3. Drive functions
3−6
Festo P.BE−CPX−CMA X−CONTROL−EN en 0908NH
Force control sequence
If Force control" is set as the control mode with a rising edge
at CPOS.START in RCB1 (record set mode) or in control byte
CDIR (direct mode), the CMAX interprets the setpoint specifi
cation as a force setpoint. It activates the force control and
adjusts the value with the set ramp. The RSB/SDIR
signalises
the Force control" status accordingly.
1 Path
2 Force
3 Speed
4 Force control until
drive breaks away
5 Feed phase (V
feed
)
6 Force buildup with
force ramp
7 MC
Path/speed/force
1
2
3
45
S
lim
F
V
lim
V
feed
Stroke monitoring
Target force
Speed monitoring
6
Time
7
Fig.3/1: Force control phases
Force control is done in phases according to Fig.3/1
(for stroke and speed monitoring, see monitoring functions,
Fig.3/2):
1. After starting the force control task until the drive moves
(phase 4 , breaking away").
2. Feed phase/prepositioning at speed setpoint until stand
still or target force has been reached (phase 5 ).
If
the drive does not encounter any counteracting force
after the force task has started, it accelerates until it has
reached the feed speed V
feed
, and then switches to posi
tioning mode and moves in the direction of the target
force until the counteracting force increases and the con
troller switches back to force control.
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