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Functional Analysis and Allocation

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In the Systems Engineering Process Functional Analysis and Allocation bridges the gap between Requirements engineering and design. This step in the process transforms stakeholder requirements into a logical[1] and functional architecture[2], and provides the inputs to the design, integration, and verification activities [3][4]

Motivation

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The Functional Analysis and Allocation step of the Systems Engineering Process is critical for managing the complexity of multidisciplinary systems.

Methodologies

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There are several methodologies for performing functional analysis:[5]

  • Functional decomposition [4]
The purpose of this method is to break down top-level functions into lower-level sub-functions to provide a hierarchical structure of the functionality.
  • Function Analysis System Technique (FAST) [6]
Like functional decomposition, FAST is used to decompose a system's functions into sub-functions. In addition, it analyzes the logical relationships between those functions. The methodology uses the FAST diagram in order to assist the brainstorming process. For each top level function, the diagram maps "how" the function is achieved, "why" the function is needed, and which functions support the main function.
  • Use Case Analysis
Use-case analysis is used for both functional requirement identification, and the refinement of those requirements. [7]

Functional Architecture Description

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The output of the Functional Analysis and Allocation process is a functional specification.

References

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  1. ^ "Logical Architecture (glossary)". INCOSE SeBoK. Retrieved 17 May 2025.
  2. ^ "Functional Architecture (glossary)". INCOSE SeBoK. Retrieved 17 May 2025.
  3. ^ Guide to the Systems Engineering Body of Knowledge (SEBoK) https://sebokwiki.org/wiki/Guide_to_the_Systems_Engineering_Body_of_Knowledge_(SEBoK). {{cite web}}: Missing or empty |title= (help)
  4. ^ a b NASA. NASA Systems Engineering Handbook, NASA/SP-2016-6105 Rev2. Washington, DC: NASA Headquarters, Office of the Chief Engineer, 2016. Available at NASA NTRS.
  5. ^ INCOSE. INCOSE Systems Engineering Handbook: A Guide for System Life Cycle Processes and Activities. Version 4.0. San Diego, CA: International Council on Systems Engineering (INCOSE), 2015.
  6. ^ SAVE International. Value Methodology Standard (VMS), 2007. Also see Miles, L. D. Techniques of Value Analysis and Engineering. McGraw-Hill, 1961.
  7. ^ Saurabh, Tiwari; Atul, Gupta (2015). "A systematic literature review of use case specifications research". Information and Software Technology. 67: 128-158. Retrieved 28 May 2025.

General References

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  • Object Management Group (OMG). OMG Systems Modeling Language (OMG SysML®), Version 1.6, 2019. Retrieved from omg.org.
  • Blanchard, B. S., & Fabrycky, W. J. Systems Engineering and Analysis. 5th ed. Pearson, 2010.
  • Martin, J. N. Systems Engineering Guidebook: A Process for Developing Systems and Products. CRC Press, 1997.
  • Dickerson, C., & Mavris, D. Architecture and Principles of Systems Engineering. CRC Press, 2009.