Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
2001-01-29
2002-04-23
Donels, Jeffrey (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S560000, C318S564000, C318S568100, C318S568110, C318S568130, C318S568220, C318S568230, C318S568250, C318S632000, 36, 36, 36
Reexamination Certificate
active
06377012
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a servo system controller having a sequence controlling section for executing a sequence program repetitively and a positioning controlling section for generating a positioning command of a servo motor based on a command issued from this sequence controlling section.
BACKGROUND ART
FIG. 14
is a block diagram showing a configuration of a conventional servo system controller. In
FIG. 14
,
100
denotes a servo system controller main body. This servo system controller main body
100
comprises a sequence controlling section
2
and a positioning controlling section
300
.
As shown in
FIG. 14
, the sequence controlling section
2
includes a sequence control CPU
4
, a control memory
5
, an input/output interface
6
, a peripheral device interface
7
, and a device memory, e.g., a common memory
41
.
A sequence program and a system program which are executed by the CPU
4
in the sequence controlling section
2
are stored in the control memory
5
.
An input unit
8
and an output unit
9
of a controlled object are connected to the input/output interface
6
.
Input information which are input from the controlled object (not shown) via the input unit
8
, internal information, output information for the controlled object are stored in the common memory
41
. The input information is updated every time when the sequence program is executed. Variables such as device names register numbers, etc. indicating storing areas for the input information, the internal information, and the output information in the common memory
41
are described in the sequence program. The internal information and the output information in the common memory
41
are updated by executing repeatedly the sequence program, and the output unit
9
is operated based on the output information to control the controlled object.
As shown in
FIG. 14
, the positioning controlling section
300
includes a positioning control CPU
10
, a control memory
11
, a positioning control program memory
12
, an area signal parameter memory
38
, a servo interface
15
, and an area signal output interface
39
.
A system program which is executed by the CPU
10
in the positioning controlling section
300
is stored in the control memory
11
.
A servo controller
20
which executes drive control of a servo motor (not shown) is connected to the servo interface
15
.
An area signal output unit
40
is connected to the area signal output interface
39
. An area signal which changes in response to a current position of the servo motor is output from the area signal output unit
40
to the outside. If the servo motor drives a table via ball screws, the current position of the servo motor indicates a current position of the table.
The sequence program, a positioning control program, and an area signal output pattern are written into the control memory
5
, the positioning control program memory
12
, and the area signal parameter memory
38
by peripheral devices via the peripheral interface
7
.
The common memory
41
in the sequence controlling section
2
is a memory which is called a dual port memory or a bilateral memory, and can be accessed by either the sequence control CPU
4
in the sequence controlling section
2
or the positioning control CPU
10
in the positioning controlling section
300
.
FIG. 15
is a diagram showing a part of a memory configuration of the common memory
41
. In
FIG. 15
,
41
a
denotes an area in which device information is stored,
41
b
denotes an area in which start information is stored, and
41
c
denotes an area in which monitor information is stored.
Next, an operation of the conventional servo system controller main body
100
shown in
FIG. 14
will be explained.
The sequence controlling section
2
writes predetermined device information into the area
41
a
of the common memory
41
and writes predetermined start information into the area
41
b
of the common memory
41
by executing the sequence program.
The positioning controlling section
300
monitors the area
41
b
of the common memory
41
, then reads the device information from the area
41
a
if the predetermined start information is written therein, and then executes the positioning control program in the positioning control program memory
12
which is designated by the device information. The positioning controlling section
300
sends a predetermined position command to the servo controller
20
via the servo interface
15
by executing this positioning control program. The servo controller
20
executes drive control of the servo motor based on this position command.
The positioning controlling section
300
compares the area signal output pattern stored in the area signal parameter memory
38
with the current position of the servo motor, and then turns an area signal which is output from the area signal output unit
40
to the outside via the area signal output interface
39
to its ON state (active state) if the current position of the servo motor is in an ON output range of the area signal output pattern.
Also, the positioning controlling section
300
stores command positions supplied to the servo controller
20
, servo control information such as the current position of the servo motor, deviation counter values, current values, revolution numbers, etc., error information, and the like in the monitor area
41
c
of the random common memory
41
during the positioning operation.
The positioning controlling section
300
stores information indicating that positioning has been completed into the area
41
c
of the common memory
41
when the positioning is completed.
As described above, the area signal output pattern has been written in advance in the area signal parameter memory
38
by the peripheral devices. The area signal output pattern written in the area signal parameter memory
38
is compared with the current position of the servo motor serving as comparison data, and then the comparison result is output from the area signal output unit
40
to the outside as the area signal.
In the above-described conventional servo system controller, there are problems described in following items (1) to (5).
(1) As described above, normally the area signal is generated by using the current position of the servo motor as the comparison data. In this case, if the area signal is generated by using other servo control information as the comparison data, the sequence program in which a comparing process program for comparing other servo control information with the comparison data is described is prepared, and then the area signal is generated by executing the scanning of this sequence program.
Since the sequence program is executed in asynchronism with the arithmetic period of the positioning controlling section, a long time (response time) is required to change the servo output after it has been detected that the servo control information reaches a predetermined value, and thus huge variation in the response time is caused. Hence, a tact time of the system is long and the machining precision is degraded. In case the machining speed is increased for purpose of reducing the tact time, such influences become remarkable. Thus, an execution time of the sequence program must be shortened in order to reduce the response time or to stabilize the response time. Therefore, there are such problems that a high performance CPU is needed and a production cost is increased.
(2) If the area signal output is generated by using, as the comparison data, contents of the device memory which are designated by the device name (variable) and the register number described in the sequence program, such area signal is also generated by executing the scanning of the sequence program in which the comparing process program is described. Accordingly, in this case, the execution time of the sequence program must also be shortened in order to reduce the response time or to stabilize the response time, like the above case. Therefore, there are such problems that the high performance CPU is needed and the product
Donels Jeffrey
Mitsubishi Denki & Kabushiki Kaisha
Smith Tyrone
Sughrue & Mion, PLLC
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