Abstract. We present a fully automatic approach for counterexample guided abstraction refinement of real-time systems modelled in a subset of timed automata. Our approach is implemented in the MOBY/RT tool environment, which is a CASE tool for embedded system specifications. Verification in MOBY/RT is done by constructing abstractions of the semantics in terms of timed automata which are fed into the model checker UPPAAL. Since the abstractions are overapproximations, absence of abstract counterexamples implies a valid result for the full model. Our new approach deals with the situation in which an abstract counterexample is found by UPPAAL. The generated abstract counterexample is used to construct either a concrete counterexample for the full model or to identify a slightly refined abstraction in which the found spurious counterexample cannot occur anymore. Hence, the approach allows for a fully automatic abstraction refinement loop starting from the coarsest abstraction towards an abstraction for which a valid verification result is found. Nontrivial case studies demonstrate that this approach computes small abstractions fast without any user interaction.
Abstract. We propose a library based incremental design methodology for constructing hybrid controllers from a component library of models of hybrid controllers, such that global safety and stability properties are preserved. To this end, we propose hybrid interface specifications of components characterizing plant regions for which safety and stability properties are guaranteed, as well as exception mechanisms allowing safe and stability-preserving transfer of control whenever the plant evolves towards the boundary of controllable dynamics. We then propose a composition operator for constructing hybrid automata from a library of such pre-characterized components supported by compositional and automatable proofs of hybrid interface specifications.
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