ACCESS: Assurance Case Centric Engineering of Safety-critical Systems

TL;DR

ACCESS introduces a model-based, assurance-centric engineering methodology for safety-critical systems that evolves around an evolving assurance case. The approach is backed by ACME, which provides fine-grained traceability to heterogeneous artifacts and supports automated verification with formal methods (Isabelle) and runtime evaluation via a Dynamic Safety Management System. The AUV case study demonstrates automated evaluation, traceability, and transformation to Isabelle/SACM, highlighting improvements in development efficiency and enabling runtime assurance. The work argues that living, runtime-enabled assurance cases can significantly enhance safety guarantees in open, adaptive robotics while remaining extensible to multiple modeling technologies. Overall, ACCESS and ACME offer a practical path toward integrated, automated, and dynamic assurance in complex cyber-physical systems.

Abstract

Assurance cases are used to communicate and assess confidence in critical system properties such as safety and security. Historically, assurance cases have been manually created documents, which are evaluated by system stakeholders through lengthy and complicated processes. In recent years, model-based system assurance approaches have gained popularity to improve the efficiency and quality of system assurance activities. This becomes increasingly important, as systems becomes more complex, it is a challenge to manage their development life-cycles, including coordination of development, verification and validation activities, and change impact analysis in inter-connected system assurance artifacts. Moreover, there is a need for assurance cases that support evolution during the operational life of the system, to enable continuous assurance in the face of an uncertain environment, as Robotics and Autonomous Systems (RAS) are adopted into society. In this paper, we contribute ACCESS - Assurance Case Centric Engineering of Safety-critical Systems, an engineering methodology, together with its tool support, for the development of safety critical systems around evolving model-based assurance cases. We show how model-based system assurance cases can trace to heterogeneous engineering artifacts (e.g. system architectural models, system safety analysis, system behaviour models, etc.), and how formal methods can be integrated during the development process. We demonstrate how assurance cases can be automatically evaluated both at development and runtime. We apply our approach to a case study based on an Autonomous Underwater Vehicle (AUV).

Figures (22)

• Figure 1: Assurance cases and engineering artifacts.
• Figure 2: Core GSN elements.
• Figure 3: GSN connectors.
• Figure 4: Modular GSN elements.
• Figure 5: The Assurance Case component of SACM sacm.