A Top-Down, Safety-Driven Approach to Architecture Development for Complex Systems

Abstract

Architecture development is an important part of the systems engineering process because the system architecture forms the foundation on which the rest of the system design is based. In addition, the system architecture plays a key role in determining the behavior of the system and represents a set of design decisions made to solve a design problem. Because modern systems are increasingly complex and software-intensive, they require architectures that fully consider system-level interactions and unsafe behaviors and ensures that the responsibilities necessary to ensure safety are carried out effectively. Furthermore, the architecture development process should organize design information in a way that assists system designers and reviewers with managing system complexity and developing an understanding of the system design and its underlying rationale.

This thesis proposes a new top-down, safety-driven approach to architecture development that is based on systems theory and incorporates a hazard analysis at the beginning of the design process to drive the identification of system-level requirements. This approach ensures that the system and its environment are analyzed as a whole and emergent properties such as safety are considered as early as possible. Using a structured process and appropriate types of abstraction, this new approach to architecture development facilitates obtaining more information about how the system needs to behave before creating a series of candidate architecture options and assessing the tradeoffs between them.

The proposed approach is applied to create a conceptual architecture for a human pilot and automated flight controller performing medevac flights in Degraded Visual Environments (DVEs). This example illustrates how the new approach can be used to develop architectures in a top-down, safety-driven manner and shows how the design information obtained using this new approach can be used to make more informed architectural decisions.