IoT module 2- 22ETC15H-2022-23 by Dr.Suresha V image.pdf

Introduction to IoT: Module 2 for 1st sem VTU students -2022-23 batch.

1. Introduction to
Internet of Things (IoT)

(Emerging Technology Course for 1st Year: VTU)
Course Code: 22ETC15H/25H

MODULE -2

IoT Sensing & Actuation

Dr. SURESHA V

Professor, Department of E&CE
K.V.G. College of Engineering, Sullia, D.K-574 327

2. Introduction to lof (22ETC15H) - Module 2: Io? Sensing & Actuation

Module 2
10T Sensing & Actuation

= Learning Outcomes
‚After reading this Module, the student will be able to:
‘List the salient features of transducers
= Differentiate between sensors and actuators
+ Characterize sensors and distinguish between types of sensors
List the mul

.ceted considerations associated with sensing

+ Characterize actuators and distinguish between types of actuators

Chapter 5: IoT Sensing and Actuation (Textbook: Page 97-111)

= Introduction

= Sensors

= Sensor Characteristics

+= Sensorial Deviations.

= Sensing Types: Scalar sensing, Multimedia sensing, Hybrid sensing, Virtual
sensing

= Sensing Considerations

= Actuators

= Actuator Types: Hydraulic actuators, Pneumatic actuators, Electric actuators
Thermal or magnetic actuators, Mechanical actuators, Soft actuators, Shape
memory polymers.

+ Actuator Characteristics

‘Text Book: Sudip Misra, Anandarup Mukherjee, Arijit Roy, "Introduction to 10T”,
Cambridge University Press 2021.

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Dr, Suresha V, Professor, Dept. of ERC. KV GC E, Sulla, D.K-S7432 Paget

3. Introduction to lof (22ETC15H) - Module 2: IoT Sensing & Actuation

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Chapter 5: IoT Sensing and Actuation

5.1 Introduction: Sensors play an important role in creating solutions using loT. A
major chunk of IoT applications involves sensing in one form or the other. It is the
front-end functional component in an loT system.

» Definition of Sensor: A sensor is a device that detects and responds to some type
of input from the physical environment. For example, heat is converted to
electrical signals in a temperature sensor, or atmospheric pressure is converted
to electrical signals in a barometer.

" Definition of Transducers: Transducers convert the energy of one kind into
another. A transducer is a physical means of enabling transduction. For example,
in a sound system, a microphone converts sound waves into electrical signals. Or
loudspeaker converts these electrical signals back into sound waves.

= Definition of Actuators: An actuator is a device that produces a motion by
converting electrical energy to mechanical energy going into the system. For

example, motors convert electrical energy to rotary motion.

+ The basic science of sensing and actuation is based on the process of
transduction, Transduction is the process of energy conversion from one form to
another. A transducer is a physical means of enabling transduction. Sensors and
actuators are deemed transducers.

+ ‘Transducers take energy in any form (for which it is

designed) —electrical,
‘mechanical, chemical, light, sound, and others—and convert it into another,
which may be electrical, mechanical, chemical, ight, sound, and others.

Table 51 Basic outline of the

ferences between transducers, sensors, and actuators

acceleration of à body) ce esse or id els)

Parameters | Transducers Sensors ‘Actuators
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Definition | one form to Saris forms of ener, typically
faa nergy no al als" | Yaris forms of ener pi
| Gin te mu To
Domain [represent sensor as | It isan input transduce. Irsa ouput tardar
Can work a sensor | Used Tor — quan | Used Tor converting Spa Tao
Function | oranactsiorbutnot | emronmenalstimufinio | proportional mechanical or
| Simultaneously. | signa, Scr ours
Hamid sensor Temperate | Motor (comen ASG energy
scnsora,Anememsters (mesure | tory malen) Force Beds
Bang | Ansseneror fw veloc), Manometer | (whch mpose à fr), and
tar Cesare sd pressure | Pumps hich comer the rar
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Dr. Suresha V, Professor, Dept. of ERC. KV GCE, Sulla, D.K-S7432

Page 2

4. Introduction to lof (22ETC15H) - Module 2: IoT Sensing & Actuation

5.2 Sensors: Sensors are devices that can measure, quantify, or respond to ambient
changes in their environment. For example, a temperature sensor converts heat into
electrical signals. Figure 5.1 shows the simple outline of a sensing task. Here, a
temperature sensor keeps on checking an environment for changes. In the event of a
fire, the temperature of the environment goes up. The temperature sensor notices
this change in the temperature of the room and promptly communicates this

information to a remote monitor via the processor.

— go —

Temperate

pen Sensor node

Figure 5.1 The outline of a simple sensing operation
+ Classification of Sensors: The various sensors can be classified based on:
(2) Power requirements
(2) Sensor output
(3) Property to be measured
1. Power Requirements: Depending on the requirements of power, sensors can be of
two types.

Active sensors: These sensors do require any external power sources for
their function. It directly responds to the external stimuli from its ambient
1.

environment and converts them into an output signal. For example, a

photodiode converts light into an electrical signal.
Passive:

ensors: Passive sensors do not require an external power source to
operate. For example, a thermistor's resistance can be detected by applying
voltage difference across it or passing a current through it.
2. Sensor Output: Depending on the type of output generated, sensors are broadly
divided into two types,
1. Analog sensor: Analog sensors generate an output signal and it is continuous
in time and amplitude. For example, a thermometer sensor continuously
responds to changes in the temperature of the liquid,

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Dr. Suresha V, Professor, Dept. of ERC. KV GC E, Sullia,D.K-57432. Pages

5. AO a fg
ea

Ji, Digital sensor: These sensors generate the output of discrete-time signals.
‘Typically, binary output signals 1 or O for ON or OFF respectively.
Examples: Digital Temperature Sensor.

3. Measured Property: Depending on the properties to be measured, sensors can be

oftwo types.

1. Scalar sensor: Scalar sensors produce an output proportional to the
magnitude of the quantity being measured, Examples: temperature sensor,
color sensor, pressure sensor, strain sensor, ete, Factors such as changes in
sensor orientation or direction do not affect these sensors.

ii. Vector sensor: The sensor which produces an output signal/voltage which is
proportional to the magnitude, direction, as well as orientation of the
‘quantity being measured, is known as a vector sensor, Examples: Sound
sensor, image sensor, velocity sensor, acceleration sensor, ete.

+ The functional blocks of a typical sensor node in oT: A sensor node is made
up of a combination of ***
(a) Sensor/sensors.(b) Processor Unit
(© RadioUnit (4) Power Unit.
(©) Actuator Unit (optional)

Figure 5.2:

rhe functional blocks of a typical sensor node in loT

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Dr. Suresha V, Professor, Dept. of E&C. KV GC E, Sul

6. Introduction to oT (22ETCISH) - Module 2:1 Sensing & Action @
Description of sensor mode: The nodes are capable of sensing the environment
they are set to measure and communicate the information to other sensor nodes
or a remote host. Typlaly, a sensor node should have low-power requirements
and he wireless. The wireless nature of sensor nodes would alto allow them to ba
freely relocatable and deployed in large numbers without bothering about
managing wires. The functional outline of atypical 10T sensor node I shown in
5.2 andthe function of each block explain below
© Processor: Iisa heat sensor node andi process all the relevant dat, capable
or executing arbitrary code.
© Sensors and actuators: The actual interface to the physical world, devices that
can observe or control physical parameters of the environment.

© Radio (Communication): It sends and receives information over a wireless

channel.
© Power supply: Some forms of batteries are necessary to provide energy. Use

both AC and DC power supply.

5.3 Sensor Characteristic

+ Sensors can be characterized by their ability to sense

the phenomenon based on the following three fundamental properties
1. Sensor Resolution: The smallest possible change that a sensor can detect is
referred to as the resolution of a sensor, For example, sensor A can detect 0.5

degree Celsius changes in temperature; whereas another sensor B can detect

up to 0:25 degree Celsius in temperature. Therefore, the resolution of sensor
B is higher than the resolution of sensor A. The more the resolution of a
sensor, the more accurate the precision. A sensor's accuracy does not depend
upon its resolution.

Sensor Accuracy: The accuracy of a sensor is the ability of that sensor to
measure the value of a system as close to its true measure as possible. For
example, a weight sensor detects the weight of a 100 kg mass as 99.98 kg. We
can say this sensor is 99:98% accurate, with an error rate of 0:02%,

ili, Sensor Precision: The principle of repeatability of a measurement defines the
precision of a sensor. For example, the temperature sensor measures 25.8°C
in repetitive measurements (10 times), and the actual value is 25°C the sensor
is precise but not accurate. On the other hand, each time, if the sensor

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Dr. Suresha V, Professor, Dept. of ERC. KV GC E, Sullia,D.K-57432. Pages

7. Introduction to lof (22ETC15H) - Module 2: Io? Sensing & Actuation

measures different values (25.1, 24.9, 25.2, 24.8, etc). The sensor is accurate

but not precise.

5.4 Sensorial Deviations:*** Various sensorial deviations are considered errors in
sensors. These deviation factors are important for critical loT applications, such
as healthcare, industrial process monitoring, etc. following are the important for

the parameter to define the quality of measurement.

1. Sensor’s limits: it is the sensor output truncated to its maximum or
minimum value,
Fullscale range of sensor: It is the measurement range between a sensor's
characterized minimum and maximum values.

il. Sensitivity error: sensitivity of a sensor may differ from the value specified
for that sensor leading to sensitivity error.

iv. Sensor offset error or bias: If the output of a sensor differs from the actual

value to be measured by a constant. For example, while measuring an actual
temperature of 0°C, a temperature sensor outputs 1.1 °C every time. In this
case, the sensor is said to have an offset error or bias of 1.1°C.

v. Non-linearity of sensor: If a sensors transfer function (TF) deviates from a
straight-line transfer function, itis referred to as its non-linearity.

vi. The drift of the Sensor: If the output signal of a sensor changes slowly and
independently of the measured property, this behavior of the sensor's output is
termed as drift,

vii. Noise in a sensor: It is a temporally varying random deviation of signals.

vill, Hysteresis error: if a sensor's output varies/deviates due to deviations in the
sensor's previous Input values. It is referred to as a hysteresis error. The present
output of the sensor depends on the past input values provided to the sensor.

ix. Quantization error: In digital sensors, this error can be defined as the difference
between the actual analog signal and its closest digital approximation during
analog-to-digital conversion.

x. The measured value by a sensor is different from the specified value refers to
sensorial deviation.

‘+ Finally, the environment itself plays a crucial role in inducing sensorial deviations.

‘Some sensors may be prone to external influences, For example, as most sensors are

semiconductor-based, they are influenced by the temperature of their environment,
SS
Dr, Suresha V, Professor, Dept. of ERC. KV GC E, Sulla, D.K-S7432 Page

8. Introduction to lof (22ETC15H) - Module 2: Io? Sensing & Actuation

5.5 Sensing Types:*** Sensing can be broadly divided into FOUR different categories
based on the nature of the environment being sensed and the physical sensors being

used.
1. Scalar sensing A Ka
2. Multimedia sensing
3. Hybrid sensing N
à. Virtual sensing
ny j

Figure 5.4 The different sensing types commonly encountered in foT

1. Scalar sensing:
= The sensors used for measuring scalar quantities such as temperature, current,
‘atmospheric pressure, rainfall, light, humidity, ete are referred to as scalar sensors.
= Scalar values do not have a directional or spatial property, simply by measuring

changes in the amplitude of the measured values over time.
= Asimple scalar temperature sensing of a fire detection event is shown in Fig 5.4(a),
2. Multimedia sensing:
= The sensors used for

measuring quantities such as images, direction, flow, speed,
acceleration, sound, force, mass, and energy are known as multimedia sensors.

= These quantities have both directions as well as a magnitude, hence these sensors
are also called “vector sensors”,

= A simple camera-based multimedia sensing using surveillance as an example is
shown in Figure 5.4(b).

3. Hybrid sensing:

= The sensors are used to measure both scalars as well as multimedia quantities at the

same time and are referred to as hybrid sensors.

——— ESS
Dr, Suresha V, Professor, Dept. of ERC. KV GC E, Sulla, D.K-S7432 Pa?

9. Introduction to oT (22ETCISH) - Module 2:1 Sensing & Action @

= For example, in an agricultural eld, measure collectively the soi! moistare, sat
temperature, and the color of the leaves to decide a plant's health by a camera sensor.

= Figure 5.(c) shows an example of hybrid sensing, where a camera and a
temperature sensor are collectively used to detect and confirm forest fires during
wildlife monitoring

à. Virtual sensing

= Virtual sensing techniques are also called soft sensing or prog sensing. A viral

sensing ystem uses information available from other measurements and process
parameters to calculate an estimate of the quantity of interest. For example, As
sensors are being used for the actual measurement of parameters; whereas virtual

data is being used for advising B. This is the virtual sensing paradigm.

5.6 Sensing Considerations:*** The following major factors influence the choice of
sensors in loT-based sensing solutions:

a) Sensing range

D) Accuracy and Precision

©) Energy

d) Device size.
a). Sensing range: It is a region where every event that takes place in this region can
be detected by the sensor. The sensing range of a sensor node defines the detection
fidelity of that node. It also is used to signify the upper and lower bounds of a sensor's
measurement range. For example, a proximity sensor has a typical sensing range of a
couple of meters. In contrast, a camera has a sensing range varying between tens of
meters to hundreds of meters.
b). Accuracy and Precision: Amore precise sensor has reproducibility of the
measurement and a more accurate sensor is closer to the actual value. It is critical in
deciding the operations of specific functional processes. Regular temperature sensors
have a very low-temperature sensing range, as well as relatively low accuracy and
precision, not suitable for industrial processes. Industrial sensors are typically very
sophisticated, and as a result, very costly. However, these industrial sensors have very
high accuracy and precision score, even under harsh operating conditions.
9. Energy: The energy consumed by a sensing solution is crucial to determine the
lifespan of the network, Hence the sensor node is so energy efficient in its operation. If
the energy requirements of the sensor nodes are too high, such a deployment will not

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Dr. Suresha V, Professor, Dept. of ERC. KV GC E, Sullia,D.K-57432. Pages

10. Introduction tol (R2ETCIS Modul 2: Sensing cation ee)
last long. and the solution wil be highly infeasible as charging or changing the energy
sources ofthese sensor nodes Is not an option

4), Device Ste: Most of the applications of OT require sensing solutions that are so
small Largar the sia fa sensor node, the larger the obstruction caused by Ie andthe
higher the cost and energy requirements, The wearable sensors are highly energy-

efficient, small in size, and almost part of the wearer's regular wardrobe.

5.7 Actuators

= Anactuator is a component of a machine that is responsible for moving and
controlling a mechanism or system, for example by opening a valve,

= The system activates the actuator through a control signal, which may be digital or
analog.

= An actuator can be a mechanical or electronic system, a software-based system.

= Figure 5.5 shows the outline of a simple actuation system. A remote user sends
‘commands to a processor.

= For example, the processor instructs a motor-controlled robotic arm to perform the
‘commanded tasks accordingly

= The robotic arm finally moves the designated boxes, which was its assigned task.

YH—á—s— !

Motorriven
mecano

vent Factory

Sensor node

Figure 5.5 The outline of a simple actuation mechanism
5.8 Actuator Types:***** Broadly, actuators can be divided into seven classes:
1. Hydraulic actuator
2. Pneumatic actuator
3. Electrical actuator
4. Thermal/magnetic actuator
5. Mechanical actuator
6. Soft actuator
7._Shape memory polymers actuator

SSIS ESE
Dr, Suresha V, Professor, Dept. of ERC. KV GC E, Sulla, DK-S7432 Page

11. Introduction to lof (22ETC15H) - Module 2: Io? Sensing & Actuation

1. Hydraulic actuators: A device that is used to change the fluid's pressure energy into
mechanical linear, rotary, or oscillatory motion. It works on the principle of
compression and decompression of fluids. Example hydraulic car jack.

2. Pneumatic actuators: This is a device that converts the energy of compressed air
into mechanical motion. It works on the principle of compression and decompression
of air. Pneumatic actuators are responsible for converting pressure into force. For
example, pneumatic rack and pinion actuators are commonly used for valve controls of
water pipes. The power source in the pneumatic actuator does not need to be stored in
reserve for its operation.

3. Electric actuators: It is a device that converts electrical energy into mechanical
motion. For example, electric motors relay switches, or solenoid valves. This class of
actuators is considered one of the cheapest, cleanest, and most speedy actuators.

4. Thermal or magnetic actuators: These actuators convert heat or magnetic energy
into mechanical motion. These actuators have a very high power density and are
typically compact, lightweight, and economical. An example of thermal actuators is
shape memory alloys (SMAs). Magnetic shape memory alloys (MSMEs) are a type of
magnetic actuator.

5. Mechanical actuators: These actuators convert the rotary motion of the actuator is
converted into linear motion to execute some movement. The use of gears, rails,
pulleys, chains, and other devices is necessary for these actuators to operate. These
actuators can be easily used in conjunction with pneumatic, hydraulic, or electrical
actuators. An example ofa mechanical actuator is a rack and pinion mechanism.

6. Soft actuators: These actuators convert molecular-level microscopic changes into
tangible macroscopic deformations in the materials. These actuators consist of
elastomeric polymers that are used as embedded fixtures in flexible materials such as
cloth, paper, fiber, particles, and others. These actuators have a high stake in modern-
day robotics, They are designed to handle tragile objects such as agricultural fruit
harvesting or perform precise operations like manipulating internal organs during
robot-assisted surgeries.

7. Shape memory polymers(SMP): SMP is considered smart materials that respond to
some external stimulus by changing their shape, and then revert to their original shape
once the affecting stimulus is removed. Features such as high strain recovery,
biocompatibility, low density, and biodegradability characterize these materials. SMP-based

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Dr. Suresha V, Professor, Dept. of ERC. KV GC E, Sul

12. Introduction to lof (22ETC15H) - Module 2: IoT Sensing & Actuation

5.9 Actuator Characteristics:*** The correct choice of actuators is necessary for the

long-term sustenance and continuity of operations, as well as for increasing the

lifetime of the actuators themselves. A set of FOUR characteristics can define all
actuators:

1. Weight: The physical weight of actuators limits their application scope. Heavier
actuators are generally preferred for industrial applications and applications
requiring no mobility of the loT deployment. In contrast, lightweight actuators are
typically used in portable systems in vehicles, drones, and home IoT applications,

2. Power Rating: It defines the minimum and maximum operating power an actuator
can safely withstand without damage to itself. Generally, it is indicated as the
power-to-weight ratio for actuators. For example, smaller servo motors used in
hobby projects typically have a maximum rating of 5 VDC, 500 mA. In contrast to
this, servo motors in larger applications have a rating of 460 VAC, 2A.

3. Torque to Weight Ratio: The ratio of torque to the weight of the moving part of an
instrument/device is referred to as its torque/weight ratio. This indicates the
sensitivity of the actuator. The higher the weight of the moving part; the lower will
be its torque-to-weight ratio for a given power.

4. Stiffness and Compliance: The resistance of a material against deformation is
known as its stiffness, whereas compliance of a material is the opposite of stiffness,
Si systems are considered more accurate than compliant systems as they have a

faster response to the change in load applied to it.

+ Acknowledgment: My sincere thanks tothe author Prof Sudip Misra, because the above contents
are prepared from his textbook “Introduction ta 107" published by Cambridge University Press
2021.

Prepared by:

Dept

tion Engineering
Reach me ati suresha.veetgnail.com
WhatsApp: [phone]

Dr, Suresha V, Professor, Dept. of ERC. KV GC E, Sulla, D.K-S7432 Page ut