Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497887
M. Kloetzer, C. Mahulea
This paper presents an automatic strategy to control a team of identical robots that should satisfy a given task expressed as a syntactically co-safe Linear Temporal Logic (LTL) formula over a set of regions of interest. The team of robots is modeled by using a Petri net system with outputs (observations), thus avoiding the use of synchronized product of automatons. The strategy starts by translating the task into a Büchi automaton and by choosing a finite string satisfying the formula. Three Integer Linear Programming (ILP) formulations are used to find in the Petri net model a sequence of reachable markings such that the generated observations produce the chosen string of the Büchi automaton. If the string is not correctly followed, another one is found and the procedure is reiterated.
{"title":"Multi-robot path planning for syntactically co-safe LTL specifications","authors":"M. Kloetzer, C. Mahulea","doi":"10.1109/WODES.2016.7497887","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497887","url":null,"abstract":"This paper presents an automatic strategy to control a team of identical robots that should satisfy a given task expressed as a syntactically co-safe Linear Temporal Logic (LTL) formula over a set of regions of interest. The team of robots is modeled by using a Petri net system with outputs (observations), thus avoiding the use of synchronized product of automatons. The strategy starts by translating the task into a Büchi automaton and by choosing a finite string satisfying the formula. Three Integer Linear Programming (ILP) formulations are used to find in the Petri net model a sequence of reachable markings such that the generated observations produce the chosen string of the Büchi automaton. If the string is not correctly followed, another one is found and the procedure is reiterated.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127452379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497873
Xiang Yin, S. Lafortune
We investigate the verification of the properties of infinite-step opacity and K-step opacity for partially-observed discrete event systems. A system is said to be infinite-step opaque (respectively, K-step opaque) if the intruder can never determine for sure that the system was in a secret state for any instant within infinite steps (respectively, K steps) prior to that particular instant. We derive a new separation principle for state estimates which characterizes the information dependence in this opacity verification problem. A new information structure called the two-way observer is proposed. Based on the two-way observer, we provide new algorithms for the verification of infinite-step opacity and the verification of K-step opacity, respectively. We show that the proposed verification algorithms have lower computational complexity than the known algorithms in the literature.
{"title":"On two-way observer and its application to the verification of infinite-step and K-step opacity","authors":"Xiang Yin, S. Lafortune","doi":"10.1109/WODES.2016.7497873","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497873","url":null,"abstract":"We investigate the verification of the properties of infinite-step opacity and K-step opacity for partially-observed discrete event systems. A system is said to be infinite-step opaque (respectively, K-step opaque) if the intruder can never determine for sure that the system was in a secret state for any instant within infinite steps (respectively, K steps) prior to that particular instant. We derive a new separation principle for state estimates which characterizes the information dependence in this opacity verification problem. A new information structure called the two-way observer is proposed. Based on the two-way observer, we provide new algorithms for the verification of infinite-step opacity and the verification of K-step opacity, respectively. We show that the proposed verification algorithms have lower computational complexity than the known algorithms in the literature.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129159129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497860
G. Desirena-Lopez, C. Vázquez, J. L. Briz, A. Ramírez-Treviño, D. Gómez‐Gutiérrez
This work presents a fluid-time scheduler based on a sliding mode controller where the sliding surface is related to fluid task executions. The scheduler is applied to a model of tasks and CPUs designed with Timed Continuous Petri Nets (TCPN) under the infinite server semantics (ISS). Also, the paper proposes an implementation of this fluid scheduler as a feasible discrete scheduler where the number of task migrations and preemptions is bounded.
{"title":"On-line scheduling in multiprocessor systems based on continuous control using Timed Continuous Petri Nets","authors":"G. Desirena-Lopez, C. Vázquez, J. L. Briz, A. Ramírez-Treviño, D. Gómez‐Gutiérrez","doi":"10.1109/WODES.2016.7497860","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497860","url":null,"abstract":"This work presents a fluid-time scheduler based on a sliding mode controller where the sliding surface is related to fluid task executions. The scheduler is applied to a model of tasks and CPUs designed with Timed Continuous Petri Nets (TCPN) under the infinite server semantics (ISS). Also, the paper proposes an implementation of this fluid scheduler as a feasible discrete scheduler where the number of task migrations and preemptions is bounded.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128968014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497888
L. Capra
Petri Nets (PN) are a well established formal model for discrete event systems (DES). Classical PNs, even if Turing powerful, lack of features for specifying in an easy way structural changes that are likely to occur during systems' lifecycle. Many different attempts to face this issue have lead to several PN extensions, among which those matching the “nets within nets” paradigm are of particular relevance. In this paper we consolidate a recently introduced formal model for reconfigurable DES rigorously based on Reisig's SPEC-inscribed nets, that have a sound algebraic initial semantics. Although inspired by the same principles and goals as the “nets within net” paradigm, our approach is uniform and consists of a single modelling layer. This permits consolidated analysis techniques to be exploited. A well known, first-order declarative language (OBJ) is used to inscribe nets.
{"title":"A pure SPEC-inscribed PN model for reconfigurable systems","authors":"L. Capra","doi":"10.1109/WODES.2016.7497888","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497888","url":null,"abstract":"Petri Nets (PN) are a well established formal model for discrete event systems (DES). Classical PNs, even if Turing powerful, lack of features for specifying in an easy way structural changes that are likely to occur during systems' lifecycle. Many different attempts to face this issue have lead to several PN extensions, among which those matching the “nets within nets” paradigm are of particular relevance. In this paper we consolidate a recently introduced formal model for reconfigurable DES rigorously based on Reisig's SPEC-inscribed nets, that have a sound algebraic initial semantics. Although inspired by the same principles and goals as the “nets within net” paradigm, our approach is uniform and consists of a single modelling layer. This permits consolidated analysis techniques to be exploited. A well known, first-order declarative language (OBJ) is used to inscribe nets.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"67 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113987417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497862
Jiacun Wang, Xiaoou Li, Gaiyun Liu
In our previous work, we proposed a resource-oriented workflow nets (ROWN) approach for acyclic workflow resource requirement analysis. Resource requirements analysis for general workflows can be done through reachability analysis. For a class of well-structured workflows, an efficient resource analysis algorithm was also developed. In this paper, we discuss how to analyze the resource requirements of workflows with loops. The main idea is to convert a cyclic workflow into an equivalent acyclic workflow in terms of maximum resource requirements and net resource consumption. An application to emergency healthcare workflow resource requirement analysis is presented to illustrate how the approach works step-by-step.
{"title":"Cyclic workflow resource requirement analysis and application in healthcare","authors":"Jiacun Wang, Xiaoou Li, Gaiyun Liu","doi":"10.1109/WODES.2016.7497862","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497862","url":null,"abstract":"In our previous work, we proposed a resource-oriented workflow nets (ROWN) approach for acyclic workflow resource requirement analysis. Resource requirements analysis for general workflows can be done through reachability analysis. For a class of well-structured workflows, an efficient resource analysis algorithm was also developed. In this paper, we discuss how to analyze the resource requirements of workflows with loops. The main idea is to convert a cyclic workflow into an equivalent acyclic workflow in terms of maximum resource requirements and net resource consumption. An application to emergency healthcare workflow resource requirement analysis is presented to illustrate how the approach works step-by-step.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130549667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497830
J. Komenda, F. Lin
In this paper, modular and more generally coordination supervisory control of networked concurrent discrete-event systems (DES) is studied. We are interested in comparison of monolithic control synthesis with modular control synthesis if communication delays in both control and observation channels are taken into account. It is shown that unlike standard DES framework, modular, and more generally, coordination control can be more permissive than monolithic control in some cases because of smaller communication delays in the local systems.
{"title":"Modular supervisory control of networked discrete-event systems","authors":"J. Komenda, F. Lin","doi":"10.1109/WODES.2016.7497830","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497830","url":null,"abstract":"In this paper, modular and more generally coordination supervisory control of networked concurrent discrete-event systems (DES) is studied. We are interested in comparison of monolithic control synthesis with modular control synthesis if communication delays in both control and observation channels are taken into account. It is shown that unlike standard DES framework, modular, and more generally, coordination control can be more permissive than monolithic control in some cases because of smaller communication delays in the local systems.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"210 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134002753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497846
T. Soleymani, S. Hirche, J. Baras
Consider an observer (reporter) who desires to inform optimally a distant agent regarding a physical stochastic process in the environment while the directed communication of the observer to the agent has a price. We define a metric, from a task oriented perspective, for the information transferred from the observer to the agent. We develop a framework for optimizing an augmented cost function which is a convex combination of the transferred information and the paid price over a finite horizon. We suppose that the decision making takes place inside a source encoder, and that the sampling schedule is the decision variable. Moreover, we assume that no measurement at the current time is available to the observer for the decision making. We derive the optimal self-driven sampling policy using dynamic programming, and we show that this policy corresponds to a self-driven sampling policy based on a quantity that is in fact the value of information at each time instant. In addition, we use a semi-definite programming relaxation to provide a suboptimal sampling policy. Numerical and simulation results are presented for a simple unstable system.
{"title":"Optimal self-driven sampling for estimation based on value of information","authors":"T. Soleymani, S. Hirche, J. Baras","doi":"10.1109/WODES.2016.7497846","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497846","url":null,"abstract":"Consider an observer (reporter) who desires to inform optimally a distant agent regarding a physical stochastic process in the environment while the directed communication of the observer to the agent has a price. We define a metric, from a task oriented perspective, for the information transferred from the observer to the agent. We develop a framework for optimizing an augmented cost function which is a convex combination of the transferred information and the paid price over a finite horizon. We suppose that the decision making takes place inside a source encoder, and that the sampling schedule is the decision variable. Moreover, we assume that no measurement at the current time is available to the observer for the decision making. We derive the optimal self-driven sampling policy using dynamic programming, and we show that this policy corresponds to a self-driven sampling policy based on a quantity that is in fact the value of information at each time instant. In addition, we use a semi-definite programming relaxation to provide a suboptimal sampling policy. Numerical and simulation results are presented for a simple unstable system.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131848221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497865
Yin Tong, Ziyue Ma, Zhiwu Li, C. Seatzu, A. Giua
Current-state opacity is a key security property in discrete event systems. A system is said to be current-state opaque if the intruder, who only has partial observations on the system's evolution, is never able to infer that the current state of the system is within a set of secret states. In this work, we address the problem of enforcing current-state opacity by supervisory control. Given a system that is modeled with a finite automaton and that is not current-state opaque with respect to a given secret, the enforcement problem consists in designing a supervisor so that the controlled system is current-state opaque. We assume that the supervisor can only observe and control a subset of events. To be more general, we assume no specific containment relationship exists between the sets of events that can be observed by the intruder and the supervisor, respectively. We call this general setting uncomparable observations. We show that the maximally permissive supervisor always exists and propose a novel approach for its design.
{"title":"Supervisory enforcement of current-state opacity with uncomparable observations","authors":"Yin Tong, Ziyue Ma, Zhiwu Li, C. Seatzu, A. Giua","doi":"10.1109/WODES.2016.7497865","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497865","url":null,"abstract":"Current-state opacity is a key security property in discrete event systems. A system is said to be current-state opaque if the intruder, who only has partial observations on the system's evolution, is never able to infer that the current state of the system is within a set of secret states. In this work, we address the problem of enforcing current-state opacity by supervisory control. Given a system that is modeled with a finite automaton and that is not current-state opaque with respect to a given secret, the enforcement problem consists in designing a supervisor so that the controlled system is current-state opaque. We assume that the supervisor can only observe and control a subset of events. To be more general, we assume no specific containment relationship exists between the sets of events that can be observed by the intruder and the supervisor, respectively. We call this general setting uncomparable observations. We show that the maximally permissive supervisor always exists and propose a novel approach for its design.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115801375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497845
M. Ghazel, Baisi Liu
This paper aims to develop a suite of customizable Petri net benchmarks to deal with various issues pertaining to fault diagnosis in discrete event systems. As reported in previous studies, the existing benchmarks generally characterize some of the numerous issues concerning fault diagnosis. This satisfies a specific case study, whereas it may constitute a barrier when performing comparative analysis between different approaches. In order to bridge this gap, we propose to develop a suite of benchmarks based on the same case study, while covering a wide spectrum of diagnosis issues, namely diagnosability according to the original definition, K-diagnosability, diagnosability under fairness conditions, of intermittent faults and in timed context. The benchmark elaborated, based on a level crossing case study, can be enlarged to deal with the combinatorial explosion problem. In addition, it can be extended to integrate additional features. A software tool is provided to generate benchmarks, according to the target issues one seeks to tackle, and the desired size of the model.
{"title":"A customizable railway benchmark to deal with fault diagnosis issues in DES","authors":"M. Ghazel, Baisi Liu","doi":"10.1109/WODES.2016.7497845","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497845","url":null,"abstract":"This paper aims to develop a suite of customizable Petri net benchmarks to deal with various issues pertaining to fault diagnosis in discrete event systems. As reported in previous studies, the existing benchmarks generally characterize some of the numerous issues concerning fault diagnosis. This satisfies a specific case study, whereas it may constitute a barrier when performing comparative analysis between different approaches. In order to bridge this gap, we propose to develop a suite of benchmarks based on the same case study, while covering a wide spectrum of diagnosis issues, namely diagnosability according to the original definition, K-diagnosability, diagnosability under fairness conditions, of intermittent faults and in timed context. The benchmark elaborated, based on a level crossing case study, can be enlarged to deal with the combinatorial explosion problem. In addition, it can be extended to integrate additional features. A software tool is provided to generate benchmarks, according to the target issues one seeks to tackle, and the desired size of the model.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131518047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-10DOI: 10.1109/WODES.2016.7497839
Xinwei Chen, Y. Wardi, S. Yalamanchili
A new technique for performance regulation in event-driven systems, recently proposed by the authors, consists of an adaptive-gain integral control. The gain is adjusted in the control loop by a real-time estimation of the derivative of the plant-function with respect to the control input. This estimation is carried out by Infinitesimal Perturbation Analysis (IPA). The main motivation comes from applications to throughput regulation in computer processors, where to-date, the testing of the proposed control technique has been assessed by simulation. The purpose of this paper is to report on its implementation on Intel's Haswell microprocessor, and compare its performance to that obtained from cycle-level, full system simulation environment. The intrinsic contribution of the paper to the Workshop on Discrete Event Systems is in describing the process of taking an IPA-based design and simulation to a concrete implementation, thereby providing a bridge between theory and applications.
{"title":"IPA in the loop: Control design for throughput regulation in computer processors","authors":"Xinwei Chen, Y. Wardi, S. Yalamanchili","doi":"10.1109/WODES.2016.7497839","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497839","url":null,"abstract":"A new technique for performance regulation in event-driven systems, recently proposed by the authors, consists of an adaptive-gain integral control. The gain is adjusted in the control loop by a real-time estimation of the derivative of the plant-function with respect to the control input. This estimation is carried out by Infinitesimal Perturbation Analysis (IPA). The main motivation comes from applications to throughput regulation in computer processors, where to-date, the testing of the proposed control technique has been assessed by simulation. The purpose of this paper is to report on its implementation on Intel's Haswell microprocessor, and compare its performance to that obtained from cycle-level, full system simulation environment. The intrinsic contribution of the paper to the Workshop on Discrete Event Systems is in describing the process of taking an IPA-based design and simulation to a concrete implementation, thereby providing a bridge between theory and applications.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"142 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114058350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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