2,733 research outputs found
Similarity-Based Supervisory Control of Discrete Event Systems
Due to the appearance of uncontrollable events in discrete event systems, one
may wish to replace the behavior leading to the uncontrollability of
pre-specified language by some quite similar one. To capture this similarity,
we introduce metric to traditional supervisory control theory and generalize
the concept of original controllability to \ld-controllability, where \ld
indicates the similarity degree of two languages. A necessary and sufficient
condition for a language to be \ld-controllable is provided. We then examine
some properties of \ld-controllable languages and present an approach to
optimizing a realization.Comment: 22 pages, 5 figure
Supervisory control with progressive events
This paper investigates some limitations of the nonblocking property when used for supervisor synthesis in discrete event systems. It is shown that there are cases where synthesis with the nonblocking property gives undesired results. To address such cases, the paper introduces progressive events as a means to specify more precisely how a synthesised supervisor should complete its tasks. The nonblocking property is modified to take progressive events into account, and appropriate methods for verification and synthesis are proposed
State-Based Control of Fuzzy Discrete Event Systems
To effectively represent possibility arising from states and dynamics of a
system, fuzzy discrete event systems as a generalization of conventional
discrete event systems have been introduced recently. Supervisory control
theory based on event feedback has been well established for such systems.
Noting that the system state description, from the viewpoint of specification,
seems more convenient, we investigate the state-based control of fuzzy discrete
event systems in this paper. We first present an approach to finding all fuzzy
states that are reachable by controlling the system. After introducing the
notion of controllability for fuzzy states, we then provide a necessary and
sufficient condition for a set of fuzzy states to be controllable. We also find
that event-based control and state-based control are not equivalent and further
discuss the relationship between them. Finally, we examine the possibility of
driving a fuzzy discrete event system under control from a given initial state
to a prescribed set of fuzzy states and then keeping it there indefinitely.Comment: 14 double column pages; 4 figures; to be published in the IEEE
Transactions on Systems, Man, and Cybernetics--Part B: Cybernetic
Progressive events in supervisory control and compositional verification
This paper investigates some limitations of the nonblocking property when used for supervisor synthesis in discrete event systems. It is shown that there are cases where synthesis with the nonblocking property gives undesired results. To address such cases, the paper introduces progressive events as a means to specify more precisely how a synthesised supervisor should complete its tasks. The nonblocking property is modified to take progressive events into account, and appropriate methods for verification and synthesis are proposed. Experiments show that progressive events can be used in the analysis of industrial-scale systems, and can expose issues that remain undetected by standard nonblocking verification
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