Verification of annotated models from executions

Abstract

Simulations can help enhance confidence in system designs but they provide almost no formal guarantees. In this paper, we present a simulation-based verification framework for embedded systems described by non-linear, switched systems. In our framework, users are required to annotate the dynamics in each control mode of switched system by something we call a discrepancy function that formally measures the nature of trajectory convergence/divergence of the system. Discrepancy functions generalize other measures of trajectory convergence and divergence like Contraction Metrics and Incremental Lyapunov functions. Exploiting such annotations, we present a sound and relatively complete verification procedure for robustly safe/unsafe systems. We have built a tool based on the framework that is integrated into the popular Simulink/Stateflow modeling environment. Experiments with our prototype tool shows that the approach (a) outperforms other verification tools on standard linear and non-linear benchmarks, (b) scales reasonably to larger dimensional systems and to longer time horizons, and (c) applies to models with diverging trajectories and unknown parameters.