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Indiana University-Purdue University Indianapolis (IUPUI) / In the past decades, the rapid innovation of technology has greatly affected the automotive industry. However, every innovation has always been paired with safety risks that needs to be quickly addressed. This is where Petri nets (PNs) have come into the picture and have been used to model complex systems for different purposes, such as production management, traffic flow estimation and the introduction of new car features collectively known as, Adaptive Driver Assistance Systems (ADAS). Since most of these systems include both discrete and continuous dynamics, the Hybrid Petri net (HPN) model is an essential tool to model these. The objective of this thesis is to develop, analyze and simulate a lane keeping support system using an HPN model. Chapter 1 includes a brief summary of the specific ADAS used, lane departure warning and lane keeping assist systems and then related work on PNs is mentioned. Chapter 2 provides a background on Petri nets. In chapter 3, we develop a discrete PN model first, then we integrate continuous dynamics to extend it to a HPN model that combines the functionalities of the two independent ADAS systems. Several scenarios are introduced to explain the expected model behavior. Chapter 4 presents the analysis and simulation results obtained on the final model. Chapter 5 provides a summary for the work done and discusses future work.

Petri Nets are a formal, graphical and executable modeling technique for the specification and analysis of concurrent and distributed systems and have been widely applied in computer science and many other engineering disciplines. Low level Petri nets are simple and useful for modeling control flows but not powerful enough to define data and system functionality. High level Petri nets (HLPNs) have been developed to support data and functionality definitions, such as using complex structured data as tokens and algebraic expressions as transition formulas. Compared to low level Petri nets, HLPNs result in compact system models that are easier to be understood. Therefore, HLPNs are more useful in modeling complex systems. There are two issues in using HLPNs - modeling and analysis. Modeling concerns the abstracting and representing the systems under consideration using HLPNs, and analysis deals with effective ways study the behaviors and properties of the resulting HLPN models. In this dissertation, several modeling and analysis techniques for HLPNs are studied, which are integrated into a framework that is supported by a tool. For modeling, this framework integrates two formal languages: a type of HLPNs called Predicate Transition Net (PrT Net) is used to model a system's behavior and a first-order linear time temporal logic (FOLTL) to specify the system's properties. The main contribution of this dissertation with regard to modeling is to develop a software tool to support the formal modeling capabilities in this framework. For analysis, this framework combines three complementary techniques, simulation, explicit state model checking and bounded model checking (BMC). Simulation is a straightforward and speedy method, but only covers some execution paths in a HLPN model. Explicit state model checking covers all the execution paths but suffers from the state explosion problem. BMC is a tradeoff as it provides a certain level of coverage while more efficient than explicit state model checking. The main contribution of this dissertation with regard to analysis is adapting BMC to analyze HLPN models and integrating the three complementary analysis techniques in a software tool to support the formal analysis capabilities in this framework. The SAMTools developed for this framework in this dissertation integrates three tools: PIPE+ for HLPNs behavioral modeling and simulation, SAMAT for hierarchical structural modeling and property specification, and PIPE+Verifier for behavioral verification.

caT, a Petri net-based hypertext system, supports the modeling of user characteristics, contextual information, as well as the policies that govern the operation of a digital library within the infrastructure that presents its contents. Traditionally, users have created caT networks from scratch, thus limiting their use to small collections. In this research, we introduce TcAT, a new authoring tool that supports features for component-based authoring, with a view to enable the creation of large caT nets that can represent complex, real-life spaces such as libraries and museums. TcAT supports graphical, template-based creation of nets as well as a textual language for easy manipulation of large structures. It implements composition operations from Petri net theory to select, categorize, and modify existing net fragments as building blocks for composing larger networks. Authors may switch modes between visual and textual authoring at will, thus combining the strengths of expressing large nets textually and selecting net fragments via point-and-click interaction. A user evaluation of the new authoring mechanisms suggests that this is a promising tool for improving the efficiency of experienced users as well as that of novice users, who are unfamiliar with the Petri net formalism.

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With load growth of distribution systems, it becomes very complicated for dispatchers to obtain restoration plan for unfaulted but out-of-service areas. In this thesis, a rule-based expert system with a colored Petri net (CPN) inference model is developed. The CPN models of distribution components such as four-way line switches are proposed to derive the proper switching operation plan for service restoration by applying reasoning in the CPN. After main transformer contingency has been identified and isolated, it is highly possible that the out of service customers can not be restored completely because of the shortage of capacity reserve. The feeders which serve more key customers with higher service priority will have better chance to be selected for restoration. With the system reconfiguration to cover the load change of service zones over a longer period, during the process of switching operation, the maximum load demand of out-of-service area over the restoration time is considered in the CPN. To prevent the over-unbalance tripping of distribution feeders during switching operation process, the maximum tolerable current unbalance between any two phases is also considered in the CPN model. To assure the restoration plan complying with the operation regulation, heuristic rules based on the standard operation procedures of Taipower distribution system are included in the best first search of the CPN. A Taipower distribution system with 67 feeders is selected for computer simulation in this thesis to demonstrate the effectiveness of the proposed methodology. It is found that the service restoration of distribution systems can be obtained very efficiently by applying the proposed CPN model.

In the final work it is made analysis of Petri nets and Petri nets simulators, analysis of modeling system composition and its methodology. There were presented topicality of theme, it’s practical and theoretical meaning, work purpose and tasks. There was made analysis of Petri net simulator on DSP and was made realization of Petri net on DSP. Presented conclusions of the final work, therefore it was mentioned practical results.

Petrinetze werden in vielen Bereichen als Modellierungstechnik verwendet. Die verschiedenen Einsatzgebiete und Modellierungsziele erfordern dabei unterschiedliche Typen von Petrinetzen. Einen Petrinetz-Typ kennzeichnen -- neben den üblichen Stellen, Transitionen und Kanten -- eine Menge zusätzlicher, spezifischer Elemente, sowie eine spezifische Schaltregel. In der Literatur findet man zahlreiche verschiedene Petrinetz-Typen. Diese Vielfalt an Petrinetz-Typen lässt sich nicht ohne weiteres überblicken. Deshalb fehlt es auch nicht an Versuchen, allgemeine Petrinetz-Typen oder Klassifikationen -- auch einzelner Aspekte -- zu etablieren. Allerdings erfassen die bisherigen Ansätze nur einen kleinen Teil aller Petrinetz-Typen. Unser semantisch orientierter Klassifizierungsansatz des Petrinetz-Hyperwürfels umfasst deutlich mehr Petrinetz-Typen und erhebt den Anspruch, universell zu sein. Der Petrinetz-Hyperwürfel hat einen syntaktisch orientierten Klassifizierungsansatz als Grundlage. Dieser Ansatz führt einerseits zum Vorschlag der Petri Net Markup Language. Damit können Petrinetze aller Typen einheitlich beschrieben werden. Andererseits führt derselbe Ansatz zu einer Basis für Petrinetz-Werkzeuge, in der die einzelnen Teile eines Petrinetz-Typs unabhängig voneinander implementiert werden. Der Petrinetz-Kern ist eine derartige Basis mit dessen Hilfe Petrinetz-Werkzeuge gebaut werden. Er implementiert Konzepte, die allen Petrinetzen gemein sind, unabhängig von konkreten Petrinetz-Typen. Gemeinsam mit dem Petrinetz-Hyperwürfel bildet der Petrinetz-Kern ein weiteres Basiswerkzeug für einen parametrisierten Petrinetz-Typ mit einer parametrisierten Schaltregel. Die Petri Net Markup Language und der Petrinetz-Kern sind die wesentlichen Beiträge der vorliegenden Arbeit. Gemeinsam bilden sie ein mächtiges Grundgerüst für Petrinetz-Werkzeuge beliebiger Petrinetz-Typen. / Petri nets are widely used for modelling systems. The different areas and goals require different types of Petri nets. Each Petri net contains beside places, transitions, and arcs several further specific elements. Furthermore, a Petri net type defines a specific firing rule. There are many different Petri net types. It is not easy to have a general view on this bulk of Petri net types. Thus, there are attempts to establish general Petri net types or classifications of Petri net types (even of particular aspects). But, current approaches include only a few of all Petri net types. Our approach is a classification by semantics of Petri nets. We call this classification Petri Net Hypercube. It is meant to be universal for all Petri net types. A syntactical classification approach is the base of the Petri Net Hypercube. This approach leads on the one hand to the proposal of the Petri Net Markup Language. This language describes Petri nets of all types. On the other hand, the same approach leads to a base of Petri net tools. The parts of a Petri net type are implemented in this base independently of each other. The Petri Net Kernel is such a base for building Petri net tools. It implements those concepts which are general concepts of each Petri net. The Petri Net Kernel forms together with the Petri Net Hypercube a further basic Petri net tool for a parameterized Petri net type with a parameterized firing rule. The Petri Net Markup Language and the Petri Net Kernel are the main contributions of this thesis. Together, they are a powerful base for Petri net tools of each Petri net type.

Resumo: Neste trabalho apresentam-se quatro ferramentas de síntese digital, capazes de converter máquinas de estados finitos modeladas em rede de Petri para uma descrição VHDL correspondente à maquina modelada. As máquinas de estados finitos nos modelos de Mealy ou Moore são representadas em rede de Petri Lugar/Transição através de duas metodologias de modelagem desenvolvidas. Uma das metodologias modela apenas máquinas do tipo Mealy, enquanto que a outra modela máquinas de Mealy e Moore. As metodologias e o tipo de tradução da rede de Petri que se deseja obter são fatores essenciais para definir as ferramentas que serão utilizadas. Duas das ferramentas desenvolvidas traduzem o modelo da rede de Petri em uma tabela de transição de estados e as outras duas ferramentas traduzem o modelo da rede de Petri em uma descrição comportamental na linguagem VHDL. Dependendo da ferramenta utilizada é necessário integrar outras ferramentas de síntese, desenvolvidas em trabalhos anteriores, no processo de tradução da rede de Petri para VHDL. A aplicabilidade das ferramentas e metodologias desenvolvidas foi concluída através de simulações dos códigos VHDL obtidos. / Abstract: In this work we present four digital synthesis tools capable of converting finite state machines modeled in Petri nets into a corresponding VHDL description. Mealy or Moore finite state machine models are represented in Place/Transition Petri nets through two possible methodologies, developed during this work. With one of the methodologies only Mealy machines can be modeled, while the with other both Mealy and Moore type machines can be dealt with. The methodologies and the kind of Petri net translation one desires to obtain are essential factors to determine the tools to be used. Two among the tools we developed translate a Petri net description into a state transition table, while the other two translate the Petri net description into a VHDL behavioral one. Depending on which of them is used it is also necessary to use some other synthesis tools developed by members of our research group. The adequacy of the developed methodologies an tools to the synthesis process has been verified through the simulation of the VHDL codes generated by our tools. / Orientador: Alexandre César Rodrigues da Silva / Coorientador: Norian Marranghello / Banca: Aledir Silveira Pereira / Banca: Marius Strum / Mestre

Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-05-19Bitstream added on 2014-06-13T20:29:09Z : No. of bitstreams: 1 dezani_h_me_ilha.pdf: 383103 bytes, checksum: 4d2db649fe811e74784845f2d0b245b4 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho descreve-se um programa de geração automática de código para o microcontrolador 8051 da Intel, a partir de uma rede de Petri, com o objetivo de minimizar o tempo gasto na codificação do programa e automatizar completamente este processo de transformação. Definiu-se o uso da rede de Petri Lugar/Transição como modelo de entrada pois, mesmo tendo um modelo mais compacto, a rede de Petri Colorida, quando transformada em código Assembly é consideravelmente maior que o código Assembly gerado para a rede de Petri Lugar/Transição. Conclui-se que o código gerado pelo programa corresponde, exatamente, ao modelo da rede e pode ser executado pela arquitetura-alvo sem a necessidade de alterações no código. / This dissertation describes a program for the automatic generation of microcontroller code. The program takes a Petri net as input and outputs the corresponding assembly code for the Intel's 8051. The goal of this work is to speed up the coding process as well as to completely automate such a transformation. We use place/transition nets because even colored Petri nets resulting in quite compact models the assembly codes produced from them are much larger than those produced from place/transition nets. Also the code generated by the program described here exactly matches the net model, and can be directly executed on the target architecture without the need for further tuning.