Date of Award

Spring 1996

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Engineering Management & Systems Engineering

Committee Director

Laurence D. Richards

Committee Member

Griffith

Committee Member

Derya Jacobs

Committee Member

Frederick Steier

Abstract

Increased emphasis is being placed on improving the performance of space projects, within tighter budgets and shorter development times. This has led to a need for more efficient space system design methods. The research described here represents an effort to develop and evaluate such a method.

Systems engineering and concurrent engineering together provide the theoretical foundation for the method. The method, derived from both this theoretical foundation and ideas from experts in the space industry, emphasizes a total systems analysis approach, taking into account given mission requirements, and the mathematical modeling of interactions between system variables and between subsystems. The emphasis makes it possible to apply the method for effectively sizing and configuring the full space project, its subsystems, and its variables.

Size and configuration issues are especially important in the early conceptual design stages. The focus of this research and the developed method was, therefore, put on facilitating the design decisions taking place during those design stages. Mass, as a proxy for cost, was selected as the evaluation and optimization criterion. To make the method practical, LabVIEW was selected for developing the total systems analysis model.

LabVIEW is a graphical programming language that is easy to learn, program, modify, and run; and, it has a good user interface. These characteristics make it well suited for rapid model development and for performing the large number of analysis runs required in the early conceptual design stages. The method was demonstrated for a V/IR (Visual/Infrared) space based Earth observation system. The mathematical model describing the interactions in this system was developed in close cooperation with subsystem specialists, primarily at NASA Langley Research Center, making it as realistic as possible. The model includes some 300 variables and 130 equations, and uses 1.7 MB of code.

The demonstration, focusing on size and configuration issues, showed how the method and model could be used for better understanding of model dynamics, for evaluating alternative technologies, for detecting technology limits, for performing inter-subsystem analyses, and for suggesting new technology developments.

It is hoped that this research will encourage engineers and project managers in the space sector to apply the developed design method to other types of space projects.

DOI

10.25777/ewsb-h718

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