Pneumatic circuits: R, C

1
Pneumatic circuits R, C

• Pressure is potential, pressure difference is
  voltage drop
• A flow restrictor is a resistance
• An air chamber is a capacitance

DP
Slope R
Resistance R
Ppc
Ppi
q
C
R
Q
pc
C
pi
2
Position to Pressure transducer/amplifiers
R
Rx
pb
C
ps
pa
Ps is pressure of supply air from wall pipe or
air cylinder X is weighted differential average
of input position and the pivot position X
controls the pressure Pb send to the control valve
3
Pneumatic proportional controller
Ps is const parameter Diaphragm is fast, so pc
and pb are equal x is weighted diff sum of e and
y
Notice the direction of x and e
4
Pneumatic proportional controller
Since pcpb
Drawing for this part can be simplified
5
Proportional derivative controller
Recall bellow pressure is related to input
pressure by 1/(RCs1)
Pbellow
6
Proportional Integral controller
So, in closed-loop TF, replace (RCs1) by
(RCs1)/RCs
7
PID controller
8
Hydraulic servo system
9
Alternative construction
10
Proportional controller
Same as last page
Same as before
11
Dashpot
12
Proportional Integral controller
Rest as before
Last page
13
Proportional derivative control
Spring force k(y-z) instead of kz new
TF1-oldTF
14
PID controller
w
Force Balance k1zADP1 k2(y-w)ADP1ADP2
15
Block diagram representation
16
e
z
w
17
Thermal systems
Conservation of heat energy
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)