Parameter groups:
74 Position status & control words (page 440)
and
.
Position controller
The position controller calculates a velocity reference (
) that is used as the
feed forward term (
) to minimize the difference between position reference
and actual values. The position controller is a P-type controller. The user can set
the controller gain (
Position control gain), the feed forward value gain (
),
and a cycle delay (
) between the reference and actual value. The delay can be
used to minimize system position error especially in master-follower setups.
The output of the position controller has a gear function (
and
) for
transferring position and speed data from the load side to the motor side.
The position controller also supervises the error (
) between the reference
position (
) and actual position (
). The maximum positive and negative
error values are stored into resettable parameters
and
for fine-tuning
purposes. If the position error exceeds the limit set by
, the action selected
by
is taken.
Settings and diagnostics
Parameter groups:
86.2 Actual position (page 463)
and
88 Position control (page 478)
.
Master reference
Parameter group
contains several settings to define the
reference source and operation in synchronized mode. The master reference source
is selected by parameter
and provides various selections:
•
analog input (AI1/AI2)
•
fieldbus reference
•
master encoder (encoder 1/2)
•
master/follower link
•
virtual master.
The follower axis is synchronized with master reference by the “Gear in” command,
whose source is defined by
(See also section
.) The gear-in
ratio (
) defines the fixed velocity ratio between the follower and master
axes. These parameters cannot be changed during operation, but
can be
used to adjust the velocity ratio on the fly. A new gear-in ratio can be activated by
a new gear-in command during operation when
is set to
and
is
set to
In addition to the synchronization ratio, PI control (see page
) or an external
source (
) can be used to adjust the follower’s velocity in synchronized mode.
Parameter
and
can be used for master reference filtering. Any undesired
Position control program features 51
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