Unit 5_measurement & control.pptx

Fundamental of Mechanical Engineering
Measurements and Control System

Syllabus
Introduction to Measurement: Concept of Measurement,
Error in measurements, Calibration, measurements of
pressure(Bourdon Tube Pressure and U-Tube Manometer),
temperature(Thermocouple and Optical Pyrometer), mass
flow rate(Venturi Meter and Orifice Meter), strain(Bonded
and Unbonded Strain Gauge), force (Proving Ring) and
torques(Prony Brake Dynamometer); Concepts of accuracy,
precision and resolution.
Introduction to Mechatronic Systems: 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, Ratchet Mechanism, Gears and its type, Belt,
Bearing.
Hydraulic and Pneumatic Actuation Systems: Overview:
Pressure Control Valves, Direction Control Valves, Rotary
Actuators, Accumulators and Pneumatic Sequencing
Problems.

Measurement
Measurement is the process of determining the value of magnitude of an unknown
quantity by comparing it with some predetermine standard of reference.
The measurement may involve a simple linear rule to scale the length of a part.
It may require a sophisticated measurement of force versus deflection during a tension
test.
Measurement provides a numerical value of the quantity of interest, within certain limits
of accuracy and precision.

Inspection
Procedure in which a part or product feature, such as a
dimension, is examined to determine whether or not it
conforms to design specification. Many inspections rely on
measurement techniques, while others use gauging
methods
• Gauging determines simply whether the part
characteristic meets or does not meet the design
specification.
• Gauging is usually faster than measuring, but not much
information is provided about feature of interest.

Metrology
Metrology is the science of measurement. It includes
all theoretical and practical aspects of measurement.
Concerned with seven fundamental quantities
(standard units International Bureau of Weights and
Measures (BIPM):
•Length (meter)
•Mass (kilogram)
•Time (second)
•Electric current (ampere)
•Temperature (degree Kelvin)
•Light intensity (candela)
•Matter (Objects that take up space and have
mass are called matter) (mole)

Metrology
From these basic quantities, most other physical quantities are derived, such
as:
• Area
• Volume
• Velocity and acceleration
• Force
• Electric voltage
• Heat energy

Characteristics
of
measurement
systems
9
The system characteristics are to be known, to choose
an instrument that most suited to a particular
measurement application. The performance
characteristics may be broadly divided into two groups,
namely ‘static’ and ‘dynamic’ characteristics.
•Static characteristics: The performance criteria for
the measurement of quantities that remain constant or
vary only quite slowly.
•Dynamic characteristics: The relationship
between the system input and output when the
measured quantity (measurand) is varying rapidly.

10
Cont…Characteristics of measurement systems
Accuracy
Accuracy describes the nearness of a measurement to the standard or true value, i.e.,
a highly accurate measuring device will provide measurements very close to the
standard, true or known values.
Example: in target shooting a high score indicates the nearness to the bull's eye and is
a measure of the shooter's accuracy. Refer to pictures below:

12
PRECISION
Precision is the degree to which several measurements provide answers very close to each
other. It is an indicator of the scatter in the data. The lesser the scatter, higher the
precision.
EXAMPLES
If we measure the length of a foot-ruler and get values of 12.01 in, 12.00 in, 11.99 in, 12.00
in. These numbers are precise enough for us to believe that if we measure it again we
would get 12.00(+-).01 in. These measurements are precise but necessarily accurate. The
foot-ruler may actually be metric ruler of 30.0 cm long. Our measurement is precise but
not accurate.
APPROXIMATIONS
Even though physicists usually try for a high degree of precision, there are times when only
a close approximation is need. Physicists some times make rough estimates for making
tentative decisions. The accuracy of estimates depends on reference materials available,
time devoted, and experience with similar problems.

Accuracy vs. Resolution
True value
measurement

Accuracy vs. Precision
Precision
without
accuracy
Accuracy
without
precision
Precision
and
accuracy

15
RESOLUTION
Resolution is the ability of the measurement system to detect and faithfully indicate small changes in the
characteristic of the measurement result.
It is the smallest change in a measured variable to which an instrument will respond.
SENSITIVITY
Sensitivity of an instrument is defined as the ratio of the magnitude of Output signal to the magnitude of
input signal. It denotes the smallest change in the measured variable to which the instrument responds. The
sensitivity of an instrument is the smallest amount it can measure, of whatever it's built to measure.
Sensitivity = Change in Output signal / Change of input signal

16
RANGE AND SPAN
 Range represents the minimum and maximum values which can be determined by an instrument
or equipment.
 Difference between upper and lower range is known as Span.
 Span can be the same for two different range instruments.

DEAD ZONE
Dead zone is defined as the largest change of input quantity for which there is no output
of the instrument.
DEAD TIME
Dead zone is defined as the largest change of input quantity for which there is no output
of the instrument.
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Sensors
A device for sensing a physical variable of a physical system or an environment.
Classification of Sensors
Mechanical quantities: Displacement, Strain, rotation velocity, acceleration, pressure, force/torque,
twisting, weight, flow
Thermal quantities: Temperature, heat.
Electromagnetic/optical quantities: Voltage, current, visual/images, light, magnetism.
Chemical quantities: Moisture, pH value
Physical
phenomenon
Measurement
Output

Specifications of Sensor
• Accuracy:
Error between the result of a measurement and the true value being
measured.
• Resolution:
The smallest increment of measure that a device can make.
• Sensitivity:
The ratio between the change in the output signal to a small change in
input physical signal. Slope of the input-output fit line.
• Repeatability/Precision:
The ability of the sensor to output the same value for the same input
over a number of trials.

Attributes of Sensors
• Operating Principle: Embedded technologies that make sensors function, such as electro-optics,
electromagnetic, piezoelectricity, active and passive ultraviolet.
• Dimension of Variables: The number of dimensions of physical variables.
• Size: The physical volume of sensors.
• Data Format: The measuring feature of data in time; continuous or discrete/analog or digital.
• Intelligence: Capabilities of on-board data processing and decision-making.
• Active versus Passive Sensors: Capability of generating vs. just receiving signals.
• Physical Contact: The way sensors observe the disturbance in environment.
• Environmental durability: will the sensor robust enough for its operation conditions

The difference between the real value and the estimated value of a
quantity is known as measurement error. An error may be positive or may be
negative. The deviation of the measured quantity from the actual quantity or
true value is called error. The errors may be classified as:
Errors in measurements
GROSS ERRORS RANDOM ERRORS SYSTEMATIC ERRORS

1) GROSS ERROR:
This class of error mainly covers human mistakes in reading instruments, recording and calculating
measurement results. Gross errors may be of any amount and therefore their mathematical analysis
is impossible.(Personal errors).
2) SYSTEMATIC ERRORS (BIAS):
Systematic errors due to faulty or improperly calibrated instruments. These may be reduced or
eliminated by careful choice and calibration of instruments. Sometimes bias may be linked to a
specific cause and estimated by analysis. In such a case a correction may be applied to eliminate or
reduce bias. Bias is an indication of the accuracy of the measurement. Smaller the bias more
accurate the data.
3. RANDOM ERRORS:
Random errors are due to non-specific causes like natural disturbances that may occur during the
measurement process. These cannot be eliminated. The magnitude of the spread in the data due to
the presence of random errors is a measure of the precision of the data. Smaller the random error
more precise is the data. Random errors are statistical in nature. These may be characterized by
statistical analysis.

 Systematic errors in the output of many instruments are due to factors
inherent in the manufacture of the instrument arising out of tolerances in the
components of the instrument.
 They can also arise due to wear in instrument components over a period
of time.
 In other cases, systematic errors are introduced either by the effect of
environmental disturbances or through the disturbance of the measured
system by the act of measurement.
SOURCES OF SYSTEMATIC ERROR

S.NO. SYSTEMATIC ERRORS RANDOM ERRORS
1 It can be controlled by magnitude
and sense.
It cannot be determine from the knowledge of
measuring system
2 It is repetitive nature It is non consistent
3 Property analyzed can be
determine and reduced
Cannot be eliminated
4 These types of errors are due to
improper condition or procedures.
Random errors are inherent in the measuring
system.
5 These include the variation in
atmospheric conditions,
misalignment errors.
It includes error due to displacement of level
joints, error due to friction.

Classifications of ERRORS
A) Error of Measurement:
B) Instrumental error
C) Error of observation
D) Based on nature of errors
E) Based on control

A) Error of Measurement:
1) Systematic error:
It is the error which during several measurements, made under
the same conditions, of the same value of a certain quantity,
remains constant in absolute value and sign or varies in a
predictable way in accordance with a specified law when the
conditions change. The causes of these errors may be known or
unknown. The errors may be constant or variable. Systematic
errors are regularly repetitive in nature.
2) Random error: This error varies in an unpredictable manner in
absolute value & in sign when a large number of measurements of
the same value of a quantity are made under practically identical
conditions. Random errors are non-consistent. Random errors are
normally of limited time duration.
3) Parasitic error: It is the error, often gross, which results from
incorrect execution of measurement.

B) Instrumental error:
1) Error of a physical measure: It is the difference between the nominal value and
the conventional true value reproduced by the physical measure.
2) Error of a measuring mechanism: It is the difference between the value
indicated by the measuring mechanism and the conventional true value of the
measured quantity.
3) Zero error: It is the indication of a measuring instrument for the zero value of
the quantity measured.
4) Calibration error of a physical measure: It is the difference between the
conventional true value reproduced by the physical measure and the nominal
value of that measure.
5) Error due to temperature: It is the error arising from the fact that the
temperature of instrument does not maintain its reference value.
6) Error due to friction: It is the error due to the friction between the moving
parts of the measuring instruments.
7) Error due to inertia: It is the error due to the inertia (mechanical, thermal or
otherwise) of the parts of the measuring instrument

C) Error of observation:
1) Reading error: It is the error of observation resulting from incorrect reading of the
indication of a measuring instrument by the observer.
2) Parallax error: It is the reading error which is produced, when, with the index at a
certain distance from the surface of scale, the reading is not made in the direction of
observation provided for the instrument used.
D) Based on nature of errors:
1) Systematic error: (already discussed)
2) Random error: (already discussed)
E) Based on control:
1) Controllable errors: The sources of error are known and it is possible to have a
control on these sources. These can be calibration errors, environmental errors and
errors due to non-similarity of condition while calibrating and measuring.
2) Non-controllable errors: These are random errors which are not controllable

Calibration
Calibration is process of defining the system response to known, controlled signal inputs.
Importance of Calibration
Assurance of accurate of measurements
Ability to trace measurements to International standards
International acceptance of test/calibration reports
Correct diagnosis of illness (medical reports)
Consumer protection (legal metrology)
Meeting the requirements of ISO 9000 and 17025

Pressure is defined as the force acting per unit area. It is the normal force exerted by
a medium(usually a fluid),on a unit area. It is measured in N/m^2
1 pascal=1N/m^2
1 bar=10^5 or 750.06 mm of hg
1 atm=760 mm Hg
Relation between various pressure terms-

Absolute Pressure (P abs)
It is the pressure measured with reference to vacuum. For a complete
vacuum, pressure measured is absolute zero pressure.
Pabs = Pgauge + Patm
Static Pressure
It is the pressure where no
motion is occurring of the
liquid. Its value increases as
the liquid head in the tank
increases.
Dynamic Pressure
It is the pressure that it
exerts on its surroundings
while the fluid is in motion. It
increases as the liquid velocity
increases.

• Absolute pressure=Atmospheric pressure + gauge pressure
• Absolute pressure=Atmospheric-vacuum pressure
Some Fluid = Some Pressure = Some absolute pressure
No Fluid = No Pressure = Zero absolute pressure
gage
atm
abs P
P
P 

WHY MEASURE PRESSURE?
Pressure negates the properties of a fluid: State, flow, forces.
Quality and Safety of Operation: Tire, compressors, etc.
Pressure measurements is used in various general, industry and research applications.

Pressure measuring instrument
Low Pressure measuring instruments
Pressure below 1 mm Hg is considered low pressure. Unit of low pressure are torr
and micron.
1 torr=1 mm hg =133.322368 pascals
1 micron=10^-3 torr
Moderate Pressure measuring instrument
For measuring pressure above 1 mm Hg and below 1000 atmosphere.
High Pressure measuring instrument
For measuring pressure above 1000 atmosphere.

It is also known as Bourdon gauges. It works in principal that volume
of gas whose pressure is to be measured is trapped and then
compressed
P1V1=P2V2
Where, P1 = Pressure of gas at initial condition (applied pressure).
P2 = Pressure of gas at final condition.
V1 = Volume of gas at initial Condition.
V2 = Volume of gas at final Condition.
essed isothermally.
(It is used foe measuring the pressure in range 0.01 to 1000 microns).

Bourdon Tube
It consists of a metal tube oval-cross section, bent in the form of circular shape having
200 to 250°.
The tube has two ends, out of which one end is sealed and closed. This end is connected to
pointer and scale through deflection arrangement. Types of Bourdon Tube
1. C-Tube, 2. Helical, 3. Spiral, 4. Twisted
Advantage
1. Bourdon gauges are more robust than manometers.
2. Bourdon tubes are also used in liquid, gas
filled thermal system for measurement of
temp.
3. They are relatively less expensive.
Limitation
1. Accuracy in precision measurements is limited
2. These are influenced by shock and vibrations.

Elastic element:
• They have been employed to design and manufacturing pressure
measuring instrument.

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Elastic elements
1. Bourdon tube

Manometer:
Manometer is a device used to measure pressure at a single
or multiple points in a single or multiple pipelines, by
balancing the fluid column by the same or another column of
fluid.
Manometers work by the principle that a column of fluid in a
tube will rise or fall until its weight is in equilibrium with the
pressure differential between the two ends of the tube.
The manometer consists of a tube filled with liquid of
known density. A pressure difference across the tube causes
the liquid to shift position. The change in position can be
measured to give the pressure. Best suited to static pressure
measurement.
For a pressure difference P is the height difference h between
the level of liquid in the two halves of the tube A and B, is
given by the equation P = pgh, where p is the density of the
fluid in the tube.
Manometers are difficult to use for small pressure changes,
unsuitable for measuring high pressure.

Pitot tube
A right angled glass tube placed in the pipe one end of the tube faces the
flow while other end is open to atmosphere hollow tube is mounted on the
wall of the pipe. Which measures only static pressure at the pipe These two
tubes senses the pressure at different place within the pipe.
V = C√2gh

Venturimeter
The converging takes place at an angle of 21° +2° the velocity of fluid increases as it
passes through the converging section and correspondingly pressure falls.
Toaccomplish a maximum recovery of kinetic energy the diffuser section is made with an
included angle 5° to 7o.
Advantages:
1. High pressure recovery is attainable.
2.Because of smooth surface, the meter is not much affected by wear and abrasion.
3. Well established characteristics.
4. Due to low value of losses the co-efficient of discharge is high.

Instruments (According to principles)
•Change in physical dimension (Thermal expansion) :
• Expansion in solids : bimetallic thermometers
• Expansion in liquids : liquid in glass thermometers
• Changes in pressure :
• Vapour filled thermometers
• Liquid filled thermometers
• Gas filled thermometers
•Change in electrical properties:
• The thermoelectric effect ( Thermocouple)
• Resistance thermometers
• Sensitivity of semiconductor device
•Change in emitted thermal radiation:
• Radiation pyrometers
• Optical pyrometers
•Colour change

Expansion Thermometers
1. Liquid in glass thermometer 2. Bimetallic thermometer
• Different common forms of
bimetallic sensors are listed:-
• Helix type.
• Spiral type.
• Cantilever type.
• Flat type.

Seebeck effect
If two wires of dissimilar metals are joined at both ends and one
end is heated, current will flow.
Voltage is a function of temperature and metal types.

Thermocouple
Thermocouples are temperature
measurement sensors that generate a
voltage that changes over temperature.
Thermocouples are constructed from
two wire leads made from different
metals. The wire leads are welded
together to create a junction. As the
temperature changes from the junction
to the ends of the wire leads, a voltage
develops across the junction.
Combinations of different metals create
a variety of voltage responses. This
leads to different types of
thermocouples used for different
temperature ranges and accuracies.

Applications
•Thermocouples are suitable for measuring over a large temperature range, up to 2300 °C.
•They are less suitable for applications where smaller temperature differences need to be measured
with high accuracy, for example the range 0-100 °C with 0.1 °C accuracy.
Advantages
• Self-powered: As the output emf increases according to temperature changes, there is no
necessity for an external power source. Thus, thermocouples are self-sufficient in their
operation.
• Simple and Robust: In terms of design, these sensors are simple. They are constructed
with different types of high strength metals, including aluminum, iron, copper, and
platinum. This allows the sensors to be used in a variety of demanding industrial
applications.
• Inexpensive: Thermocouples are known to be inexpensive in terms of price.
• Wide Temperature Range: Thermocouples directly measure the temperature in an
application. They have the capabilities to measure temperatures up to 2600oC.

Pyrometer
A pyrometer is a noncontact device and it is also known as a radiation thermometer. The main function
of this instrument is to detect the surface temperature of an object by measuring the temperature of
the electromagnetic radiation generated from the object.
So, thermal radiation can be measured by using this non-conductive device. By using this, we can
determine the temperature of the surface of the object. There are different types of pyrometers
available in the market like infrared and optical pyrometers.
Optical Pyrometer
In an optical pyrometer, the temperature measurement is
done by comparing the brightness. A color disparity with
the increase in temperature can be taken as an index of
the temperature. This type of pyrometer contrasts the
intensity of the generated image through a source of the
temperature of the lamp.
The current within the lamp is regulated until the lamp’s
brightness is equivalent to the image brightness generated
through the source of temperature. When the light
intensity of any wavelength depends on the temperature
of the radiating object, then the flow of current through
the lamp becomes a measure of the temperature source
when adjusted.

Advantages:
• It is used for high temperatures.
• It is used to check the distant objects as well as moving the object’s temperature.
• Accuracy
• It can be measured without connecting with the target.
• Less weight
• It is flexible and portable.
Disadvantages:
• More chances of human error while adjusting the image.
• It measures the temperature of only hot surfaces.
• Due to the radiation of thermal background, dust, and smoke, the accuracy of this device can be affected.
• These do not apply to the temperature measuring of burning gases because they do not emit visible energy.
• It is expensive.
Applications
• It is used to measure the temperature of highly heated materials
• It is useful to measure furnace temperatures.
• It is used in critical process measurements of semiconductor, medical, induction heat treating, crystal growth, furnace
control, glass manufacture, medical, etc.

Strain Measurements
Strain
gauge

• Strain in a body subjected to direct tensile and compressive force is defined as ratio of
change in length to its original length .
• It is a dimensionless quantity .
L
L




The strain gauge
The strain gauge is a transducer used to measure strain and associated stress. When a metal wire
(or conducting wire) is stretched or compressed, its length and diameter change due to which the
resistance and also the resistivity of the wire will change.
Types of Strain Gauges
• Unbonded strain gauges
• Bonded strain gauges.
Unbonded strain gauges
In an unbounded strain gauge, the strain gauge is not directly bonded to the surface which is
subjected to stress. It consists of resistance wire stretched between frames A and B with the help
of insulated pins as shown. These two frames are movable with respect to each other, and this
arrangement can be connected in one of the arms of Wheatstone's bridge. When the pressure or
force which is to be measured is applied, frame A moves with respect to frame B. This causes a
change in the length and cross-section of the strain gauge which in turn causes its resistance to
change.
Due to this change in resistance, the bridge will be unbalanced and produces some output
voltage, which indicates the change in resistance, which in turn gives the value of applied
pressure.
Advantages of Unbonded Strain Gauge :
•It has greater accuracy.
•This gauge can be used in the range of ±0.15% strain.
Disadvantages of Unbonded Strain Gauge :
•It requires more space.

Bonded strain gauges
Bonded strain gauges are directly placed or bonded on the surface of the
device or component which is subjected to stress.
The figure below shows the measurement of pressure or strain using a
metal foil bonded strain gauge. A metal foil strain gauge of 0.02 mm is
bonded on the surface of the device under observation.
When a force or pressure is applied to the device, its physical dimensions
will change. Since a metal foil strain gauge is pasted on its surface, the
dimensions of the metal foil strain gauge change, which causes it to
change its resistance.
This change in resistance can be measured by connecting this gauge in
one of the 4 arms of the balanced Wheatstone bridge. This connection
makes the bridge unbalance, and some output voltage will be generated
which gives the value of resistance. This measured resistance gives the
applied force.
Advantages of Bonded Strain Gauge :
•Accuracy is more.
•This can be available in different shapes.
•High sensitivity and stability.
•Perfect bonding can be done.
•Can measure high pressure.
Disadvantages of Bonded Strain Gauge :
•These are sensitive to change in temperature.

Force Measurement
(The Proving Ring)
The proving ring is a device used to measure force. It
consists of an elastic ring of known diameter with a
measuring device located in the center of the ring.
Proving rings can be designed to measure either
compression or tension forces. Some are designed to
measure both. The basic operation of the proving ring in
tension is the same as in compression.
The proving ring consists of two main elements, the ring
itself and the diameter-measuring system, shown on the
right in the exploded view of a proving ring. Forces are
applied to the ring through the external bosses. The
resulting change in diameter, referred to as the deflection
of the ring, is measured with a micrometer screw and the
vibrating reed mounted diametrically within the ring.
To read the diameter of the ring, the vibrating reed is set
in motion by gently tapping it with a pencil. As the reed is
vibrating, the micrometer screw on the spindle is adjusted
until the usa-button on the spindle just contacts the
vibrating reed, dampening out its vibrations.

Torque Measurement
(Prony Brake Dynamometer)
Pony Brake is one of the simplest
dynamometers for measuring power output
(brake power). It is to attempt to stop the
engine using a brake on the flywheel and
measure the weight which an arm attached
to the brake will support, as it tries to rotate
with the flywheel.
The Prony brake shown in the above consists of a wooden block, frame, rope, brake shoes and
flywheel. It works on the principle of converting power into heat by dry friction. Spring-loaded bolts
are provided to increase the friction by tightening the wooden block.
The whole of the power absorbed is converted into heat and hence this type of dynamometer must
the cooled.
The brake power is given by the formula
Brake Power (Pb) = 2πNT
Where T = Weight applied (W) × distance (l)

Definitions of Mechatronics
According to Mechatronics forum, UK
The synergistic integration of Mechanics and Mechanical Engineering,
Electronics, Computer Technology and IT to produce or enhance
products or systems.
According to W. Bolton
A mechatronic system is not just a marriage of Mechanical and Electrical
system and it is more than just a control system: it is a complete
Integration of all of them.
Concluded Definition:
“Mechatronics is synergistic Integration of Mechanical Engineering,
Electronics and Intelligent computer control in design and
manufacturing of products and process.”

Graphical Representation of Mechatronics showing Integrated
and Inter-disciplinary approach of nature

Evolution OR Development of Mechatronics
Development of Mechatronics has gone through 3 stages:
1. Stage 1 (1970’s)
2. Stage 2 (1980’s)
3. Stage 3 (1990’s)
Stage 1 (1970’s)
• Technologies developed rather independently and individually.
• Main focus was on servo technology.
• Simple implementation aided technologies related to control
methods.
Example: Automatic door openers and Auto focus Cameras.

Stage 2 (1980’s)
• Synergistic Integration of different technologies takes place.
• Concept of Hardware Software Co-design started.
• Main focus was on Information Technology.
• Microprocessors were embedded into mechanical systems to
improve performance.
Example: Optoelectronics (Integration of Optics and Electronics)
Stage 3 (1990’s)
• Centered on communication technologies to connect products into
large networks.
• Production of the computational Intelligent systems, technologies
and products.
• Miniaturization of components in the form of micro actuators and
micro sensors.
Example: Micro mechatronics

1996: First Journal (IEEE) on Mechatronics was released
After 2000: Application in aerospace, defense engineering, Bio-Mechanics, Automotive
Electronics, Banking (ATM) etc.
SCOPE OF MECHATRONICS
Mechatronics combine the various discipline to create a smart product
which is better than the sum of its parts depending upon the market
demand.
• Dynamic market conditions
• Producing next generation products
• Integration of modern technologies in product
• Variety in product ranges

• Batch production runs
• Change in design perspective
• Product quality and consistency
• Ease of reconfiguration of the process
• Demand for increased flexibility
• Better design of products.
• Better process planning.
• Reliable and quality oriented manufacturing.
• Intelligent process control.
• Intelligent product development

Application Areas of Mechatronics
• Machine Vision
• Automation and Robotics
• Development of unmanned vehicles
• Design of sub-systems for automotive engineering
• Sensing and control systems
• Operation and maintenance of CNC machines
• Expert systems and Artificial Intelligence
• Industrial electronics and consumer products
• Medical Mechatronics and medical imaging system
• Structural dynamic system
• Transportation and vehicular systems

• Diagnostic and reliability techniques
• Computer integrated manufacturing (CIM) systems
• Micro/ Nano mechatronics
• Mechatronics in energy systems
• Human machine interface
• Mechatronics application in cyber-physical system

ELEMENTS OF MECHATRONICS SYSTEMS
ACTUATORS AND SENSORS
SIGNALS AND CONDITIONING
DIGITAL LOGIC SYSTEMS
SOFTWARE AND DATA
ACQUISTION SYSTEMS
COMPUTERS AND DISPLAY
DEVICES

Elements of a Mechatronics system
• Actuators and Sensors
Actuators produce motion or cause some action.
Sensors detect the state of the system parameters, inputs and outputs.
• Signals and conditioning
Input conditioning devices: Discrete circuits, Amplifiers, A/D convertor, D/D convertor
Output conditioning devices: D/A convertor, D/D convertor, power transistors, power
OP-amplifiers.
• Digital Logic systems
Logic circuits, microcontrollers, PLC, Sequencing and timing control, control algorithms
• Software and data acquisition systems
Software is used to control the acquisition of data through DAC board
Data loggers, computer with plug-in boards.

Advantages and Disadvantages of Mechatronics
Advantages:
• It is cost effective and can produce high quality products.
• Production of parts and products of International standard gives better
reputation and return.
• It serves effectively for high dimensional accuracy requirements.
• It provides high degree of flexibility to modify or redesign the products.
• It provides excellent performance characteristics.
• It results automation in production, assembly and quality control.
• Mechatronics systems provide the increased productivity in manufacturing
organization.
• Reconfiguration feature by pre supplied programs facilitate the low volume
production.
• It provides the facility of remote controlling as well as centralized monitoring and
control.
• It has greater extend of machine utilization
• Higher life is expected by proper maintenance and timely diagnosis of the faults.

Disadvantages
• Initial cost is high
• Maintenance and repair may workout costly
• Multi-disciplinary engineering background is required to design and
implementation.
• It needs highly trained workers to operate.
• Techno-economic estimation has to be done carefully in the selection of
mechatronic system.
• It has complexity in identification and correction of problems in the systems.

Autotronics
• Autotronics is an innovative approach in Automotive Mechatronics.
• Modern cars are as much electronic as they are mechanical, thus
creating a new AUTOTRONIC area (AUTOmobile + elecTRONIC).
• modern car has several control modules, which monitor and manage
most of the major systems in the vehicle.
Control in Automotive: Engine and drive line control, cruise control,
suspension control, anti-lock braking and airbag control, climate
control, GPS-based navigation system, stability management system,
instrumentation, infotaiment, etc.
Systems such as 'by-wire' braking and steering systems, collision
warning, voice recognition, Internet access, night vision enhancement
and collision avoidance systems all start to be introduced.

Bionics
Bionics or biologically inspired engineering is the application of
biological methods and systems found in nature to the study and
design of engineering systems and modern technology.
Bionics Biology + Electronics
In robotics, bionics and biomimetic are used to apply the way animals
move to the design of robots. BionicKangaroo was based on the
movements and physiology of kangaroos.
In medicine, bionics means the replacement or enhancement
of organs or other body parts by mechanical versions. Bionic implants
differ from mere prostheses by mimicking the original function very
closely, or even surpassing it.
in computer science, cybernetics tries to model the feedback and
control mechanisms that are inherent in intelligent behavior,
while artificial intelligence tries to model the intelligent function
regardless of the particular way it can be achieved.

Avionics
Avionics are the electronic systems used on aircraft, artificial satellites,
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.
The cockpit of an aircraft is a typical location for avionic equipment,
including control, monitoring, communication, navigation, weather, and
anti-collision systems. The majority of aircraft power their avionics
using 14- or 28-volt DC electrical systems.

Sensor or Transducer:
Sensor or Transducer is a device which converts a physical quantity, property or
condition into output.
(Physical Quantity or Property or Condition) (Voltage or Resistance or
(INPUT) Capacitance) (OUTPUT)
Example: A thermocouple is a sensor which converts changes in temperature
into a voltage.
Signal Processor: Signal processor or conditioner receives the output signal from
the sensor or transducer and manipulates or processes it into a suitable input signal
to control system.
• Signal processor performs filtering and amplification functions.
Example: A/D Convertor
SENSOR/TRANSDUCER

Sensor & Transducer
The main difference between a sensor and a transducer is that
a sensor senses the difference or change in the environment they are
exposed to and gives an output in the same format whereas
a transducer takes a measurement in one form and converts it to
another.
for example, a measurement which is not electrical and converts it
into an electrical signal. This process is called “transduction”.
.

Sensor & Transducer
• A transducer is a device that is used to convert a non-electrical signal into an electrical
signal. Transducers are referred to as energy converters.
• Example of transducers are:
• Thermocouple
• Microphones
• Sensor is a device used to measure the physical changes that occur in the surroundings
like temperature, light, etc, and convert it into a readable signal.
• Examples of sensors are:
• Barometer
• Accelerometer
• The transducer consists of a sensor and signals conditioning circuits and finds
application in communication systems to convert the electricity to electromagnetic
waves.

Sensor Definition:
A Sensor is defined as a device which measures a physical quality
(light, sound, space) and converts them into an easily readable
format. If calibrated correctly, sensors are highly accurate devices.
Not all transducers are sensors, but most sensors are transducers.
For example, a thermistor is a type of sensor; it will respond to the
change in temperature but does not convert the energy into a
different format to what it was originally sensed in.

Transducer Definition:
Transducer is an electronic device which converts energy from one form
to another. There are six different types of measurements; mechanical,
magnetic, thermal, electric, chemical and radiation, a transducer can
take a measurement in one format and convert it to another. A
thermistor on its own is a sensor but, when it is incorporated into a
bigger circuit or device it will become an element of a transducer; for
example, a thermometer is a transducer.

Sensor Transducer
Working principle
Senses a physical
measurement and makes it
readable for the user but keeps
it in the same format
Senses the physical
measurement and converts it
from one form to another -
e.g.: Non- electrical to
electrical
Examples
Thermistor, motion sensor,
pressure switch
Microphones, pressure
transducer, linear transducer.
Uses / applications
Patient monitoring, infrared
toilet flushes, liquid dispensing
in drinks machines.
HVAC monitoring, engine
controls, steering systems,
ramp and bridge lifting
systems.

Kinematic Link
Kinematic Pair
A kinematic link is defined as a resistant body
having two or more pairing elements which
connect it to other bodies for the purpose of
transmitting force or relative motion.
e.g. Piston, cylinder, crank & connecting rod in IC
Engines
The two kinematic links or elements of a
machine, when in contact with each other to
perform the constrained relative motion
between them , are said to form a
kinematic pair.
For example, the connecting rod with the
crank forms a kinematic pair, the piston with
the cylinder forms a fourth pair..etc.

Kinematic Chain
A kinematic chain is an assembly of rigid bodies connected by joints to provide
constrained (or desired) relative motion.
Types of Kinematic Chains
The most important kinematic chains are those which consist of four lower pairs, each
pair being a sliding pair or a turning pair. The following three types of kinematic chains
with four lower pairs are important from the subject point of view :
1. Four bar chain or quadric cyclic chain 2. Single slider crank chain, 3. Double slider crank chain.

cam
•A cam is a uniformly rotating machine element
which gives reciprocating or oscillating motion to
another element known as follower.
•The cam and the follower have a line contact and
constitute a higher pair.
•The cams are usually rotated at uniform speed by a
shaft, but the follower motion is predetermined and
will be according to the shape of the cam.
•The cam and follower is one of the simplest as well
as one of the most important mechanisms found in
modern machinery today.
•The cams are widely used for operating the inlet
and exhaust valves of internal combustion engines,
automatic attachment of machineries, paper cutting
machines, spinning and weaving textile machineries,
feed mechanism of automatic lathes etc.

Gear
•Gears are toothed wheels that transmit
motion from one shaft to another and
determine the speed, torque, and direction of
rotation of machine elements.
•Gears mesh their teeth with the teeth of
another corresponding gear or toothed
component which prevents slippage during
the transmission process.
•The gear that provides the initial rotational
input, called driving gear (i.e.,) rotates along
with its shaft component, whereas the gear
or toothed component which is impacted by
the driving gear and exhibits the final output
is called as the driven gear

•A ratchet is a mechanical device that allows
continuous linear or rotary motion in only one
direction while preventing motion in the opposite
direction.
•A ratchet is composed of three main parts: a round
gear, a pawl, and a base.
•The geometry of the gear or rack is usually
designed with a ramp feature on one side of the
tooth leading to a sharp drop off which restricts
motion of the pawl when the linear or rotational
direction is reversed.
Ex.1: Turnstile
The one-way flow of human traffic in places like the
subway.
Ex.2: Zip Tie
The design of the ratchet mechanism allows for the
zip tie to be tightened, but locks when a force is
applied in an attempt to loosen the tie.
Train Ratchet Mechanism
Turnstile Zip Tie

Belts
•Belt drive, in machinery, a pair of pulleys attached to
usually parallel shafts and connected by an encircling
flexible belt (band) that can serve to transmit and modify
rotary motion from one shaft to the other.
•Most belt drives consist of flat leather, rubber, or fabric
belts running on cylindrical pulleys or of belts with a V-
shaped cross section running on grooved pulleys.
•To create an effective frictional grip on the pulleys,
belts must be installed with a substantial tension.
•Because of the wedging action of the belts in the
grooves, V belts require less tension than do flat belts
and are particularly suitable for connecting shafts that
are close together.
•Flat and V belts slip when overloaded, and in some
applications this condition may be more desirable than
a rigid drive because it limits the transmitted torque and
may prevent breakage of parts.

Bearing
•A bearing is a machine element that constrains
relative motion to only the desired motion, and
reduces friction between moving parts.
•Machines that use bearings include automobiles,
airplanes, electric generators and so on.
•They are even used in household appliances that we
all use every day, such as refrigerators, vacuum
cleaners and air-conditioners.
•Bearings support the rotating shafts of the wheels,
gears, turbines, rotors, etc. in those machines, allowing
them to rotate more smoothly.
•They fulfill the following two major functions.
•1: Reduce friction and make rotation more smooth
•2: Protect the part that supports the rotation, and
maintain the correct position for the rotating shaft

Hydraulic controls
Direction control valves
Pressure control valves
Flow control valves
Check valves
OLD DEFINITION:
Anything which is in affiliation with water is called hydraulics.
NEW ERA DEFINITION:
Transmission & control of forces & movements by means of fluids is called hydraulics.

Pneumatic system
Pneumatic systems
use air as the
medium which is
abundantly available
and can be exhausted
into the atmosphere
after completion of
the assigned task.

Basic Components of Pneumatic System

Important components of a pneumatic system
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.
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.

Receiver tank
The air is compressed slowly in the compressor. But since the
pneumatic system needs continuous supply of air, this
compressed air has to be stored. The compressed air is stored
in an air receiver as shown in Figure. The air receiver
smoothens the pulsating flow from the compressor. It also
helps the air to cool and condense the moisture present. The
air receiver should be large enough to hold all the air delivered
by the compressor. The pressure in the receiver is held higher
than the system operating pressure to compensate pressure
loss in the pipes. Also the large surface area of the receiver
helps in dissipating the heat from the compressed air.
Generally the size of receiver depends on,
• Delivery volume of compressor.
• Air consumption.
• Pipeline network
• Type and nature of on-off regulation
• Permissible pressure difference in the pipelines

Compressor
It is a mechanical device which converts mechanical
energy into fluid energy. The compressor increases
the air pressure by reducing its volume which also
increases the temperature of the compressed air. The
compressor is selected based on the pressure it needs
to operate and the delivery volume.
The compressor can be classified into two main types
a. Positive displacement compressors and
b. Dynamic displacement compressor
Positive displacement compressors include piston type,
vane type, diaphragm type and screw type.

Piston compressors
Piston compressors are commonly
used in pneumatic systems. The
simplest form is single cylinder
compressor. As the piston moves
down during the inlet stroke the
inlet valve opens and air is
drawn into the cylinder. As the
piston moves up the inlet valve
closes and the exhaust valve
opens which allows the air to be
expelled. The valves are spring
loaded. The single cylinder
compressor gives significant
amount of pressure pulses at the
outlet port. The pressure
developed is about 3-40 bar.

Air treatment stages
For satisfactory operation of the pneumatic system the
compressed air needs to be cleaned and dried. Atmospheric
air is contaminated with dust, smoke and is humid. These
particles can cause wear of the system components and
presence of moisture may cause corrosion. Hence it is
essential to treat the air to get rid of these impurities. The air
treatment can be divided into three stages as shown in
Figure.

Filters
To prevent any damage to the compressor, the
contaminants present in the air need to be filtered out.
This is done by using inlet filters. These can be dry or
wet filters. Dry filters use disposable cartridges. In the
wet filter, the incoming air is passed through an oil
bath and then through a fine wire mesh filter. Dirt
particles cling to the oil drops during bubbling and are
removed by wire mesh as they pass through it. In the
dry filter the cartridges are replaced during servicing.
The wet filters are cleaned using detergent solution.

Cooler
As the air is compressed, the temperature of the air increases.
Therefore the air needs to be cooled. This is done by using a cooler. It
is a type of heat exchanger. There are two types of coolers commonly
employed viz. air cooled and water cooled.

Relief valve
Relief valve is the simplest type
of pressure regulating device. It
is used as a backup device if the
main pressure control fails.
It consists of ball type valve held
on to the valve seat by a spring
in tension. The spring tension
can be adjusted by using the
adjusting cap. When the air
pressure exceeds the spring
tension pressure the ball is
displaced from its seat, thus
releasing the air and reducing
the pressure.

Non-relieving pressure regulator
If outlet pressure is too low,
the spring forces the
diaphragm and poppet to
move down thus opening
the valve to admit more
air and raise outlet
pressure. If the outlet
pressure is too high the air
pressure forces the
diaphragm up hence
reduces the air flow and
causing a reduction in air
pressure.

Actuators
Actuators are output devices which convert energy
from pressurized hydraulic oil or compressed air into
the required type of action or motion.
Actuators can be classified into three types.
1. Linear actuators: These devices convert
hydraulic/pneumatic energy into linear motion.
2. Rotary actuators: These devices convert
hydraulic/pneumatic energy into rotary motion.
3. Actuators to operate flow control valves: these are used to
control the flow and pressure of fluids such as gases, steam
or liquid.
Typical pressure of hydraulic cylinders is about 100 bar and
of pneumatic system is around 10 bar.

Single acting cylinder
These cylinders produce work in one direction of motion
hence they are named as single acting cylinders. 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.

Limited rotation actuators
It consists of a single rotating vane connected to output shaft
as shown in Figure. It is used for double acting operation
and has a maximum angle of rotation of about 270°. These
are generally used to actuate dampers in robotics and
material handling applications.

VALVES
Valve are defined as devices to control or regulate the commencement,
termination and direction and also the pressure or rate of flow of a
fluid under pressure which is delivered by a compressor or vacuum
pump or is stored in a vessel.
1. Direction control valve
2. Non return valves
3. Flow control valves
4. Pressure control valves

DIRECTION CONTROL VALVES
Pneumatic systems like hydraulic system also require control valves to
direct and regulate the flow of fluid from the compressor to the
various devices like air actuators and air motors.

ISO DESIGNATION OF DIRECTION CONTROL
VALVES
Port Markings of Direction Control Valve

NON RETURN VALVES
Non return valves permit flow of air in one direction only, the other
direction through the valve being at all times blocked to the air flow.
Mostly the valves are designed so that the check is additionally loaded by
the downstream air pressure, thus supporting the non-return action.
Check valve
The simplest type of non-return valve
is the check valve, which completely
blocks air flow in one direction while
permitting flow in the opposite
direction with minimum pressure
loss across the valve.

Shuttle valve
It is also known as a
double control valve or
double check valve. A
shuttle valve has two
inlets and one outlet. At
any one time, flow is
shut off in the direction
of whichever inlet is
unloaded and is open
from the loaded inlet to
the outlet. A shuttle
valve may be installed,
for example, when a
power unit (cylinder) or
control unit (valve) is to
be actuated from two
points, which may be
remote from one other.

2/2 valve (2 Port Valves)
• A 2/2 valve gets its name because it has two ports and
two states.
• A port is where we can connect a pipe and a state is
simply a position that the valve can be in.
• The ports are numbered to help us make the right
connections. The numbers will be stamped onto the
casing of the valve.

3/2 valve
• A 3/2 valve gets its name because
it has three ports and two states.
• A port is where we can connect a
pipe and a state is simply a
position that the valve can be in.
• The ports are numbered to help
us make the right connections.
The numbers will be stamped
onto the casing of the valve.

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