| Abstract: |
Modern cyber-physical systems usually assume a certain degree of autonomy. Such systems, like Ambient Assisted Living systems aimed at assisting elderly people in their daily life, often need to perform safety-critical functions, for instance, fall detection, health deviation monitoring, communication to caregivers, etc. In many cases, the system users have distributed locations, as well as different needs that need to be serviced intelligently and simultaneously. These features call for intelligent, adaptive, scalable and fault-tolerant system design solutions, which are well embodied by multi-agent architectures. Analyzing such complex architectures at design phase, to verify if an abstraction of the system satisfies all the critical requirements is beneficial. In this paper, we start from an agent-based architecture for ambient assisted living systems, inspired from the literature, which we model in the popular Architecture Analysis and Design Language. Since the latter lacks the ability to specify autonomous agent behaviours, which are often intelligent, non deterministic or probabilistic, we extend the architectural language with a sub-language called Agent Annex, which we formally encode as a Stochastic Transition System. This contribution allows us to specify behaviours of agents involved in agent-based architectures of cyber-physical systems, which we show how to exhaustively verify with the state-of-art model checker PRISM. As a final step, we apply our framework on a distributed ambient assisted living system, whose critical requirements we verify with PRISM. |