6
6.2
Positioning mode (P0700 = 3, from SW 2.1)
6-382
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SIMODRIVE 611 universal Description of Functions (FBU) – 04.05 Edition
When traversing an axis, a difference is obtained between the position
reference value and position actual value, dependent on the following
quantities (following error):
The instantaneous traversing velocity
The stabilizing characteristics of the position control loop, i.e. of the
selected position control loop gain (Kv factor, P0200:8)
Fluctuations of the following error for a traversing axis signify inaccu-
rate positioning.
In order to be able to check these fluctuations, the following error moni-
toring must be appropriately set.
The dynamic following error monitoring is activated/de–activated with
P0318:8, and is based on the continuous comparison between the
measured and a calculated position actual value.
To calculate the following error, a model is used, which simulates the
dynamic performance of the position control loop.
A tolerance bandwidth (P0318:8) for the maximum following error devi-
ation is permitted so that the monitoring does not erroneously respond
as a result of slight speed fluctuations (caused by load changes or by a
control loop model error).
Following error
x
v
max
–v
max
Velocity
v
P0318:8
P0318:8
Fig. 6-16 Following error
When the monitoring function responds, the drive is braked down to
standstill with the deceleration set in P0104 (max. deceleration) and
fault 131 (following error too high) is output.
A changeover is made into the tracking mode.
Table 6-27
Parameters for the dynamic following error monitoring
No.
Name
Min.
Standard
Max.
Units
Effective
0318:8
Dynamic following error monitoring
tolerance
0
1 000
200 000 000
MSR
Immedi-
ately
The parameter defines the maximum deviation between the measured and the calculated posi-
tion actual value before an error is signaled.
The tolerance bandwidth is intended to prevent the dynamic following error monitoring errone-
ously responding caused by slight speed fluctuations resulting from operational control se-
quences (e.g. load surges).
0
Dynamic following error monitoring is de–activated
1
The dynamic following error monitoring is active with this value
Dynamic following
error monitoring
Mode of operation
Fault
6 Description of the Functions
01.99
! not 611ue !