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Subtitle-A modular and timed discrete event modeling framework is used to analyze the correct function of logic controllers for continuous processes in a rigorous manner. Abstract-An approach to the formal verification of logic controllers for processes with switched continuous dynamics is presented. The method builds on modular, timed discrete event models(More)
This case study compares the usefulness and applicability of eight computer tools with respect to the validation of logic control programs for continuous processes. Six simulation packages (Taylor's MATLAB-based simulator, SIMULINK/STATEFLOW, GPROMS, SHIFT, DYMOLA, and BASIP) and two verification tools (SMV and HYTECH) were applied to a single process(More)
We describe two approaches to derive Timed and Linear Hybrid Automata from continuous models given as systems of ordinary diierential equations. A semiquantitative modeling method is applied which yields a qualitative description of the system dynamics and quantitative bounds for the residence times in the discrete states or the state variable derivatives.(More)
The paper presents a concept for the reachability analysis of switched continuous systems in which switching only occurs when the continuous state trajectory crosses thresholds defined by a rectangular partitioning of the state space. It combines an existing approach for approximating such systems by rectangular automata with an existing reachability(More)
Rectangular automata are well suited for approximate mod-eling of continuous{discrete systems. The exact analysis of these au-tomata is feasible for small examples but can encounter severe numerical problems for even medium-sized systems. This paper presents an analysis algorithm that uses conservative overapproximation to avoid these numerical problems.(More)
This paper describes the use of timed Condition/Event (C/E) systems, a real-time extension of the C/E system framework introduced by Sreenivas and Krogh, for building models of chemical plants in a modular fashion and as a basis for the model-based analysis of their discrete control. The approach is illustrated by applying it to the safety control logic of(More)
The paper describes a model-based approach to the formal verification of sequential control programs for chemical processes. It is assumed that the control software is represented as a Sequential Function Chart (SFC) which may include timing constraints for the control actions. The verification method is based on a timed Condition/Event (C/E) model of the(More)
In this paper we integrate two diierent approaches for the speciication and veriication of timed systems being used in control theory and computer science. These are the timed condition/event systems and the timed automata formalisms. Our main result states that timed condition/event systems can be eeciently transformed into timed automata which then can be(More)