The attached narrated power point presentation explains the methods for establishing functions in design process. The material will be useful for KTU second year B Tech students in Electronics and Communication Engineering who prepare for the subject EST 200, Design and Engineering.

1. 1
EST 200, Establishing
Functions
MEC

2. 2
Contents
• Introduction.
• Expressing Functions.
• Basic and Secondary Functions.
• Determining Functions.
• Function – Means Tree.
• Specification Types.
• Utility Plot.
• Quality Function Deployment.

3. 3
Functionality
• Understanding functionality is essential to
successful design.
• Functions are those things a designed
device or system is supposed to do.
• Doing something to transform an input into
an output.
• Engineering functions involve the
transformation or flow of energy, materials,
or information.

4. 4
Functionality
• An account for all of the energy going into
and coming out of a device or a system.
• Energy can’t simply disappear, even when
it is dissipated.
• Material movement – added, mixed, split
etc.
• Information/signal flow – as hard copies
and/or soft copies, through online and/or
offline and/or by wireless.

5. 5
Expressing Functions
• Functions - things a designed device
must do.
• Statement of function:
eg : Functions of a bookshelf.
- to resist forces due to gravity.
- to support books, trophies etc.
• Avoid tying a function to a particular
solution, eg: for a cigarette lighter : avoid
“applying flame to tobacco”.

6. 6
Categories of Functions
• Basic function - the specific, overall
function that must be performed.
• Secondary functions :
(1) other functions needed to perform the
basic function.
(2) those that result from doing the basic
function.

7. 7
Secondary Functions
• Required secondary functions are those
needed for the basic function.
• Unwanted secondary functions :
- undesirable unanticipated side effects.
- may affect how a new design is
perceived and accepted.

8. 8
Functions – An Example
• Example of overhead projection
equipment :
- Basic function : to project images.
- Secondary functions : converting
energy, generating light and focusing
images.
- Unwanted secondary functions :
generating heat and noise.
• A projector that produces loud noise ???

9. 9
Functions – An Example
• Example of hand drill machine :
- Basic function : to drill holes on hard
surfaces.
- Secondary functions : converting
electrical energy to mechanical energy
for rotation.
- Unwanted secondary functions :
generating sparks, dust, unpleasant
noise.
• A noise free hand drill that sucks dust ???

10. 10
Determining Functions
• Black Box Concept.
• Reverse Engineering.
• Enumeration.
• Function - Means Tree as a graphical
representation of functions.

11. 11
Concept of a Black Box
BLACK
BOX
Inputs Outputs
Functions
Inputs enter the box Outputs leave the box

12. 12
Top Level Black Box -
Example of a Power Drill

13. 13
Top Level Black Box
• A top level black box prompts some
questions.
- How does this actually happen?
- Functions are performed by the
black box?
- Subfunctions performed inside black
box?
(How inputs are transformed to outputs?)

14. 14
Black Box to Glass Box -
Example of a Power Drill
Subfunctions

15. 15
Glass Box –
Example of a Radio Receiver

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Reverse Engineering
• Dissect, deconstruct, or disassemble.
• Find out in detail just how it works.
• Apply what we learn to our own design
problem.
• May not be able to use that design for any
number of reasons.
• May not do all the things we want, or may
not do them very well, may be too
expensive, patent protected or competitors
design.

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Reverse Engineering
• Helps gain insight into our own design
problem by looking at how others have
thought about the same or similar
problems.
• Look at parts and their functions.
• Look at alternate ways to do the same
thing.
eg : Toggle switches as alternative to
push buttons.
• Alterations needed?

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Reverse Engineering
• Analytical approach.
• Reveals the underlying physical structure.
• Attempts to look at the physical structure
to identify the means to make functions
happen.
• Try to analyze the functions of a device.,
• How those functions can be implemented.

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Why can’t we use the same
design?
• Device or design developed to meet the
goals of a particular client and a target set
of users.
• Users have different concerns than we
have.
• Adaptation limits our thoughts and
creativity.
• May require a new subfunction or new
means for a function.

20. 20
Why can’t we use the same
design?
• Restricts ourselves to the most immediate
expression of functions found in someone
else’s design.
• May run into serious intellectual property
and ethical issues.

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Enumeration
• List all of the functions that we can readily
identify.
• A functional analysis leads us immediately
to the basic functions of the device.
• May be problematic for determining
secondary functions.
• Requires engineering background.
• Successful enumeration requires
thoughtful questioning.

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Enumeration
• Asking thoughtful questions.
• Proper use of verb–noun pairs to express
each and every function.
• Ask what happens if there is no ‘X’.
Eg : What happens if a bridge disappears
or collapses immediately?
• Ask how ‘X’ might be used/maintained
over its life.
• Leads us to the function of ‘X’.

23. 23
Function – Means Tree
• Graphical representation of a design’s
basic and secondary functions.
• Tree top level shows the basic function(s)
to be met.
• Succeeding levels show
- means by which primary function(s) may
be implemented.
- secondary functions necessitated by
those means.

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Function – Means Tree
• Relates what we must do to how we might
do it.
• Allows us to work with appealing means or
implementations.
• Provides list all of the functions that have
been identified, common to all or many of
the alternatives and which are particular to
a specific means.
• Not a substitute for framing the problem/
for generating alternatives.
• Should be used in combination with some
of the other tools.

25. 25
Function – Means Tree
for a Lighter
Functions in rectangles.
Means in trapezoids

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Specifying Functions
• Determining the functions of a designed
object or system essential to the design
process.
• Functional requirements don’t mean much
if we don’t consider how well a design
must perform its functions.
• Eg : For a device that produces musical
sounds, specify how loudly, how clearly,
and at what frequencies the sounds are
produced.

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Design Specifications
• Provide a basis for determining a design,
they are the targets against which we
measure our success in performing or
achieving them.
• Specify in engineering terms a design’s
functions, as well as its features and
behaviors.
• Represent different ways of formalizing a
design’s functional performance, its
features and behaviors for engineering
analysis and design.

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Types of Specifications
• Prescriptive specifications specify values
for attributes of design.
• Procedural specifications specify
procedures for calculating attributes.
• Performance specifications specify
performance levels that a function must
demonstrate to be successful.
• Interface performance specifications
specify how those systems interact.

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Measuring Specifications
• Express functions in engineering terms
that engineering principles can be applied.
• Cast functions into terms so as to measure
how well a design realizes a specific
function.
• Establish a range over which a measure is
relevant to our design.
• Establish the extent to which ranges of
improvements in performance matter.

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Utility Plot
• Graph of usefulness of an incremental or
marginal gain in performance against the
level of a particular design variable.
• Utility or value of a design gain as the
ordinate (y-axis) normalized to the range
from 0 to 1.
• Level of the attribute being assessed on
the abscissa (x-axis).
• No gains in utility at levels 0 and 1.

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Utility Plot
Linear Approximation
S Curve

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Utility Plot
• To establish the range of interest for each
design variable that reflects the function.
• Should have an understanding of what can
/cannot be measured.
• A threshold below which no meaningful
gains can be made.
• A saturation plateau above which no
useful gains can be achieved.
• A range-of-interest zone between the
threshold and the plateau.

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Using Performance Specifications
• Users/consumers want to know if the
product is appropriate for intended use.
• Manufacturers/distributors publish a
product’s performance specification after
the product reaches the market.
• End users will know what they can expect
from a product.
• Designers examine performance
specifications of similar or competing
designs.

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Interface Performance
Specifications
• Details how devices or systems must work
together with other systems.
• Important when several design teams
work on different parts of a final product.
• All the parts required to work together
smoothly.
• Boundaries between subsystems must be
clearly defined.

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Interface Performance
Specifications
• Anything that crosses a boundary to be
specified in sufficient detail.
• Specifications may be a range of values of
variables, physical or logic devices that
support a boundary, or an agreement that
a boundary cannot be breached.
• Designers to have understanding on
where the boundary is and how it might be
crossed.

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Interface Performance
Specifications
• Teams on both sides of a boundary likely
to place constraints on the counterparts on
the other side.
• Identify the inputs and outputs that must
be matched.
• Deal with any side effects or undesired
outputs.
• Helps to minimize the total time to design,
test, build, and bring to market new
products.

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Accounting for Customer
Requirements
• Ensure that proper attention was paid to
what the customer would like to see in our
design.
• Ensures a design’s quality – fitness for
use.
• Quality of a product or service means
conformance to the specifications and
requirements.

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Design for Quality
• Quality design meets/exceeds objectives,
satisfies all constraints, is fully functional
and better than alternative designs.
• Designers use a notion called Quality
Function Deployment (QFD).
• QFD expressed in a tool called House of
Quality (HoQ).
• HoQ matrix combines information on
stakeholders, desirable characteristics of
designed products, current designs,
performance measures, and trade-offs.

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House of Quality
Explore the
interrelationships.

40. 40
House of Quality
• HoQ useful for gathering and organizing
information.
• HoQ for fostering discussions within a
design team and with stakeholders.
• HoQ entails a lot of time and effort.
• Whether and when to build a HoQ are
decisions that can only be made by a
design team in the context of its design
problem.

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HoQ for Design of Computer
Housing for a Laptop.
Roof of the house helps
to identify trade-offs
between objectives,
features and behaviors.

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Reference
• Clive L Dim, Patrick Little and Elizabeth J
Orwin, “Engineering Design, A Project
Based Introduction”, 4th Edition, Wiley,
U.S.A, 2014.

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Thank You