Establishing Functions.

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EST 200, Establishing Functions

• MEC

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Contents

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

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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.

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Functionality

• An account for all of the energy going into and
  coming out of a device or a system.
• Energy cant 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.

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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.

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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.

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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.

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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 ???

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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 ???

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Determining Functions

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

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Concept of a Black Box

BLACK BOX
Inputs
Outputs
Functions
Outputs leave the box
Inputs enter the box
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Top Level Black Box - Example of a Power Drill
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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?)

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Black Box to Glass Box - Example of a Power Drill

Subfunctions
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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 cant 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.

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Why cant we use the same design?

• Restricts ourselves to the most immediate
  expression of functions found in someone elses
  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 verbnoun 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.

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Function Means Tree

• Graphical representation of a designs 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.

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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 dont mean much if we
  dont 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 designs
  functions, as well as its features and behaviors.
• Represent different ways of formalizing a
  designs 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 products
  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 designs 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.
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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