Here discussed about open loop and closed loop control system with proper examples diagram.

1. Jamshedul Islam
B.Sc in Textile Engineering (Final Year)
Port City International University, Chittagong, Bangladesh.

2. Open Loop Control System
Any physical system which does not automatically correct for variation in its output, is called an open-loop
system.
Sun/Weather
Solar Cell
PlantSolar Energy Control Signal Electricity
Fig: Representation Diagram of Open loop Control
System

3. In this system,
 We get electricity by conversion of sunlight, where the sunlight is controlled by the sun that means it is
depends on the weather.
 When the sunlight is fall over the solar cell plant that means signal is reach over here then get output
that is electricity.
 In this system, have not any feedback or error signal that’s why implementation feature is not
available.
 Here the power of electricity is depends on the amount of solar power that means output variation is
depending upon on the weather of the earth which is independent.

4. 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 is called closed loop control system. Open loop
control system can be converted in to closed loop control system by providing a feedback. This feedback
automatically makes the suitable changes in the output due to external disturbance.
Controller Actuator Plant
Input Output
Operator Pumper Football
Default
Position
Actual
Position
Measurement Sensor
Feedback loop
Fig: Example Diagram of Closed loop Control System

5. In this system,
 Here desired output is actual shape of the football which is controlled by operator. Due to disturbance
we can’t get actual position after actuating at that time found out output is give a feedback signal into
feedback device or sensor.
 Then the feedback signal (positive or negative) is passed into error signal section, after that operator
controlled that, to get desired result.
 By this feedback process controller has adjusted unless get required output through this
implementation process which known as closed loop control system.
 Finally, we understand that in this control system is not dependent on input to get the desired output
because of the feedback loop mechanism.