 is set to the reference
position for the portion to be worked and, during the working
for the portion to be worked according to the teaching data,
the top end 28 may be followed after the displacement of the
portion to be worked by the actuation of the conveying devices
34 and 36 based on the detection signal from the detection
de~ice. ~urthermore, although the reference position is set
to the working start point for the work piece, the reference
position may alternatively be set to a corner 59 of the work
piece 13. In this case, the images for the corner 59 are stored
in the memory device 41 upon teaching operation. Upon playback
operation, the top end 28 is situated at first to the corner 59
to obtain the images thereof and the images thus obtained are
compared with the stored images to detect the displacement of
the work piece 13, and the conveying de~ices 34 and 36 may be
actuated so as to compensate the displacement on the manipulator
1. In this case, while the displacements for each of the work
¦ pieces 13 on the conveying device 35 can desirably be compensat~
¦ ed, the displacement of the portion to be worked itself can
not be compensated with ease. ~ccordingly, it is preferred to
i
l ll
I ,
set the reference position at the portion to be worked in
the case where the portions to be worked are somewhat
different for each of the work pieces 13. Furthermore,
this invention can be applied not only to the robot for
sealing working but also to those robots for welding or
coating working in which suitable tool can be selected
depending on the types of the working, that is, a welding
torch for the welding and a paint spray nozzle for the
coating respectively~
Thus, it will be seen that the robot of this invention
is capable of decreasing the amount for the positional
correction during playback operation and thereby enabling
the use of a correction device with a narrower operation
range. It is also capable of performing the correcting
operation rapidly and applying working accurately to the
portions being worked.
- 12 -
