Design of Mechatronics System

UNIT 5
LECTURE-1
 Design process

DESIGN OF MECHATRONICS
SYSTEMS

INTRODUCTION
 Mechatronics is a methodology used for the optimal
design of electromechanical products.
 A methodology is collection of practices, procedures and
rules used by those who work in particular branch of
knowledge or discipline.
 The familiar technological disciplines include
thermodynamics, electrical engineering, computer
science and mechanical engineering, to name several.
 The mechatronic system is multi-disciplinary, embodying
four fundamental disciplines: electrical, mechanical,
computer science and information technology.
 The mechatronic design methodology is based on a
concurrent, instead of sequential, approach to discipline
design, resulting in products with more synergy.

INTRODUCTION
• Design through mechatronics approach requires
the integration of a wide range of material and
information to provide more flexible and of high
performance products including wide range of
features.
• The mechatronic approach to engineering design
thus involves an integration of the electronics and
computing technologies with the mechanical
system through out the design process.
• This mechatronic approach may be used to
provide enhanced performance products and
other outputs to customer.

DESIGN OF MECHATRONICS SYSTEMS

 Modelling: Block diagram or visual interface for creating
intuitively understandable behavioural models of physical
or abstract phenomena. The ability to encapsulate
complexity and maintain several levels of sub model
complexity is useful.
 Simulation: Numerical methods for solving models
containing differential, discrete, hybrid, partial, and
implicit nonlinear se well as linear equations. Must have
a lock for real-time operation and be capable of
executing faster than real time.
 Project Management: Database for maintaining project
information and sub models for eventual reuse.
 Design: Numerical methods for constrained optimization
of performance functions based on model parameters
and signals. Monte Carlo type capability is also desirable.

 Analysis: Numerical methods for frequency domain, time
domain, and complex domain design.
 Real-Time Interface: A plug-in card is used to replace part of
the model with actual hardware by interfacing to it with
actuators and sensors. This is called a hardware-in the-loop
simulation or rapid prototyping and must be executed in real
time..
 Code Generator: To produce efficient high-level source code
from the block diagram or visual modelling interface. The
control code will be compiled and used on the embedded
processor. The language is usually C.
 Embedded Processor Interface: The embedded processor
resides in the final products, and this feature provides
communication between it and the computer-aided
prototyping environment. This is called a full system
prototype.

The mechatronic design methodology is
concerned not only with producing high quality
products but with maintaining them as well, an area
referred to as life cycle design.
Several important life cycle factors are described below.
1. Delivery: Time, cost, and medium
2. Reliability: Failure rate, materials, and tolerances.
3. Maintainability: Modular design.
4. Serviceability: On board diagnostics, prognostics, and
modular design.
5. Upgradeability: Future compatibility with current
designs. Disposability: Recycling and disposal of
hazardous materials

LECTURE-2
 STAGES OF DESIGN IN MECHATRONICS

Stages in designing Mechatronic
Systems
• The design of mechatronic systems can be
divided into a number of stages.

Systems
1. The Need:
The design process starts with the need of a
customer.
By adequate market research and knowledge,
the potential needs of a customer can be
clearly identified.
In come cases, company may create a market
need but failures are more in this area.
Hence, market research technology is
necessary.

Systems
2. Analysis of the Problem:
This is the first stage and also the critical stage
in the design process.
After knowing the customer need, analysis
should be done to know the true nature of the
problem.
Shady, to define a problem accurately, analysis
should be done carefully otherwise.
The design leads to waste of time and may not
fulfil the need.

Systems
3. Preparation of a Specification:
The second stage of the mechatronic process
involves in the preparation of a specification.
The specification must be given to understand
everyone the requirements and functions to be
met.
The specification might have the statements
about mass dimensions, types, accuracy,
input/output requirements, interfaces, power
requirements, operating environment, relevant
standards and codes of practice, space
requirements and constrain payload, velocities
and speed of motion, accelerations, resolution,
control functions, life etc.

Systems
4. Conceptualization:
In this stage, possible solutions should be
generated for each of the functions required.
Such as shape, size, material cost etc.,.,
It should be possible to think of at least six
solution for realizing each function.
For obtaining a solution, similar problems that
are solved linearly days are compared or
newly generated techniques may be used.

Systems
5. Optimization:
This stage involves in a selection of a best
solution for the problem.
Optimization is defined as a technique in
which a best solution is selected among a
group of solutions to solve a problem.
The various possible solutions are evaluated
and the most suitable solution is selected.

Systems
6. Detail Design:
Once optimizing a solution is completed, the
detail design of that solution is developed.
This may require a production of prototype
etc., Mechanical layout is to be made whether
physically all components can be
accommodated.
Also whether components are accessible for
replacement/ maintenance is to be checked.

Systems
7. Production of working Drawings:
The selected design or solution is then
translated into working drawings, circuit
diagrams, etc.
So that the item can be made. Drawings also
include the manufacturing tolerances for each
component.

LECTURE-3
 TRADITIONAL AND MECHATRONICS APPROACH

INTRODUCTION
 Mechatronics systems are the blend of different forms of
engineering implementations. Mainly it is the combination of
mechanical systems and electronics. But it's not only limited
to that. These systems tend to get more and more efficient in
the future.
 Unlike the traditional systems whose design are finalized by
iterations of Design Equations and Numerical analysis, the
mechatronics systems are properly designed using Modelling
and Simulations, prototyping and hence properly tested by
deploying.
 So, In general, the conventional systems are bulky and has a
complex mechanism. You might get to see a lot of cable
connections and a lot of connected components.

INTRODUCTION
 Whereas the mechatronics systems will be compact
with a simple mechanism and lesser number of
moving parts. Most of the times these uses bus-
based or wireless communication. And each part and
its own dedicated tasks.
 I just saw an example of washing machines. The
traditional ones used to be manual and had to be
used with a lot of precautions. On the contrary, the
latest ones are highly smart and can even be
remotely operated. Detects motion as well. So
basically, it uses a lot of sensors.

TRADITIONAL vs MECHATRONICS APPROACH
S.NO TRADITIONAL APPROACH MECHATRONICS APPROACH
1 Bulk system Compact system
2 It is a complex process
involving interaction
between many skills and
disciplines
It is the basic integration of
various engineering
technology with mechanical
engineering
3 Manual control Control through
microprocessor with
controller
4 Complex mechanism Simplified mechanism
5 Non adjustable movement
cycles
Programme movements
6 Constant speed drives Variable speed drives

TRADITIONAL vs MECHATRONICS APPROACH
S.NO TRADITIONAL APPROACH MECHATRONICS APPROACH
7 Mechanical
synchronisation
Electronic synchronisation
8 Accuracy determined by
tolerance of mechanism
Accuracy achieved by
feedback
9 It consists of more
components
It consists of less
components
10 Rigid heavy structures Light structure
11 Less accuracy More accurate
12 Less flexibility More flexibility
13 Less cost High cost

LECTURE-4
 CASE STUDIES OF MECHATRONICS SYSTEM
1. PICK AND PLACE ROBOT

INTRODUCTION
 A pick and place robot is the one which is used to
pick up an object and place it in the desired location.
 It can be a cylindrical robot providing movement in
horizontal, vertical and rotational axes, a spherical
robot providing two rotational and one linear
movement, an articulate robot or a scara robot (fixed
robots with 3 vertical axes rotary arms).

Parts of a Pick N Place Robot
Let us see what the pick and place robot actually consists of:
 A Rover: It is the main body of the robot consisting of several rigid bodies like
a cylinder or a sphere, joints and links. It is also known as a manipulator.
 End Effector: It is the body connected to the last joint of the rover which is
used for the purpose of gripping or handling objects. It can be an analogy to
the arm of a human being.
 Actuators: They are the drivers of the robot. It actually actuates the robot. It
can be any motor like servo motor, stepper motor or pneumatic or hydraulic
cylinders.
 Sensors: They are used to sense the internal as well as the external state to
make sure the robot functions smoothly as a whole. Sensors involve touch
sensors, IR sensor etc.
 Controller: It is used to control the actuators based on the sensor feedback
and thus control the motion of each and every joint and eventually the
movement of the end effector.

PICK AND PLACE ROBOT
The robot has three axes and about these
three axes only motion occurs. The following movements
are required for this robot
A. Clockwise and Anti-clockwise rotation of the robot unit
on its base
B. Horizontal Linear movement of the arm to extend or
contraction
C. Up and down movement of the arm and
D. Open or close movement of the gripper

The above movements are accomplished by
the use of pneumatic cylinders operated by
solenoid controlled values with limit switches.
The limit switches are used to indicate when a
motion is completed.
The clockwise rotation of the robot unit can
be obtained from a piston and cylinder
arrangement during its extension and that of
counter clockwise during its retraction.

The upward and downward movement of the arm
can be obtained from a piston and cylinder
arrangement during the extension and retraction of
a piston respectively.
Similarly, the gripper can be opened or closed by
the piston in a linear cylinder during its extension.
The micro controller used to control the solenoid
values and hence the movements of the robot unit.
The type of microcontroller used in M68C11.

• A software program is used to control the robot.
• Eight C port lies PC0 – PC7, are used to sense the
position of eight separate limit switches used for
eight different robotic movements.
• Also one line from port D is used to start or stop the
robot operation.
• The switch in its one position will provide +5V (a logic
high signal), to the corresponding port lines and the
switch in another position will provide 0V (a logic low
signal), to the port lines.

 So the two positions of a switch will provide either a
logic high or logic low to the corresponding PC0 –
PC7, and PD, lines.
 Eight part B lines (PB0 – PB7) are used to control eight
different movement. These are Base CW, Base CEW,
Arm extends, Arm retract, Arm up, Arm down
Gripper close and
 Gripper open of the robot.
 PB0, is connected to the Triac opto isolator through a
resistor.

 TRIAC isolator consists of LED and TRIAC.
 For example, when the base has to rotate in
clockwise direction, a high signal is sent through line
PB0
 The diode is forward biased and the TRIAC opto
isolation operates, regulating the supply to the
solenoid value which in turn operated the piston rod
of the pneumatic cylinder.
 The base clockwise continues the rotation till it
reader the position of second limit switch

Advantages
• Before moving further, let us see few reasons why
pick and place robots are preferred:
• They are faster and can get the work done in seconds
compared to their human counterparts.
• They are flexible and have the appropriate design.
• They are accurate.
• They increase the safety of the working environment
and actually never get tired.

Applications of Pick and Place Robot:
• Defence Applications: It can be used for surveillance and
also to pick up harmful objects like bombs and diffuse
them safely.
• Industrial Applications: These robots are used in
manufacturing, to pick up the required parts and place it
in correct position to complete the machinery fixture. It
can be also used to place objects on the conveyer belt as
well as pick up defective products from the conveyer
belt.
• Medical Applications: These robots can be used in
various surgical operations like in joint replacement
operations, orthopaedic and internal surgery operations.
It performs the operations with more precision and
accuracy.

LECTURE-5
2. ENGINE MANAGEMENT SYSTEM

INTRODUCTION
 EMS stands for Engine Management System which
consists of a wide range of electronic and electrical
components such as sensors, relays, actuators and
an Engine Control Unit.
 Furthermore, they work together to provide the
Engine Management System with vital data
parameters that are essential for governing various
engine functions effectively.
 The Engine Management system is incorporated in
the modern day engine technologies, such as MPFi &
Gdi (Gasoline direct injection) systems in Petrol
engines and CRDi (Common Rail Direct Fuel Injection
System) system in diesel engines for improved
performance.

INTRODUCTION
What is the engine management system in a car?
• It is the brain of the car that controls the fuel supply
and the ignition by combining the two separate
functions into one main system.
• The Engine Management System controls the whole
of the combustion process, making the engine more
efficient and less polluting than ever before.

ENGINE MANAGEMENT SYSTEM
Engine management system is now-a-days, used
in many of the modem cars.
This car includes many electronic control systems
such as microcontrollers for the control of various
engine factors.
The main objective of the system is to ensure that
the engine is operated at its optimum settings.
The engine management system of a car is
responsible for managing the ignition and fuelling
requirements of the engine.

 The power and speed of the engine are controlled by
varying the ignition timing and the Air fuel mixture. In
modern cars, this is done by microprocessor.
 To control the ignition delay, the crank shaft drives a
distribution which makes electrical contacts for each spark
plug in turn and a timing wheel.
 This timing wheel generates pulses - to indicate the
crankshaft position.
 The microprocessor then adjusts the timing at which high
voltage pulses are sent to the distributor so that they occur
at right moments of time.

 To control the amount of air-fuel mixture entering into a cylinder
during the suction stroke, the microprocessor varies the time for
which a solenoid is activated to the inlet valve on the basis of inputs
received by the engine temperature and the throttle position.
 The amount of fuel to be injected into the air stream can be
determined on input from a sensor of the mass rate of air, or
computed from other measurements. The microprocessor then
gives as output to control of fuel inject valve.
 The system hence consists of number of sensor for observing
vehicle speed, Engine temperature, oil and fuel pressure, air flow
etc.,
 These sensors supplies input signals to the microprocessor after
suitable signal conditioning and provides output signals via drivers
to actuate corresponding actuators.

1. ENGINE SPEED SENSORS:
The Engine speed sensor is an inductive type
sensor used to measure or sense the engine
speed. It consists of a coil and a sensor wheel.
When the teeth of the wheel pass through the
sensor, the inductance of the coil changes.
This change in inductance produces an
oscillating voltage.

2. ENGINE TEMPERATURE SENSOR:
The engine temperature sensor is used to
sense the temperature of the engine.
It is usually a thermistor or a thermocouple.
The thermocouple consists of a bimetallic
strip or a thermistor whose resistance
changes when there is a variation in
temperature of the engine.

3. HOT WIRE ANEMOMETER:
Hot wire anemometer is used as a mass
airflow rate sensor in which a heated
wire gets cooled when air passes across
it.
The amount of coding depends on the
mass flow rate.

4. OXYGEN SENSOR:
The oxygen sensor is usually a closed end
tube made of zirconium oxide with porous
platinum electrodes on the inner and outer
surfaces.
When the temperature is above 300˚C the
sensor become permeable to oxygen ions so
that melt age will be produced between the
electrodes.

The various drivers such as fuel injection
drivers, ignition coil driver’s solenoid drivers
and are used to actuate actuators according to
the signal by various sensors.
Analog signals are converted into digital signals
by using ADC and are sensed by various sensors
which in turn sent to the microcontroller.
The microcontroller compares these input
values with the set points stored in its memory
and it issues control signals to the
corresponding our drivers.

 The microcontroller compares these input values
with the set points stored in its memory and it issues
control signals to the corresponding our drivers.
 The output signals are converted into analogue signal
by using ADC.
 The transient protection circuit prevents any sudden
surge a rise or far in the power supply in the power
supply to the micro controller.
 A+12V voltage regulator is used to supply the dc
voltage required for the microcontroller operation.

Advantages
1. Good acceleration response
2. Idle speed control which is affected by engine
coolant temperature, on-off of the air conditioning
compressor and battery voltage
3. Cruise control
4. Self-diagnostic system
5. Reduced fuel consumption
6. Increased safety
7. Improved operation (Single lever Power Control)

LECTURE-6
3. AUTOMATIC CAR PARKING BARRIER SYSTEM

INTRODUCTION
 Consider the coin-operated car park system with
barriers.
 The main requirement of the system is that, the in-
barrier is to be opened to allow the car inside if
correct money (coin) is inserted in the collection box
and the out barrier is to be opened to allow the car
outside, if the car is detected at the car park side of
the barrier.
 Figure shows the automatic car park barrier along
with the mechanism to lift and lower it.

INTRODUCTION
 When the current flows through the solenoid A, the
piston in the cylinder extends to move upward and
causes the barrier to rotate about its pivot and thus
the barrier rises to allow the car inside.
 When the current flows through the solenoid A
ceases, the spring on the solenoid valve makes the
contacts to open and thus makes the valve to its
original position.
 When the current flows through solenoid B, the
piston in the cylinder moves downward end causes
the barrier to get down. Limit switches are used to
detect when the barrier is down and also when fully
up.

INTRODUCTION
 This control can be controlled by PLC as shown in figure.
 X400 – coin operated switch at entrance to car park
 X401 – switch activated when entrance barrier is out
 X402 – switch activated when entrance barrier is down
 X403 – switch activated when car at exit barrier
 X404 – switch activated when exit barrier is -up
 X405 – switch activated when exit barrier is down
 Y430 – solenoid on valve A for entrance barrier
 Y43 1– solenoid on valve B for entrance barrier
 Y432 – solenoid on valve A for exit barrier
 Y433 – solenoid on valve B for exit barrier

INTRODUCTION
This control can be controlled by PLC as
shown in figure.
 Six inputs (X400 to X405) is required for the PLC to
sense the six limit switch position namely coin-
operated switch, entrance barrier up switch, down
switch, car at exit barrier switch, exit barrier up
switch, Exit barrier down switch as indicated in the
diagram.
 When ever, a switch is operated, 0V signal is
provided to the corresponding inputs and otherwise
+24v signal is provided to the inputs. Four outputs
(Y430 to Y433) is required to operate the two
solenoid valves A and B.

Program
LD X400
OR Y430
ANI M100
ANI Y431
OUT Y430
LD X401
OUT T450
K 10
LD T450
OUT M100
LD M100
OR Y431
ANI X402
ANI Y430
OUT Y431
LD X403
OR Y432
ANI M101
ANI Y433
OUT Y432
LD X404
OUT T451
K 10
LD
T45 1
OUT
M101
LD
M101
OR
Y433
ANI
X405
ANI
Y432
OUT
Y433
END

Program
• Assume a 10 sec delay for the car is to come
inside the barrier and to go outside the
barrier.
• These time delays provided by T450 and T451
energising their Internal relays respectively.

Design of Mechatronics System

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