An Introduction to Systematic Design

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An Introduction toSystematic Design

• David Beams
• ENGR 1200

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Systematic Design a 10-step processas described
by Eide et al.

• Identification the need
• Definition of the problem
• Search
• Identification of constraints
• Identification of criteria
• Development of alternative solutions
• Analysis
• Decision
• Specification
• Communication

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Identification of the need

• How are needs identified?
• Need to make a profit
• Customer experience
• Corporate experience
• Keeping abreast of the competition
• Realization that old solutions are no longer
  viable
• Laws and/or regulations
• Examples
• Planter monitor (idea conceived by farmers)
• Mini-van (idea initially conceived at Ford but
  first introduced by Chrysler)
• Douglas DC-3 answer to the Boeing 247
• Catalytic converters and unleaded gasoline
• CAFE standards

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What happens when needs are not properly
identified?

• Poor results or outright commercial failure
• New Coke (a marketing disaster)
• Ford Edsel (also a marketing disaster)
• Early ventures in home computers (Commodore, TI,
  Timex Computer Corp)
• Failure to anticipate needs may result in the
  decline or even disappearance of industries
• Lee Iacocca attributes much of the decline of the
  American automobile industry in the 1970s and
  1980s to the failure to anticipate the demands
  for quality, reliability, and good fuel
  efficiency
• Many electronics firms that were leaders in the
  era of vacuum tubes failed to retain their
  leadership in the era of semiconductors.

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Principles of Problem Definition

• Broad definition first
• Being overly specific too early may foreclose
  solutions
• Symptom vs. cause
• Example combine shaft-speed monitors
• Solving the wrong problem
• the classic case of solving the wrong problem was
  the unlamented seat-belt interlock of 1974
• Is the construction of more roads to ease traffic
  congestion in urban areas be a case of solving
  the wrong problem? Would improved public
  transportation (buses, light rail) be a better
  solution?

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Search

• What is already known about the problem?
• There may be an existing solution.
• There may be a body of existing knowledge.
• However, a body of existing knowledge may limit
  the solution space because of accepted orthodoxy
  that has never been challenged.
• Where can an engineer search for information?
• Internet
• Trade journals
• Scientific or technical journals
• Manufacturers representatives
• Catalogs
• Colleagues and experts in the particular field

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Constraints and Criteria

• Constraints are limits imposed on the solution
  space by physical principles or other practical
  limitations
• Example no violation of conservation of energy
• Example a solution that is far too expensive
  for the customer base for which it is intended
• Example life-cycle considerations in design
• Criteria are desirable characteristics or
  attributes of possible solutions
• Aesthetics
• Ease of use
• Ease of assembly or maintenance
• Resistance to wear

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Alternative Solutions

• Design at a relatively high level of abstraction
  begins once the problem has been adequately
  understood and the dimensions of the solution
  space explored.
• Multiple approaches and design solutions are
  generated.

Analysis and Decision

• Alternative solutions are judged to determine the
  overall best approach according to the attributes
  that the final design must possess and the
  relative importance of those attributes.

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Specification

• Detailed design work takes place at this stage.
• Notice the degree of planning that took place
  before this step. Many (most) engineers want to
  jump directly to the detailed design phase. My
  own observation is that software engineers tend
  to be the most prone to circumvent the
  preliminary steps.

Communication

• Vital at all stages of the engineering design
  process.