Syllabus

Introduction to Mechatronics: Evolution, Scope, Advantages and

disadvantages of Mechatronics, Industrial applications of Mechatronics,
Introduction to autotronics, bionics, and avionics and their applications. Sensors
and Transducers: Types of sensors, types of transducers and their
characteristics.
Overview of Mechanical Actuation System – Kinematic Chains, Cam,
Train Ratchet Mechanism, Gears and its type, Belt, Bearing
Hydraulic and Pneumatic Actuation Systems: Overview:
Pressure Control Valves, Cylinders, Direction Control Valves,
Rotary Actuators, Accumulators, Amplifiers, and Pneumatic
Sequencing Problems. 2

Q.1 What is “Mechatronics”?

Mechatronics is a concept of Japanese origin (1970’s) and
can be defined as the application of electronics and
computer technology to control the motions of mechanical
systems.

3
 Mechatronics......
 It is a multidisciplinary approach to
product and manufacturing system
design (Figure).

 It involves application of electrical,

mechanical, control and computer
engineering to develop products,
processes and systems with greater
flexibility, ease in redesign and ability
of reprogramming.

 It concurrently includes all these

disciplines.
4

Mechatronics......

 Mechatronics can also be termed as replacement

of mechanics with electronics or enhance
mechanics with electronics.

 For example, in modern automobiles,

mechanical fuel injection systems are now
replaced with electronic fuel injection systems.

 This replacement made the automobiles more

efficient and less pollutant.
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 Mechatronics.....

 By employment of reprogrammable
microcontrollers/microcomputers, it is now easy to add
new functions and capabilities to a product or a system.

 Today’s domestic washing machines are

“intelligent” and four-wheel passenger automobiles
are equipped with safety installations such as air-
bags, parking (proximity) sensors, antitheft
electronic keys etc.
6

Q.2 What are the Advantages of Mechatronics?

1. Mechatronics enhances functionality and features.

2. It brings more efficiency.
3. Mechatronics adds intelligence to design of the system.
4. Mechatronics solutions are less expensive when compared to mechanical
solutions.
5. A mechatronic solution improves design and reliability.
6. It is also more user-friendly and safer to use.
7. Mechatronic uses microcontroller, by which precision, position, speed, flow
rate, and variables can be controlled.
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Q.3 What are the Dis-advantages of Mechatronics?

1. High initial cost of the system.

2. Imperative to have knowledge of different engineering field for design and
implementation.
3. Specific problem for various system would have to be addressed separately
and properly.
4. It is expensive to incorporate mechatronic approach to an existing/old
system.
5. Maintenance and servicing are costly .

Q.4 What are the Industrial application of

Mechatronics?

 Mechatronics based automated systems such as automatic

inspection and quality assurance, automatic packaging, record
making, and automatic dispatch help to expedite the entire
manufacturing operation.
 It is widely used in aeronautics engineering for unmanned
aerial vehicles and automatic pilots. In the defense industry it is
used for automatically guided vehicles and mine detection
robots. 9
 Q.5 Write short notes on Autotronics.
Definition: Autotronics can be defined as the combination of automobile
and electronics or we can say that the use of electronics science in
automobile vehicles is called autotronics.
Major Areas:
 The use of electronics in the automobile field makes the system safe, improved and
efficient.
 At present, in the new generation automobiles almost 75%-85% of automobile parts are
embedded with electronics system.
 The main areas of automobiles using autotronics are engine controlling system, airbags,
antilock braking system, lightening interiors, GPS, music systems etc.
 In the autotronics systems the use of control units like sensors, motors and digital
equipment establishes a communication between the various essential system and
components of the vehicle. 10

Q.6 Write short notes on Bionics.

 Bionics is a field of technology that combines the study of biology

in nature and its patterns, with mechatronics, which combines
mechanical, electronics and software.
 Bionics consists of many different subject areas, but one of the most
eye-catching and popular is bionic implants.
 These implants aim to improve the standard of living for people
who have damaged body parts such as arms, legs, eyes, or even
ears.
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 Working of bionic implants
 It’s extremely hard to mimic the actions created by regular limbs. It’s something that
software and hardware engineers have a lot of trouble working with.
 To solve this, all the successful bionics systems use machine learning to mimic physical
movements.
 Myoelectric (Myo = muscles) sensors are used in bionic limbs to generate an electrical
signal from muscle contractions.
 This is useful because it can get signals from the still functional nerve endings of the
amputated limb. This means that the sensors can pick up when the user wants to
move that area.
 In some cases, to improve the accuracy of myoelectric sensors, small incisions are
made to place them closer to the muscle/nerve endings.
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Q.7 Write short notes on Avionics.

 Avionics are the electronics systems used in aircraft, artificial satellite,
and spacecraft. Avionic systems include communications, navigation, the
display and management of multiple systems, and the hundreds of systems
that are fitted to aircraft to perform individual functions.

 Avionics grew in 1950’s and 1960 as electronic devices which replaces the
mechanical or analog equipment in the aircraft.
 Avionics equipment on a modern military or civil aircraft account for around;
• 30% of the total cost of the aircraft
• 40% in the case of a maritime patrol/antisubmarine aircraft or helicopter.
• Over 75% of the total cost in the case of an airborne early warning aircraft
(AWACS).
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 NEED FOR AVIONICS:
 To enable the flight crew to carry out the aircraft mission safely and
efficiently. For civil airliner the mission is carrying passengers to their
destination. For military aircraft the mission is intercepting a hostile
aircraft, attacking a ground target, reconnaissance or maritime patrol.
Advantages
 Increased safety
 Air traffic control requirements
 All weather operation
 Reduction in fuel consumption
 Improved aircraft performance and control and handling and reduction in
maintenance costs
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Q.8 Define Sensor with an example.

 Sensor: A sensor is a device that provides usable output in response to
change in a specified physical quantity which is measured. A device that
receives and responds to a signal .
 The physical quantity may be temperature, force, pressure, displacement,
flow etc.
 For example, the bulb of a thermometer senses the temperature of the body
in contact

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 Q.9 Define transducer with an example.
 The transducer is a device that changes the physical attributes of the non-
electrical signal into an electrical signal which is easily measurable. The
process of energy conversion in the transducer is known as the
transduction(figure). It consists of two parts:
1. Sensing element/detector
For example : thermometer
2. Transduction element

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Q.10 List the types of sensors.

• Temperature Sensor
• Proximity Sensor
• Accelerometer
• IR Sensor (Infrared Sensor)
• Pressure Sensor
• Light Sensor
• Ultrasonic Sensor
• Smoke, Gas and Alcohol Sensor
• Touch Sensor, colour sensor
• Humidity Sensor
• Flow and Level Sensor
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 Q.11 List the types of transducers.

Types of transducers:
There are of many different types of transducer, they can be classified
based on various criteria as:
1. Transducer based on Quantity to be Measured
• Temperature Transducers (e.g thermocouple)
• Pressure transducers (e.g. a diaphragm)
• Displacement transducers (e.g. LVDT)
• Oscillator transducers
• Flow transducers
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2. Transducer based on the Principle of Operation

• Capacitive
• Inductive
• Resistive
• Photoelectric
• chemical
3. Transducer based on need of an External Power Source
 Active Transducer: Active transducers are those which do not require any power
source for their operation. For example, a thermocouple, thermometer etc.
 Passive Transducer: Transducers which require an external power source for their
operation is called as a passive transducer. For example, a strain gauge,
thermistor etc.
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 Q.12 Explain Characteristics of sensors and transducers
 The performance characteristics are mainly divided into two
categories:
i) Static characteristics ii) Dynamic characteristics
i. Static characteristics:
Static characteristics refer to the characteristics of the system when the input is either held constant or
varying very slowly. Range, sensitivity, linearity, resolution, accuracy, precision, response time etc are
important static characteristics.

ii. Dynamic characteristics:

Dynamic characteristics refer to the performance of the instrument when the input variable is changing
rapidly with time. For example, human eye cannot detect any event whose duration is more than one-
tenth of a second; thus, the dynamic performance of human eye cannot be said to be very satisfactory.
Few important dynamics characteristics are dynamic error, speed of response.
20

Q.13 Define Kinematic Link or Element with an example.

Kinematic Link or Element:

 Every part of a machine which is
having some relative motion with
respect to some other parts will
be known as kinematic link or
element.

 Examples : Piston, Connecting

rod, crank, lever etc.
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 Q.14 Define Kinematic chain with an example.

Kinematic Chain:
 “If all the links are connected in
such a way that first link is
connected to last link in order to
get the close chain and if all the
relative motion in this close chain
are constrained then such a chain
is known as kinematic chain”.

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 Q.15 Define mechanism and machine.

Mechanism:
 “If one of the links of kinematic
chain is fixed then it will be
known as mechanism”.
Machine:
 “When a mechanism is utilized in
order to get desired output with
respect to given input then it will
be known as a machine”.
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Q.16 Define CAM with diagram.

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 Q.17 What are the types of CAM ?.

Types of Cams:
Cams can be classified according to
 Shape
 Follower movement
 Manner of constraint of the follower
1. Wedge and flat cams
2. Radial or disc cams
3. Spiral cams
4. Cylindrical cams
5. Spherical cams 26

1. Wedge and flat cams

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2. Radial or disc cams

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3. Spiral cams

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4. Cylindrical cams

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5. Spherical cams

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Q.18 What are the types of followers ?.

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33
 Q.19 What is the use of gears or gear drive ?

Gears are used to

 Transmit power
 Change the velocity
 Change the direction

Gear Ratio:

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Q.20 Explain the types of gears .

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 38

Spur gear : This is Cylindrical gear. Teeth are parallel to axis. This is
a highly demanded gear, which is easy to manufacture and to
assemble.
Helical gear : This is a Cylindrical gear. Teeth have helix curve.
Helical gear provides more strength, less oscillation and lower
noise level compared with Spur gears.
Internal gear : This is a cylindrical gear ring with teeth formed at
the inner diameter.
Straight bevel (Miter) gear: Miter gear has shaft angle of 90° and
gear ratio of 1:1.
Rack and pinion : „A rack is a gear whose pitch diameter is infinite,
resulting in a straight line pitch circle. Used to convert rotary
motion to straight line. 39
 Q.21 What do you mean by gear trains ?.

 The term gear train is defined as a series of intermeshed

gear wheels.
 It is required when large distance is there between two
gears.
 It is required when very high/very low velocity ratio is
required.

 Gear train may be simple gear train or may be

compound gear train.
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41
 Q.22 Explain Simple Gears Train.
 Every shaft is having only one gear as shown in the fig.
 For such a gear train, the overall gear ratio is the ratio of
the angular velocities at the input and output shafts.

42

43
 Q.23 Explain Compound Gears Train.

 At least one of the intermediate shaft must have more

than one gear in use.

46

47
 Q.24 What do mean by Ratchet Mechanism
 In Ratchet Mechanism, gearing are arranged in such a way that certain links are
temporarily or periodically locked together or connected during the action of the
mechanism.
 This locking of relative motion may be so effected that relative motion of the two
links is only possible in one sense or direction (when the gear is called by
Reuleaux a Running-ratchet Train), or movement in both directions may be
rendered impossible when the ratchet acts, in which case the gear is known as a
Stationary-ratchet Train.

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 Each consists of a frame or arm a, ratchet-wheel b, and

ratchet or click c. In the first figure b is evidently
capable of left-handed rotation only, so long as the
ratchet c (sometimes called a pawl) is resting against
its teeth.
 In the second figure motion is only possible when the
pawl is lifted clear.

52
 Q.25 What is belt drive?
 Belt drives use the friction that develops between the pulleys attached to
the shafts and the belt around the arc of contact in order to transmit a
torque.
 The torque is due to the differences in tension that occur in the belt during
operation.
 Let T1 is the tension in the tight side and T2 is the tension in slack side.

53

 In previous case driven wheel rotating in the same direction

as the driver wheel.

 As shown in the diagrams below driven wheel is rotating in

the opposite direction as the driver.

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 Q.26 What are the various types of belts
used for power transmission?

Flat : The belt has a rectangular cross-section and produces

less noise. They can transmit power over a long distance
between pulley centers
 Round : The belt has a circular cross-section and used with
grooved pulleys.
V : V-belts are used with grooved pulleys and are less
efficient than flat belts.

55

Q.27 Write the definition of bearing and its

classification.

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 57

Q.28 Explain Hydraulic system.

 The controlled movement of parts or a controlled application of
force is a common requirement in the industries.
 These operations are performed mainly by using electrical
machines or diesel, petrol and steam engines as a prime mover.
 These prime movers can provide various movements to the
objects by using some mechanical attachments like screw jack,
lever, rack and pinions etc.
 However, these are not the only prime movers. The enclosed
fluids (liquids and gases) can also be used as prime movers to
provide controlled motion and force to the objects or
substances.
58
 Hydraulic system……

 The specially designed enclosed fluid systems can provide both

linear as well as rotary motion.
 The high magnitude controlled force can also be applied by using
these systems.
 This kind of enclosed fluid based systems using pressurized
incompressible liquids as transmission media are called as
hydraulic systems.
 The hydraulic system works on the principle of Pascal’s law
which says that the pressure in an enclosed fluid is uniform
in all the directions.
59

Hydraulic system……..
 The Pascal’s law is
illustrated in figure.

 As the pressure is same in

all the direction, the smaller
piston feels a smaller force
and a large piston feels a
large force.

 Therefore, a large force can

be generated with smaller
force input by using
hydraulic systems. 60
Q.29 What are the Basic Components of Hydraulic
System?

61

Basic Components of Hydraulic System………..

The hydraulic systems consists a number of parts for its
proper functioning. It consists of:
 a movable piston connected to the output shaft in an
enclosed cylinder
 storage tank
 filter
 electric pump
 pressure regulator
 control valve
 leak proof closed loop piping.
62
Q.30 What are the applications of hydraulic systems
The hydraulic systems are mainly used for precise control of
larger forces. The main applications of hydraulic system can be
classified in five categories:

1. Industrial: Plastic processing machineries, steel making and

primary metal extraction applications, automated production lines,
machine tool industries, paper industries, loaders, crushes, textile
machineries, R & D equipment and robotic systems etc.

2. Mobile hydraulics: Tractors, irrigation system, earthmoving

equipment, material handling equipment, commercial vehicles,
tunnel boring equipment, rail equipment, building and construction
machineries and drilling rigs etc. 63

3. Automobiles: It is used in the systems like breaks, shock

absorbers, steering system, wind shield, lift and cleaning etc.

4. Marine applications: It mostly covers ocean going vessels,

fishing boats and navel equipment.

5. Aerospace equipment: There are equipment and systems

used for rudder control, landing gear, breaks, flight control and
transmission etc. which are used in airplanes, rockets and
spaceships.

64
 Q.31 Explain Pneumatic system.

 Pneumatic technology deals with the study of behavior and

applications of compressed air in our daily life in general
and manufacturing automation in particular.

 Pneumatic systems use air as the medium which is

abundantly available and can be exhausted into the
atmosphere after completion of the assigned task.

65

Q.32 What are the Basic Components of

Pneumatic System?

66
Important components of a pneumatic system are shown in fig.

a) Air filters: These are used to filter out the contaminants from the air.

b) Compressor: Compressed air is generated by using air compressors. Air

compressors are either diesel or electrically operated. Based on the
requirement of compressed air, suitable capacity compressors may be used.

c) Air cooler: During compression operation, air temperature increases.

Therefore coolers are used to reduce the temperature of the compressed air.

d) Dryer: The water vapor or moisture in the air is separated from the air by
using a dryer.

67

e) Control Valves: Control valves are used to regulate,

control and monitor for control of direction flow, pressure etc.

f) Air Actuator: Air cylinders and motors are used to obtain

the required movements of mechanical elements of
pneumatic system.

g) Electric Motor: Transforms electrical energy into

mechanical energy. It is used to drive the compressor.

h) Receiver tank: The compressed air coming from the

compressor is stored in the air receiver
68
 Q.33 What do you mean by Valves in hydraulic
and pneumatic systems.

Valves are used with hydraulic and pneumatic

systems to direct and regulate to fluid flow.

1. Direction Control Valves

2. Pressure Control Valves

69

Q.34 What do you mean by Direction Control Valves?

 Pneumatic and hydraulic systems use directional control Valves to direct

the flow of fluid through a system.

 They do not vary the rate of fluid flow but either completely open or
completely closed i.e. ON/OFF devices.

 They might be activated to switch the fluid flow direction by means of

mechanical, electrical or fluid pressure signals.

 A common type of directional control valve is the spool valve.

70
Spool Direction Control Valves

71

Spool Direction Control Valves…..

 A spool moves horizontally within the valve body to control
the flow.
 In fig (a) the air supply is connected to port 1 and port 3 is
closed.
 Thus the device connected to port 2 can be pressurized.
 When the spool is moved to the left ( in fig b) the air supply is
cut off and port 2 is connected to port 3.
 Port 3 is a vent to the atmosphere and so the air pressure in
the system attached to port 2 is vented.
 Thus the movement of the spool has the air firstly to flow into
the system and then be reversed and flow out of the system.
72
Q.35 What do you mean by Pressure Control Valves?

 These are used to control the pressure in hydraulic and

pneumatic system
 There are three main types of pressure control valves
.
a) Pressure regulating valves

b) Pressure – limiting/relief valves

c) Pressure sequence valves

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a) Pressure regulating valves

 These are used to control the operating pressure in a

circuit and maintain it at a constant value.

74
 b) Pressure – limiting/relief valves
 These are used as safety devices to limit the pressure in a circuit
to below some safe value.
 The valve opens and vents to the atmosphere, or back to the
sump, if the pressure rises above the safe value.
 It has one orifice which is normally closed.

 When the inlet pressure

overcomes the force exerted by
the spring, the valve opens and
vents to the atmosphere, or
back to the sump.
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c) Pressure sequence valves

 These are used to sense the pressure of an external line
and give a signal when it reaches some pre-set value.
 With the pressure limiting valve, the limiting pressure is set
by the pressure at the inlet to the valve.
 We can adapt such a valve to give a sequence valve.
 This can be used to allow to flow occur to some part of the
system when the pressure has risen to the required level.
For example in an automatic machine we might require
some operation to start when the clamping pressure applied
to a work piece is at some particular value.
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 Pressure sequence valves

77

Q.36 Define Actuators.

 Actuators are output devices which convert energy from pressurized
hydraulic oil or compressed air into the required type of action or
motion.
 In general, hydraulic or pneumatic systems are used for gripping and/or
moving operations in industry. These operations are carried out by using
actuators.

 In general actuators can be classified into two types.

1. Linear actuators: These devices convert hydraulic/pneumatic energy

into linear motion.(Ex-cylinder)

2. Rotary actuators: These devices convert hydraulic/pneumatic energy

into rotary motion. (Ex-Gear motor) 78
The construction of hydraulic and pneumatic linear
actuators is similar.

However they differ at their operating pressure

ranges.

Typical pressure of hydraulic cylinders is about

100 bar and of pneumatic system is around 10
bar.
79

Q.37 Explain working single acting cylinder.

 These cylinders produce work in
one direction of motion hence they
are named as single acting
cylinders.
 Figure shows the construction of a
single acting cylinder.
 The compressed air pushes the
piston located in the cylindrical
barrel causing the desired motion.
 The return stroke takes place by
the action of a spring.
 Generally the spring is provided on
the rod side of the cylinder. 80
 Q.38 Explain working double acting cylinder.
 The main parts of a hydraulic double
acting cylinder are: piston, piston rod,
cylinder tube, and end caps.
 As shown in the fig. the piston rod is
connected to piston head and the
other end extends out of the cylinder.
 The piston divides the cylinder into
two chambers.
 The seals prevent the leakage of oil
between these two chambers.
 The cylindrical tube is fitted with end
caps. .
81

Double acting cylinder…….

 The pressurized oil, air enters the
cylinder chamber through the ports
provided.
 In the rod end cover plate, a wiper
seal is provided to prevent the leakage
of oil and entry of the contaminants
into the cylinder.
 The piston seal prevents metal to
metal contact and wear of piston head
and the tube. These seals are
replaceable.
 End cushioning is also provided to
prevent the impact with end caps.
82
 Q.39 Explain rotary Rotary Actuators.
 Rotary actuators convert energy of pressurized
fluid into rotary motion. Rotary actuators are
similar to electric motors but are run on
hydraulic or pneumatic power.
 It consists of two inter meshing gears inside a
housing with one gear attached to the drive
shaft.
 Figure shows a schematic diagram of Gear
motor.
 The air enters from the inlet, causes the rotation
of the meshing gear due to difference in the
pressure and produces the torque.
 The air exits from the exhaust port.
 Gear motors tend to leak at low speed, hence
are generally used for medium speed
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applications.