1 research outputs found
Early-Stage Resource Estimation from Functional Reliability Specification in Embedded Cyber-Physical Systems
Reliability and fault tolerance are critical attributes of embedded
cyber-physical systems that require a high safety-integrity level. For such
systems, the use of formal functional safety specifications has been strongly
advocated in most industrial safety standards, but reliability and fault
tolerance have traditionally been treated as platform issues. We believe that
addressing reliability and fault tolerance at the functional safety level
widens the scope for resource optimization, targeting those functionalities
that are safety-critical, rather than the entire platform. Moreover, for
software based control functionalities, temporal redundancies have become just
as important as replication of physical resources, and such redundancies can be
modeled at the functional specification level. The ability to formally model
functional reliability at a specification level enables early estimation of
physical resources and computation bandwidth requirements. In this paper we
propose, for the first time, a resource estimation methodology from a formal
functional safety specification augmented by reliability annotations. The
proposed reliability specification is overlaid on the safety-critical
functional specification and our methodology extracts a constraint satisfaction
problem for determining the optimal set of resources for meeting the
reliability target for the safety-critical behaviors. We use SMT
(Satisfiability Modulo Theories) / ILP (Integer Linear Programming) solvers at
the back end to solve the optimization problem, and demonstrate the feasibility
of our methodology on a Satellite Launch Vehicle Navigation, Guidance and
Control (NGC) System.Comment: 23 page