Open & Closed Loop Control Systems Video Lecture - Electrical Engineering (EE)

This video is on the topic open-loop and
closed loop systems Hello friends in
this video we are going to study about
the types of control systems there are
two types of control systems open-loop
control systems and closed loop control
systems in open-loop control systems the
output it is directly controlled by the
input
so we can say that any system which is
not having the feedback structure then
it will be a open-loop control system
that is why the open-loop control
systems they are also known as non
feedback systems
let's take an example to illustrate the
open-loop control systems
this example is about the speed control
of an automobile so you can see that the
input to the system is the desired speed
desired speed means the speed which we
want there is a controller at a engine
of the automobile and the output of the
engine or the system is the actual speed
so in this open-loop system there is no
way in which the actual speed is
controlled automatically okay so the
actual speed it may be far away from the
desired speed that is the automobile
when it is running on the road and then
the speed which we are getting it may be
different from the our desired speed so
there may be a controller which is
attached in it and it is working on the
engine so the speed which we want maybe
we don't get it as an output so this is
an open-loop system
okay s and there is no feedback
structure in this system so that we can
have an interpret of the actual speed
and we can make it close to the desired
speed so this is an example of an
open-loop control system now if we draw
the generalized block diagram of an
open-loop control system then how it
will be
this is let's compare it with our
example this is our input this is our
controller the output of the controller
is the control input now this control
input it is given to the system on this
system there may be some disturbances
which are acting on it if the
disturbances they are produced inside
the system then they will be called
internal disturbances and there might be
disturbances which are due to the
external environment so that those
disturbances are known as external
disturbances so we are having a input
which is known as the disturbance input
now the signal which is coming out of
the system it is called the output of
the system so this is the way in which
we can represent a generalized open-loop
control system
now let's see some examples of open loop
control system let's take examples from
which we see in our daily life okay
so the first example of open loop
control system is the electric errand
which we see in our Oh remember that
this electric Aaron is not that
automatic electric current this is the
simple electric Aaron the input to which
it is the power supply and the power
supply is connected to the electric
current and the output of the electric
iron is the heat so it is the open loop
control system second example is a fan
water tank in water times the input is
the water which is getting stored in the
tank and the output is also the water
now the boy water tanks when they are
filled up to the upper level then there
is no phenomena or there is no process
in that that we can get an indication
that the water tank is full so these are
the ordinary water tanks the next
example of open loop control system is
emotion heater
in emotion heater also there the output
is the heating of the element and there
is no mechanism we just apply the power
supply and the heater it gets heated up
and there is no mechanism that when it
has attained the maximum temperature
then the power supply should be switched
off so this is an example of an
open-loop control system so we have
studied the definition of open-loop
control system and we have drawn the
generalized block diagram of the
open-loop control system and then we
studied few examples on it now let's
study the second type of control system
which is the closed loop control system
in closed loop control system the output
has an effect on the control action of
the input
that is in the control closed-loop
control systems the output it is feed
back to the input
that is by the closed loop control
system they are also known as the
feedback systems
now to get an example of the closed-loop
control system
let's take the earlier example which we
have taken for the open-loop control
system so let's draw the diagram for it
so in this example the input is the
desired speed and this input it is given
to the controller and the controller it
gives us the control input and this
control input it is given to the engine
an engine gives us the output as the
actual speed now this speed it is
feedback to the input by the speed
sensor the speed sensor it senses the
speed actual speed and a comparison is
made between the desired speed under
actual speed if the actual speed it is
less than the desired speed then the
according to that manipulations are done
so that the controller it will do some
control action on the engine so that we
get the desired speed as the output now
this speed sensor it feedbacks the
actual speed to the drivers eye and the
brain system the driver looks that what
speed he wants and what he is actually
getting so the brain system and the
drivers eye they are using this actual
speed and comparing it with the desired
speed now when the driver he has made
the comparison between the actual speed
and the desired speed then he will now
see done some can do some control action
on it and this control action will be
done by the combination of the linked
muscles of the driver and the
accelerator and the pedal accelerator
so the driver even subdue some changes
on the leg muscles and x-ray he will
either press it more or release it the
accelerator pedal so that the speed will
be changed and then that manipulations
will be done on the engine and we will
get the desired output so this is the
example of the speed control of an
automobile or we can say that it is an
example of a closed loop control system
where the output it is feed back to the
input
now let's represent the closed loop
control system in a generalized way
so this is the way in which we can
represent a general closed-loop control
system we have an input and this input
it is applied to the comparator which
compares the input with the feedback
signal according to that it gives the
input to the controller now the
controller it does some control action
on the input and gives the output as the
control input this control input it is
given to the system and the system gives
us the output now the output which we
get it is feedback to the measurement
device or it is measured by this device
and this device will give the output as
a feedback signal to the comparator
again the comparison is made and
according to the input the output will
be changed now there are also some
disturbances which are acting on the
system so they are represented by the
disturbance these disturbances can be
noise or unwanted signals which we don't
want in a system so this is the general
block diagram of a closed loop control
system now let's see some examples of
closed loop control system
first example is voltage stabilizers
voltage stabilizers are used in houses
of many of us
so the voltage stabilizers the first
example of closed loop control system is
voltage stabilizers for in voltage
stabilizers the voltage it is regulated
that is how much voltage the device is
needed that voltage will be provided by
the the instrument voltage stabilizer
okay so the output it is controlled by
the input the next example of closed
loop control system is
automatic electric it's automatic
electric Aaron the temperature which we
bond we can change it by moving the norm
so in this way we are adjusting the
temperature of the electric atom so the
desired temperature which we are wanting
that is provided by the device so this
is an example of a closed loop control
system next example is what it ends with
float ball the ordinary water times we
have seen that they are example of the
open loop closed system so open loop
control system because in those systems
there is no process or no mechanism was
present there they went the water tank
is filled how we are going to get that
information so in water tanks which are
having the float ball the bend the water
tank it is completely filled then the
float ball it cuts the supply of water
into the water tank okay so there is no
wastage of water these water times
having the float ball they are an
example of closed loop control system so
these were the examples of the closed
loop control system in this video we
have studied about the open loop curve
control systems and closed loop control
system we have represented these systems
as the general block diagram and then we
have seen some examples of open loop and
closed loop control systems so I hope
that you have clearly understood the
topic thank you