2,269 research outputs found
Feedback control logic synthesis for non safe Petri nets
This paper addresses the problem of forbidden states of non safe Petri Net
(PN) modelling discrete events systems. To prevent the forbidden states, it is
possible to use conditions or predicates associated with transitions.
Generally, there are many forbidden states, thus many complex conditions are
associated with the transitions. A new idea for computing predicates in non
safe Petri nets will be presented. Using this method, we can construct a
maximally permissive controller if it exists
Synthesis of control implementation for discrete manufacturing systems
International audienceThe paper presents the concepts and steps required to synthesize a correct control implementation for discrete manufacturing systems, starting from Grafcet speci-® cations. A formal framework implementing the synthesis steps is also presented and illustrated with an example of a drilling system
Synthesis of Control Elements from Petri Net Models
Methods are presented for synthesizing delay-insensitive circuits whose behavior is specified by Petri net models of macromodular control elements. These control elements implement five natural functions used in asynchronous system design. Particular attention is paid to modules requiring mutual exclusion where metastability must be carefully controlled
Desynchronization: Synthesis of asynchronous circuits from synchronous specifications
Asynchronous implementation techniques, which measure logic delays at run time and activate registers accordingly, are inherently more robust than their synchronous counterparts, which estimate worst-case delays at design time, and constrain the clock cycle accordingly. De-synchronization is a new paradigm to automate the design of asynchronous circuits from synchronous specifications, thus permitting widespread adoption of asynchronicity, without requiring special design skills or tools. In this paper, we first of all study different protocols for de-synchronization and formally prove their correctness, using techniques originally developed for distributed deployment of synchronous language specifications. We also provide a taxonomy of existing protocols for asynchronous latch controllers, covering in particular the four-phase handshake protocols devised in the literature for micro-pipelines. We then propose a new controller which exhibits provably maximal concurrency, and analyze the performance of desynchronized circuits with respect to the original synchronous optimized implementation. We finally prove the feasibility and effectiveness of our approach, by showing its application to a set of real designs, including a complete implementation of the DLX microprocessor architectur
Supervisor Synthesis for Discrete Event Systems under Partial Observation and Arbitrary Forbidden State Specifications
In this paper, we consider the forbidden state problem in discrete event
systems modeled by partially observed and partially controlled Petri nets. Assuming
that the reverse net of the uncontrollable subnet of the Petri net is structurally
bounded, we compute a set of weakly forbidden markings from which forbidden markings can be reached by firing a sequence of uncontrollable/unobservable transitions.
We then use reduced consistent markings to represent the set of consistent
markings for Petri nets with structurally bounded unobservable subnets. We determine
the control policy by checking if the firing of a certain controllable transition
will lead to a subsequent reduced consistent marking that belongs to the set of weakly
forbidden markings; if so, we disable the corresponding controllable transition. This
approach is shown to be minimally restrictive in the sense that it only disables
behavior that can potentially lead to a forbidden marking. The setting in this paper
generalizes previous work by studying supervisory control for partially observed and
partially controlled Petri nets with a general labeling function and a finite number of
arbitrary forbidden states. In contrast, most previous work focuses on either labeling
functions that assign a unique label to each observable transition or forbidden states
that are represented using linear inequalities. More importantly, we demonstrate
that, in general, the separation between observation and control (as considered in
previous work) may not hold in our setting
A Conceptual Framework for Adapation
This paper presents a white-box conceptual framework for adaptation that promotes a neat separation of the adaptation logic from the application logic through a clear identification of control data and their role in the adaptation logic. The framework provides an original perspective from which we survey archetypal approaches to (self-)adaptation ranging from programming languages and paradigms, to computational models, to engineering solutions
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