Linking Abstract Analysis to Concrete Design: A Hierarchical Approach to Verify Medical CPS Safety
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Compositional verification
Model-based development
Medical cyber-physical systems
Computer Engineering
Computer Sciences
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Abstract
Complex cyber-physical systems are typically hierarchically organized into multiple layers of abstraction in order to manage design complexity and provide verification tractability. Formal reasoning about such systems, therefore, necessarily involves the use of multiple modeling formalisms, verification paradigms, and concomitant tools, chosen as appropriate for the level of abstraction at which the analysis is performed. System properties verified using an abstract component specification in one paradigm must then be shown to logically follow from properties verified, possibly using a different paradigm, on a more concrete component description, if one is to claim that a particular component when deployed in the overall system context would still uphold the system properties. But, as component specifications at one layer get elaborated into more concrete component descriptions in the next, abstraction induced differences come to the fore, which have to be reconciled in some meaningful way. In this paper, we present our approach for providing a logical glue to tie distinct verification paradigms and reconcile the abstraction induced differences, to verify safety properties of a medical cyber-physical system. While the specifics are particular to the case example at hand - a high-level abstraction of a safety-interlock system to stop drug infusion along with a detailed design of a generic infusion pump - we believe the techniques are broadly applicable in similar situations for verifying complex cyber-physical system properties.