Vo
l.
16
No.4
}oumal
01
Southwest }iaotong University (English Edition)
Oc
t.
2008
Arti
cle
ID:
1005-2429
(2008)
04
-0
386-06
High-Accuracy Pneumatic Position Control by Applying
Nonlinear Control
and
Arranging
Transient
Process
W
ANG
Yan-bo
(王燕波
γ
,
BAO
Gang
(包刚)
School
01
Mechatronics , Harbin
Instit
μ
te
01
Technology , Harbin
15
ω
01
,
China
Abs
位
act
By
applying
a nonlinear control
and
arranging
a transient
process
,由
.e
initiative error of
the
pneumatic
se.
凹
o
positioning
system
is
reduced
largely
,
and
a larger
gain
of
the
controller
is
used
to
improve
the
responding
speed
of
出巳
system
at
也
e
same
damping
ratio.τ
'h
erefore
,
a
compromise
is
made
among
the
responding
speed
,
overshoot
,
robustness
, adaptability
and
stability.
In
addition
,
ad
归
larniC
output
feedback
controller,
including
position
velocity
and
acceleration
(PV
A)
feedback
,
is
designed
to
improve
the
performance
of
th
巳
system.
An
d a nonlinear controller
is
reconstructed
based
on
出
e
linear output
feedback
controller
to
decrease
noises
and
disturbances.τ
'h
e
d
严
1
缸咀
c
responses
of
the
system
are
simulated
and
tested.
Results
show
出
at
出
e
error
is
kept
within
0.02
mm
under
different
mass
loads
and
出
e
positioning
transient
process
is
smooth
,
without
overshoot
and
speedy.
K
句
'words
Pn
eumatic
position control
sys
臼
m;
Transient process;
Nonlinear
control
Introduction
Muscles
of
industrial robots are powered
by
ser-
vo-actuators.
To
be
cost-effective manipulators , actu-
ators must provide a fast
, accurate and reliable motion
with low cost-to-benefit
and
large power-to-weight
ratios.
Pn
eumatic cylinder systems have the potential
to
provide all
of
these features.
However
, due to the
strong
non-line
缸
ity
,
complexity in modeling , low
natural frequency and
air compressibility ,
it
is diffi-
cult
to achieve good performances
for
the pneumatic
servo system. Since
1950s
, scholars have studied the
pneumatic servo technologies
, such as extended PID
control[l]
, neural networks[2] , adaptive
control[
剖,
Received
2007-11-29
Foundation
item
Th
e
National
Natural
Science
Foundation
of
China
(No. 50085002)
Biography W
ANG
Yan-bo
(1978
寸,
P
hD.
His
research
interest
is
in
pneumatic
transmission
and
control
*
Correspondíng
autho
r.
Te
l.:
+ 86451
-86
413446; E-mail:
1978wyb@sohu.
com
fuzzy control
[4]
, position velocity
and
acceleration
(PVA)
feedback control[5].
A1
1 these control strate-
gies[I-7] have found limited applications
in practice.
Except for stability
and
steady-state
accuracy
,出
e
position servo control requires the no-overshoot,
smooth transient, anti-jamming
and
robustness; and
the
perfOIτnance
must
be
kept
even
if
出
e
parameters
of
the system are changed.
In this
paper
,
an
improvement is made
to
由
e
typical pneumatic servo contro
l.
The
conflict is re-
leased between the overshoot
and
big
gain
by
缸
Tan
ging transition process. Non-
Ii
near
feedback is adopt-
ed
and
the characteristics ,
higher
gain when error is
small
and
lov
.J
er
gain
when
error is large, are real-
ized.
The
experimental results show that these control
methods obviously improve the
perfo
口
nance
of
the
pneumatic position control system. Furthermore
, the
control arithmetic used
is
simple and easy to realize.
1
Pn
eumatic Servo Positioning
System
The
pneumatic servo positioning system con-
trolled by proportional valve is shown in Fig. 1.