Engineering Design GE121 Understanding the Clients Problem

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Engineering DesignGE121Understanding the
Clients Problem

• Lecture 2A

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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
  objectives
• Identifying constraints on the designer
• Revising the problem statement
• This set of activities is known as Problem
  Definition

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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
  memo
• 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

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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
  problem

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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

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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)

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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
  similar?
• And for each question above, may also ask
• What does that mean?
• Why do you want that?

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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
  places
• 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
  users
• 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
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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
  desirable
• Other differences
• Material choice should probably be deferred until
  later
• Limit on deflection is beginning to translate
  features into design specifications

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Goals/Objectives, Constraints, Functions,
Implementations

• 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.

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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

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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
  rejected
• 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

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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

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How deep is an objectives tree?What about pruned
entries?

• 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

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Objectives Tree for Beverage Container Design
p56
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Objectives Tree
Fig 3.2 p57
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Combined Tree Includes Criteria (ovals)
Fig 3.3 p58
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Activity

• 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.