
10
Manual – MOVI-PLC® Application Solution "SyncCrane"
2
Functional principle of indirect positioning and synchronization
Description
2.3
Functional principle of indirect positioning and synchronization
2.3.1
The Problem
Existing applications with evaluation of the absolute encoder as IPOS encoder (see
IPOS manual chapter "Position detection and Positioning") limit the control dynamics
due to the properties of the absolute encoder systems and the mechanical conditions
(e.g. mounting of the encoder system).
Due to mechanical feedback, the entire system is susceptible to vibrations, which often
requires complex optimization of the control parameters on site.
The IPOS-based application module "DriveSync" was implemented according to this
principle. Especially when it comes to lifting devices and assembly-hall cranes, where
evaluation of an absolute encoder is necessary in addition, compromises have to be
made in project planning with respect to dynamics.
The SyncCrane application solution simplifies startup and operation.
2.3.2
Conventional solution: Direct position control with absolute encoders
The necessary SHELL parameters are determined during guided startup (SHELL/DIP
startup). Direct position control is part of the firmware. This means no additional
programming is required.
During the positioning operation, the cyclically read-in actual position (absolute encoder/
motor encoder position) is read in by the profile generator and corrected by adjustment
of the n-controller in case of deviations.
Deviations caused, for example, by slip between motor encoder and absolute encoder
thus directly affect the speed profile of the drive.
The following figure shows direct position control with position correction.
536585611
v
max
Maximum velocity
nC
Speed controller
a
max
Maximum acceleration
n
act
Actual speed
PG
Profile generator
ABS
Absolute encoder
PC Position
controller
IPOS
IPOS
plus®
program
DIP 11B
PG
PC
nC
M
–
+
n
act
V
max
a
max
IPOS
–
+
X62
ABS
P
i
f
kVA
Hz
n
P
i
f
kVA
Hz
n
Содержание MOVI-PLC
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