Developing an Objectives-Constraints Tree - Eahoover

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					            Developing an
      Objectives-Constraints Tree


      Creating a graphical representation
      of design objectives and constraints



Taken from engineering design: a project-based introduction by dym & little
The development of an Objectives-Constraints
Tree proceeds from the Attributes List and PCC.
  • The hierarchy of the Objectives-Constraints Tree comes
    from the results of the Pairwise Comparison Chart.
  • Primary objectives are listed in the first level of the tree.
  • Secondary objectives are grouped as subsets of the
    primary objectives. The same concept holds for
    subsequent levels of the tree.
  • Constraints should be listed as a subset of related
    objectives.
  • The other objectives and constraints listed in the tree
    come from the Attributes List.
  • Objectives are listed in rectangular boxes, and
    constraints are listed in ovals.
Below is an example (not exhaustive) of an
Objective-Constraints Tree for a ladder design.
                      Stable          On floors

                       Stiff       On level ground

             Safe    OSHA req.

                     Insulator
                                                         Electrical
                                       Indoors
    Ladder                                              Maintenance
                      Useful          Outdoors
    Design

                      < $200       Of right height

        Marketable
                                   Light in weight
                     Portable
                                 Small, transportable
                                                              Objectives
                     Durable
                                                              Constraints
Below is an example (not exhaustive) of an
Objective-Constraints Tree for a ladder design.



                          Subsets of “safe”




                                          Subset of “marketable”



                                                      Objectives

                                                      Constraints

				
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posted:1/10/2013
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