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Engineering Design GE121 Understanding the Clients Problem


May not need to redesign the intersection may only need to re-time the lights ... 'Design a new ladder for electricians or other maintenance and construction ... – PowerPoint PPT presentation

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Title: Engineering Design GE121 Understanding the Clients Problem

Engineering DesignGE121Understanding the
Clients Problem
  • Lecture 2A

What does the Client Want?
  • Will now focus on tools for the preprocessing
    phase of Design
  • Focused on understanding and documenting the
    nature of the design problem
  • Introduces
  • Use of Objectives Trees
  • Attaching weights or relative values on those
  • Identifying constraints on the designer
  • Revising the problem statement
  • This set of activities is known as Problem

Objectives TreesTranslating / Clarifying
Clients Wants
  • Client usually begins the design process with
    some sort of problem statement
  • Often verbal, or a very brief single sentence
  • Design a bottle for our new childrens fruit
    juice product
  • The Claremont Colleges need to reconfigure the
    intersection of Foothill Avenue and Dartmouth
    Avenue so students can cross the road

Translating / Clarifying Clients Wants
  • This problem statement may contain
  • Errors - incorrect or faulty information (or
    omission of key information)
  • Should be Foothill Boulevard, not Avenue
  • Biases - presumptions about the problem situation
    that may prove to be inaccurate or reflect a
    limited viewpoint of the client
  • May not need to redesign the intersection may
    only need to re-time the lights
  • Implied solutions - the clients idea of how to
    solve the problem
  • If students are jaywalking, reconfiguring the
    intersection may not do anything to solve the

Translating / Clarifying Clients Wants
  • We want to focus on a clearer understanding of
  • What the client wants
  • What potential users need
  • Technological, environmental, political,
    marketing and other contexts in which our gadget,
    process or project will function
  • Will result in Defining our Design Problem much
    more clearly and realistically

Object Attributes Objectives Trees
  • Can usually identify characteristics of the
    design space for potential solutions that are
    likely to be very good
  • These can be represented as objectives trees
  • Objectives trees are hierarchical structures
  • They are for the object/process/project being
    designed, not for the design process
  • The top levels represent the most important
    goals, the lower levels branch out to describe
    these goals in terms of subgoals
  • Reading an objectives tree downward reveals how a
    goal is defined (what is included in that goal)
  • Reading an objectives tree upward reveals why a
    subgoal is important (why do you want to do that)

Object Attributes Objectives Trees
  • Design a new ladder for electricians or other
    maintenance and construction professionals
    working on conventional job sites
  • To clarify Talk with management (made the
    request), some potential users, some of companys
    marketing people, some experts
  • Questions
  • What features or attributes would you like?
  • What do you want it to do?
  • Are there already ones on the market that do
  • And for each question above, may also ask
  • What does that mean?
  • Why do you want that?

Attribute List (from Brainstorming session)
  • Ladder should be useful
  • Used to string conduit and wire in ceilings
  • Used to maintain and repair outlets in high
  • Used to replace light bulbs and fixtures
  • Used outdoors on level ground
  • Used suspended from something in some cases
  • Used indoors on floors or other smooth surfaces
  • Could be a step ladder or short extension ladder
  • A folding ladder might work
  • A rope ladder would work, but not all of the time
  • Should be reasonably stiff and comfortable for
  • Step deflections should be less than 0.05 in

Should allow person of medium height to
reach/work at levels up to 11 ft Must support
weight of average worker Must be safe Must meet
OSHA requirements Must not conduct
electricity Could be made of fiberglass, but not
aluminum Should be relatively inexpensive Must be
portable between job sites Should be light Must
be durable Neednt be attractive or stylish
List 3.2 p51
Attribute List Analysis
  • Not all statements are of the same kind
  • Some are binary (Yes/No answers) Must not
    conduct electricity
  • Relatively inexpensive means lower price is
  • Other differences
  • Material choice should probably be deferred until
  • Limit on deflection is beginning to translate
    features into design specifications

Goals/Objectives, Constraints, Functions,
  • Definitions are required to clarify what we mean
    by each of these
  • Goals or Objectives
  • Expressions of desirable attributes of a design
    or solution to the problem that we strive to
    achieve What it will be, as opposed to what
    it will do
  • Can often be expressed in terms of more or
    less of something, such as more durable which
    is better than a less durable design.

Definitions (contd)
  • Constraints
  • Limitations on the design which must be met for
    the design to be acceptable
  • Clearly defined limits that can be thought of as
    binary in that they are either met or not
  • Any design that fails to meet a constraint is to
    be rejected
  • Objectives versus constraints
  • Often confused / incorrectly interchanged
  • Constraints (e.g. less than 25) allow us to
    reject unacceptable alternatives
  • Objectives (e.g. inexpensive) allow us to select
    among designs that are at least acceptable
    (minimally satisfy all constraints

ConstraintsIdentifying Limits, OR What Cant the
Client Have?
  • Constraints are very important in limiting the
    design space
  • Tend to lead to certain design alternatives being
  • Constraints may be hard or soft
  • In many cases, soft constraints are ones which
    the client may have imposed while still at an
    early stage of the problem definition process
  • They can be challenged and, in some cases, relaxed

Definitions (contd)
  • Functions
  • Things the design must do
  • Usually expressed in terms of verb-object
    combinations, such as resist force or convert
    power to heat OR doing
  • Means or Implementations
  • Ways of performing the functions that the design
    must do
  • Very much solution-oriented

How deep is an objectives tree?What about pruned
  • Objectives tree can go as deeply as the designer
    chooses or finds necessary
  • When the point is reached that the design team is
    listing implementations rather than subgoals, it
    is time to stop
  • A pruned Objective Tree is solution independent
  • Constraints can be re-entered in the appropriate
    portion of a Combined Tree
  • Functions and implementations can be noted and
    retained for later

Objectives Tree for Beverage Container Design
Objectives Tree
Fig 3.2 p57
Combined Tree Includes Criteria (ovals)
Fig 3.3 p58
  • Your proposal will be written mostly as
    objectives. What features should the end product
    have? However, there may be some aspects that
    must be included in the final product. Make sure
    that you have clearly identified each type of
    characteristic or function.
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