The Safe-SADT method for aiding designers to choose and improve dependable architectures for complex automated systems

Dependability evaluation is crucial to controlling the risks associated with system failure, and for this reason, it is one of the fundamental steps in automated system design. However, the dependability evaluation methods that are currently exploited are not appropriate, given the level of complexity of such industrial systems. The ineffectiveness of the existing methods led us to develop and propose the Safe-SADT (structured analysis and design technique) method. Our method allows the explicit formalization of functional interactions, the identification of the characteristic values affecting the dependability of complex systems, the quantification of the reliability, availability, maintainability, and safety (RAMS) parameters of the system's operational architecture, and the validation of that operational architecture in terms of the dependability objectives and constraints set down in the functional requirement specifications (FRS). The results presented in this paper are limited to RAM quantification.