Reachability analysis of complex planar hybrid systems

Artikel i vetenskaplig tidskrift, 2013

Hybrid systems are systems that exhibit both discrete and continuous behavior. Reachability, the question of whether a system in one state can reach some other state, is undecidable for hybrid systems in general. In this paper we are concerned with GSPDIs, 2-dimensional systems generalizing SPDIs (planar hybrid systems based on "simple polygonal differential inclusions"), for which reachability have been shown to be decidable. GSPDIs are useful to approximate 2-dimensional control systems, allowing the verification of safety properties of such systems. In this paper we present the following two contributions: (i) an optimized algorithm that answers reachability questions for GSPDIs, where all cycles in the reachability graph are accelerated. (ii) An algorithm by which more complex planar hybrid automata are over-approximated by GSPDIs subject to two measures of precision. We prove soundness, completeness, and termination of both algorithms, and discuss their implementation.