Calculating The Time Constant For The Parallel Model - Siemens SINUMERIK 840C Installation Instructions Manual

10.94
The following servo gain factor settings are recommended:
FD-KV (NC MD252*/435*..442*) = 1
Drv
FD-KV (NC MD1420*/487*) = FD-KV
CC
Please note, however, that only FD-KV
LINK OFF state. If the following drive must contribute to the execution of a multi-
dimensional path motion in the LINK OFF state, then FD-KV
FD-KV from the part program in the LINK OFF state.
max
• Drive start-up for LINK ON (I-action component)
The I-action component of the compensatory controller (FD-KI
compensate for slowly changing disturbance variables (drift, temperature, etc.). It is
parameterized with a unit of 1/s
calculated as follows:
FD-KV [1/s]+ FD-KV
Drv
T = ––––––––––––––––––––––––––––––––––––
N
FD-KI (NC MD 1424*/488*) [1/s
CC
• Drive start-up for LINK ON (D component)
You should always leave the compensatory controller D component (NC MD 1428*/489*)
1)
set to the value "0".
Notes:
• The compensatory controller setting can be checked and documented by means of the
analog signal "Positional difference for synchronism" which can be output by the control
via analog outputs on the mixed I/O module.
• For this purpose, the mixed I/O module must be installed in the NC area.
• Please refer to the section headed "Drive servo start-up" for details of how to set the
mixed I/O module in order to output the analog signal.

Calculating the time constant for the parallel model

To ensure that the compensatory controller operates correctly, allowance must be made in the
controller for the setpoints generated by the simulated leading axes and the overlaid motion of
the following axis. The purpose of the parallel model is to produce an actual value from this
setpoint.
The parallel model must be set to the position control loop time constant of the following axis.
The time constant is influenced by the servo gain factor and the feedforward control.
The time constant must be entered in NC MD 1432* or 489* and is automatically calculated
when the maximum value 16000 is input.
Owing to the influence exerted by the speed controller, the automatically calculated value must
be checked and re-optimized if required.
Checking the time constant of the parallel model:
• Deactivate compensatory controller
• Activate link
• Activate FD overlay
• Select service display for following axis
• Traverse FD in jog
_______
1) Please note "Parameter set switchover" function description with SW 4 and higher.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
1)
1)
-1
max
(NC MD252*/435*..442*) remains active in the
Drv
2 . The reset time T of the compensatory controller is thus
N
[1/s]
CC
2 ]
1)
6FC5197- AA50
12 Functional Descriptions
12.18.13 Start-up
can be reset to
Drv
) is used solely to
CC
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