Depuis plusieurs années, de nombreuses recherches ont été menées autour du diagnostic. Cependant, il est impératif de se préoccuper dès la phase de conception d’un système des objectifs de diagnostic à atteindre. Aussi, de nombreux travaux se sont intéressés à analyser et à caractériser les propriétés de la diagnosticabilité d’un système. La diagnosticabilité est la propriété d’un système garantissant qu’il génère des observations permettant de détecter et discriminer les fautes en temps fini après leur occurrence.Le sujet de cette thèse porte sur les méthodes permettant d’établir les propriétés de la diagnosticabilité des systèmes à événements discrets dans le cadre distribué, sans construction du modèle global du système. Ce cadre est de première importance pour les applications réelles : systèmes naturellement distribués, systèmes trop complexes pour traiter leur modèle global, confidentialité des modèles locaux les uns par rapport aux autres. L’analyse de la diagnosticabilité de tels systèmes distribués se fonde sur des opérations de synchronisation des modèles locaux, par les observations et les communications. D’abord, nous étudions comment optimiser cette analyse de la diagnosticabilité en faisant abstraction de l’information nécessaire et suffisante à partir des objets locaux pour décider la diagnosticabilité globale. L'efficacité de l’algorithme peut être grandement améliorée par la synchronisation des objets locaux et abstraits en comparaison avec celle des objets locaux et non abstraits.Ensuite, nous proposons, dans le cadre distribué, l'algorithme de la diagnosticabilité de motifs d'événements particuliers a priori inobservables dans les systèmes. Ces motifs peuvent être simplement l’occurrence, brutale ou graduelle, d’une faute permanente ou transitoire, plusieurs occurrences d’une faute, plusieurs fautes en cascade, etc. Dans le cadre distribué, la reconnaissance du motif d’événements s’effectue d’abord progressivement dans un sous-système et ensuite la diagnosticabilité de ce motif peut être déterminée par la méthode abstraite et distribuée. Nous prouvons la correction et l'efficacité de notre algorithme à la fois en théorie et en pratique par la mise en œuvre de l’implémentation sur des exemples.Finalement, nous étudions le problème de la diagnosticabilité dans les systèmes distribués avec composants autonomes, où l’information observable est distribuée au lieu d’être centralisée comme jusqu’alors. En d'autres termes, chaque composant ne peut appréhender que ses propres événements observables. Nous donnons la définition de la diagnosticabilité conjointe. Et puis nous discutons de l'indécidabilité de diagnosticabilité conjointe dans le cas général, c'est à dire, les événements de communication ne sont pas observables, avant de proposer un algorithme pour tester sa condition suffisante. De plus, nous obtenons également un résultat de décidabilité et de l'algorithme lorsque les communications sont observables. / Over the latest decades, much research work has been done on automatic fault diagnosis. However, it is imperative to analyze at system design stage how correctness and efficiency and diagnosis algorithm can achieve. Thus many studies were interested in analyzing and characterizing the properties of diagnosability of a system. Diagnosability is the property of a system ensuring that it generates observations for detecting and discriminating faults in finite time after their occurrence.In this thesis, we investigate how to optimize distributed diagnosability analysis by abstracting necessary and sufficient information from local objects to decide global diagnosability decision. The algorithm efficiency can be greatly improved by synchronization of abstracted local objects compared to that of non abstracted local ones.Then we extend the distributed diagnosability algorithm from fault event first to simple pattern and then to general pattern, where pattern can describe more general objects in the diagnosis problem, e.g., multiple faults, multiple occurrences of the same fault, ordered occurrences of significant events, etc. In the distributed framework, the pattern recognition is first incrementally performed normally in a subsystem and then pattern diagnosability can be determined by adjusting abstracted method used in fault event case. We prove the correctness and efficiency of our proposed algorithm both in theory through proof and in practice through implementation.Finally we study joint diagnosability problem in systems with autonomous components, i.e., observable information is distributed instead of centralized. In other words, each component can only observe its own observable events. We give joint diagnosability definition. And then we discuss the undecidability of joint diagnosability in the general case, i.e., communication events are not observable, before proposing an algorithm to test its sufficient condition. In addition, we also get a decidability result and algorithm when communications are observable.

Les modèles à événements discrets sont, souvent, réalisés afin d’être simulés et par conséquent exécutés sur ordinateur.Certains codeurs de simulation optent pour une programmation impérative pour implémenter les comportements décrits par leurs machines à états.D’autres codeurs optent plutôt pour une programmation orientée objet.Ce paradigme de programmation, basé sur la notion d’objet, décline une nouvelle façon de voir un programme et son architectureToutes les solutions proposées manquent de clarté.Elles sont extrêmement coûteuses en terme de maintenabilité du code implémenté.L’utilisation exclusive des instructions conditionnelles rend toute correction au niveau du code difficile à réaliser, voire impossible dans certains cas. Aussi, elles souffrent au niveau de la réutilisabilité d’une partie du code. En effet, l’utilisation de telles instructions produit un code compacte, avec une forte cohésion entre les variables et fonctions du modèle implémenté. Par conséquent, le concepteur pourra réutiliser ce code qu’en un seul bloc.Toute dislocation du code est impossiblePour toutes ces raisons, nous proposons une nouvelle conception des modèles à événements discrets afin d’améliorer les qualités du code produit. Cette solution est basée sur le paradigme objet pour exploiter pleinement ses avantages tout en contournant ses limites. A cet effet, la solution proposée et détaillée dans cette thèse est un nouveau patron. Dans ce patron, les états et les événements sont réifiés pour avoir plus d’abstraction et de clarté. La réification permettra aux événements d’encapsuler des données et des comportements. Ainsi, nous pouvons déléguer aux événements de nouvelles responsabilités / Discrete event systems (State machine or Discrete Event system Specification) are often modeled in order to be simulated and therefore executed on a computer. Some simulation designers choose for imperative programming to implement the behaviors described by their state machines and others. Whereas, few of them choose for object-oriented programming: this paradigm of computer programming, based on the notion of object, declines a new way of seeing a program and its architecture.All of the proposed solutions found in the litterature lack clarity. They are extremely expensive in terms of debugging, reusing and changing the implemented model. The exclusive use of conditional statements if-else or switch case makes any code correction difficult to perform, even impossible in some cases. They also suffer from the reusability of some parts of the code. Indeed, the use of such instructions produces a compact code, with a strong cohesion (coupling) between the variables and functions of the implemented model. Therefore, the designer can reuse the corresponding code only in one block. Any extraction of a a piece of code which corresponds to a piece of behavior is impossible.For all these reasons, we propose a new design of discrete event systems, from the state machine to the DEVS, in order to improve the producted code qualities. This solution is based on the object paradigm to fully exploit its advantages while circumventing its limits. To this end, the solution proposed and detailed in this thesis is a new State-Event Design Pattern and its variants. Thus, the designer of simulation models will have a library of patterns to choose in order to satisfy his design requirements.

Neste trabalho à apresentada uma proposta de conversÃo de modelos de cÃlulas de manufatura (FMS) em Redes de Petri Coloridas (RPC) para Ladder Logic Diagram (LLD). Explora-se modelos de RPC controlados - construidos usando-se como metodologia de controle supervisÃrio as RestriÃÃes de Controle sobre Cores Decompostas (RCCD) - e modelos nÃo controlados. Enfatiza-se a transformaÃÃo de RPC nÃo controlada para LLD e a facilidade de inclusÃo do controle. Os resultados aqui descritos demonstram que a metodologia facilita o trabalho de um programador de CLP em LLD minimizando os possÃveis erros durante a fase de programaÃÃo. Para exemplificar a metodologia foi desenvolvido um conversor de RPC para LLD, produzido em ambiente JAVA, afim de evidenciar a dinÃmica de conversÃo. Para a validaÃÃo dos resultados do conversor à usado um robà articulado vertical controlado via CLP, que opera comparativamente com e sem supervisÃo, o qual fora modelado primeiramente em RPC sem supervisÃo, depois aplicada a tÃcnica RCCD, a supervisÃo e a conversÃo para LLD. / In this dissertation, is presented a proposal of conversion of models of manufacturing cell (FMS) from Colored Petri Nets (CPN) to Ladder Logic Diagram (LLD). It explores the controlled CPN models - constructed using the methodology of supervisory Control Restrictions on Decomposed Colors (CRDC) - and not controlled models. It emphasizes the transformation of CPN not controlled for the LLD and ease for inclusion of control. The results described herein demonstrate that the methodology facilitates the work of a PLC programmer in LLD minimizing possible errors during the programming phase. To illustrate the methodology we developed a converter from CPN to LLD, produced in JAVA, in order to clarify the dynamic conversion environment. To validate the results of the converter, is controlled by PLC, a vertical articulated robot which works compared with and without supervision which had been firstly modeled in CPN without supervision, then applied to CRDC, the supervision and the conversion technique for LLD.

This master’s thesis deals with analysis of state machines for embedded applications. The issue of finite-state machine is described theoretically. The document also contains a proposal for funding for modeling finite state machines in Matlab/Simulink. It is designed data representation of finite automaton. Over this data representation algorithm of minimization is applied. Finally, the algorithm is implemented to generate code in C language.

Discrete event systems (DES) are a special class of dynamical systems with discrete-valued state space and event-driven transitions. DES are ubiquitous in today's world and are used in different sectors such as manufacturing systems, transport networks and computer networks. They offer unique capabilities, such as flexibility and adaptability; at the same time, they can be challenging to model and analyze. Moreover, the complexity of DES is scaled up when disturbances are present. Many different kinds of real life DES can be modeled using dioid algebra which is a powerful tool for describing nonlinear behaviors using linear system models. Dioid algebra is an exotic algebra of formal series which can be understood as a set of only positive numbers without negatives. This special algebraic structure is useful in modeling DES because such systems feature variables that cannot be inverted with respect to some variables. Nonlinear behaviors of DES are able to be modeled as linear systems in terms of dioid algebra in order to use classical control techniques in scheduling and control of DES.This dissertation presents the scheduling and control of DES using a special dioid called max-plus algebra, which is a set of real numbers with the operation of maximum and addition replacing the usual classical operations of addition and multiplication, respectively. This dissertation also studies the behavior of DES when disturbances are present. Two different paths to the scheduling of DES are presented: using dioid algebra and using linear programming methods. The control of DES with disturbances and uncertainties is also explored, particularly, the solutions of the disturbance decoupling problem and the modified disturbance decoupling problem using various controller structures are presented. Disturbance decoupling in this dissertation means the scheduling of the DES will not not be affected by the presence of the disturbances. On the other hand, modified disturbance decoupling means the scheduling will not be worse than the delays caused by the disturbances in industrial just-in-time (JIT) standards. JIT means that the operations start with just enough time to be completed by the desired schedule in order to minimize waste and costs in work in progress and material storage.The applicability of the approach presented in this dissertation is demonstrated in real-world processes including a large-scale high throughput screening (HTS) system in drug discovery and an optimal scheduler for an airport's runways. The main contributions of this dissertation are max-plus and mathematical programming solutions for scheduling and control of discrete event systems with disturbances. The results present a theoretical scheduling prior to exhaustive scheduling algorithms in large-scaled industrial systems.

Indiana University-Purdue University Indianapolis (IUPUI) / In the healthcare industry, several modern patient identification and patient matching systems have been introduced. Most of these implement patient identification by their first, middle and last names. They also use Social Security Number and other similar national identifiers. These methods may not work for many developing and underdeveloped countries where identifying a patient is a challenge with highly redundant and interchangeable first and last names of the patient, this is aggravated by the absence of a national identification system. In order to make the patient identification more efficient, Muzima, an interface of OpenMRS (Open source medical records system) introduced an additional identifier, fingerprint, through a module to the system. Ordinary and Time Petri nets are used to analyze this module. Chapter 1 introduces Muzima fingerprint module and describes the workflow of this interface followed by the related work, importance and applications of Petri nets. Chapter 2 introduces Ordinary and Time Petri nets using examples. Chapter 3 discusses about the mathematical modeling of the Muzima Fingerprint module using Petri nets. Chapter 4 explains the qualitative and quantitative analysis done on the Muzima fingerprint module. Chapter 5 discusses about the programming and simulation done to prove the theoretical results obtained. Chapter 6 provides the conclusion and future work for the thesis.

In decentralized control, agents have only a partial view and partial control of the system and must cooperate to achieve the control objective. In order to synthesize a decentralized control solution, a specification must satisfy the co-observability property. Existing co-observability verification methods require the possibly intractable construction of the complete system. To address this issue, we introduce an incremental verification of co-observability approach. Selected subgroups of the system are evaluated individually, until verification is complete. The new method is potentially much more efficient than the monolithic approaches, in particular for systems composed of many subsystems, allowing for some intractable problems to be manageable. Properties of this new strategy are presented, along with a corresponding algorithm and an example. To further increase the scalability of decentralized control, we wish to adapt the existing Hierarchical Interface-Based Supervisory Control (HISC) to support it. We introduce the Hierarchical Interface-Based Decentralized Supervisory Control (HIDSC) framework that extends HISC to decentralized control. To adapt co-observability for HIDSC, we propose a per-component definition of co-observability along with a verification strategy that requires only a single component at a time in order to verify co-observability. Finally, we provide and prove the necessary and sufficient conditions for supervisory control existence in the HIDSC framework and illustrate our approach with an example. As the entire system model never needs to be constructed, HIDSC potentially provides significant savings. / Thesis / Doctor of Philosophy (PhD)

This thesis focuses on the issues related to the implementation of theoretical timed discrete-event systems (TDES) supervisors. In particular, we examine issues related to implementing TDES as sampled-data (SD) controllers, which were introduced by Wang and Leduc. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes state, and updates its outputs. / This thesis focuses on the issues related to the implementation of theoretical timed discrete-event systems (TDES) supervisors. In particular, we examine issues related to implementing TDES as sampled-data (SD) controllers, which were introduced by Wang and Leduc. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes state, and updates its outputs. We first introduce the sampled-data setting from Wang, and then define the sampled-data properties he identified, including the SD controllability property. We then introduce Wang's formal representation of an SD controller as a Moore synchronous finite state machine (FSM). We then discuss Wang's modular and centralized translation method. We next introduced new modular results for the SD controllability point 3.1, SD controllability point 3.2, SD controllability point 4, activity loop free and S-singular prohibitable behaviour that allow one to verify the properties using only a portion of the system, instead of having to construct the entire system model. This should allow faster verification times as well as allow larger systems to be verified. We then introduce for the first time algorithms to verify Wang's CS Deterministic and non self-loop ALF properties. The remainder of the thesis focuses on developing algorithms and software to automatically convert a TDES first into an FSM, and then into a VERILOG module. VERILOG is a hardware description language which allows our FSM to be compiled and implemented on digital logic devices such as an FPGA. We then tested our method by modelling a simple door locking system as TDES, checking that the system satisfies the required sampled-data properties, and then translating the result into VERILOG. The above algorithms and methods have all been implemented as a part of the graphical DES research tool, DESpot. / Thesis / Master of Computer Science (MCS)

This thesis focuses on issues related to implementing theoretical Discrete-Event Systems (DES) supervisors, and the concurrency and timing delay issues involved. Sampled-data (SD) supervisory control deals with timed DES (TDES) systems where the supervisors will be implemented as SD controllers. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes states, and updates its outputs. In this thesis, we identify a set of existing TDES properties that will be useful to our work, but not sufficient. We extend the TDES controllability definition to a new definition, SD controllability, which captures several new properties that will be useful in dealing with concurrency issues, as well as make it easier to translate a TDES supervisor into an SD controller. We then establish a formal representation of an SD controller as a Moore Finite State Machine (FSM), and describe how to translate a TDES supervisor to a FSM, as well as necessary properties to be able to do so. We discuss how to construct a single centralized controller, as well as a set of modular controllers and show that they will produce equivalent output. Next, we capture the enablement and forcing action of a translated controller in the form of a TDES supervisory control map, and show that the closed-loop behavior of this map and the plant is the same as that of the plant and the original TDES supervisor. We also show that our method is robust with respect to nonblocking and certain variations in the actual behavior of our physical system. We also introduce a set of predicate-based algorithms to verify the SD controllability property, as well as certain other conditions that we require. We have created a software tool for verifying these conditions and provide the source code in the appendix. We have implemented these algorithms using binary decision diagrams (BDD). For illustrative purpose, we have produced a set of examples which fail the key conditions discussed in this thesis, as well as a successful application example based on a Flexible Manufacturing System. We also presented the corresponding FSM, translated from the example's supervisors. / Thesis / Master of Applied Science (MASc)

O objeto de estudo deste trabalho é a construção de modelos que permitam a estruturação do projeto do controle de sistemas flexíveis de manufatura que considerem não somente estados de operação normal, mas também estados anormais, isto é, em situações de falhas. Entende-se como falha o desvio de pelo menos uma propriedade do sistema que leva o mesmo a um estado de defeito, que por sua vez se define como um comportamento incomum, não projetado, do sistema sob estudo, que finalmente é manifestado como um defeito. Sistemas flexíveis de manufatura são sistemas que executam múltiplos processos visando à produção de diversos bens. O processo é um conjunto de ações de transformação que por sua parte requerem um conjunto de recursos que são compartilhados por outros processos simultaneamente. Sistemas flexíveis de manufatura envolvem um número relativamente grande de componentes, máquinas, equipamentos e operadores humanos, que interagem de maneira diversificada manipulando um grande conjunto de informação e diferentes materiais em ambientes que podem até ser agressivos. Independentemente de qualquer programa de manutenção, falhas são eventos que são possíveis de acontecer em qualquer sistema de tal natureza. Num ambiente ideal, o funcionamento de todos os componentes poderia ser monitorado com o objetivo de detectar as falhas prematuras, mas devido ao custo envolvido, isso se torna inviável. Neste sentido surge o desafio de detectar as falhas a partir da observação do contexto do funcionamento do processo, mediante a monitoração de alguns parâmetros, em geral de fácil acesso, e tomando em consideração manifestações (sintomas) das falhas de um ponto de vista qualitativo. O presente trabalho propõe a utilização de redes Bayesianas para o diagnóstico de falhas em sistemas flexíveis de manufatura. As redes Bayesianas constituem uma ferramenta útil para a representação das relações que existem entre as causas (componentes em estado de falha) e os sintomas (observações anormais do processo). A partir deste modelo, inferências podem ser feitas para o diagnóstico do sistema.Por outro lado, nos últimos anos a rede de Petri tem sido utilizada exitosamente na representação dos aspectos de controle de sistemas produtivos e particularmente de sistemas de manufatura e, desta forma, considera-se aqui tal ferramenta para a modelagem do sistema não só em condições normais de funcionamento como também para a representação do tratamento de falhas, no contexto de um sistema tolerante a anomalias do processo. Especial ênfase é dada à estruturação de uma metodologia que permita a concepção de um procedimento eficaz para a construção de modelos de controle. / The objective of the present work is the construction of models proper for the easy implementation of flexible manufacturing control systems able to handle not only with normal behavioral conditions, but with abnormal (or faulty) behavior as well. A fault is defined as a deviation of at least one system property that drives the system into an error state. An error is defined as an uncommon behavior, not expected from the system functionalities. Flexible manufacturing systems are systems that execute multiple processes for the production of several items in several ways. A process is a sequence of certain transformation tasks that require a set of resources shared simultaneously by multiple processes. In this sense, flexible manufacturing systems are constituted of a relatively great number of devices, machines, equipments and human operators that work together manipulating great quantities of information and materials. This work is usually performed in aggressive environments. So, independent of any maintenance program, faults are events that cannot be totally avoided. In an ideal environment, the monitoring of all components is the way to avoid faults. Nevertheless, due to the cost involved, this is an impossible task. In this context, there is a challenge to properly detect faults from the observation of the systems context, through the monitoring and observation of some parameters in general easy to access, including also qualitative information from operators. In the present work, it is proposed the use of Bayesian networks for the fault diagnosis in flexible manufacturing systems. Bayesian networks constitute a useful tool for the modeling of the causal relation between the causes (faulty components) and the symptoms (manifestations). Based on this model, inference can be done for the system diagnosis task. Additionally, in the last years Petri net has been successfully used for the modeling of control systems of productive systems and particularly, manufacturing control systems. In this work, beyond the use of Petri net for the modeling of normal situations of the system, Petri net is used for the modeling of the fault treatment techniques. This drives the system tolerance to faults. Especial emphasis is laid into methodological issues that allows for the structuration of a systematic procedure proper for the modeling and construction of control systems.