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Figure 2: Syst
The inner-loop
means of a dr
temperature-c
valve pressure
modulator con
means of a pie
in response to
electronics. A
the piezo beam
the pressure u
pressure unde
spool valve m
sensor transm
loop electronic
4.3 Detai
Oper
A more detaile
Assume the u
Unit is in
A
Custom
ch
characteriz
No soft lim
Valve
has
12 mA.
Loop
calib
command.
Actuator
is
open.
Given these c
source of 50 p
so the Comma
Command.
S
is also at 50 p
the spool valv
the pressures
This is commo
tem Positioning
p controls the p
river module. T
compensated h
e modulator. T
ntrols the air pr
ezo beam bend
o an applied vo
As the voltage t
m bends, closi
under the diaph
er the diaphrag
oves up or dow
mits the position
cs for control p
iled Sequen
rations
ed example ex
nit is configure
Analog comman
haracterization
zation is
Linear
mits enabled. N
zero deviation
bration: 4 mA =
.
s tubed and po
conditions, 12 m
percent.
Custo
and source is p
ince zero devia
percent. With th
ve will be at a m
above and be
only called the
g Algorithm
position of the s
The driver mod
hall effect senso
The piezo valve
essure under a
der. The piezo
oltage from the
to the piezo val
ng off against a
hragm to increa
gm increases o
wn respectively
n of the spool b
purposes.
nce of Posi
plains the cont
ed as follows:
nd source.
is disabled (th
r
).
No MPC set.
with a present
0 % command
sitioner is conf
mA represents
om characteriza
passed 1.1 to th
ation exists, the
he stem at the
middle position
low the piston
null
or
balance
Use
spool valve by
ule consists of
or and a piezo
e pressure
a diaphragm by
o beam deflects
inner-loop
lve increases,
a nozzle causin
ase. As the
r decreases, th
y. The hall effe
back to the inne
tioner
trol function.
erefore
t input signal of
d, 20 mA = 100
figured air-to-
a Command
ation
is disable
he
Control
e Stem Positio
desired positio
that balances
in the actuator
ed
spool positio
er instructions
f a
y
s
ng
he
ect
er-
f
0%
d
n
on,
.
on.
Assume
The pos
percent
become
Control
50 % =
position
sends a
position
to the b
top of th
the stem
75 perc
decreas
opening
zero. A
balance
desired
One im
point: In
called
I
algorith
balance
zero sp
offset.
that mu
a null p
importa
automa
– Digital Positi
e the input sign
sitioner sees th
t. Linear chara
es 75 percent.
Command an
+25 %, where
n. With this po
a signal to mov
n. As the spoo
bottom of the ac
he actuator. T
m to start movi
cent. As the ste
se. The contro
g. This proces
At this point, the
ed position. St
d stem position
mportant parame
nner loop offse
Inner loop
offse
hm. In order fo
ed position, the
pool command.
The value of th
ust be sent to th
position with ze
ant for proper c
atically during s
ioner 3200MD
nal changes fro
his as a Comm
acterization, the
Deviation is th
d Stem Positio
e 50 percent is
sitive deviation
ve the spool up
ol moves up, the
ctuator and air
This new pressu
ing towards the
em moves, the
ol algorithm beg
ss continues un
e spool will be
tem movement
is now achieve
eter has not be
et. Referring to
et is added to t
r the spool to r
e control algorit
This is the pu
his number is e
he spool positio
ro deviation. T
control and is o
stroke calibratio
LGENIM0059
om 12 mA to 16
mand source of
e
Control Comm
he difference b
on: Deviation =
the present ste
n, the control a
p from its prese
e supply air is
r is exhausted f
ure differential
e desired positi
e
Deviation
beg
gins to reduce
ntil the
Deviatio
back in its null
t will stop and t
ed.
een discussed
o Figure 2, a nu
he output of th
remain in its nu
thm must outpu
urpose of the
In
equivalent to th
on control to br
This parameter
ptimized and s
on.
9-04 09/11
7
6 mA.
75
mand
between
75 % -
em
lgorithm
ent
applied
from the
causes
ion of
gins to
the spool
on
goes to
or
the
to this
umber
e control
ull or
ut a non-
nner loop
he signal
ring it to
r is
set
