SEW-Eurodrive MOVI-PLC, Manual, Page: 13 / 108

Manual – MOVI-PLC® Application Solution "SyncCrane"
13
2
Functional principle of indirect positioning and synchronization
Description
The following figure shows the speed profile (motor encoder) with override for indirect
position control.
2.3.4 Conclusion
The table below contains a comparison of both solutions and their effects on internal
position control.
Result The following properties do not have an effect on the speed profile of the drive but on
the target position of the position controller if positioning tasks are solved using indirect
position control:
• Slip
• Properties of the absolute encoder
• Mechanical elasticities between absolute encoder sensing and the drive
This leads to a higher dynamic response and thus to improved operating characteristics
for dynamic positioning applications.
This solution with indirect positioning has been successfully implemented at SEW-
EURODRIVE for some time in the area of SRUs with cornering ability, etc.
536580619
V [m/s]
t [s]
Optimal speed process
Real speed process
Direct position control Indirect position control
Mechanical mounting Direct effect No direct effect
Position resolution Direct effect No direct effect
Properties, such as time delay Direct effect No direct effect
Dynamic response that can be
achieved Low due to summation of nega-
tive effects High
Startup effort High, since optimum setting has
to be found iteratively Low
Effort for implementation in the
program No Only parameter setting effort when
function modules are available.
P
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f
kVA
Hz
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P
i
f
kVA
Hz
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