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Approaching Problem Definition in Engineering Design: Strategies and Metrics

This document outlines the critical process of defining engineering problems, emphasizing clarity in client objectives, constraints, and metrics. It details the importance of accurately representing client needs, identifying potential biases, and distinguishing between objectives and implied solutions. The text discusses various techniques, such as questioning and brainstorming, to facilitate problem understanding and enhancement. Examples like the Objective Tree and Pair-wise Comparison Chart (PCC) illustrate effective methods for prioritizing objectives in design, ultimately guiding engineers towards successful solutions.

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Approaching Problem Definition in Engineering Design: Strategies and Metrics

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  1. ECET 4550: Alternate EnergyFall 2011 Laboratory Topic: The Problem to be Solved “Statement of the Problem” Florian Misoc, 2010

  2. Chapter Objectives • Identifying and Representing the Client’s Objectives • Measurable Quantities • Setting Priorities • Constrains: Limitations and Delimitations • Case Study and Examples Florian Misoc, 2010

  3. Introduction • Problem Definition = the most important step in the design process • Problem Definition: pre-design phase of design • Frame the problem => engineering terms • Focus on tasks 1 – 4: • Clarify Objectives • Establish Metrics for Objectives • Identify Constrains • Revise Client’s Problem Statement Florian Misoc, 2010

  4. Identifying and Representing the Client’s Objectives • Client’s original problem statement: • Initial statements: brief, general idea • No hint on: intended market, shape of the product, material to be used, etc. • Initial statement has limitations: errors, bias, imply solutions • Clarify what client wants: what potential users need, • Technological & marketing context Florian Misoc, 2010

  5. Identifying and Representing the Client’s Objectives • Errors: incorrect information, faulty and/or incomplete data, mistakes regarding the problem • Biases: presumptions about the situation, involving a person’s preference • Implied Solution: client’s best guess at solutions, frequently found in the original problem statement (related to bias) Florian Misoc, 2010

  6. Errors of the Design Process Source: http://softwareindustrialization/CategoryView,category,Design.aspx

  7. Errors of the Design Process Source: http://softwareindustrialization/CategoryView,category,Design.aspx

  8. Errors of the Design Process Source: http://softwareindustrialization/CategoryView,category,Design.aspx

  9. Errors of the Design Process Source: http://softwareindustrialization/CategoryView,category,Design.aspx

  10. Identifying and Representing the Client’s Objectives: Questions & Brainstorming Two kinds of activity: • Asking questions of the client/stakeholder, with varying degree of interest in the problem/design • Brainstorming: group effort to generate, retain, and organize new ideas to solve the problem Florian Misoc, 2010

  11. Identifying and Representing the Client’s Objectives: Asking Questions Questions to understand the scope of the project: • What features/attributes you desire for …..? • What do you want this …. to do? • Are there already …. with similar attributes? Ask also: • What does it mean? • How are you going to do that? • Why do you want that? Florian Misoc, 2010

  12. Identifying and Representing the Client’s Objectives: Brainstorming • Focus on quantity: maxim quantity = quality. Great number of ideas = greater the chance of effective solution. • Withhold criticism: focus on extending or adding to ideas, reserve criticism for a later 'critical stage' of the process • Welcome unusual ideas: looking from new perspectives and suspending assumptions (may provide better solutions) • Combine and improve ideas: Good ideas = combinations of ideas: slogan "1+1=3” Florian Misoc, 2010

  13. Brainstorming: preliminary / start-up Florian Misoc, 2010

  14. Florian Misoc, 2010

  15. Identifying and Representing the Client’s Objectives: Concept Definitions • Objective: something toward which effort is directed (an aim/end-of-action) • Constraint: restricted, compelled to avoid, compelled to perform • Function: fitness for use, “for which a thing is made-for” • Means: method used to attain and end Florian Misoc, 2010

  16. Client’s Objectives: Objective Tree Florian Misoc, 2010

  17. Measurable Quantities Six Scale Types: • Nominal Scales: distinguish among categories • Partially Ordered Scales: hierarchies • Ordinal Scales: rank / order • Ratio Scales: percentage • Interval Scales: reference to a base-point • Multidimensional Scale: compounds of other scales Florian Misoc, 2010

  18. Pair-wise Comparison Chart (PCC) Should be applied in constrained “top-down” fashion: • Objectives are compared when at the same level (in the objective tree) • Higher level objectives: compared first • Only “top objectives” need to be ranked • “Low level objectives” are ranked ONLY for complex systems Florian Misoc, 2010

  19. Weighted Objectives: American Beverage Company Florian Misoc, 2010

  20. Weighted Objectives: National Beverage Company Florian Misoc, 2010

  21. Pair-wise Comparison Chart (PCC) • Pair-wise comparison chart for the “ladder design” Florian Misoc, 2010

  22. Measuring Achievement of Objectives • VDI 2225: VerbandDeutscherIngenieure/ Association of German Engineers • No Mathematical foundation for scaling or normalizing the PCC ranking • PCC ranking = subjective preferences • Never weigh objectives: it could amplify the error (no mathematical foundation) Florian Misoc, 2010

  23. Scale of Awarding Points Florian Misoc, 2010

  24. Metrics for Objectives • Metric = repeatable: conducting the test/experiment (under identical conditions & restrains) would lead to identical results/outcomes • Metric outcomes: understandable units of measure • Metric assessment: unambiguous interpretation Florian Misoc, 2010

  25. Setting Priorities “Lack of planning from your part does not translate in a priority from my part…” Priority level: determined in the same fashion as awarding points Priority # 1: SAFETY!!! (read the “oath of the engineer”) Florian Misoc, 2010

  26. Constrains: Limitations and Delimitations • Limitations:are imposed by the available equipment, environmental conditions, time constrains, etc., and are out of experimenter’s control • Delimitations: are imposed by the experimenter, as to restrict the purpose of said research Florian Misoc, 2010

  27. Case Study and Examples Read and summarize: • Example 3.4.2: Establishing metrics for the beverage container • Example 3.6.1: Objectives and Constrains for the “Danbury Arm Support” • Example 3.6.2: Metrics for the Objectives “Danbury Arm Support” Due: same time as assignment of Chapter 3 Florian Misoc, 2010

  28. Assignment: • Exercise # 3.1, page 77 • Exercise # 3.2, page 77 & 78 • Exercise # 3.5, page 78 • Exercise 3.6, page 78: as it applies to your particular group project Florian Misoc, 2010

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