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The following topics are dealt with: discrete event system; supervisory control; max-plus algebra; max-plus system; SAT-solving; stochastic control and analysis; software tools; optimization; dynamical system; controller synthesis; systems biology; Petri nets; model checking; modular control; decentralized control and fault diagnosis.
Summary form only given. Networked digital devices interacting with physical and engineered systems are becoming ubiquitous and will be more so in the future. A deep understanding of the interactions between the cyber and physical worlds is essential in being able to build robust and safe systems, and this issue is receiving increased attention in the US by the networking and information technology...
In this work we present a new polynomial complexity approach to state avoidance for nondeterministic and partially observed discrete event systems. Our approach generates control based on a covering of the system state space that identifies overlapping sets of indistinguishable states. This approach is shown to be more permissive than existing state-feedback control techniques.
The concept of a coordinator is proposed for control of modular discrete-event systems. The coordinator makes all subsystems conditionally independent generators as defined in the paper. The coordinator receives part of the partial observations of the subsystems and its task is to satisfy the global part of the specification and of the nonblockingness. The complete supervisor then consists of the...
A two-pass algorithm for compositional synthesis of modular supervisors for large-scale systems of composed finite-state automata is proposed. The first pass provides an efficient method to determine whether a supervisory control problem has a solution, without explicitly constructing the synchronous composition of all components. If a solution exists, the second pass yields an over-approximation...
This paper deals with supervisory control of discrete event systems with the introduction of sensors that distinguish certain occurrences of observable events. Distinguishing sensors are formally represented by an entity named distinguisher that maps the original events into disjoint sets of refined events and specify which of them could actually occur according to the evolution of the system. The...
Given a finite transition system and a regular predicate, we address the problem of computing a controller enforcing the opacity of the predicate against an attacker (that partially observes the system), supposedly trying to push the system to reveal the predicate. Assuming that the controller can only control a subset of the events it observes (possibly different from the ones of the attacker), we...
We provide an introduction to the max-plus algebra and explain how it can be used to model a specific class of discrete event systems with synchronization but no concurrency. Such systems are called max-plus linear discrete event systems because they can be described by a model that is ldquolinearrdquo in the max-plus algebra. We discuss some key properties of the max-plus algebra and indicate how...
This paper deals with the computation of a maximal flow in single input single output (max, +) linear systems. Assuming known a system composed of some subsystems - each one being described by a transfer function and some secondary inputs interfering with the principal flow on consecutive sub-systems, the computation of a maximal principal output is addressed. Transfer functions, inputs and outputs...
This paper addresses the problem of approximately computing the Lyapunov exponent of stochastic maxplus linear systems. Our approach allows for an efficient simulation of bounds for the Lyapunov exponent. Depending on the simulation budget the bounds can be made arbitrarily close. We illustrate the effectiveness of our bounds with application to (real-life) railway systems.
A new framework for control of (max,+) automata is introduced. The tensor product of their linear representations used in this paper is an extension of parallel composition from Boolean to (max,+) automata and can be nicely applied to both logical and timing aspects of supervisory control. Case of uncontrollable events that can neither be disabled nor delayed is studied within a behavioral framework...
Satisfiability solving, the problem of deciding whether the variables of a propositional formula can be assigned in such a way that the formula evaluates to true, is one of the classic problems in computer science. It is of theoretical interest because it is the canonical NP-complete problem. It is of practical interest because modern SAT-solvers can be used to solve many important and practical problems...
Many systems can be naturally represented in some decidable fragments of first order logic. The expressive power provided by a background theory allows to describe important aspects such as real time, continuous dynamics, and data flow over integer variables. The corresponding verification problems can be tackled by means of Satisfiability Modulo Theory (SMT) solvers. SMT solvers are based on the...
Boolean satisfiability (SAT) solvers have been the subject of remarkable improvements since the mid 90s. One of the main reasons for these improvements has been the wide range of practical applications of SAT. Indeed, examples of modern applications of SAT range from termination analysis in term-rewrite systems to circuit-level prediction of crosstalk noise. The success of SAT solvers motivated many...
This paper discusses how satisfiability solvers may be used to verify and synthesize discrete event supervisors as defined in the supervisory control theory. By using the supervisory control theory it is possible to generate control functions that are correct by construction. However, the computations for verification and synthesis of the supervisors are NP-complete and in order to make the method...
This paper concerns the application of Infinitesimal Perturbation Analysis (IPA) to a fluid queue with flow control. The control law restricts the inflow rate to the queue by an amount that is proportional to the loss rate, and the control signal incurs a delay. The performance measure consists of a weighted sum of the loss volume and cumulative workload, and it is treated as a function of the buffer...
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