Control Systems Block Diagram Dr. Juma Yousuf Alaydi
Control SystemsBlock Diagram
Dr. Juma Yousuf Alaydi
Block Diagram Reduction
Figure 1: Single block diagram representation
Figure 2: Components of Linear Time Invariant Systems (LTIS)
Figure 3: Block diagram components
Figure 4: Block diagram of a closed-loop system with a feedback element
BLOCK DIAGRAM SIMPLIFICATIONS
Figure 5: Cascade (Series) Connections
Figure 6: Parallel Connections
Block Diagram Algebra for Summing Junctions
Figure 7: Summing Junctions
Block Diagram Algebra for Branch Point
Figure 8: Branch Points
Block Diagram Reduction Rules
Table 1: Block Diagram Reduction Rules
Table 2: Basic rules with block diagram transformation
Example 1
R
_+
_
+1G 2G 3G
1H
2H
++
C
Example
R
_+
_
+1G 2G 3G
1H
1
2
G
H
++
C
Example
R
_+
_
+21GG 3G
1H
1
2
G
H
++
C
Example
R
_+
_
+21GG 3G
1H
1
2
G
H
++
C
Example
R
_+
_
+121
21
1 HGG
GG
3G
1
2
G
H
C
Example
R
_+
_
+121
321
1 HGG
GGG
1
2
G
H
C
Example
R
_+232121
321
1 HGGHGG
GGG
C
Example
R
321232121
321
1 GGGHGGHGG
GGG
C
Example 2
Find the transfer function of the following block diagrams
2G3G1G
4G
1H
2H
)(sY)(sR
1. Moving pickoff point A ahead of block2G
2. Eliminate loop I & simplify
324 GGG B
1G
2H
)(sY4G
2G
1H
AB
3G
2G
)(sR
I
Solution:
3. Moving pickoff point B behind block324 GGG
1GB
)(sR
21GH 2H
)(sY
)/(1 324 GGG
II
1GB
)(sRC
324 GGG
2H
)(sY
21GH
4G
2G A3G 324 GGG
4. Eliminate loop III
)(sR
)(1
)(
3242121
3241
GGGHHGG
GGGG
)(sY
)()(1
)(
)(
)()(
32413242121
3241
GGGGGGGHHGG
GGGG
sR
sYsT
)(sR
1GC
324
12
GGG
HG
)(sY324 GGG
2H
C
)(1 3242
324
GGGH
GGG