Safe Decomposition of Startup Requirements: Verification and Synthesis

Abstract

The initialization of complex cyber-physical systems often requires the interaction of various components that must start up with strict timing requirements on the provision of signals (power, refrigeration, light, etc.). In order to safely allow an independent development of components, it is necessary to ensure a safe decomposition, i.e. the specification of local timing requirements that prevent later integration errors due to the dependencies. We propose a high-level formalism to model local timing requirements and dependencies. We consider the problem of checking the consistency (existence of an execution satisfying the requirements) and compatibility (absence of an execution that reaches an integration error) of the local requirements, and the problem of synthesizing a region of timing constraints that represents all possible correct refinements of the original specification. We show how the problems can be naturally translated into a model checking and synthesis problem for timed automata with shared variables. Exploiting the linear structure of the requirements, we propose an encoding of the problem into SMT. We evaluate the SMT-based approach using MathSAT and show how it scales better than the automata-based approach using Uppaal and nuXmv.