4.1.2 A Model‐Based Requirements Database Tool for Complex Embedded Systems

It has become clear that spacecraft system complexity is reaching a threshold where customary methods of control are no longer affordable or sufficiently reliable. At the heart of this problem are the conventional approaches to systems and software engineering based on subsystem-level functional decomposition, which fail to scale in the tangled web of interactions typically encountered in complex spacecraft designs. Furthermore, there is a fundamental gap between the requirements on software specified by systems engineers and the implementation of these requirements by software engineers. Software engineers must perform the translation of requirements into software code, hoping to capture accurately the systems engineer's understanding of the system behavior, which is not always explicitly specified. This gap opens up the possibility for misinterpretation of the systems engineer's intent, potentially leading to software errors. This problem is addressed by a systems engineering methodology called State Analysis, which provides a process for capturing system and software requirements in the form of explicit models. This paper describes (1) how requirements for complex aerospace systems can be developed using State Analysis, (2) how these requirements inform the design of the system software, and (3) how this process has been aided through a State Analysis Database (SDB) and supporting multi-platform client. The SDB provides a productive, collaborative development environment for State Analysis that is shared by both systems and software engineers.