Data processing: generic control systems or specific application – Specific application – apparatus or process – Robot control
Reexamination Certificate
1998-07-10
2001-08-07
Lee, Thomas (Department: 2182)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Robot control
C700S056000, C700S262000
Reexamination Certificate
active
06272397
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an orthogonal type three-axis robot used for mounting or removing parts into or from a printed board or the like and, and a control method for effecting a height control.
2. Description of Related Art
Orthogonal type three-axis robots are conventionally used for industrial purposes, and have a function to package parts into or remove parts from a printed board. The orthogonal type three-axis robot used in an MDF (Main Distributing Frame) is operative to insert or remove a connection pin into or from a hole formed in a matrix board
1
which is a form of printed boards.
FIG. 1
is a plan view showing a matrix board
1
, while
FIGS. 2 and 3
show perspective views of a through hole
2
and a connection pin
3
, respectively.
FIG. 4
is a perspective view generally showing an example of the conventional orthogonal type three-axis robot.
As shown in
FIG. 1
, formed on the matrix board
1
are a plurality of lines Lx
l
, to Lx
N
(N is a natural number) on a primary side (referred to as primary lines hereinafter), and a plurality of lines Ly
l
to Ly
M
on a secondary side (referred to as secondary lines hereinafter). When an arbitrary one Lx
n
of the primary lines Lx
l
to Lx
N
and an arbitrary one Ly
m
of the secondary lines Ly
l
to Ly
M
of the secondary lines Ly
l
to Ly
M
are to be connected to each other, it is only necessary to connect the line Lx
n
to line Ly
m
at a point where the lines cross each other. For the purpose, the through holes
2
are proved at points where each of the primary lines Lx
l
to Lx
N
crosses each of the secondary lines Ly
l
to Ly
M
. When the connection pin
3
is inserted into the through hole
2
at a point where the line Lx
n
crosses the line Ly
m
, the line Lx
n
and the line Ly
m
are connected to each other, thereby one communication line that creates linking between the primary and secondary sides is formed.
The matrix board
1
has a multi-layered structure as represented by its cross section shown in
FIG. 2
, in which the lines Lx
l
to Lx
N
are formed in one of the layers, while the lines Ly
l
to Ly
M
are formed in another layer. The connection pin
3
, on the other hand, has a circular cylinder-shaped head section
3
a
, and a rod-shaped under-neck section
3
b
extending from the head section
3
a
, as illustrated in FIG.
3
. The head section
3
a
and under-neck section
3
b
are made from such a material as an insulating plastic, and a gold plating
3
c
is applied over the circumferential surface of an intermediate section of the under-neck section
3
b.
With this structure, the gold plating
3
c
is used for the connection between the lines Lx
l
and Lx
N
and lines Ly
l
to Ly
m
, and the length of the gold plating
3
c
is made equal to a distance between the lines Lx
l
to Lx
N
and lines Ly
l
to Ly
M
in the height or thickness direction. By inserting the connection pin
3
into the through-hole
2
until the under-neck section
3
b
described above contacts the layers having the primary and secondary lines, a desired one of the lines Lx
l
to Lx
N
can selectively be connected to a desired one of the lines Ly
l
to Ly
M
.
FIG. 4
shows an orthogonal type three-axis robot used for inserting the connection pin
3
at a specified position on the matrix board
1
shown in
FIG. 1
, in which a frame
11
facing a mother board
10
on which a plurality of matrix boards
1
are carried is provided. The frame
11
comprises four supporting elements
11
a
,
11
b,
11
c,
and
1
d
which together form a rectangular shape, and provided between the supporting elements
11
b
and
11
d,
which are opposite to each other, is a movable supporting element
12
which can freely move in the longitudinal direction of the supporting elements
11
b,
11
d,
namely in the direction of X-axis, which is a lateral direction of the matrix board
1
. An X-axis step motor is provided on the supporting element
11
b,
and X-axis belts
14
a
,
14
b
driven by the X-axis step motor and moving the supporting element
12
are attached to the supporting element
11
b
and supporting element
11
d
respectively.
Provided on the supporting element
12
are a hand element
15
made of a metal material, which is typically shown in
FIG. 5
, and functions as a holding device for holding the connection pin
3
, a hand opening and closing direct current (DC) motor
16
for opening or closing the hand element
15
, a Z-axis step motor
17
for moving a position of the hand element
15
in the height or thickness direction, namely in the direction of Z axis, a Y-axis step motor
18
, and a Y-axis feed belt
19
driven by the Y-axis step motor
18
which moves the hand element
15
, hand opening and closing DC motor
16
, and Z-axis step motor
17
in the longitudinal direction of the matrix board
1
, namely the direction of Y-axis.
To minimize an installation area of the orthogonal type three-axis robot, for instance, four matrix boards
1
are fixed to the mother board
10
, and two mother boards
10
are provided on both sides of the robot. Provided on each mother board
10
are a plurality of connectors
10
a
for accommodating the primary lines Lx
l
to Lx
N
and secondary-lines Ly
l
to Ly
N
for each board. A step motor is used for each of the motors
13
,
17
,
18
in order to reduce the cost of the robot. A cylinder may also be used in place of the DC motor
16
for opening or closing the hand element
15
.
Now, description is made for operations for mounting (or, inserting) the connection pin
3
by the orthogonal type three-axis robot shown in FIG.
4
.
The robot first checks the position of an original point on each of the matrix boards
1
upon start of the power supply, and then moves the hand element
15
to an original point Po on a target matrix board
1
by driving the step motors
13
,
17
, and
18
. Instructions regarding the position for inserting the connection pin
3
are given to the robot from a system of a higher rank. The inserting position is given as relative moving distances of the hand element
15
in the directions of X, Y, and Z-axes from the original position Po. After the hand element
15
returns to the original position Po, the robot computes the height of the board
1
for determining the height of a working surface of the hand element
15
, by using the hand element
15
as a measuring device for measuring the height of the matrix board
1
.
FIG. 5
is a side view showing a relation between the board and hand element in FIG.
4
.
Provided on the surface of each board
1
and projecting therefrom is a reference point PI for the measurement of height. This reference point PI is, for instance, made from metal, and is connected to a ground layer provided on a rear surface of the board
1
. The robot moves the hand element
15
to a position above (in the direction of Z axis) the reference point PI in the state where a voltage is loaded thereto. Then the robot moves the hand element
15
toward the matrix board
1
in the direction of Z axis until the hand element
15
comes into contact with the reference point PI. As a result of this contact, a current flows from the hand element
15
to the ground, and a height of the reference point PI is measured by using a moving distance of the hand element
15
in the direction of Z axis. The height of the reference point PI measured as described above is stored as the height of the matrix board
1
.
After this step, the robot performs the position control of the hand element
15
in the direction of X axis, the direction of Y axis, and the direction of Z axis based on an inserting position of the connection pin
3
is given by the system of higher rank and the height of the board
1
, and inserts the connection pin
3
into a specified position of the board
1
.
However, when inserting the connection pin
3
by using a conventional method of controlling the height of an orthogonal type three-axis robot, the following problem has been encountered.
Namely, if there exists any distorti
Abe Takashi
Amano Taro
Yamada Masashi
Lee Thomas
Mai Rijue
OKI Electric Industry Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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