Approaches to the Formal Verification of Hybrid Systems

Abstract

This paper presents two different approaches to the problem of formally verifying the correctness of control systems which consist of a logic controller and a continuous plant and, thus, constitute a hybrid system. One approach aims at algorithmic verification and combines Condition/Event Systems with Timed Automata. The first framework is used to model the controller and the plant in a block-diagram representation, which is then translated into the latter model for analysis by available tools. A second approach is presented which is based on deductive verification. It allows for a structured analysis of compositional specifications formulated in a temporal logic called cTLA. This logic is a compositional style of the Temporal Logic of Actions established in Computer Science by Lamport. Both approaches are introduced using a common example and the results of their application are discussed. As an outlook, a possible strategy for integrating algorithmic and deductive verification of hybrid systems is sketched at the end of the paper.