Formulas for calculating supremal controllable and normal sublanguages

Supremal controllable and normal sublanguages have been shown to play an important role in supervisor synthesis. In this paper, we discuss the computation of supremal controllable and normal sublanguages. We derive formulas for both supremal controllable sublanguages and supremal normal sublanguages when the languages involved are closed. As a result, those languages can be computed without applying recursive algorithms. We also discuss those aspects of these formulas.     

The infimal prefix-closed and observable superlanguange of a given language

The supervisory control of discrete-event systems under partial observation is examined. In particular, the condition of observability needed to solve the two main existing problems is investigated. A fixed-point characterization of observability is given and is shown to yield an effective test for observability where the system under consideration is specified by regular languages. A formula for the infimal prefix-closed observable superlanguage of a given language is presented. Where the system is specified by regular languages, the formula for the infimal observable language is effectively computable.     

On computation of supremal controllable, normal sublanguages

In this paper, we present an algorithm for the computation of the controllable, normal sublanguage of a given language, encountered in the solution of the supervisory control of discrete-event systems under partial observation. The algorithm produces the desired result under certain assumptions on the plant and the event projection map. In particular, the plant has to be nonblocking. The advantage of the algorithm over the solution available in the literature is that it does not involve iterations on the supremal controllable sublanguage and supremal normal sublanguage operators.     

Synthesis of controllable and normal sublanguages for discrete-event systems using a coordinator

Synthesis of normal or controllable and normal sublanguages of global specification languages without computation of the global modular plant is a difficult problem. In this paper, these sublanguages are computed using a coordinator. We recall the notion of conditional controllability, introduce a notion of conditional normality, and prove necessary and sufficient conditions where such a computation is possible. Specifically, we show that conditionally controllable and conditionally normal languages computed by our method are controllable and normal with respect to the global plant. The optimality (supremality) of the resulting languages is also discussed.     

计算DES监控中优于闭可识别语言的闭可观子语言

本文给出一种求闭能观子语言的算法，该算法经ｍ步（系统中离散事件个数）收敛；并且证明无论对系统中事件如何排序，由该算法求出的闭能观子语言总包含最大闭可识别子语言。     

Abstraction‐Based Verification and Synthesis for Prognosis of Discrete Event Systems

In this paper, we develop a theoretical framework for abstraction‐based failure prognosis of partially observed discrete event systems. The purpose of using abstraction is to verify prognosability and synthesize a prognoser based on the abstracted models with fewer states and transitions. We present conditions under which prognosability can be verified and a prognoser can be synthesized based on the abstracted models of the system and the specification.     

Robust supervisory control of a class of timed discrete event systems under partial observation

This paper studies robust supervisory control of timed discrete event systems proposed by Brandin and Wonham. Given a set of possible models which includes the exact model of the plant, the objective is to synthesize a robust supervisor such that it achieves legal behavior for all possible models. We show that controllability for each possible model and observability for a suitably defined aggregate model are necessary and sufficient conditions for the existence of a solution to the robust supervisory control problem. Moreover, when there does not exist a solution, a maximally permissive robust supervisor is synthesized under the assumption that all controllable events are observable.     

On optimal control of a class of partially observed discrete event systems

We are interested in a new class of optimal control problems for discrete event systems. We adopt the formalism of supervisory control theory (Proc. IEEE 77(1) (1989) 81) and model the system as a finite state machine (FSM). Our control problem is characterized by the presence of uncontrollable as well as unobservable events, the notion of occurrence and control costs for events and a worst-case objective function. We first derive an observer for the partially unobservable FSM, which allows us to construct an approximation of the unobservable trajectory costs. We then define the performance measure on this observer rather than on the original FSM itself. We then use the algorithm presented in Sengupta and Lafortune (SIAM J. Control Optim. 36(2) (1998)) to synthesize an optimal submachine of the C-observer. This submachine leads to the desired supervisor for the system.     

一类离散事件系统的监控器综合

前向无同步前向无冲突网是每个变迁有且只有一个输入库所并且每个库所最多有一个输入变迁的受限Petri网.针对不可控影响子网为前向无同步前向无冲突网的广义互斥约束,显式地给出了最大允许控制策略的计算方法.并用一个例子给予了说明.     

State observability and condition observability for a class of interacting discrete event systems

This paper introduces the concepts of state observability and condition observability for condition systems, a class of systems composed of discrete state components which interact via discrete binary signals called conditions. Given a set of externally observed conditions, state observability implies that the state of the system can be determined from the observations, and condition observability implies that all unobserved input and output conditions of the system can be determined from the observations. In this paper, we present a class of systems which is state observable and condition observable. We present a method to synthesize an observer system to provide state and condition signal estimates for a single component subsystem.     

A modified normality condition for decentralized supervisory control of discrete event systems

In this paper, we study nonblocking decentralized supervisory control of discrete event systems. We introduce a modified normality condition defined in terms of a modified natural projection map. The modified normality condition is weaker than the original one and stronger than the co-observability condition. Moreover, it is preserved under union. Given a marked language specification, there exists a nonblocking decentralized supervisor for the supremal sublanguage which satisfies L_m(G)-closure, controllability, and modified normality. Such a decentralized supervisor is more permissive than the one which achieves the supremal L_m(G)-closed, controllable, and normal sublanguage.     

Decentralized DES Supervisory Control for Coordination of ULTC and SVC

This paper discusses the issues involved in modeling and synthesizing a discrete‐event supervisory control system in a decentralized structure to coordinate the behavior of an under‐load tap‐changing transformer (ULTC) and a static VAR compensator (SVC) in electrical power systems. The control specifications are modeled as some automata, and it is shown that they are controllable. The designed closed‐loop control system is non‐blocking. The consistency of the high‐level model in a two‐level hierarchical control system is investigated. The proposed supervisory control is tested by inspecting its behavior in a simulated situation. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Maximizing robustness of supervisors for partially observed discrete event systems

We consider a robust supervisory control problem to synthesize a supervisor for the nominal plant model which maximizes robustness. Cury and Krogh have first addressed this problem by unnecessarily restricting the upper bound of the legal behavior. In our previous work, we have solved the problem without restricting the upper bound of the legal behavior when the specification is described by prefix-closed languages. In this paper, we extend our previous work to the partial (event) observation case. First, we synthesize a supervisor that maximizes robustness. This result shows that robustness can be optimized under partial observation, while permissiveness cannot be optimized in general. We next consider a special case where all the controllable events are observable. In this special case, we synthesize a maximally permissive supervisor for the nominal plant model which maximizes not only the robustness but also permissiveness for the maximal set of admissible plant variations.     

Well-posedness and regularity for an Euler–Bernoulli plate with variable coefficients and boundary control and observation

The open loop system of an Euler–Bernoulli plate with variable coefficients and partial boundary Neumann control and collocated observation is considered. Using the geometric multiplier method on Riemannian manifolds, we show that the system is well-posed in the sense of D. Salamon and regular in the sense of G. Weiss. Moreover, we determine that the feedthrough operator of this system is zero. The result implies in particular that the exact controllability of the open-loop system is equivalent to the exponential stability of the closed-loop system under proportional output feedback.     

一种新的离散事件系统控制方案

给定离散事件系统（ＤＥＳ）Ｇ及某个规定的最大允许合法语言文明（ＭＰＬＬＳ）Ｋ，监督控制在任务就是寻找一个监控器Ｓ，使得系统在监控下不会突破该ＭＰＬＬＳ，也即满足：Ｌ（Ｓ／Ｇ）包含于Ｋ，传统的实现方法要求给定ＭＰＬＩＳＫ计算其最大可控子语言Ｋ＾↑因此难免显示地构造Ｓ。本文给了一种新的方案可以不必对Ｋ＾↑和Ｓ作显式计算，监控任务是随ＤＥＳＧ的演化结合规定的ＭＰＬＬＳＫ用动态方法实现，该方案在很大程度上     

基于RW框架的离散事件系统监督控制理论计算和仿真平台

介绍了一种以基于RW框架的离散事件系统监督控制理论为理论基础的计算和仿真平台,并通过实例验证了该平台的仿真效果和所包含的功能。该平台力求以完整的功能列表、友好的用户界面和强大的图形输出,帮助研究人员更好地应用该理论。     

Centralized and distributed algorithms for on-line synthesis of maximal control policies under partial observation

This paper deals with the on-line control of partially observed discrete event systems (DES). The goal is to restrict the behavior of the system within a prefix-closed legal language while accounting for the presence ofuncontrollable andunobservable events. In the spirit of recent work on the on-line control of partially observed DES (Heymann and Lin 1994) and on variable lookahead control of fully observed DES (Ben Hadj-Alouane et al. 1994c), we propose an approach where, following each observable event, a control action is computed on-line using an algorithm oflinear worst-case complexity. This algorithm, calledVLP-PO, has the following additional properties: (i) the resulting behavior is guaranteed to be amaximal controllable and observable sublanguage of the legal language; (ii) different maximals may be generated by varying the priorities assigned to the controllable events, a parameter ofVLP-PO; (iii) a maximal containing the supremal controllable and normal sublanguage of the legal language can be generated by a proper selection of controllable event priorities; and (iv) no off-line calculations are necessary. We also present a parallel/distributed version of theVLP-PO algorithm calledDI-VLP-PO. This version uses several communicating agents that simultaneously run (on-line) identical versions of the algorithm but on possibly different parts of the system model and the legal language, according to the structural properties of the system and the specifications. While achieving the same behavior asVLO-PO, DI-VLP-PO runs at a total complexity (for computation and communication) that is significantly lower than its sequential counterpart.     

Lon Works现场总线控制系统的组态监控平台设计与应用

组态监控平台是LonWorks现场总线控制系统的一个重要组成部分。在此介绍了一个LonWorks现场总线控制系统的组态监控平台 ,它由控制组态平台和监视组态平台两部分组成 ,完成控制组态和监视组态功能。通过在LonWorks现场总线控制系统CS2 0 0 0中的实际应用 ,说明了该组态监控平台的主要功能。