explaining the introduction of Block Diagram.

1. Block Diagram Representation of
Control Systems
By MSc. Student
Mohammed AboAjmaa
1By Mohammed AboAjmaa SDU
Dr. Selçuk Comlekçi
A COURSE OFFERED BY
T.C
Suleyman Demirel University
College of Engineering
Electronic And Communications Eng. Department

2. What is Block Diagram
A bock diagram is pictorial representation of the functions
performed by each component and of the flow signals . In a block
diagram all system variables are linked to each other through
functional block, the functional block is a symbol for the
mathematical operation on the input signal to the block that
produces the output. A block diagram is high-level type of flowchart.
It is useful tool in designing new processes or improving existing
processes.
2By Mohammed AboAjmaa SDU

3. 3By Mohammed AboAjmaa SDU
Note: Team members who construct a block
diagram must have a clear understanding of
how the process
operates.

4. Examples about Block Diagram
1- 522113  xaxax
2- 112211  nnn xaxaxax
Draw the Block Diagrams of the following equations:
4By Mohammed AboAjmaa SDU

5. An open-loop controller is a type of controller that
computes its input into a system using only the
current state and its model of the system. A
characteristic of the open-loop controller doesn’t
use feedback to determine if its output has achieved the
desired goal of the input. This means that the system
doesn’t observe the output of the
processes.
Open-loop control system
GH(s)= Open-loop transfer function
5By Mohammed AboAjmaa SDU

6. 6By Mohammed AboAjmaa SDU
Ex:
A digital camera is used to take a photograph, it is
transferred to the computer where processing of the
picture takes place and finally a printout is
produced. This is a open system because no attempt
is made to improve the picture. If the person taking
the picture decides to improve the final printout
using graphics software he has to change to closed
loop system by adding
controller.

7. Closed-loop Control Systems
Feedback control systems are often referred to as closed-loop
control systems. In practice, the term feedback control and
closed-loop control are used interchangeably. In a feedback
control system the actuating error signal is the difference
between the input signal and the feedback signal (which may be
the output signal itself or a function of output signal and its
derivative or integration). The feedback is a fed to the controller
so as to reduce the error and bring the output of the system to a
desired value. The term closed-loop control always mean the use
of feedback control action in order to reduce system
error.
7By Mohammed AboAjmaa SDU

8. The General Form Of Feedback Control
System
8By Mohammed AboAjmaa SDU

9. Characteristic Equation
The control ratio is the closed loop transfer function of the
system:
)()(1
)(
)(
)(
sHsG
sG
sR
sC


The denominator of closed loop transfer function determines the
characteristic equation of the system:
Which given by: 0)()(1  sHsG
9By Mohammed AboAjmaa SDU

10. For the above system The behavior depends on the
value of gain (K).
10By Mohammed AboAjmaa SDU

11. 11By Mohammed AboAjmaa SDU
Ex: Weather Station:
INPUT:
The heat from the sun causes
the temperature sensor to
produce data and this is sent
to the computer.
PROCESS:
Data is received by the
computer and it is
processed. The processed
data is displayed on the
monitor as a graph.
OUTPUT:
The temperature
levels are printed
out. This is one
form of output.
Feedback
The temperature is continuously
monitored and this is called feedback.
As long as the sensor works, the
computer processes and the printer
prints out - feed back is taking place.

12. 12By Mohammed AboAjmaa SDU

13. Reduction techniques
The aim of reduction technique is to simplify
the block diagram and get transfer function.
C(s)
R(s)
=?
13By Mohammed AboAjmaa SDU

14. Reduction techniques procedure
:1. Combining blocks in cascade or in parallel
1G 2G 21GG
1G
2G
21 GG 
14By Mohammed AboAjmaa SDU

15. 2. Moving a summing point behind a block:
G G
G
:3. Moving a summing point ahead of a block
G G
G
1
15By Mohammed AboAjmaa SDU

16. 4. Moving a pickoff point behind a block:
G G
G
1
5. Moving a pickoff point ahead of a block:
G G
G
16By Mohammed AboAjmaa SDU

17. 6. Eliminating a feedback loop:
G
H
G
1H
G
G
1
GH
G
1
17By Mohammed AboAjmaa SDU

18. Find the transfer function of the following
block diagrams:
2G 3G1G
4G
1H
2H
)(sY)(sR
18By Mohammed AboAjmaa SDU

19. Sol:
1-
2-
19By Mohammed AboAjmaa SDU

20. 3-
4-
5-
)()(1
)(
)(
)(
32413242121
3241
GGGGGGGHHGG
GGGG
sR
sY



20By Mohammed AboAjmaa SDU

21. Thanks For Listening
21By Mohammed AboAjmaa SDU