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Lecture 01 : Introduction : Sensing and Actuation — Transcript

by NPTEL IIT Kharagpur · 4,503 words · 690 segments · language en · Watch on YouTube

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0:00[Music]
0:20so in this course you are going to learn
0:26about industry 4.0 and industrial IOT
0:32III ot so we will get into the depth of
0:36each of these in detail throughout the
0:39course however let us first try to
0:42understand what is central to each of
0:46these technologies so a IOT is
0:50industrial IOT which is about the
0:53applications of IOT in the industry so
0:57there are some industry specific
0:58requirements for which the existing IOT
1:02technology which have applications in
1:04different different domains will have
1:07specific requirements of industries and
1:09will have to be tailored to cater to
1:11those industrial requirements so that is
1:16where industrial IOT comes into picture
1:19and is so much popular particularly in
1:22the industry nowadays most of the
1:24industries globally they are
1:26transforming they have been mandated to
1:29transform to be industry 4.0 compliant
1:33and they are transforming towards that a
1:38adoption of a IOT technologies so we
1:43will be learning about the different
1:45aspects of each of these industry 4.0
1:47and I IOT but first let us try to
1:50understand what is I o T so very briefly
1:55IOT is about Internet of Things you know
1:59a technology which tries to build up an
2:03Internet work of different things and
2:06what are these things these things are
2:08different physical objects different
2:11physical objects that we use that we see
2:13around us and so on these physical
2:16objects could be anything and everything
2:19that we can think of starting from
2:24things like the truth process which we
2:28use very early in the morning to the air
2:31conditioner of the room to the heating
2:35system in the projection system in front
2:37of us and this also includes the
2:41traditional computational devices such
2:45as computers PDAs laptops and so on so
2:51computational as well as the traditional
2:53computational devices plus the present
2:57the present different physical objects
3:01all these objects that I mentioned like
3:03the toothbrush projection system heating
3:05system
3:06you know this refrigeration system and
3:09so on so all of these things would be
3:12inter networked would be interconnected
3:14and then this inter network is going to
3:20send lot of data which will have to be
3:23processed in order to make use out of
3:28the data that have been retrieved so
3:32there are different uses of it so IOT
3:36finds applications in building smart
3:38homes for instance smart cities and so
3:42on so there are even different
3:43components of smart cities like smart
3:46transportation smart parking smart
3:48healthcare and so on and so forth so IOT
3:50finds applications in making cities and
3:53homesmart in the industrial context we
3:56are trying to think about an extension
3:59of all of these to serve making
4:04industrial processes much more efficient
4:06and autonomous so we will look into each
4:10of these now before we do that in this
4:13lecture let us try to understand that
4:15what is central to the IOT or a IOT so
4:21what is central are basically certain
4:23things known as sensors and actuators
4:27and there are few other associated
4:29peripheral technologies also which we
4:32will cover in subsequent lectures but
4:34sensing and actuation is key to
4:37Oh tea as well as a IOT right so let us
4:41try to understand what is this sensor
4:43and what is this actuator so before we
4:48do we need to understand that both
4:52sensors and actuators can be classified
4:56as transducers so these are like
4:59transducers so so sensors actuators are
5:01transducers so what what is a transducer
5:05so transducer basically is something
5:07that converts the signal in one form
5:11into a signal in another form so so let
5:18us you know let us look at this diagram
5:21in front of us so we have over here we
5:26have a sensor we have an actuator so
5:33this sensor plus the processor which
5:39will basically process the input that is
5:41coming from these sensors this is a
5:46transducer so this is a transducer
5:49similarly actuator plus processor is
5:54also it transducer alright so as you can
5:59see over here this transducer and the
6:05sensor inside it take some input signal
6:09and produce a certain output sense
6:13certain output which will be processed
6:16further and based on the processed data
6:20there will be something that will be
6:22actuated so all throughout as we can see
6:26there is some kind of energy
6:28transformation that is happening and
6:31this actuator then produce a certain
6:33output so this is how sensors or
6:39transitive earth sensors or actuators as
6:42transducers work so let us look further
6:46so we have the concept of transducer
6:49which as I said
6:51is some device which converts a signal
6:55from one physical form to another
6:57physical form and these physical forms
7:00could be like electrical form mechanical
7:04form you know magnetic form thermal
7:07chemical optical and so on so what we
7:12are seeing is that a transducer is not
7:15nothing but an energy converter it
7:18converts the energy from one form to the
7:23energy in another form so for instance
7:29things like microphone the traditional
7:33microphone the microphone basically
7:35converts sound signals to electrical
7:38signals which basically are then you
7:43know amplified further and the speaker's
7:46basical through the speakers we are able
7:47to hear right so this is basically the
7:50concept of how a microphone works so
7:54microphone is an example a traditional
7:56example of a transducer a speaker is
8:00also likewise a converter of energy from
8:04electrical form to sound so a speaker is
8:07also another example of the transducer
8:12similarly we have antennas which will
8:16convert electric electromagnetic energy
8:17into electrical energy and vice versa so
8:21antenna is also a transducer and there
8:24are many many other examples such as a
8:26strain gauge which is also an example of
8:29a transducer so let us try to understand
8:37sensors as transducers so what is that
8:40sensor sensor as this name suggests
8:43sense is something senses what sense is
8:47the physical quantity the physical
8:50changes the physical characteristic of
8:54the environment in which it is operating
8:58so a temperature sensor for example will
9:02sense the changes in the temperature of
9:05the N
9:05in which the sensor the temperature
9:08sensor has been deployed is operating so
9:12this is an example so it is basically a
9:15the characteristic of a device or
9:18material to detect the presence of a
9:21particular physical quantity and in this
9:23particular example that I have given you
9:25this physical quantity is this
9:27temperature so the changes to detect the
9:30presence the change in the temperature
9:33is what a temperature sensor would do so
9:37the output of the sensor is a signal
9:38which is converted to some human
9:41readable form and these human readable
9:43forms can be different different forms
9:45changes in the current characteristics
9:47changes in the voltage current required
9:50characteristics changes in the
9:52resistance changes in the capacitance
9:55changes in the impedance so these
9:57changes are understandable by humans so
10:03this is this human understandable or
10:05readable form that is referred to over
10:07here so a sensor basically performs some
10:17function of input by sensing or feeling
10:20the physical changes in the
10:21characteristic of a system in response
10:23to some stimulus so these stimulus are
10:27basically physical parameters this
10:30stimulus could be changes in the
10:31temperature changes in the lighting
10:33condition changes in the gas so these
10:37gases could be like a gas sensor for
10:38instance would sense changes in
10:41different gases for which they have been
10:43in a fabricated to sense so a for
10:46example there could be a methane sensor
10:48methane gas sensor a carbon dioxide
10:50sensor carbon monoxide sensor oxygen
10:53sensor so these are basically sensors
10:55which have been devised to sense the
10:59changes in the amounts of these gases in
11:03the environment right so gas sensors are
11:05basically incidentally very much useful
11:08to monitor different presence of
11:11different gases particularly in our
11:13current context of environment
11:14monitoring gas sensors are very useful
11:16they are also very useful for mining
11:18environments so for example
11:20ten sensors are used in the mines to
11:21detect the the the increase in methane
11:25gas possible increase in methane gas in
11:28coal mines and as you know that these
11:31gases are very dangerous so it is very
11:33important so IOT in mines for example
11:35you need to use different gas sensors
11:37right if it is for gas monitoring
11:39application so these sensors are very
11:41much useful so temperature pressure
11:43pressure means atmospheric pressure
11:45atmospheric temperature or it could be
11:47temperature of any any particular object
11:50so all these different sensors could be
11:52used for for this particular purpose so
11:56then we have that something is sensed
12:00and the response is in the form of some
12:04changes in the resistive cap resistive
12:08capacities changes in the capacitive
12:12capacities and so on or or changes in
12:15current voltage characteristics in so
12:17all these characteristics current
12:18voltage resistance capacitance impedance
12:22you know so all these so these come as
12:24in the form of the output so here are
12:30some pictures of certain sensors and
12:34these are the ones the sensors actually
12:36that I have in my lab and there are many
12:39other sensors also I picked up these
12:41ones in order to show you how different
12:44sensors look like and these are not the
12:47only ones actually the sensors basically
12:49they come in different shapes and sizes
12:50so there are some these are like you
12:53know macro sized sensors but you could
12:55also have micro sized sensors which are
12:57like MEMS based sensors there could be
12:59nano sensors also so these are like you
13:02know even more you know advanced kind of
13:05sensors that are available and these
13:09sensors have different different
13:11purposes so this is a temperature and
13:15humidity sensor this is a gas sensor for
13:19detecting LPG gas methane carbon
13:21monoxide and so on
13:23this is an ultrasonic sensor this is a
13:26camera sensor you can see the camera
13:28over here camera sensor this is PIR
13:31sensor
13:33this is rain detector sensor and this is
13:37fire detector sensor so you have so many
13:40different different types of sensors now
13:42let me see if I can show you some of
13:45these different sensors so this is a PIR
13:52sensor okay this is a PIR sensor and we
14:01have this is an ultrasonic sensor this
14:08ultrasonic sensor can help you to detect
14:12how far a particular object is so this
14:17sensor can help you in that
14:18so obstacles basically obstacles can be
14:23detected with the help of this sensor
14:26and this basically works on the basis of
14:29you know ultrasound is sound wave that
14:32is sent from one of these two cylinders
14:34that you can see over here so one
14:37cylinder sends a you know sound signal
14:39it gets reflected by that obstacle and
14:41is detected by the other and then based
14:44on that you know this entire sensor
14:47works like you know how far a particular
14:49obstacle is where if there is an
14:51obstacle in its range and so on let me
14:55show you another sensor of different
14:57type this is basically the color sensor
15:01it can detect colors different types of
15:04colors this is an accelerometer sensor
15:11accelerometer then we have the gas
15:18sensor carbon monoxide more specifically
15:21this sensor can detect carbon monoxide
15:25gas then we I have also brought for you
15:31another sensor which is the rain gauge
15:33right serene basically rainfall sensor
15:35this will detect the rainfall right so
15:40we have different different sensors now
15:43let us go back to our discussion what we
15:46were having
15:47earlier so we have these different types
15:53of sensors these sensors have their own
15:56different ways of operating but let us
15:59try to understand first the
16:03characteristics of sensors at a very
16:06high level in general the
16:08characteristics of sensors can be
16:09classified into two types the static
16:12characteristics and the dynamic
16:14characteristics so before that let me
16:17try to tell you about how a particular
16:20sensor works so different sensors have
16:22different operating mechanisms but in
16:24general what happens is after you have
16:27you know after you know a sensor starts
16:31its operation so it takes a while in
16:34general not necessarily in many cases it
16:37will take a while to come to something
16:39called the steady state so it will come
16:41to a steady state of operation and then
16:44it will work in that steady state so
16:47static characteristics basically are
16:50about the characteristics of a
16:52particular sensor in the steady state
16:55condition in the steady state once the
16:57sensor has come to its steady state in
17:00that steady state how the output of a
17:02sensor changes in response to the input
17:05change and dynamic characteristics are
17:08before that so these dynamic
17:10characteristics are about the properties
17:13of the system systems transient response
17:15transient response to an input right so
17:20before basically the sensor achieves the
17:23steady state this is what it captures so
17:26this static characteristics could be
17:28characteristics such as accuracy and as
17:31this name suggests it is about the
17:33correctness of the output compared to
17:35the suit to a superior system how much
17:37accurately in other words how much
17:39correctly how much accurately the sensor
17:41measures whatever it is supposed to
17:44sense right then we have another
17:49characteristic static characteristic
17:51which is the range range means the range
17:53of operation lowest value to highest
17:55value how much is the range of operation
17:57of a particular sensor lowest
17:59temperature to highest temperature
18:01of a particular temperature sensor is
18:03the range of that particular sensor
18:06right then we have resolution and
18:11resolution is about the smallest change
18:14in the input that a sensor is capable of
18:17sensing smallest change the resolution
18:19like the resolution of a camera for
18:21instance similarly you have the
18:22resolution of a of a sensor like a
18:25temperature smallest change in
18:26temperature for instance that a
18:28particular temperature sensor is able to
18:31sense or detect is basically the
18:33resolution of a particular sensor error
18:36is basically the difference between the
18:38standard value and the value produced by
18:40the sensor that is the error
18:41characteristic sensitivity sensitivity
18:46indicates the ratio of incremental
18:48change in the response of the system
18:50with respect to the incremental change
18:52in the input parameter right so that is
18:55basically the sensitivity of a sensor
18:57then the linearity characteristic is
18:59about that the deviation of a sensor has
19:02in its value from the straight line
19:06curve so if you draw the curve of
19:08behavior of a particular sensor so the
19:11deviation it has from the straight line
19:13is the linearity of linearity
19:15characteristic of a particular sensor
19:17then you have the characteristic like
19:20drift drift is about that if you keep a
19:22particular sensor for long duration of
19:24time in a particular temperature for if
19:28it is a temperature sensor or any other
19:29sensor for a particular reading
19:31condition if you are keeping it for a
19:33sufficiently long duration of time then
19:35the difference in measurements that will
19:37so over the period of time is the drift
19:40then we have the repeatability
19:42characteristic which is the deviation
19:45from the measurements in a sequence
19:47under the same condition conditions so
19:48whether the same value can be repeatedly
19:51obtained under the same conditions by
19:53the same sensor is basically the
19:55repeatability characteristic of that
19:57particular sensor now let us come to
20:02those were the static characteristics
20:03now let us come to the dynamic
20:06characteristic so dynamic
20:10characteristics is about if you are
20:12changing the input
20:14inputs how well the sensor responds to
20:18its changes in the input so the
20:21transients that are received are
20:23captured through the dynamic
20:25characteristics so you have different
20:27things like zero ordered system which is
20:31basically a system which where the
20:33output shows a response to the input
20:35signal with no delay and these zero
20:40order systems do not include energy
20:42storing requirements so basically a
20:45potentiometer for instance measures the
20:49C the linear and rotary displacements
20:51right so this is an example of a zero
20:56order system first order system are when
21:01the output approaches its final value
21:04gradually this is faster gradually is
21:06very key to this particular thing the
21:09first order system and these systems
21:12will have some kind of mechanism for
21:14energy storage and dissipation both
21:17right so typically you know let us say
21:20there could be a capacitance for example
21:22a capacitor which will store this energy
21:25and dissipate over the duration of time
21:27in these systems second order systems
21:31will have complex output response not
21:34gradually but a complex output response
21:36and this output response of these
21:39sensors will typically oscillate before
21:42the steady-state right so it will be
21:45something like this it will be something
21:48like if you are plotting then you know
21:52it could be something like this before
21:55that steady state is arrived so this
22:00oscillation for solution between certain
22:03values right so these are basically for
22:06the complex you know output response of
22:10these systems these are the second order
22:14systems now let us look at how these
22:19sensors could be classified the sensors
22:22could be classified in different
22:23different ways they could be classified
22:25as either passive sensor or active sense
22:27analog sensor or digital sensor scalar
22:30sensor or vector sensor so let us look
22:32at what are these a passive sensor
22:35cannot independently sense the input so
22:38examples of passive sensors are
22:40accelerometer soil moisture water level
22:44temperature sensor and so on but active
22:48sensors are the ones which can
22:50independently sense the input for
22:54instance rather as the sensor is an
22:57example of an active sensor a sounder
23:00altimeter sensors and so on then let us
23:05look at another classification analog
23:07versus analog versus digital so analog
23:12sensors again as these name suggests
23:14produces output which is some continuous
23:18function of the input parameter examples
23:21would be temperature sensor light
23:23detection sensor LDR pressure sensor
23:27analog pressure sensors the analog
23:29variants of these pressure sensors
23:31analog Hall effect sensor or magnetic
23:33sensors and so on a LDR source
23:35continuous variation in its resistance
23:37as a function of intensity of light
23:39falling on it digital sensors are
23:44basically the ones where the response is
23:46of binary nature and these have been
23:50designed in order to overcome some of
23:53the limitations of the analog sensors
23:55which produces continuous function part
23:57of the output with respect to the input
24:00changes change characteristics so so
24:04there is some analog to you know digital
24:07conversion that is there in most of
24:10these digital sensors so examples of
24:12digital sensors would be PIR sensor
24:15digital thermo temperature sensor and so
24:18on scaler sensors and vector sensors
24:24scalar sensor are basically the ones
24:27which will measure only the magnitude of
24:30the input parameter only the magnitude
24:33you know basically it is a difference
24:35between scalar values and the vector
24:37values the which basically shows the
24:40difference in this
24:41since enforces the vector sensor so the
24:44response of a sensor is a function of
24:46the magnitude of the input parameter
24:47only the magnitude of it so nothing else
24:50and these are not affected by the
24:54direction of the input parameter so
24:57examples of it would be temperature
24:58sensor gas sensor strain sensor color
25:01sensor smoke sensors these are all
25:02examples of the scalar sensor because
25:06you know these the detection of these
25:08parameters do not depend on the change
25:10in the direction of the input change the
25:14direction of temperature change in the
25:16direction of gas it saturates it doesn't
25:18get affected by that but the quantity of
25:21the temperature quantity of the gas
25:23present you know and so on then we have
25:28the vector sensors which are basically
25:31the response of the sensor depends on
25:33the magnitude of the magnitude the
25:35direction and the orient is not only the
25:37magnitude but also the direction and the
25:39orientation examples would be
25:40accelerometer gyroscope magnetic field
25:43motion detector sensors and so on so let
25:47us look at how an actuator basically
25:50works so as you can see in this
25:53particular figure an actuator takes two
25:57inputs one input is the energy so there
26:01has to be some kind of an energy supply
26:02energy source and some signal some
26:06signal and together these will be taken
26:11by the actuator to produce some kind of
26:13a motion such as the force or whatever
26:18so an actuator is a part of the system
26:21that deals with the control action that
26:23is required the mechanical action so so
26:27typically mechanical but this could be
26:28mechanical or electromechanical and so
26:32on so you could have you know mechanical
26:34actuators or yet mechanical actuators
26:38and so on
26:44so let me now show you some pictures of
26:49actuators that I have in my lab there
26:52are many others but these are some of
26:54these pictures of actuators so this is
26:58an actuator this is an electric relay so
27:03this relay what it does is it transforms
27:05the electrical energy into some kind of
27:11mechanical action so or it could be
27:14electromechanical as well so you know
27:17these relays are very much useful for
27:20performing taking an electric signal and
27:23performing some kind of mechanical
27:27option or sorry mechanical operation
27:29such as you know turning on a particular
27:34valve turning off a valve turning on a
27:38device such as a compressor turning off
27:41a device such as a compressor and so on
27:42so this is a relay which is an actuator
27:45then this is a motor a DC motor this is
27:50a DC motor as you can see over here this
27:53is a DC motor and this motor is also an
27:57actuator and you know what a motor does
27:59so this is one motor there could be
28:02different different types of motors and
28:04each of these is basically an actuator
28:09examples of actuators and let me show
28:13you another actuator which is basically
28:16another type of motor which is known as
28:18the stepper motor
28:19so this stepper motor is also an example
28:23of another type of actuator you could
28:26also have actuators like these which I
28:28think most of you have already seen
28:30right so you have these these could also
28:34be actuators right and you know what it
28:37is these are the LEDs so a really a an
28:42LED could be turned on or off in
28:45response to something something being
28:48sensed let us say it gas being present
28:51so you turn on the LED so that becomes
28:54an example of an actuator
28:59okay so let us now go forward so an
29:03actuator basically what it does is it
29:06takes a control signal as an input and
29:10also the input of some energy source and
29:15then it performs its operation so here
29:19is the picture of a DC motor and I
29:21already show you so do you live the you
29:24know how a DC motor looks like
29:25similarly aerial relay is another
29:27example electric relay these are
29:30different different examples electric
29:31motors solenoid valves hard drives
29:34stepper motor chrome drive then you have
29:37hydraulic cylinder piezoelectric
29:38actuator pneumatic actuators these are
29:41different different types of actuators
29:42and these actuators can come in
29:44different shapes and sizes these could
29:46be micro actuators macro actuators and
29:49so on depending on the size of these
29:51actuators so the class shooters can be
29:55classified into different types and
29:57these are some of these examples
29:59Electric linear electric rotary fluid
30:02power linear fluid power rotary linear
30:04chain actuator manual linear manual
30:06rotary these are some different types of
30:09classifications of actuators now let us
30:11look at this electric linear actuator so
30:16as this name suggests these are
30:19basically powered by electric signal
30:21these actuators are powered by electric
30:23signal and these basically that electric
30:26signal electric energy in these
30:28actuators is transformed to achieve some
30:33kind of linear displacement and that is
30:35why these are known as you know electric
30:39linear actuators these could be you know
30:42examples could be electric bill and this
30:46is the picture that you can see the
30:47animated one so electric bill opening
30:50and closing of dampers locking doors
30:52breaking machine motions and so on these
30:55are examples of use of electric linear
30:59actuators then the next one is Electric
31:03rotary actuator so you know an example
31:07is what you see in front of you now
31:09these are powered by electrical
31:11signals these are powered by electrical
31:13signals and converts the electrical
31:14energy into as this name suggests the
31:17rotational motion so the previous one
31:20was electrical energy into linear
31:22displacement and this one is electrical
31:26energy into rotational motion so you
31:28know what a turn verbs valves and
31:32different different other you know
31:34electrical motors for example these are
31:37all examples of electric rotor actuator
31:41then you have the fluid power linear
31:44actuator and again as this name suggests
31:46these are powered by different electric
31:49fluid
31:49sorry hydraulic fluids gas or air
31:52pressure and so on and produces linear
31:54displacement then you have fluid power
31:58rotary actuator again or by fluid such
32:02as gas liquids and so on but produces
32:06rotational motion like the example that
32:08you see the picture that you see in
32:10front of you rotational motion is
32:11produced as a as an output of these
32:15these actuators then you have the linear
32:19chain actuator which basically consists
32:22of devices mechanical devices such as
32:25sprockets and sixth sense of chains
32:27which produce you know linear motion by
32:32the free ends of the specially designed
32:34chips and the picture is in front of you
32:37in order to understand how these work so
32:40these are primarily used in motion
32:41control applications then we have the
32:46manual linear actuator which provides
32:48linear displacement through the
32:50translation of manually rotated screws
32:52or gears so here basically it is not
32:54automatic here it is manual so manual
32:57rotation is performed on some screws or
32:59whatever and consequently there is some
33:01linear displacement so these are the
33:02manual linear actuators so these are you
33:05know examples of these could be found in
33:08gear boxes hand operated operated knobs
33:10wheels etc and they are primarily used
33:13for manipulating tools and work pieces
33:16then you have the manual rotary
33:18actuators which provide rotary output
33:20through the translation of manually
33:22rotated screws reverse or gears gears
33:25and these are primarily used for the
33:27operation of bulbs so with this we come
33:30to an end of this particular lecture on
33:34sensors and actuators and as I told you
33:37at the outset sensors are and actuators
33:40are basically key to the building of IOT
33:44and a IOT based systems and you know
33:49everywhere throughout you will see that
33:51in this course we are talking about the
33:54use of sensors and actuators and this
33:56preliminary understanding about each of
33:58these the sensors and actuators is
34:00necessary for you to have an in-depth
34:03understanding about how a IOT works so
34:08these are some of these references in
34:09front of you there are many more to be
34:12there but I think these will be
34:14sufficient and whatever I have discussed
34:15is sufficient for you to have the basic
34:18understanding to go forward and
34:20understand the other lectures in this
34:23course thank you

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