This document discusses different types of control systems. It describes open loop and closed loop control systems. Open loop systems do not use feedback, so they are less accurate than closed loop systems which use feedback to reduce errors. Examples of open loop systems include a TV remote, microwave oven, and alarm system. Closed loop systems are found in applications like dryers, heating systems, elevators, and traffic collision avoidance. The document also covers requirements for good control systems and differences between tracking and control systems.

1. Introduction
Many of the devices used in the home or in
industry require an electronic control system so
that they can operate correctly.
A control system is interconnection of
components forming a system configuration that
will provide a desired response.
Practically every aspects of our day-to-day life is
affected less or more by some control system. A
bathroom toilet tank, a refrigerator, an air
conditioner, a geezer, an automatic iron, an
automobile all are control system.

2. Requirement Of Good Control System
Accuracy: error detector should be present in
control system to increase accuracy
Sensitivity : It should be sensitive to input signal only
Noise : control system should be able tor reduce
noise effect for better performance
Stability: system must be able to remove offset
Bandwidth: bandwidth should be large as possible
for frequency response
Speed :This is the time taken by control system to
achieve its stable output

3. Types Of Control Systems
There are two main types of control system.
They are as follow:
Open loop control system
Closed loop control system

4. Open loop control system
 Open-loop control systems are the systems in which the
output has no effect on the control action.
 In other word an open loop system is a system without
feedback.
Block diagram of Open loop control

5. Examples of open loop control system
1.Open-loop Drying System
 An operator would set a timer (controller) to say 30 minutes and at the end of the 30
minutes the drier will automatically stop and turn-off even if the clothes are still wet .
In this case, the control action is the manual operator assessing the wetness of the
clothes and setting the process accordingly
So in this example, the clothes dryer would be an open-loop system as it does not
monitor or measure the condition of the output signal, which is the dryness of the
clothes. Then the accuracy of the drying process, or success of drying the clothes will
depend on the experience of the user (operator).

6. Examples of open loop control system…
2. Open loop alarm system
 The function of the sensor is to collect data regarding the concerned
house.
 When the electronic sensor is triggered off (for example, by the entry
of an unauthorized person), it will send a signal to the receiver.
 The receiver will then activate the alarm, which will in turn generate
an alarm signal. The alarm signal will not cease until the alarm is
stopped manually.
Block diagram of an open loop control system (burglar alarm)

7. Examples of open loop control system
3.A simple electric fire is used to heat a room
When the supply is turned on, the room temperature increases.
 However, without any further intervention the room will
probably become too warm.
The only way to correct this would be to turn off the supply.

8. Examples of open loop control system
4. TV Remote control

9. Examples of open loop control system
5. Microwave Oven

10. Advantages of open loop system
Simple in construction and design.
Economical.
Easy to maintain.
Generally stable.
Convenient to use as output is difficult to
measure.

11. Disadvantages of open loop system
They are inaccurate.
They are unreliable.
Any change in output cannot be corrected
automatically.

12. Closed loop control system
 Control system in which the output has an effect on the input
quantity in such a manner that the input quantity will adjust itself
based on the output generated
 In other word a closed loop system is called a feedback control
system.

13. Examples of closed loop control system
1.Closed -loop Drying System
This sensor would monitor the actual dryness of the clothes and
compare it with (or subtract it from) the input reference.
The error signal (error = required dryness – actual dryness) is
amplified by the controller, and the controller output makes the
necessary correction to the heating system to reduce any error.
For example if the clothes are too wet the controller may increase
the temperature or drying time. Likewise, if the clothes are nearly
dry it may reduce the temperature or stop the process so as not to
overheat or burn the clothes

14. Examples of closed loop control system…
2.Closed -loop heating system control
The temperature sensor is installed in the room to be controlled
and sends a signal back along the feedback path to the comparison
device incorporated in the controller.
The comparison device compares the value of temperature at
the sensor to that of the desired value or set point on the
controller.

15. Examples of closed loop control system…
3.human-operated liquid-level control system.
In the human-operated system, the eyes, brain, and muscles
correspond to the sensor, controller, and pneumatic valve
respectively.

16. Examples of closed loop control
system…
4. Elevator control system.

17. Examples of closed loop control
system…
5. Traffic collision avoidance system TCAS

18. Advantages of closed loop control system
Closed loop control systems are more
accurate even in the presence of non-linearity.
Highly accurate as any error arising is
corrected due to presence of feedback signal.
Bandwidth range is large.
Facilitates automation.
The sensitivity of system may be made small
to make system more stable.
This system is less affected by noise

19. Disadvantages of closed loop control system
They are complicated to design.
Required more maintenance.
Feedback leads to oscillatory response.
Overall gain is reduced due to presence of
feedback.
Stability is the major problem and more care
is needed to design a stable closed loop
system.

20. Difference between closed loop and open loop
system

21. TRACKING SYSTEM
A tracking system is the one which determines
the location or direction of a target on a near-
continuous basis.
An ideal tracking system would maintain
contact and constantly update the target's
bearing, range and elevation.
The difference between Tracking and Control
System is that, the desired input in control
system now comes from the tracker.

22. Example Of Control System
Radar Servo Control System

23. Example Of Tracking System
Radar Servo Tracking System