MECHATRONICS

WEEK 1

1
 The Instructor.
Engr. Prof. Dr. S.M. Usman Ali shah
Professor & Chairperson
Department of Electrical Engg.
NED University of Engg. & Technology

2
 The Course.
Pre-requisites

Under-graduate courses in:

Instrumentation and Controls
Digital Electronics
Microprocessors and Applications
Computer Architecture & Organization

3
 The Course.
Tentative Course Plan
Week1
Introduction to the subject and areas of applications.
Week2
Transducers
Week3
Transducers (continued..)
Week 4
Signal Conditioning Elements
Week 5
Signal Conditioning Elements (contd.)
Week 6
Data Acquisition Systems

4
Week 7
Control Systems Engineering

Week 8
Process Control

Week 9
Process Control (contd.)

Week 10
Belts and Gears

Week 11
Belts and Gears (contd.)

Week 12
Mechanical Systems and Mechanical Processes

5
Week 13
Introduction to Microelectromechanical Systems (MEMS)

Week 14
Mechatronics applications in MEMS

Week 15
Mechatronics applications in MEMS (contd.)

Week 16
Applications of Computers in Mechatronics

6
 Mechatronics
Mechanisms and Electronics.
Conventional mechanical systems
started going electrical/electronics
from 1970.
Electrical and electronic systems can
be integrated with mechanical systems
and processes because of their
fantastic features, powers and
applications!
7
 Mechatronics can be defined as a
multidisciplinary approach to product
and manufacturing system design.
Its the synergistic integration of
mechanical engineering with
electronics and intelligent computer
control in designing, manufacturing
processes and production.
Thru mechatronics atomized and
efficient manufacturing/production
systems for high quality products!
8
 Applications of mechatronics are in
every field of production, consumer
products, monitoring and control of
welding process, intelligent robotic
control using ultrasonic
measurements, temperature controllers
etc.

9
 Ultrasonic sensors (also known as
transducers when they both send and
receive) work on a principle similar to radar
or sonar which evaluate attributes of a target
by interpreting the echoes from radio or
sound waves respectively. Ultrasonic
sensors generate high frequency sound
waves and evaluate the echo which is
received back by the sensor. Sensors
calculate the time interval between sending
the signal and receiving the echo to
determine the distance to an object.

10
 Mechatronics is truly a multidisciplinary
field!

11
Mechatronics Design Elements

12
 Sensor: The combination of a
transducer and a signal processor.
Signal Conditioning element may
perform the following operations:
Signal boosting
Noise Reduction
Removal of dc offset if any
Resolving Compatibility issues
Removal of wrong/in access or
duplicate information present
13
 Most commonly, signal conditioning
units would include op-amps with
suitable passive elements.
Other signal conditioning elements
(SCE) are adder, subtractor, integrator,
differentiator, current/voltage or
voltage/current converters, sample and
hold amplifiers, instrumentation
amplifiers etc.
For a computer based system, A/D
converters are used as SCEs.
14
 Mechatronic systems employ actuators
which are part of the physical process being
monitored and controlled.
Actuation.result of a direct physical action
on a process.
Actuators input low power signal from
computer or signal conditioning units, its
output high output signals (physical
quantities) that are applied to the process as
input.

15
 Actuator examples: Solenoids, steeper
motor etc.
Programmable Logic Controllers (PLCs)
industrial devices used for interfacing and
controlling analog to digital devices.
A PLC is a sequential logic device..
Can u differentiate a sequential and a
combinational logic device?
PLC generates output signal according to
logic operations performed on the input
signals.
16
 The major difference between a computer
controller and a programmable controller?
Programmable controllers are designed to
interface directly whereas a computer
systems requires data acquisition, signal
processing, memory, logic and peripherals
before process implementation.
PLC are programmed with ladder logic, a
graphical method of laying out the
connectivity and logic between system
inputs and outputs.
17
 A typical PLC would include:

Integrated Power Supply

Central Processing Unit (CPU)
Memory Elements
Programmer/Monitor
Input/Output Modules

18
 A Microcontroller provides a small flexible
control platform and it can easily be
embedded in a mechatronic system.
Microcontroller ?
A microcomputer on a single integrated
circuit containing microprocessor, memory
input/output capabilities and other on-chip
resources.
Large mechatronic systems would employ
desktop/personal/laptop computers as
control platforms.
19
 Scope of Mechatronics
Better design planning
CAD (computer aided designing)
based designing that involves
computers in the designing in three
stages.conceptual, preliminary, final.

20
 Better Process Planning
Use of computer in process planning,
Computer Aided Process Planning (CAPP).
More logical and consistent process
planning.
Lower Manufacturing Costs.
High product quality.

21
 Reliable and Quality Oriented Manufacturing
Because of computer integrated
manufacturing (CIM), reliable and high
quality oriented products can be
manufactured.

22
 Intelligent Process Control
Developments in digital computer systems
have increased their use in process control.
In power plants, process and manufacturing
industries, computer aided process control
is used for passive and active applications.

23
 Passive Applications include acquisition
and manipulation (i.e monitoring and
alarming) of data from various processes.

Active applications involve acquisition and

manipulation with additional features like
process control, process and plant
optimization and tuning of various
controllers for best operating performance.

24
 Nowadays, in mechatronic systems,
artificial neural networks are used in
manufacturing systems for process control
and inspection to improve production
performance and production quality.

25
Artificial Neural Networks (ANN)
An artificial neural network (ANN), often just called a
"neural network" (NN), is a mathematical model or
computational model based on biological neural
networks. It consists of an interconnected group of
artificial neurons and processes information using a
connectionist approach to computation. In most
cases an ANN is an adaptive system that changes its
structure based on external or internal information
that flows through the network during the learning
phase.
In more practical terms neural networks are non-
linear statistical data modeling tools. They can be
used to model complex relationships between inputs
and outputs or to find patterns in data.

26
 In general, mechatronics helps industries
achieve greater productivity, reliability and
higher quality by incorporating intelligent
self correcting sensory and feedback
system.

27
 General Parameters for
designing an intelligent
mechatronic system
Analyze product design and
development specifications
Select process variables, set points,
processes, etc.
Design proper analog and digital
circuits.
Select mechanical components and
devices.
28
 Design proper mechanical systems like
hydraulic, pneumatic etc.
Select sensors, actuators and control
components.
Design accurate and precise control system
for various process variables.
Develop computer based system (real time
interfacing).
Develop necessary computer software and
database
29
 Integrate the above stated parameters
effectively.
Monitor the performance of designed
system.

The intelligent designing of mechatronic

system is not only to produce high quality
product but it should also be safe,
affordable to customers (low cost), portable
and produced quickly.

30
 Moreover it must be:
Serviceable
Maintainable
Upgradeable

31
Applications of Mechatronics
Automatic Washing Machines,
Dishwashers
CD Players, VCR controllers
Document Scanners, MI Equipments
IC Manufacturing Systems
Robotics that used in welding, nuclear
inspection and robot manipulators

32
 Fax and Photocopier machines
Laser Printers, Hard Disk drive head
positioning systems
Air-conditioners and elevator controls
Flexible manufacturing systems
Automotive mechatronics (like outdoor
locking, collision avoidance, ignition
systems, anti-roll systemsABS)

33
MECHATRONICS
(SP-506)
WEEK 2

1
Artificial Neural Networks (ANN)
An artificial neural network (ANN), often just called a
"neural network" (NN), is a mathematical model or
computational model based on biological neural
networks. It consists of an interconnected group of
artificial neurons and processes information using a
connectionist approach to computation. In most
cases an ANN is an adaptive system that changes its
structure based on external or internal information
that flows through the network during the learning
phase.
In more practical terms neural networks are non-
linear statistical data modeling tools. They can be
used to model complex relationships between inputs
and outputs or to find patterns in data.

2
 In general, mechatronics helps industries
achieve greater productivity, reliability and
higher quality by incorporating intelligent
self correcting sensory and feedback
system.

3
 General Parameters for
designing an intelligent
mechatronic system
Analyze product design and
development specifications
Select process variables, set points,
processes, etc.
Design proper analog and digital
circuits.
Select mechanical components and
devices.
4
 Design proper mechanical systems like
hydraulic, pneumatic etc.
Select sensors, actuators and control
components.
Design accurate and precise control system
for various process variables.
Develop computer based system (real time
interfacing).
Develop necessary computer software and
database
5
 Integrate the above stated parameters
effectively.
Monitor the performance of designed
system.

The intelligent designing of mechatronic

system is not only to produce high quality
product but it should also be safe,
affordable to customers (low cost), portable
and produced quickly.

6
 Moreover it must be:
Serviceable
Maintainable
Upgradeable

7
Applications of Mechatronics
Automatic Washing Machines,
Dishwashers
CD Players, VCR controllers
Document Scanners, MI Equipments
IC Manufacturing Systems
Robotics that used in welding, nuclear
inspection and robot manipulators

8
 Fax and Photocopier machines
Laser Printers, Hard Disk drive head
positioning systems
Air-conditioners and elevator controls
Flexible manufacturing systems
Automotive mechatronics (like outdoor
locking, collision avoidance, ignition
systems, anti-roll systemsABS)

9
Transducers

10
 INTRODUCTION
Its a converter of one form of energy
into the other.
Energy can be mechanical, electrical,
acoustical, optical etc.
Their classification depends upon
method of conversion, nature of the
output signal and applications.

11
 MAIN SECTIONS OF
INSTRUMENTATION
Sensing device (input device)
Signal Conditioning or Signal
Processing Stage.
Output Stage

12
 CLASSIFICATION OF
TRANSDUCERS
1) Based upon the method of
transduction i.e resistive, capacitive,
inductive etc.
2) Active and Passive Transducers
Active Transducer: Do not need an
external supply, these are self
generating e.g Piezoelectric Crystal
Transducer.

13
 Passive Transducers: They do need an
external supply for generating the
output e.g a potentiometer etc.
3) Analog and Digital Transducers:
Analog transducer converts any
physical quantity into analog current
/voltage output i.e continuous function
of time such as a thermocouple.
Digital Transducers convert input
physical quantity into a digital signal in
terms of 0s and 1s such as a rotary
encoder. 14
 4) Transducers and Inverse
Transducers: Inverse transducer
converts electrical/electronic signals
into a mechanical output either linear in
nature or rotary.
5) Primary & Secondary Transducers:
Consider the following diagram for
that:

15
LVDT : LINEAR VOLTAGE DIFFERENTIAL
TRANSFORMER

16
 SELECTION PARAMETERS
OF TRANSDUCERS
LINEARITY
STABILITY
REPEATABILITY
SENSITIVITY
ACCURACY
ENVIRONMENTAL CONDITIONS
(CORROSION, HUMIDITY, MOISTURE,
SHOCKS, FRICTION ETC.)
17
 FREQUENCY RESPONSE (FLAT AND
STABLE DESIRED)
RUGGEDNESS
LOADING EFFECT (MUST BE MINIMAL)

18
Resistance Transducers

19
 R= L /A
Operating Mechanism: Resistance of
the sensing element changes with the
physical quantity.
Examples: Potentiometers whether
translational or rotational and strain
gauges.
Shown below:

20
21
22
23
POWER RATINGS

24
LINEARITY AND SENSITIVITY OF
POTENTIOMETERS

25
 For higher sensitivity the input voltage
should be high which demands high
value of resistance RP.
For good linearity the resistance of the
pot should be low, but this would
increase the power dissipation.
Thus linearity and sensitivity must be
adjusted properly because:

26
 RP small, linearity gets improved.
RP small, it handles low input voltage.
RP small, the linearity gets improved
but power dissipation increases.
Also the sensitivity gets decreased
since Ein is small and Eout will also be
small.
Linearity can be improved by
connecting a resistor RLin with Rm as
shown below:
27
28
 Sensitivity.
Generally calculated thru voltage,
current and power rating.
Another key factor. maximum stroke.
Shorter the stroke of the device, higher
the sensitivity.
For rotational POTs, the maximum
stroke rate is 15V /degree, and for
translational POTs it is 300V/inch.
29
 Resolution of POTs.
Depends upon:
Construction of the resistive element
and its size.
For getting higher value of resistance,
metal wire (resistance) is placed in a
small area for rotary POTs.
For translational POTs, resolution is
limited to 0.001 to 0.002.
30
 The best angular resolution is
given by:
0.12 to 0.24/D

where D is in inches.
Selection of potentiometer for a
particular application would depend
upon resolution, operating
temperature, humidity, shocks,
vibration etc.
31
 Pots are often attacked by noise that
disturbs the resolution and linearity of
Pots. Noise occurs due to:
1) The output voltage variations or
fluctuations when arm slides over
resistive elements with inadequate
damping.
Wiper bouncing on the resistive
element at higher speed.
Dust collected b/w wiper surface and
winding (resistance).
32
MECHATRONICS
(SP-506)
WEEK 3

1
 For higher sensitivity the input voltage
should be high which demands high
value of resistance RP (the total
resistance of the Potentiometer).
For good linearity the resistance of the
pot should be low, but this would
increase the power dissipation.
Thus linearity and sensitivity must be
adjusted properly because:

2
 RP small, linearity gets improved.
RP small, it handles low input voltage.
RP small, the linearity gets improved
but power dissipation increases.
Also the sensitivity gets decreased
since Ein is small and Eout will also be
small.
Linearity can be improved by
connecting a resistor RLin with Rm as
shown below:
3
4
 Sensitivity.
Generally calculated thru voltage,
current and power rating.
Another key factor. maximum stroke.
Shorter the stroke of the device, higher
the sensitivity.
For rotational POTs, the maximum
stroke rate is 15V /degree, and for
translational POTs it is 300V/inch.
5
 Resolution of POTs.
Depends upon:
Construction of the resistive element
and its size.
For getting higher value of resistance,
metal wire (resistance) is placed in a
small area for rotary POTs.
For translational POTs, resolution is
limited to 0.001 to 0.002.
6
 The best angular resolution is
given by:
0.12 to 0.24/D

where D is in inches.
Selection of potentiometer for a
particular application would depend
upon resolution, operating
temperature, humidity, shocks,
vibration etc.
7
 Pots are often attacked by noise that
disturbs the resolution and linearity of
Pots. Noise occurs due to:
1) The output voltage variations or
fluctuations when arm slides over
resistive elements with inadequate
damping.
Wiper bouncing on the resistive
element at higher speed.
Dust collected b/w wiper surface and
winding (resistance).
8
INDUCTIVE TRANSDUCERS

9
 Displacement or positional change, converted into
a change in inductance.
How? by the variation in number of turns,
geometric configuration and permeability of the
magnetic circuit.
Self inductance = L=N2/S, N=number of turns in
the coil and S is the reluctance of the magnetic
coil.
S=1/orA
o=Permeability of Free Space
o=Relative Permeability
A=Cross Sectional Area of the Coil in m2

10
11
12
 LINEAR VARIABLE
INDUCTANCE TRANSFORMER
(LVDT)

13
 Linear motion is converted into
electrical signals.

14
 Two winding Primary and Secondary
on a Cylindrical former,.
Former must be mechanically rigid to
absorb shocks, vibrations and
temperature.
Secondary windings are wound on
opposite sides of the primary.
Moveable core (usually of Nickel-Iron
alloy to reduce eddy currents)
connected with a non-magnetic handle.
15
16
Mode 0 output is Zero as ES1=ES2
Mode 1 output is ES2-ES1
Mode 3 output is ES2-ES1
17
18
 At null position, a small output voltage
is present due to:
Stray Electric & Magnetic field between
the windings.
Harmonics present in the input voltage
Ein.
Temperature Effects.
Improper isolation between the
windings.

19
 Applications of LVDT
Used as a secondary transducer for the
measurement of force, pressure, liquid
level, temperature etc.
Mainly LVDT is used for the
measurement of displacement in the
range 1.25mm to 250mm.
Also utilized in thickness
measurement, level indicators and
numerical machines.
20
 Numerical Controls & Machines
Numerical control (NC) refers to the
automation of machine tools that are
operated by abstractly programmed
commands encoded on a storage
medium, as opposed to manually
controlled via handwheels or levers or
mechanically automated via cams
alone.

21
Numerical Controls & Machines
The outdated servo based design
control systems have been replaced by
the modern computer numerical
controlled (CNC) machine tools that
have revolutionized the design
process!

22
 Advantages of LVDT
Tolerance to high degree of shocks and
vibrations.
Lesser Power Consumption.
Non Contacting Sliding Core hence,
minimal Frictional Losses.
No requirement of an output
amplification stage.
Good resolution, high sensitivity about
40V/mm and low hysteresis.
23
 Disadvantages of LVDT
Performance can be degraded due to
stray magnetic fields and temperature.
Limited Dynamic response due to
frequency of exciting signal and mass
of sliding core.
A demodulator circuit is necessary if
the receiving instrument operates on
dc.

24
 Sensitivity of LVDT
Depends upon:
Constructional Parameters
Excitation Supply
Primary Winding Current
Linearity
Low Voltage at the null position.

25
26
ROTARY VARIABLE
DIFFERENTIAL
TRANSFORMER
(RVDT)

27
 Used for the measurements of the
angular displacements by converting
them to electrical signals.
Operating principle same as that of
LVDT.
Construction same as one primary and
two secondary windings but.the
sliding core in RVDT is cam-shaped
and rotated inside the windings thru
shaft as shown:

28
29
CAPACITIVE TRANSDUCERS

30
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32
33
MECHATRONICS
(SP-506)
WEEK 4

1
 Sensitivity of LVDT
Depends upon:
Constructional Parameters
Excitation Supply
Primary Winding Current
Linearity
Low Voltage at the null position.

2
3
ROTARY VARIABLE
DIFFERENTIAL
TRANSFORMER
(RVDT)

4
 Used for the measurements of the
angular displacements by converting
them to electrical signals.
Operating principle same as that of
LVDT.
Construction same as one primary and
two secondary windings but.the
sliding core in RVDT is cam-shaped
and rotated inside the windings thru
shaft as shown:

5
6
CAPACITIVE TRANSDUCERS

7
8
9
10
PIEZOELECTRIC
TRANSDUCERS

11
 The Piezoelectric effect:
Application of force on the
piezoelectric crystal results in the
change in dimensions, which generates
electric charge or electric potential
across the surface of the crystal.
Its reverse is also truei.e
application of a electric potential
across the crystal results in the change
in change in dimensions of the crystal
due to deformation.
12
13
 For the piezoelectric crystal the
generated charge Q is given by:
Q= d x F coulomb
Where F is the applied force and d is
called the charge sensitivity.
The charge sensitivity is defined as
charge generated per unit force applied
to the crystal.
Due to the applied force the thickness
of the crystal changes.

14
 F = (A . Y/ t ) t
Where F= applied force.
A = Area of the crystal =WL in m2
t= thickness of the crystal in m
Y = Youngs modulus for the material of
crystal in N/m2.
W= Width of the Crystal in m
L= Length of the Crystal in m

15
 Advantages of Piezoelectric
Transducers
More Stability
Not affected by temperature variations
and humidity
Maximum output
Useful for dynamic parameter
measurements
Quartz crystal has good stability, so it
is used as a frequency generator or
oscillator.
16
 Typical Applications
Vibration pickups
Accelerometers
Pressure Sensors
Velocity Measurement
Sound Pressure Measurement

17
Strain Gauges

18
 Work on the principle of
piezoresistivity.
If a metallic wire or conductor is
stretched or compressed, its resistance
changes due to change in length,
resistivity and cross sectional area.

19
Classification of Strain
Gauges

20
21
Bonded Metal Foil Strain Gauges
(0.0002 inches thick)

22
 The surface area increases for the
same volume!
This means much greater heat
dissipation capacity and better
bonding.
Foil type gauges are mounted on
flexible insulating carrier films of about
0.025mm thick of polymide, glass,
phenolic etc.

23
Bonded semiconductor strain
gauges (for the
measurements of micro-
strains)

24
Temperature Transducers

25
Thermocouple

26
27
28
 Thermistors (Semiconductor
Temperature Sensors)
Resistance varies with temperature
changes.
Recall the property of emission of
electrons inside a semiconductor as
temperature increases.resistivity
decreases, conductivity increases.
Can be thought of as resistance has
decreased.

29
30
31
32
RESISTANCE TEMPERATURE
DETECTOR (RTD)

33
 Basic concept: The electrical
resistance of different materials
changes with the change in
temperature.

34
35
36
37
 Benefits.
Operating Point
Fast Response
Environmental Conditions
Ability to withstand corrosion, friction
etc.

38
 Applications
Suitable for temperature sensing of
fluids and gasses.

39
MECHATRONICS
(SP-506)
WEEK 5

1
RESISTANCE TEMPERATURE
DETECTOR (RTD)

2
 Basic concept: The electrical
resistance of different materials
changes with the change in
temperature.

3
4
5
6
 Benefits.
Operating Point
Fast Response
Environmental Conditions
Ability to withstand corrosion, friction
etc.

7
 Applications
Suitable for temperature sensing of
fluids and gasses.

8
Signal Conditioning Elements

9
 Purpose
To provide excitation source to passive
transducers and also to amplify their
output to suitable higher level.

To amplify the output of the active

transducers.

10
 Commonly used signal
conditioning devices
Amplifiers, adder, subtractor,
integrator, differentiator, bridges,
converters (voltage to current and
current to voltage), A/D and D/A
converters etc.
Instrumentation Amplifiers are used to
enhance small signals from
transducers which are less than a few
mV in amplitude.

11
Electronic measurement
system

12
Types of Signal Conditioning
Systems
DC Signal Conditioning Systems

AC Signal Conditioning Systems

13
DC Signal Conditioning
System

14
 Calibration and zeroing circuit for
indicating the unbalanced condition of
the bridge circuit.
Bridge output is amplified thru dc
amplifier since it is easier to calibrate at
lower frequencies and not affected by
the overloading effect.
Drawback of the DC amplifier, the drift
in its output level.
Produces low frequency noise signals
in its output. To avoid, we use drift
amplifiers. 15
 Low pass filter rejects high frequency
components from the output.
A DC signal conditioning system is
affected by drift problems so an AC
signal conditioning systems is
preferred.

16
AC Signal Conditioning
System

17
 Transducer such as a strain gauge is
connected in the arm of the bridge, that
is driven by a carrier oscillator.
As the physical quantity changes, the
carrier frequency gets amplitude
modulated with the bridge output.
This modulated signal is amplified thru
an ac amplifier.
Phase sensitive demodulator
demodulates the amplified signal and
carrier frequency is filtered out.
18
 Phase sensitive demodulator is used
so that polarity of dc output can
indicate direction of the parameter
change in the bridge output.
Final Stage is the filter to reject high
frequency.
The problem with such a system is to
maintain a stable carrier oscillator.
Carrier frequency is in the range 50Hz
to 20kHz and it should be 5 times of the
input signal frequency.
19
 Operational Amplifier (Op-
Amp)a refresher
Basically a differential amplifier of high
gain, high (almost ) input impedance
and low output impedance.

20
21
22
 Typical Applications of OP
Amps as Signal Conditioning
Elements

23
Inverting Amplifier

24
Non-Inverting Amplifier

25
A Voltage Follower

26
Summing Amplifier

27
 The output is an inverted sum of the
inputs.
Also called Scaling or Weighed
Amplifier.
Output is proportional to the sum of the
input voltages.
If Rf/R1=1/n, then the circuit is called
averaging circuit.

28
Subtractor Circuit

29
Sample and Hold Amplifier

30
31
 Three ports: input, output, Sample and
Hold Command port.
Command is either to sample or hold
the input.
Aperture time: If some delay is placed
in the command mode from the sample
mode to hold mode. Typically its
around 50ns.

32
Logarithmic Amplifier

33
34
Transducer Bridges
=R/R
Vout=VR/4
Iout=(VR/R) {/4(1+/2)}

35
INSTRUMENTATION
AMPLIFIERS

36
 Generally they are used with
transducers.
Purpose:
To amplify low level input signals
High Closed loop gain
To provide high common mode
rejection ratio and low power
consumption
To provide high input impedance and
low thermal drifts.
37
 Features of Instrumentation
Amplifiers
Simple Gain Adjustments
High input and low output impedance
High Common Mode Rejection Ratio
Possibility of Handling Differential
inputs
High Gain and Maximum Accuracy

38
MECHATRONICS
(SP-506)
WEEK 6

1
Sample and Hold Amplifier

2
3
 Three ports: input, output, Sample and
Hold Command port.
Command is either to sample or hold
the input.
Aperture time: If some delay is placed
in the command mode from the sample
mode to hold mode. Typically its
around 50ns.

4
Logarithmic Amplifier

5
6
Transducer Bridges
=R/R
Vout=VR/4
Iout=(VR/R) {/4(1+/2)}

7
INSTRUMENTATION
AMPLIFIERS

8
 Generally they are used with
transducers.
Purpose:
To amplify low level input signals
High Closed loop gain
To provide high common mode
rejection ratio and low power
consumption
To provide high input impedance and
low thermal drifts.
9
 Features of Instrumentation
Amplifiers
Simple Gain Adjustments
High input and low output impedance
High Common Mode Rejection Ratio
Possibility of Handling Differential
inputs
High Gain and Maximum Accuracy

10
INSTRUMENTATION AMPLIFIER

11
12
 RG here adjusts the gain.
A3 here is connected in differential
mode.

13
14
 Monolithic three op amps based
instrumentation amplifiers in IC form:
AD521
INA101
INA102
INA104

15
CHOPPER STABILIZED
AMPLIFIERS

16
 Advantages:
Low Drift
Higher DC gain
Wide Bandwidth

17
18
 DC signal is being converted into AC
thru a chopper or modulator.
Peak to Peak amplitude of the
converted AC signal is the same as that
of the DC input signal.
Converted AC signal is amplitude
modulated using carrier frequency
oscillator.
AC amplification having low drift and
higher gain.

19
 This amplified AC signal is
demodulated for conversion to higher
amplitude DC.
Chopper frequency is 2kHz with a
bandwidth of 200 Hz.
Consider the following circuit now:

20
21
 A low frequency chopper amplifier
amplifies the signal where high
frequency signals are bypassed.

Function of the chopper amplifier is to

increase the gain at lower frequency
signals resulting in reduction of drift
effect of dc amplifier.

22
INTEGRATOR CIRCUITS

23
24
 The system has an output voltage
equation:

The equation indicates that the output

voltage is directly proportional to the
inverted integral of the input voltage
and inversely proportional to the time
constant R1C.

25
 For accurate integration, the time period T
of the input signal must be more that the
time constant.
Operating Recommendations:
Capacitor must have minimum leakage.
Usually nTeflo, Polystyrene or Mica
capacitors in the range .001 to 10F are
used.
Integrator circuit would convert cosine
wave at the input, into sine wave, similarly
a square wave at the input into a
rectangular wave etc.

26
DIFFERENTIATOR CIRCUITS

27
 Such circuits provide an output voltage
that is a derivative of the input voltage.
Consider the following circuit:

28
 RfC is the time constant of the
differentiator circuit.
This circuit has the following
drawbacks:
1) The gain Rf/XC increases with
increase in frequency at the rate of
20dB/decade, which makes the circuit
unstable.
2) The input impedance XC decreases
with increase in frequency, generating
noise signals at high frequency signals.
29
 This is a practical differentiator in
which these problems have been
solved.

30
CONVERTERS

31
Voltage to Current Converter

1) V/C converter using floating load

2) V/C converter using grounded load

32
V/C Converter using floating
load

33
V/C converter using ground
load

34
Current to Voltage Converter
(Transresistance Amplifier)

35
OP AMP PROTECTION

36
37
38
MECHATRONICS
(SP506)
WEEK7

1
CONVERTERS

2
 VoltagetoCurrentConverter

1)V/Cconverterusingfloatingload

2)V/Cconverterusinggroundedload

3
V/CConverterusingfloatingload

4
V/Cconverterusinggroundload

5
CurrenttoVoltageConverter
(TransresistanceAmplifier)

6
OPAMPPROTECTION

7
8
9
DATAACQUISITIONSYSTEMS

10
 DataAcquisitionSystem(DAS):Collectionof
datainanalogordigitalformat.
Storesanddisplaysthedata,passonthedata
totheprocessingcontrolsystemsasand
whenrequired.
Data?VoltageorCurrentsignalsfrom
transducers.

11
 FeaturesofaDAS
Acquiredataquickly,accurately&precisely.
Onlinerecordingormonitoringatrealtime.
Capabilitytoprocessandforwardthedata.
MustbeFlexibleforupgradations&
modificationsinthesystem.

12
GeneralizedDAS

13
SingleChannelDataAcquisition
System

DPM: Data Processing

Module

14
 Drawbacks.
Slowoperation
FreeRunninginternallydeterminedrateof
processing
Forhandlingbinaryoperatedinstruments,
theBCDcodehastobeconvertedtobinary,
thattakesfurthertime!

15
MultichannelDataAcquisition

S/H Circuit increases

the processing speed!

16
Microprocessorbasedinstrumentsystem
(IntelligentInstrumentSystem)

17
 Advantages.
Increaseinoperationalspeed.
AutomaticControlSystem.
Averaging,Linearization,Totalization,
Calibration,alarming,adjustments,testing
etc,becomeautomated.
BetterFlexibility.
Memoryinterfacingprovidesstorageofinfo
anddata.
Modification,configurationchangeovereasy
thrusoftware.
18
MICROPROCESSORBASEDDATA
ACQUISITIONSYSTEM

19
20
CONTROLSYSTEMENGINEERING

21
 CLASSIFICATION

OpenLoopControlSystem

ClosedLoopControlSystem

22
OpenLoopControlSystem

23
ClosedLoopControlSystem

24
ClosedLoopSystem:Anexample

25
Deterministic&StochasticControl
System
Inanycontrolsystem,iftheresponsetothe
inputispredictableandrepeatable,the
systemwouldbecalledDeterministic.
Iftheresponseisunpredictableandnon
repeatable,itscalledStochasticControl
System.

26
 Classificationofcontrolsystemonthebasis
ofcontrolsignalused.
SISO:SingleInputandSingleOutput
MIMO:MultipleInputandMultipleOutput.

27
28
CONTROLSYSTEMSBLOCK
DIAGRAMS

29
30
31
32
TRANSFERFUNCTIONSINBLOCK
DIAGRAMS

33
RULESFORBLOCKDIAGRAMS
MINIMIZATION

34
35
36
MECHATRONICS
(SP506)
WEEK8

1
 Deterministic&StochasticControl
System
Inanycontrolsystem,iftheresponsetothe
inputispredictableandrepeatable,the
systemwouldbecalledDeterministic.
Iftheresponseisunpredictableandnon
repeatable,itscalledStochasticControl
System.

2
 Classificationofcontrolsystemonthebasis
ofcontrolsignalused.
SISO:SingleInputandSingleOutput
MIMO:MultipleInputandMultipleOutput.

3
4
CONTROLSYSTEMSBLOCKDIAGRAMS
&BLOCKDIAGRAMSALGEBRA

5
6
7
8
9
TRANSFERFUNCTIONSINBLOCK
DIAGRAMS

10
11
RULESFORBLOCKDIAGRAMS
MINIMIZATION

12
13
14
15
16
17
18
(Rule 3)

19
20
21
22
23
PROCESSCONTROL

24
 ObjectiveofProcessControl

Toregulateormaintainaparticularquantity
atreferencevalue(setpoint)byavoiding
externalinterference.

25
 ManualProcessControl:
Limitations
SlowSpeed
Inaccuracy
ImproperControlAction
Difficulttooperateinhazardousworking
condition
RepeatabilityProblems

26
 ModernProcessControl

Basedupon:
Computerbased(Digital)Controllers
PLCbasedControllers
FuzzyLogicControllers

27
 ConceptofProcessControl

Circle: Indicates an algebraic function

Rectangle: Indicates a dynamic function

28
29
 ProcessGain.
ProcessGain:Theratioofchangeinthe
output(dc)andthechangeintheinputthat
causedit(dm).
Primeobjectiveofprocesscontrolisto
maintainthedesiredquantityatafixed
value.
Automaticcontrolsystemsuseafeedback
pathformonitoringthecontrolledvalue.

30
 AutomaticControllers:Analog&
Digital
Theirmainfunctions:

31
AnalogControllers

32
 Advantages:
Simple
LessExpensive
DoesntneedA/DorD/Aconverters
Easiertointerfacewithotherelementsofthe
controlsystems

33
 Limitations
SufferedbyerrorscausedduetoHysteresis
NonLinearity
Drift

34
35