Runtime Model-Based Assurance of Open and Adaptive Cyber-Physical Systems

Abstract

Cyber-Physical Systems (CPSs) in domains such as automotive and autonomous vehicles that perform safety-critical functions require the justification and demonstration of system dependability. Assurance cases provide an explicit means for assessing confidence in system safety, security, and other properties of interest. The Structured Assurance Case Metamodel (SACM) issued by the Object Management Group (OMG) defines a standardized metamodel for representing structured assurance cases. SACM provides the foundations for model-based system assurance with great potential to be applied in emergent open and adaptive CPS domains. Thus, assurance cases are expected to be exchanged, integrated, and verified at runtime to ensure the dependability of CPSs. However, existing design-time system assurance activities are insufficient to enable dynamic safety and security assurance of CPSs at runtime. In this paper, we introduce extensions to SACM to support the specification and synthesis of executable assurance cases from design, analysis, and process models to demonstrate CPS safety and security at runtime. We evaluate the feasibility of our approach in an illustrative study in the automotive domain.