On Symbolic Analysis of Discrete Event Systems Modeled as Automata with Variables
Licentiatavhandling, 2012

In benefit of the current revolution in computer technology, nowadays, society is dependent on dedicated computer-aided systems more than ever to assist us in every aspect of daily life. Thereby, designing reliable control logic of those systems to avoid malfunctioning behavior is of importance. At some certain level of abstraction, the dynamics of many computer-aided systems can be characterized by a set of states and the state evolution depends entirely on the occurrence of discrete events. Such dynamic systems are referred to as discrete event systems (DES), which is the main subject of this thesis. Supervisory Control Theory (SCT) is a formal methodology for generating control function for DESs based on a model of an uncontrolled plant and speci- fications that the closed-loop system must fulfill. SCT makes it easier to handle changes for the system to be controlled. This is, for example, important for man- ufacturing systems where both the products to be produced and the production equipment may change frequently. With such a model-based framework, it is possible to use algorithms to generate large parts of the control logic. Although SCT shows great promise to assist control engineers to create cor- rect control functions, industrial acceptance has been limited so far. One of the main obstacles with SCT is the state-space explosion problem which arises from the failure of explicit enumerating and storing large number of states due to lack of memory. To alleviate this problem, a well-known strategy is to utilize compact data structures such Binary Decision Diagrams (BDDs) to efficiently represent set of states. By encoding system models, the computation of control functions can be carried out implicitly (symbolically). In this thesis, DESs are modeled as Extended Finite Automata (EFAs), which are ordinary automata augmented with variables. By taking advantage of the EFA structure, this thesis presents a set of BDD-based algorithms and formal analysis for exploring the state-space of large-scale DESs. Specifically, by using one of the partitioning techniques, the algorithms partition the state-space of a considered DES into a set of BDDs according to the included events and explore them in an efficient and structural manner. The work presented in this thesis has been implemented and integrated into the SCT tool Supremica and the algorithm efficiency is demonstrated on a set of academic and industrial examples.

Partitioning Techniques

Discrete Event Systems

Supervisory Control Theory

Extended Fi- nite Automata

Binary Decision Diagrams

EA, Hörsalsvägen 11
Opponent: Feng Lei, Associate Professor, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden

Författare

Zhennan Fei

Chalmers, Signaler och system, System- och reglerteknik, Automation

Modeling sequential resource allocation systems using Extended Finite Automata

IEEE International Conference on Automation Science and Engineering,; (2011)p. 444 - 449

Paper i proceeding

Efficient Symbolic Supervisory Synthesis and Guard Generation: Evaluating partitioning techniques for the state-space exploration

ICAART 2011 - Proceedings of the 3rd International Conference on Agents and Artificial Intelligence,; Vol. 1(2011)p. 106-115

Paper i proceeding

Symbolic reachability computation using the disjunctive partitioning technique in Supervisory Control Theory

2011 IEEE International Conference on Robotics and Automation (ICRA),; (2011)p. 4364 - 4369

Paper i proceeding

Ämneskategorier

Datorteknik

Produktionsteknik, arbetsvetenskap och ergonomi

Styrkeområden

Produktion

R - Department of Signals and Systems, Chalmers University of Technology

EA, Hörsalsvägen 11

Opponent: Feng Lei, Associate Professor, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden

Mer information

Skapat

2017-10-08