Quantifying flexibility in the operationally responsive space paradigm
Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
Donna H. Rhodes and Adam M. Ross.
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Designing complex space systems that will deliver value in the presence of an uncertain future is difficult. As space system lifetimes are now measured in decades, the systems face increased risk from uncertain future contexts. Tradespace exploration increases the designer's system knowledge during conceptual design and with dynamic analysis can predict the system's behavior in many possible future contexts. Designing flexible systems will allow mitigation of risk from uncertain future contexts and the opportunity to deliver more value than anticipated by the designers. Flexibility is a dynamic property of a system that allows it to take advantage of emergent opportunity and to mitigate risk by enabling the system to respond to changing contexts in order to retain or increase usefulness to system stakeholders over time. Identifying flexible designs has traditionally been accomplished through subjective or heuristic methods, leading to a qualitative assessment of system flexibility. Objective and quantitative measures of flexibility are required for analysis of flexibility in tradespace exploration, as the number of designs is often too large for traditional qualitative approaches. Value Weighted Filtered Outdegree is introduced as a metric for identifying valuably flexible systems in tradespace studies in order to improve decision making during the conceptual design phase. Dynamic Multi-Attribute Tradespace Exploration (Dynamic MATE) is used as the basic tradespace exploration method for Value Weighted Filtered Outdegree. Dynamic MATE applies decision theory to computer simulation of thousands of system designs, across hundreds of unique future contexts. Epoch-Era Analysis is used to parameterize future contexts for dynamic analysis of the designs' performance. Although dominated in static analysis, flexible designs are valuable in the presence of changing contexts. The usefulness of Value Weighted Filtered Outdegree is established through application to the design of a satellite radar system. The metric was able to identify designs that are valuably flexible, and exclude designs that carry change capability that does not add value to the design across selected epochs. Showing another application of Value Weighted Filtered Outdegree, a comparison of flexibility for an Operationally Responsive Space architecture is conducted which highlights the advantages of a modular architecture in the presence of changing user requirements.
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections."June 2009." Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 171-176).
DepartmentMassachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
Massachusetts Institute of Technology
Aeronautics and Astronautics.