Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497871
Liping Bai, N. Wu, Zhiwu Li, Mengchu Zhou
This work studies the buffer space configuration problem to obtain an optimal one-wafer cyclic schedule for single-arm multi-cluster tools with a linear topology. To do so, a Petri net model is developed to describe the dynamic behavior of the system by extending the resource-oriented Petri nets such that a schedule can be parameterized with robots' waiting time. Based on this model, conditions for the existence of a one-wafer cyclic schedule with the lower bound of cycle time are presented, and algorithm is developed to find such an optimal schedule. The algorithm requires only simple calculation to set the robots' waiting time and configure the buffer spaces between two individual tools. An example is presented to show the application and power of the proposed method.
{"title":"Buffer space configuration and scheduling analysis of single-arm multi-cluster tools","authors":"Liping Bai, N. Wu, Zhiwu Li, Mengchu Zhou","doi":"10.1109/WODES.2016.7497871","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497871","url":null,"abstract":"This work studies the buffer space configuration problem to obtain an optimal one-wafer cyclic schedule for single-arm multi-cluster tools with a linear topology. To do so, a Petri net model is developed to describe the dynamic behavior of the system by extending the resource-oriented Petri nets such that a schedule can be parameterized with robots' waiting time. Based on this model, conditions for the existence of a one-wafer cyclic schedule with the lower bound of cycle time are presented, and algorithm is developed to find such an optimal schedule. The algorithm requires only simple calculation to set the robots' waiting time and configure the buffer spaces between two individual tools. An example is presented to show the application and power of the proposed method.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"150 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":"115430031","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.2016.7497870
Wei Wei, Zheng Wang
Reduction of energy consumption has attracted much attention of the researchers and practitioners in the field of sustainable manufacturing. However, the issue of integrated optimal production and energy control for sustainable manufacturing systems has not yet been investigated sufficiently. In this paper, we study such a problem for a single machine and single product-type manufacturing system, with the objective of minimizing the sum of production cost and energy consumption cost. To solve this problem, a Markov decision process model is developed, based on which, we obtain the integrated optimal production and energy control policy by the policy iteration method. Furthermore, we reveal the structural characteristics of optimal control policy and analyze the influence of system parameters on it by comparing different cases.
{"title":"Integrated optimal production and energy control of a single machine and single product-type manufacturing system","authors":"Wei Wei, Zheng Wang","doi":"10.1109/WODES.2016.7497870","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497870","url":null,"abstract":"Reduction of energy consumption has attracted much attention of the researchers and practitioners in the field of sustainable manufacturing. However, the issue of integrated optimal production and energy control for sustainable manufacturing systems has not yet been investigated sufficiently. In this paper, we study such a problem for a single machine and single product-type manufacturing system, with the objective of minimizing the sum of production cost and energy consumption cost. To solve this problem, a Markov decision process model is developed, based on which, we obtain the integrated optimal production and energy control policy by the policy iteration method. Furthermore, we reveal the structural characteristics of optimal control policy and analyze the influence of system parameters on it by comparing different cases.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"229 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":"114233510","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.2016.7497851
Carlos E. V. Nunes, M. V. Moreira, M. S. Alves, J. Basilio
Failure diagnosis is a crucial task in modern industrial systems, and several works in the literature address this problem by modeling the system as a Discrete-Event System. Most of them assumes perfect communication between sensors and diagnosers, i:e:, no loss of observation of events, or event communication delays between the measurement sites and the diagnosers. However, industrial systems can be large and physically distributed. In these cases, communication networks can be used to provide an efficient way to establish communication between devices with a view to diagnosing failure occurrence. The use of networks can introduce delays in the communication of event occurrences to local diagnosers, leading to an incorrect observation of the order of occurrence of events generated by the system and, consequently, an incorrect diagnosis decision by the local diagnoser. In this paper, we address the problem of decentralized diagnosis of networked Discrete-Event Systems subject to event communication delays, and we introduce the definition of network codiagnosability of the language of a system subject to event communication delays. We also propose an algorithm to verify this property.
{"title":"Network codiagnosability of Discrete-Event Systems subject to event communication delays","authors":"Carlos E. V. Nunes, M. V. Moreira, M. S. Alves, J. Basilio","doi":"10.1109/WODES.2016.7497851","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497851","url":null,"abstract":"Failure diagnosis is a crucial task in modern industrial systems, and several works in the literature address this problem by modeling the system as a Discrete-Event System. Most of them assumes perfect communication between sensors and diagnosers, i:e:, no loss of observation of events, or event communication delays between the measurement sites and the diagnosers. However, industrial systems can be large and physically distributed. In these cases, communication networks can be used to provide an efficient way to establish communication between devices with a view to diagnosing failure occurrence. The use of networks can introduce delays in the communication of event occurrences to local diagnosers, leading to an incorrect observation of the order of occurrence of events generated by the system and, consequently, an incorrect diagnosis decision by the local diagnoser. In this paper, we address the problem of decentralized diagnosis of networked Discrete-Event Systems subject to event communication delays, and we introduce the definition of network codiagnosability of the language of a system subject to event communication delays. We also propose an algorithm to verify this property.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"19 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":"124917231","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.2016.7497877
M. Ibrahim, Jun Chen, Ratnesh Kumar
Providing a resiliency measure for power systems is one of the challenges towards its Dynamic Security Assessment. This paper introduces a resiliency measure, called Level-of-Resilience (LoR), determined by examining: (i) the Region-of- Stability-Reduction (RoSR), as the RoS evolves under attack and recovery actions as captured by a “modal-RoS”, (ii) the eventual Level-of-Performance-Reduction (LoPR), as measured by percentage of reduction of load served, and (iii) Recovery-Time (RT), which is the time system takes to detect and recover from an attack or a fault. We illustrate our measure by comparing resiliency level of two power systems under two different attack scenarios.
{"title":"A resiliency measure for electrical power systems","authors":"M. Ibrahim, Jun Chen, Ratnesh Kumar","doi":"10.1109/WODES.2016.7497877","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497877","url":null,"abstract":"Providing a resiliency measure for power systems is one of the challenges towards its Dynamic Security Assessment. This paper introduces a resiliency measure, called Level-of-Resilience (LoR), determined by examining: (i) the Region-of- Stability-Reduction (RoSR), as the RoS evolves under attack and recovery actions as captured by a “modal-RoS”, (ii) the eventual Level-of-Performance-Reduction (LoPR), as measured by percentage of reduction of load served, and (iii) Recovery-Time (RT), which is the time system takes to detect and recover from an attack or a fault. We illustrate our measure by comparing resiliency level of two power systems under two different attack scenarios.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"41 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":"116359803","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.2016.7497883
Florian Göbe, T. Timmermanns, Oliver Ney, S. Kowalewski
The supervisory control theory is a conceptual framework to keep a discrete-event system in a desired state space by disabling controllable events. This paper introduces a new software tool to create supervisors for actual, physical plants in terms of a PLC code implementation. It points out the differences between SCT-synthesized supervisors and controllers and identifies a scenario in which practical applications can benefit from supervision. The presented tool provides a graphical user interface for the modeling and a template-based code generator. For safety specifications, a slightly altered automaton principle, called restricting specification, is used with the goal to decrease the manual modeling effort. Furthermore, event preemption is supported, which allows to permissively supervise controllers that react to uncontrollable events. This paper intends to give a brief overview of the key features of the tool.
{"title":"Synthesis Tool for Automation Controller Supervision","authors":"Florian Göbe, T. Timmermanns, Oliver Ney, S. Kowalewski","doi":"10.1109/WODES.2016.7497883","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497883","url":null,"abstract":"The supervisory control theory is a conceptual framework to keep a discrete-event system in a desired state space by disabling controllable events. This paper introduces a new software tool to create supervisors for actual, physical plants in terms of a PLC code implementation. It points out the differences between SCT-synthesized supervisors and controllers and identifies a scenario in which practical applications can benefit from supervision. The presented tool provides a graphical user interface for the modeling and a template-based code generator. For safety specifications, a slightly altered automaton principle, called restricting specification, is used with the goal to decrease the manual modeling effort. Furthermore, event preemption is supported, which allows to permissively supervise controllers that react to uncontrollable events. This paper intends to give a brief overview of the key features of the tool.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"134 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":"115902122","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.2016.7497838
F. Vázquez-Abad, Silvano Bernabel
We study the problem of dynamic routing of robotic bees towards the hive, with the intended purpose of minimizing the time it takes for all the bees to arrive at the destination. Due to uncertainty in position measurements, the stochastic problem cannot ensure collision-free paths. We study the effects that the algorithm parameters have in reducing the computational complexity and expected number of collisions. The dynamic path allocation assumes signals are received every ε units of time. We provide a weak convergence proof that the stochastic dynamic allocation converges to the optimal deterministic path when ε → 0. Next we explore via experimentation how the various algorithm parameters affect the overall performance. A k-nearest neighbors strategy is implemented to lessen the need for small step size ε and safety parameter. Δ. In this manner we achieve a faster completion time, reduce collisions and computational complexity.
{"title":"Stochastic path optimization for robotic bees using cloud computing","authors":"F. Vázquez-Abad, Silvano Bernabel","doi":"10.1109/WODES.2016.7497838","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497838","url":null,"abstract":"We study the problem of dynamic routing of robotic bees towards the hive, with the intended purpose of minimizing the time it takes for all the bees to arrive at the destination. Due to uncertainty in position measurements, the stochastic problem cannot ensure collision-free paths. We study the effects that the algorithm parameters have in reducing the computational complexity and expected number of collisions. The dynamic path allocation assumes signals are received every ε units of time. We provide a weak convergence proof that the stochastic dynamic allocation converges to the optimal deterministic path when ε → 0. Next we explore via experimentation how the various algorithm parameters affect the overall performance. A k-nearest neighbors strategy is implemented to lessen the need for small step size ε and safety parameter. Δ. In this manner we achieve a faster completion time, reduce collisions and computational complexity.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"222 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":"131592058","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.2016.7497891
F. Basile, P. Chiacchio, J. Coppola
In a previous paper we presented an approach to identify a Time Petri net system, given a set of observed timed sequences. The set of transitions, which coincides with the set of events, is assumed to be known, while the net structure, the initial marking and the firing duration of transitions are computed in one stage solving a mixed-integer linear programming problem derived from a set of logical predicates. In this paper we extend this approach by allowing that two transitions may share the same event label. Then, the identified model is a labeled Time Petri net system. The identification problem can still be solved via a mixed-integer linear programming problem but the constraint set previously determined is modified.
{"title":"Identification of labeled Time Petri nets","authors":"F. Basile, P. Chiacchio, J. Coppola","doi":"10.1109/WODES.2016.7497891","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497891","url":null,"abstract":"In a previous paper we presented an approach to identify a Time Petri net system, given a set of observed timed sequences. The set of transitions, which coincides with the set of events, is assumed to be known, while the net structure, the initial marking and the firing duration of transitions are computed in one stage solving a mixed-integer linear programming problem derived from a set of logical predicates. In this paper we extend this approach by allowing that two transitions may share the same event label. Then, the identified model is a labeled Time Petri net system. The identification problem can still be solved via a mixed-integer linear programming problem but the constraint set previously determined is modified.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"4 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":"130959076","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.2016.7497841
J. Berkhout
This paper extends the random surfer approach of Google's PageRank algorithm to general finite Markov chains that may consist of several ergodic classes and possible transient states. We will introduce the new concept of an extended ergodic projector of a Markov chain and we will show how the extended ergodic projector allows for intuitive better ranking of transient states. Numerical examples are provided to illustrate the effect of this new ranking approach.
{"title":"Google's PageRank algorithm for ranking nodes in general networks","authors":"J. Berkhout","doi":"10.1109/WODES.2016.7497841","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497841","url":null,"abstract":"This paper extends the random surfer approach of Google's PageRank algorithm to general finite Markov chains that may consist of several ergodic classes and possible transient states. We will introduce the new concept of an extended ergodic projector of a Markov chain and we will show how the extended ergodic projector allows for intuitive better ranking of transient states. Numerical examples are provided to illustrate the effect of this new ranking approach.","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":"121956582","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.2016.7497867
M. Schuh, J. Lunze
A tracking control framework for plants modeled by deterministic I/O automata is presented. The control aim is to steer the plant into a desired final state while at the same time guaranteeing its adherence to some safety constraints. It is proposed to control the plant by a tracking controller which consists of a trajectory planning unit and a controller. The trajectory planning unit searches for a reference trajectory that leads to the desired final state and avoids illegal transitions corresponding to safety constraints. The controller, which is modeled by a deterministic I/O automaton, steers the plant along this reference trajectory. It is proved that the plant in the closed-loop system with the proposed tracking controller always fulfills the given control aim, if it is controllable, that is, if there exists a path leading to the desired final state in the automaton graph of the plant without the illegal transitions.
{"title":"Tracking control of deterministic I/O automata","authors":"M. Schuh, J. Lunze","doi":"10.1109/WODES.2016.7497867","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497867","url":null,"abstract":"A tracking control framework for plants modeled by deterministic I/O automata is presented. The control aim is to steer the plant into a desired final state while at the same time guaranteeing its adherence to some safety constraints. It is proposed to control the plant by a tracking controller which consists of a trajectory planning unit and a controller. The trajectory planning unit searches for a reference trajectory that leads to the desired final state and avoids illegal transitions corresponding to safety constraints. The controller, which is modeled by a deterministic I/O automaton, steers the plant along this reference trajectory. It is proved that the plant in the closed-loop system with the proposed tracking controller always fulfills the given control aim, if it is controllable, that is, if there exists a path leading to the desired final state in the automaton graph of the plant without the illegal transitions.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"1 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":"129762922","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.2016.7497852
S. Takai, Ratnesh Kumar
We previously introduced an inference-based decentralized diagnosis framework for discrete event systems, where inferencing over the ambiguities of the self and the others is used to issue local decisions, and a global decision is taken to be the one with the least ambiguity level. In this setting, we introduced the notion of N-inference diagnosability to characterize the detection of any failure within a bounded delay, using at most N-levels of inferencing, and subsuming both disjunctive and conjunctive ways of decision fusions. In this paper, we compute the delay bound within which the occurrence of any failure can be detected for an N-inference diagnosable system. Computing the delay bound is important to execute mitigation actions in a timely manner, and is a figure of merit of a diagnosis scheme.
{"title":"Delay bound of inference-based decentralized diagnosis in discrete event systems","authors":"S. Takai, Ratnesh Kumar","doi":"10.1109/WODES.2016.7497852","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497852","url":null,"abstract":"We previously introduced an inference-based decentralized diagnosis framework for discrete event systems, where inferencing over the ambiguities of the self and the others is used to issue local decisions, and a global decision is taken to be the one with the least ambiguity level. In this setting, we introduced the notion of N-inference diagnosability to characterize the detection of any failure within a bounded delay, using at most N-levels of inferencing, and subsuming both disjunctive and conjunctive ways of decision fusions. In this paper, we compute the delay bound within which the occurrence of any failure can be detected for an N-inference diagnosable system. Computing the delay bound is important to execute mitigation actions in a timely manner, and is a figure of merit of a diagnosis scheme.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"204 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":"127693143","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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