Work transport control method

Details Work transport control method Work transport control method

1998-03-30

2001-03-20

Grant, William (Department: 2121)

Data processing: generic control systems or specific application

Specific application, apparatus or process

Product assembly or manufacturing

C700S121000, C414S935000

Reexamination Certificate

active

06205368

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method of controlling a transport system and, more particularly, to a method of controlling the transport system including a transport robot or manipulator having two manipulator arms that is generally used in the manufacture of semiconductor devices or liquid crystal displays.
2. Description of the Prior Art
In the transport system used for transporting works such as, for example, semiconductor wafers or liquid crystal substrates, a robot or manipulator having two manipulator arms is generally employed to increase the efficiency of transport of the works. An example of the prior art transport system utilizing the two-arm robot is shown in FIG.
7
. Referring to
FIG. 7
, reference numeral
4
represents a load lock chamber for accommodating a stack of works, and reference numerals
5
to
8
represent processing chambers in which chemical vapor deposition and etching are carried out successively to the works. A transport robot or manipulator
10
is shown as positioned at a center region of the circle having respective portions occupied by the chambers
4
to
8
and includes a first manipulator arm AM
1
and a second manipulator arm AM
2
. This transport robot
10
is controlled by a main controller
20
through first and second robot controllers
30
and
31
for controlling the respective first and second manipulator arms AM
1
and AM
2
.
In the prior art transport system shown in
FIG. 7
, each work is removed from the load lock chamber
4
through a vacuum-side door and is then transported to any one of the processing chambers
5
to
8
. The work which has been subjected to a predetermined process such as, for example, chemical vapor deposition, in the processing chamber is subsequently transported either to the next one of the processing chambers
5
to
8
for subsequent processing or back to the load lock chamber
4
.
A circuit block diagram of each of the first and second robot controllers
30
and
31
shown in
FIG. 7
is shown in
FIG. 8
, and the manner in which communications are exchanged among the controllers
20
,
30
and
31
are diagrammatically shown in FIG.
9
. As shown in
FIG. 8
, each of the first and second robot controllers
30
and
31
includes an input/output (I/
0
) circuit
30
a
or
31
a
for interfacing between the main controller
20
and the respective robot controller
30
or
31
, and a transport control circuit
30
b
and
31
b
for feeding a servo-driver
30
c
or
31
c
with position information required to execute a transport command, said servo-driver
30
c
or
31
c
being operable in response to the position information to drive a motor for actuating the associated manipulator arm AM
1
or AM
2
.
Let it be assumed that the transport system shown in
FIGS. 7 and 8
is instructed to execute two commands
1
and
2
, as shown in
FIG. 9
, to transport the work in the load lock chamber
4
to the processing chamber
6
and to transport the work in the processing chamber
7
to the processing chamber
5
, respectively.
When the command
1
is to be executed, the main controller
20
transmits to the first robot controller
30
a first swivel instruction to swivel the first manipulator arm AM
1
to a position aligned with the load lock chamber
4
. In response to this first swivel instruction, the first robot controller
30
causes the first manipulator arm AM
1
to be swivelled to the position aligned with the load lock chamber
4
, followed by generation to the main controller
20
a first completion signal indicative of completion of the swivel of the first manipulator arm AM
1
to the position aligned with the load lock chamber
4
. After having received the first completion signal, the main controller
20
transmits to the first robot controller
30
a first removal instruction to cause the first manipulator arm AM
1
to remove the work from the load lock chamber
4
. The first robot controller
30
having received the first removal instruction causes the first manipulator arm AM
1
to remove the work from the load lock chamber
4
and then supplied the main controller
20
with a second completion signal indicative of completion of removal of the work from the load lock chamber
4
.
In response to the second completion signal, the main controller
20
transmits to the first robot controller
30
a second swivel instruction to swivel the first manipulator arm AM
1
to a position aligned with the processing chamber
6
. The first robot controller
30
upon receipt of the second swivel instruction causes the first manipulator arm AM
1
to be swivelled to a position aligned with the processing chamber
6
and subsequently supplies the main controller
20
with a third completion signal indicative of completion of swivel of the first manipulator arm AM
1
to the position aligned with the processing chamber
6
. Generation of this third completion signal from the first robot controller
30
takes place upon completion of swivel of the first manipulator arm AM
1
to the position aligned with the processing chamber
6
.
Upon receipt of the third completion signal, the main controller
20
supplies the first robot controller
30
with a first placement instruction to set the work carried by the first manipulator arm AM
1
to the processing chamber
6
. After the work has been set to the processing chamber
6
, the first robot controller
30
generates a fourth completion signal to the main controller
20
, informing the main controller
20
of completion of placement of the work in the processing chamber
6
. In this way, the command
1
is executed completely.
The command
2
is executed in a manner substantially similar to that described above in connection with the command
1
with communications being exchanged between the main controller
20
and the second robot controller
31
as shown in a lower portion of
FIG. 9
, to thereby complete the required work handling.
As discussed above, in the prior art transport system, the main controller
20
is required to transmit detailed and specific instructions to any one of the first and second robot controllers
30
and
31
and, therefore, communication between the main controller
20
and any one of the first and second robot controller
30
and
31
tends to be complicated and time-consuming.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention has been devised to substantially eliminate the above discussed problems inherent in the prior art transport system and is intended to provide a method of controlling the transport system wherein the time required to execute a command is advantageously reduced to thereby increase the efficiency of transport of works.
In order to accomplish this object, the present invention provides a method of controlling a transport system for transporting a work from one station to another, which system includes a plurality of stations arranged in a circular row, a transport robot assembly disposed generally coaxially of the circular row of the stations and including two manipulator arms, a main controller for controlling the transport system in its entirety relative to the transport robot assembly, and a robot controller for controlling sequential operation of the transport robot assembly. The transport system control method of the present invention is practiced by causing the main controller to transmit to the robot controller a transport command for causing the transport robot assembly to transport the work, said transport command including only the number of one of the stations from which the work is to be transported and the number of another one of the stations to which the work is to be transported; in response to receipt of the transport command, calculating the direction and angle of swivel require d for each of the manipulator arms to angularly move to remove an d transport the work from said one of the stations towards said another one of the stations, in reference to the current position of the respective manipulator arm and the n

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