Joao Basilio - Academia.edu (original) (raw)

Papers by Joao Basilio

O primeiro estágio do projeto de diagnosticadores de falhas para sistemas industriais consiste na... more O primeiro estágio do projeto de diagnosticadores de falhas para sistemas industriais consiste na obtenção de um modelo que descreva tanto o comportamento normal como o de falha. No contexto de diagnose de falhas de sistemas a eventos discretos (SED), o Mapeamento de Sensores (MS) é uma ferramenta utilizada para a obtenção de modelos por autômatos. Porém a sua aplicação, além de ser limitada a estados associados a uma única leitura de sensores, pode também levar à incorreta estimação em tempo real dos estados do sistema monitorado, tendo em vista que as informações associadas a comandos e leituras de sensores são agrupadas em um mesmo evento. Neste artigo um novo método, o Mapeamento de Sensores Baseado na Especificação de Linguagens (MS-BEL), será proposto para a obtenção de autômatos que modelam o comportamento dos sensores do sistema. A ideia por trás do método proposto é alterar o MS utilizando-se regras usualmente adotadas na especificação da linguagem admissível necessária par...

Anais do 14º Simpósio Brasileiro de Automação Inteligente

The industry 4.0 paradigm is usually associated with large factories with several smart machines ... more The industry 4.0 paradigm is usually associated with large factories with several smart machines that demand a powerful and versatile connectivity infrastructure. In this context, a single robot is seldom able to deal with the logistics of an entire factory, being necessary the use of multiple robots. Thus, in this paper we extend the DES-based navigation architecture for a single robot, previously proposed in Gonzalez et al. (2018), to deal with multiple mobile robots.

2007 IEEE International Conference on Control Applications, 2007

This paper extends an existing sensor mapping procedure, defines compatibility of models and prop... more This paper extends an existing sensor mapping procedure, defines compatibility of models and proposes an integrated methodology based on existing methodologies for the construction of diagnosers for discrete event systems modeled by Petri Nets. An industrial application is used as a case study to illustrate the theoretical results of the paper.

Linear Algebra and its Applications, 2004

In this paper, algorithms for the computation of all matrices of the generalized polynomial Bezou... more In this paper, algorithms for the computation of all matrices of the generalized polynomial Bezout identity are proposed. The algorithms are based on the computation of minimal polynomial basis for the right null spaces of certain polynomial matrices. For this reason, an algorithm for the computation of minimal polynomial bases is also proposed. Since this algorithm relies solely on singular value decompositions of certain real matrices, formed with the coefficients of the polynomial matrix whose minimal polynomial bases one is interested in finding, it can be said to be robust.

Revista Controle & …, 2010

18th IFAC World Congress ( …, 2011

We address the problem of robust diagnosability of discrete event systems described by a class of... more We address the problem of robust diagnosability of discrete event systems described by a class of automata, where each automaton in the class generates a distinct language. We introduce a new definition which generalizes all previous definitions of robust diagnosability; for this reason it is referred here to as generalized robust diagnosability. We also present a necessary and sufficient condition for the generalized robust diagnosability and propose a polynomial time algorithm for its verification.

We discuss in this paper a new method for fault diagnosis in discrete event systems (DES) modeled... more We discuss in this paper a new method for fault diagnosis in discrete event systems (DES) modeled by acyclic labeled Petri nets, in which different transitions can be labeled by the same event. The proposed online diagnoser makes its decision about the occurrence of failure by storing the sequence of observed events and verifying, after each occurrence of an observable event, whether three sets of inequalities are satisfied: two sets represent the normal behavior of the system, while the third one defines the faulty behavior of the system. The online diagnostic method proposed in this work has the advantage over those previously proposed because they are based only on the verification of sets of inequalities requiring no knowledge of the automaton theory, being self-contained within the formalism of the Petri net. Keywords— Discrete event systems, Petri net, Fault diagnosis. Resumo— Abordamos neste artigo um novo método para diagnose de falhas em sistemas a eventos discretos (SED) m...

We propose two algorithms in this paper: the first algorithm verifies if a regular language K is ... more We propose two algorithms in this paper: the first algorithm verifies if a regular language K is relative observable with respect to an ambient language C, a plant and a projection, and has polynomial complexity; the second algorithm computes the supremal relative observable sublanguare of a given language K with respect to an ambient language C, a plant and a projection, and has exponential complexity in the number of the states of the automaton whose marked language is K, being, therefore, considerably smaller than that recently proposed in the literature, which has doubly exponential complexity. Keywords— Discrete event systems, automaton, supervisory control, observability, supremal sublanguage. Resumo— Neste artigo, dois algoritmos são propostos: o primeiro algoritmo verifica se uma linguagem regular K é observável relativa em relação a uma dada linguagem ambiente C, uma planta e uma projeção, e tem complexidade polinomial; o segundo algoritmo calcula a sublinguagem observável ...

IFAC-PapersOnLine, Jul 1, 2017

We address in this paper the problems of online diagnosis and verification of language diagnosabi... more We address in this paper the problems of online diagnosis and verification of language diagnosability of discrete event systems (DES) modeled by acyclic labeled Petri nets, in which, different transitions can be labeled by the same event (observable, unobservable and failure). The proposed diagnoser makes its decision regarding the failure occurrence by storing the sequence of observed events and, after each occurrence of observable event, it verifiers if two sets of inequalities are satisfied; the first set accounts for the normal whereas the second one accounts for the faulty behavior of the system. We also consider the problem of diagnosability verification by creating new sets of inequalities that, when satisfied, allow us to decide whether the language generated by the Petri net is diagnosable. Our method for online diagnosis has the advantage over previously ones for relying only on the verification of set of inequalities. Regarding language diagnosability, our verification algorithm does not require any knowledge of automaton theory, being self-contained within the Petri net formalism.

Anais do 14º Simpósio Brasileiro de Automação Inteligente

Predictability is a discrete event system (DES) property that aims to foresee some specific event... more Predictability is a discrete event system (DES) property that aims to foresee some specific event occurrence, usually seen as failures. Due to common restrictive assumptions, such as nonexistence of cycles of states connected with unobservable events only and language liveness, the existing methods for predictability verification do not include some classes of DES with more general behavior. In this paper, we revisit the problem of predictability in a more general scenario, in which, we remove the above assumption, and present a diagnoser-based algorithm for its verification. Resumo: A preditibilidadeé uma propriedade de sistemas a eventos discretos (SED) que objetiva prever a ocorrência de eventos específicos, geralmente referidos como falhas. Devido a hipóteses restritivas, tais como ausência de ciclos de estados conectados somente por eventos não observáveis e que a linguagem seja viva, esses métodos não abrangem algumas classes de SEDs com comportamentos mais gerais. Neste artigo, o problema de preditibilidadeé revisitado em um contexto mais geral, no qual as hipóteses acima são removidas, além de propor um algoritmo para a sua verificação.

International Journal of Control

We address in this paper the design of robust supervisors that are able to cope with intermittent... more We address in this paper the design of robust supervisors that are able to cope with intermittent loss of observations and also make the controlled system achieve the specification language under nominal operation. In order to do so, we introduce a definition of robust observability that leverages possible observations of the events that are subject to intermittent loss of observations and address language permissiveness by extending the recently introduced definition of relative observability to robust relative observability. We present necessary and sufficient conditions for the existence of robust supervisors that make the controlled system achieve robustly controllable and observable or relatively observable languages and present a characterisation of all achievable languages. A running example illustrates all the results presented in the paper, and an example taken from the open literature is used to illustrate the efficiency of the robust design strategy proposed in the paper.

Discrete Event Dynamic Systems

Diagnosability is an intrinsic property of the language generated by discrete event systems (DES)... more Diagnosability is an intrinsic property of the language generated by discrete event systems (DES) and the computational procedure to determine whether a language possesses or not this property is called diagnosability verification. For regular languages, diagnosability verification is carried out by building either diagnoser or verifier automata; the former is known to have worst-case exponential complexity whereas the latter has polynomial complexity in the size of state space of the automaton that generates the language. A question that has been asked for some time now is whether, in average, the state size of diagnosers is no longer exponential. This claim has been supported by the size of diagnoser automata usually obtained in practical and classroom examples, having, in some cases, state space size much smaller than that of verifiers. In an effort to clarify this matter, in this paper we carry out an experimental study on the average state size of diagnosers and verifiers by means of two experiments: (i) an exhaustive experiment, in which ten sets of automata with moderate cardinality were generated and for these sets of automata, diagnosers and verifiers were built, being the exact average state size for these specific instances calculated; (ii)an experiment with sampling, which considers 1660 sets of different instance sizes and, for each one, sample sets of 10,000 automata are randomly generated with uniform distribution and we compute sets of diagnosers and verifiers for each set of randomly generated automata, which have been used to estimate an asymptotic model for the average state sizes of diagnosers and verifiers.

ABSTRACT We deal with the problem of finding sets of observable events (event bases) that ensure ... more ABSTRACT We deal with the problem of finding sets of observable events (event bases) that ensure language diagnosability of discrete-event systems modeled by finite state automata. We propose a methodology to obtain such event bases by exploiting the structure of the diagnoser automaton, and in particular of its indeterminate cycles. We use partial diagnosers, test diagnosers, and other new constructs to develop rules that guide the update of the observable event set towards achieving diagnosability. The contribution of this paper is the description of such rules and their integration into a set of algorithms that output minimal diagnosis bases.

One approach to online fault diagnosis of discrete-event systems is through the use of the diagno... more One approach to online fault diagnosis of discrete-event systems is through the use of the diagnosers. Diagnosers are deterministic automata whose states are sets formed with the states of the plant together with labels that indicate if the trace that has occurred so far possesses or not the fault event. The decision regarding fault occurrence is taken based solely on observable events, i.e., events whose occurrences can be recorded by sensors. However, if one or more sensors that provide information on event occurrences fail, the diagnoser may either come to a halt or may even provide wrong information regarding fault occurrence. In order to overcome this deficiency, this paper proposes a robust diagnoser that deploys the redundancy that may exist in a set formed of diagnosis bases (set of events that guarantee fault diagnosability) with a view to ensure the fault diagnosis even in the occurrence of permanent sensor failures.

In the usual approaches to fault diagnosis of discrete event systems it is assumed that not only ... more In the usual approaches to fault diagnosis of discrete event systems it is assumed that not only all sensors work properly but also all information reported by sensors always reaches the diagnoser. Any bad sensor operation or communication failure between sensors and the diagnoser can be regarded as loss of observations of events initially assumed as observable. In such situations, it may be possible that either the diagnoser stands still or report some wrong information regarding the fault occurrence. In this paper we assume that intermittent loss of observations may occur and we propose an automaton model based on a new language operation (language dilation) that takes it into account. We refer to this problem as robust diagnosability against intermittent loss of observations (or simply robust diagnosability, where the context allows). We present a necessary and sufficient condition for robust diagnosability in terms of the language generated by the original automaton and propose two tests for robust language diagnosability, one that deploys diagnosers and another one that uses verifiers. We also extend the results to robust codiagnosability against intermittent loss of observations.

… Control Conference (ACC), …, 2010

Failure diagnosis is an important task in large complex systems and as such this problem has rece... more Failure diagnosis is an important task in large complex systems and as such this problem has received in the last years considerable attention in the literature. The rst step to diagnose failure occurrences in discrete event systems is the veri cation of the system diagnosability. Several works in the literature have addresses this problem using either diagnosers or veri ers for the centralized and decentralized architectures. In this paper a new polynomial time algorithm to verify the decentralized diagnosability property of a discrete event system is proposed. The algorithm has lower computational complexity than other methods proposed in the literature and can also be applied to the centralized case.

This paper extends an existing sensor mapping procedure, defines compatibility of models and prop... more This paper extends an existing sensor mapping procedure, defines compatibility of models and proposes an integrated methodology based on existing methodologies for the construction of diagnosers for discrete event systems modeled by Petri Nets. An industrial application is used as a case study to illustrate the theoretical results of the paper.

Anais do 14º Simpósio Brasileiro de Automação Inteligente

In this paper, we address the problem of decentralized failure diagnosis of networked discrete ev... more In this paper, we address the problem of decentralized failure diagnosis of networked discrete event systems (NDES) in the presence of Denial-of-Service (DoS) attacks. We propose an automaton model for NDES subject to DoS attacks that represent the adverse effects of DoS attacks on the observations of local diagnosers. We formulate a new diagnosis property, to be referred here to as DoS-robust codiagnosability, and present a systematic way to verify whether the language generate by a NDES is DoS-robustly codiagnosable.

Anais do 14º Simpósio Brasileiro de Automação Inteligente

Bicycle sharing has, as principle, to allow people to travel between two points using a bicycle, ... more Bicycle sharing has, as principle, to allow people to travel between two points using a bicycle, being public bicycle sharing systems (PBSS) originated from. PBSS are formed with stations where users can pick up bicycles to move themselves around the stations. Depending on the usage of the stations, they may have all the bicycles removed from them or may become full, restricting the movement of bicycles through the stations. One way to solve this issue is to implement balancing strategies by using a vehicle to exchange bicycles between stations, balancing them. In this paper, we proposed a model of a generic PBSS using Petri nets in order to evaluate different strategies based on a single simulation algortithm. The proposed model is then validated by an analyze of the design of Integra UFRJ PBSS system with the combination of three different balancing strategies, also proposed in this paper. Resumo: Compartilhamento de bicicletas possui como princípio possibilitar que um indivíduo trafegue de um ponto a outro com bicicletas. Com base nessa concepção, originaram-se os sistemas públicos de compartilhamento de bicicletas (SPCB), que consistem de estações onde os usuários podem retirar bicicletas para se locomoverem entre elas. Dependendo do uso das estações, elas podem ficar vazias ou lotadas, restringindo a movimentação de bicicletas nelas. Uma maneira de solucionar esse problemaé implementar estratégias de balanceamento utilizando um veículo para realizar trocas de bicicletas entre as estações, equilibrando-as. Neste artigo, será proposto um modelo de um SPCB genérico em redes de Petri para avaliar diferentes estratégias em umúnico algoritmo de simulação. O modelo proposto será validado pela análise do desempenho do projeto de SPCB Integra UFRJ com a combinação de três tipos diferentes de estratégias de balanceamento formuladas neste artigo.

O primeiro estágio do projeto de diagnosticadores de falhas para sistemas industriais consiste na... more O primeiro estágio do projeto de diagnosticadores de falhas para sistemas industriais consiste na obtenção de um modelo que descreva tanto o comportamento normal como o de falha. No contexto de diagnose de falhas de sistemas a eventos discretos (SED), o Mapeamento de Sensores (MS) é uma ferramenta utilizada para a obtenção de modelos por autômatos. Porém a sua aplicação, além de ser limitada a estados associados a uma única leitura de sensores, pode também levar à incorreta estimação em tempo real dos estados do sistema monitorado, tendo em vista que as informações associadas a comandos e leituras de sensores são agrupadas em um mesmo evento. Neste artigo um novo método, o Mapeamento de Sensores Baseado na Especificação de Linguagens (MS-BEL), será proposto para a obtenção de autômatos que modelam o comportamento dos sensores do sistema. A ideia por trás do método proposto é alterar o MS utilizando-se regras usualmente adotadas na especificação da linguagem admissível necessária par...

Anais do 14º Simpósio Brasileiro de Automação Inteligente

The industry 4.0 paradigm is usually associated with large factories with several smart machines ... more The industry 4.0 paradigm is usually associated with large factories with several smart machines that demand a powerful and versatile connectivity infrastructure. In this context, a single robot is seldom able to deal with the logistics of an entire factory, being necessary the use of multiple robots. Thus, in this paper we extend the DES-based navigation architecture for a single robot, previously proposed in Gonzalez et al. (2018), to deal with multiple mobile robots.

2007 IEEE International Conference on Control Applications, 2007

This paper extends an existing sensor mapping procedure, defines compatibility of models and prop... more This paper extends an existing sensor mapping procedure, defines compatibility of models and proposes an integrated methodology based on existing methodologies for the construction of diagnosers for discrete event systems modeled by Petri Nets. An industrial application is used as a case study to illustrate the theoretical results of the paper.

Linear Algebra and its Applications, 2004

In this paper, algorithms for the computation of all matrices of the generalized polynomial Bezou... more In this paper, algorithms for the computation of all matrices of the generalized polynomial Bezout identity are proposed. The algorithms are based on the computation of minimal polynomial basis for the right null spaces of certain polynomial matrices. For this reason, an algorithm for the computation of minimal polynomial bases is also proposed. Since this algorithm relies solely on singular value decompositions of certain real matrices, formed with the coefficients of the polynomial matrix whose minimal polynomial bases one is interested in finding, it can be said to be robust.

Revista Controle & …, 2010

18th IFAC World Congress ( …, 2011

We address the problem of robust diagnosability of discrete event systems described by a class of... more We address the problem of robust diagnosability of discrete event systems described by a class of automata, where each automaton in the class generates a distinct language. We introduce a new definition which generalizes all previous definitions of robust diagnosability; for this reason it is referred here to as generalized robust diagnosability. We also present a necessary and sufficient condition for the generalized robust diagnosability and propose a polynomial time algorithm for its verification.

We discuss in this paper a new method for fault diagnosis in discrete event systems (DES) modeled... more We discuss in this paper a new method for fault diagnosis in discrete event systems (DES) modeled by acyclic labeled Petri nets, in which different transitions can be labeled by the same event. The proposed online diagnoser makes its decision about the occurrence of failure by storing the sequence of observed events and verifying, after each occurrence of an observable event, whether three sets of inequalities are satisfied: two sets represent the normal behavior of the system, while the third one defines the faulty behavior of the system. The online diagnostic method proposed in this work has the advantage over those previously proposed because they are based only on the verification of sets of inequalities requiring no knowledge of the automaton theory, being self-contained within the formalism of the Petri net. Keywords— Discrete event systems, Petri net, Fault diagnosis. Resumo— Abordamos neste artigo um novo método para diagnose de falhas em sistemas a eventos discretos (SED) m...

We propose two algorithms in this paper: the first algorithm verifies if a regular language K is ... more We propose two algorithms in this paper: the first algorithm verifies if a regular language K is relative observable with respect to an ambient language C, a plant and a projection, and has polynomial complexity; the second algorithm computes the supremal relative observable sublanguare of a given language K with respect to an ambient language C, a plant and a projection, and has exponential complexity in the number of the states of the automaton whose marked language is K, being, therefore, considerably smaller than that recently proposed in the literature, which has doubly exponential complexity. Keywords— Discrete event systems, automaton, supervisory control, observability, supremal sublanguage. Resumo— Neste artigo, dois algoritmos são propostos: o primeiro algoritmo verifica se uma linguagem regular K é observável relativa em relação a uma dada linguagem ambiente C, uma planta e uma projeção, e tem complexidade polinomial; o segundo algoritmo calcula a sublinguagem observável ...

IFAC-PapersOnLine, Jul 1, 2017

We address in this paper the problems of online diagnosis and verification of language diagnosabi... more We address in this paper the problems of online diagnosis and verification of language diagnosability of discrete event systems (DES) modeled by acyclic labeled Petri nets, in which, different transitions can be labeled by the same event (observable, unobservable and failure). The proposed diagnoser makes its decision regarding the failure occurrence by storing the sequence of observed events and, after each occurrence of observable event, it verifiers if two sets of inequalities are satisfied; the first set accounts for the normal whereas the second one accounts for the faulty behavior of the system. We also consider the problem of diagnosability verification by creating new sets of inequalities that, when satisfied, allow us to decide whether the language generated by the Petri net is diagnosable. Our method for online diagnosis has the advantage over previously ones for relying only on the verification of set of inequalities. Regarding language diagnosability, our verification algorithm does not require any knowledge of automaton theory, being self-contained within the Petri net formalism.

Anais do 14º Simpósio Brasileiro de Automação Inteligente

Predictability is a discrete event system (DES) property that aims to foresee some specific event... more Predictability is a discrete event system (DES) property that aims to foresee some specific event occurrence, usually seen as failures. Due to common restrictive assumptions, such as nonexistence of cycles of states connected with unobservable events only and language liveness, the existing methods for predictability verification do not include some classes of DES with more general behavior. In this paper, we revisit the problem of predictability in a more general scenario, in which, we remove the above assumption, and present a diagnoser-based algorithm for its verification. Resumo: A preditibilidadeé uma propriedade de sistemas a eventos discretos (SED) que objetiva prever a ocorrência de eventos específicos, geralmente referidos como falhas. Devido a hipóteses restritivas, tais como ausência de ciclos de estados conectados somente por eventos não observáveis e que a linguagem seja viva, esses métodos não abrangem algumas classes de SEDs com comportamentos mais gerais. Neste artigo, o problema de preditibilidadeé revisitado em um contexto mais geral, no qual as hipóteses acima são removidas, além de propor um algoritmo para a sua verificação.

International Journal of Control

We address in this paper the design of robust supervisors that are able to cope with intermittent... more We address in this paper the design of robust supervisors that are able to cope with intermittent loss of observations and also make the controlled system achieve the specification language under nominal operation. In order to do so, we introduce a definition of robust observability that leverages possible observations of the events that are subject to intermittent loss of observations and address language permissiveness by extending the recently introduced definition of relative observability to robust relative observability. We present necessary and sufficient conditions for the existence of robust supervisors that make the controlled system achieve robustly controllable and observable or relatively observable languages and present a characterisation of all achievable languages. A running example illustrates all the results presented in the paper, and an example taken from the open literature is used to illustrate the efficiency of the robust design strategy proposed in the paper.

Discrete Event Dynamic Systems

Diagnosability is an intrinsic property of the language generated by discrete event systems (DES)... more Diagnosability is an intrinsic property of the language generated by discrete event systems (DES) and the computational procedure to determine whether a language possesses or not this property is called diagnosability verification. For regular languages, diagnosability verification is carried out by building either diagnoser or verifier automata; the former is known to have worst-case exponential complexity whereas the latter has polynomial complexity in the size of state space of the automaton that generates the language. A question that has been asked for some time now is whether, in average, the state size of diagnosers is no longer exponential. This claim has been supported by the size of diagnoser automata usually obtained in practical and classroom examples, having, in some cases, state space size much smaller than that of verifiers. In an effort to clarify this matter, in this paper we carry out an experimental study on the average state size of diagnosers and verifiers by means of two experiments: (i) an exhaustive experiment, in which ten sets of automata with moderate cardinality were generated and for these sets of automata, diagnosers and verifiers were built, being the exact average state size for these specific instances calculated; (ii)an experiment with sampling, which considers 1660 sets of different instance sizes and, for each one, sample sets of 10,000 automata are randomly generated with uniform distribution and we compute sets of diagnosers and verifiers for each set of randomly generated automata, which have been used to estimate an asymptotic model for the average state sizes of diagnosers and verifiers.

ABSTRACT We deal with the problem of finding sets of observable events (event bases) that ensure ... more ABSTRACT We deal with the problem of finding sets of observable events (event bases) that ensure language diagnosability of discrete-event systems modeled by finite state automata. We propose a methodology to obtain such event bases by exploiting the structure of the diagnoser automaton, and in particular of its indeterminate cycles. We use partial diagnosers, test diagnosers, and other new constructs to develop rules that guide the update of the observable event set towards achieving diagnosability. The contribution of this paper is the description of such rules and their integration into a set of algorithms that output minimal diagnosis bases.

One approach to online fault diagnosis of discrete-event systems is through the use of the diagno... more One approach to online fault diagnosis of discrete-event systems is through the use of the diagnosers. Diagnosers are deterministic automata whose states are sets formed with the states of the plant together with labels that indicate if the trace that has occurred so far possesses or not the fault event. The decision regarding fault occurrence is taken based solely on observable events, i.e., events whose occurrences can be recorded by sensors. However, if one or more sensors that provide information on event occurrences fail, the diagnoser may either come to a halt or may even provide wrong information regarding fault occurrence. In order to overcome this deficiency, this paper proposes a robust diagnoser that deploys the redundancy that may exist in a set formed of diagnosis bases (set of events that guarantee fault diagnosability) with a view to ensure the fault diagnosis even in the occurrence of permanent sensor failures.

In the usual approaches to fault diagnosis of discrete event systems it is assumed that not only ... more In the usual approaches to fault diagnosis of discrete event systems it is assumed that not only all sensors work properly but also all information reported by sensors always reaches the diagnoser. Any bad sensor operation or communication failure between sensors and the diagnoser can be regarded as loss of observations of events initially assumed as observable. In such situations, it may be possible that either the diagnoser stands still or report some wrong information regarding the fault occurrence. In this paper we assume that intermittent loss of observations may occur and we propose an automaton model based on a new language operation (language dilation) that takes it into account. We refer to this problem as robust diagnosability against intermittent loss of observations (or simply robust diagnosability, where the context allows). We present a necessary and sufficient condition for robust diagnosability in terms of the language generated by the original automaton and propose two tests for robust language diagnosability, one that deploys diagnosers and another one that uses verifiers. We also extend the results to robust codiagnosability against intermittent loss of observations.

… Control Conference (ACC), …, 2010

Failure diagnosis is an important task in large complex systems and as such this problem has rece... more Failure diagnosis is an important task in large complex systems and as such this problem has received in the last years considerable attention in the literature. The rst step to diagnose failure occurrences in discrete event systems is the veri cation of the system diagnosability. Several works in the literature have addresses this problem using either diagnosers or veri ers for the centralized and decentralized architectures. In this paper a new polynomial time algorithm to verify the decentralized diagnosability property of a discrete event system is proposed. The algorithm has lower computational complexity than other methods proposed in the literature and can also be applied to the centralized case.

This paper extends an existing sensor mapping procedure, defines compatibility of models and prop... more This paper extends an existing sensor mapping procedure, defines compatibility of models and proposes an integrated methodology based on existing methodologies for the construction of diagnosers for discrete event systems modeled by Petri Nets. An industrial application is used as a case study to illustrate the theoretical results of the paper.

Anais do 14º Simpósio Brasileiro de Automação Inteligente

In this paper, we address the problem of decentralized failure diagnosis of networked discrete ev... more In this paper, we address the problem of decentralized failure diagnosis of networked discrete event systems (NDES) in the presence of Denial-of-Service (DoS) attacks. We propose an automaton model for NDES subject to DoS attacks that represent the adverse effects of DoS attacks on the observations of local diagnosers. We formulate a new diagnosis property, to be referred here to as DoS-robust codiagnosability, and present a systematic way to verify whether the language generate by a NDES is DoS-robustly codiagnosable.

Anais do 14º Simpósio Brasileiro de Automação Inteligente

Bicycle sharing has, as principle, to allow people to travel between two points using a bicycle, ... more Bicycle sharing has, as principle, to allow people to travel between two points using a bicycle, being public bicycle sharing systems (PBSS) originated from. PBSS are formed with stations where users can pick up bicycles to move themselves around the stations. Depending on the usage of the stations, they may have all the bicycles removed from them or may become full, restricting the movement of bicycles through the stations. One way to solve this issue is to implement balancing strategies by using a vehicle to exchange bicycles between stations, balancing them. In this paper, we proposed a model of a generic PBSS using Petri nets in order to evaluate different strategies based on a single simulation algortithm. The proposed model is then validated by an analyze of the design of Integra UFRJ PBSS system with the combination of three different balancing strategies, also proposed in this paper. Resumo: Compartilhamento de bicicletas possui como princípio possibilitar que um indivíduo trafegue de um ponto a outro com bicicletas. Com base nessa concepção, originaram-se os sistemas públicos de compartilhamento de bicicletas (SPCB), que consistem de estações onde os usuários podem retirar bicicletas para se locomoverem entre elas. Dependendo do uso das estações, elas podem ficar vazias ou lotadas, restringindo a movimentação de bicicletas nelas. Uma maneira de solucionar esse problemaé implementar estratégias de balanceamento utilizando um veículo para realizar trocas de bicicletas entre as estações, equilibrando-as. Neste artigo, será proposto um modelo de um SPCB genérico em redes de Petri para avaliar diferentes estratégias em umúnico algoritmo de simulação. O modelo proposto será validado pela análise do desempenho do projeto de SPCB Integra UFRJ com a combinação de três tipos diferentes de estratégias de balanceamento formuladas neste artigo.