| 1. |
- Bergagård, Patrik, 1984, et al.
(författare)
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Derivation of placement transitions for offline calculation of restart states
- 2013
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 1946-0759 .- 1946-0740.
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Konferensbidrag (refereegranskat)abstract
- This paper presents a preprocess to an existing method for offline calculation of restart states for manufacturing systems modeled by operations. In the existing method, placement transitions are used to model restart in restart states from potential error states, and supervisory control theory is used to calculate which of these transitions are valid. With the proposed preprocess, the precedence andthe alternative dependencies between the operations are exploited in order to reduce the number of such placement transitions which are required in the model used by theexisting method. With such a reduced model, the valid restart states for larger and more complex systems can be calculated.
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| 2. |
- Noori-Hosseini, Mona, 1982, et al.
(författare)
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A survey on efficient diagnosability tests for automata and bounded Petri nets
- 2013
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 1946-0759 .- 1946-0740. - 9781479908622 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- This paper presents a survey and evaluation of the efficiency of polynomial diagnosability algorithms for systems modeled by Petri nets and automata. A modified verification algorithm that reduces the state space by exploiting symmetry and abstracting unobservable transitions is also proposed. We show the importance of minimal explanations on the performance of diagnosability verifiers.Different verifiers are compared in terms of state spaceand elapsed time. It is shown that the minimal explanationnotion involved in the modified basis reachabilitygraph, a graph presented by Cabasino et al. [3] for diagnosability analysis of Petri nets, has great impact alsoon automata-based diagnosability methods. The evaluationoften shows improved computation times of a factor1000 or more when the concept of minimal explanation isincluded in the computation.
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| 3. |
- Ollinger, Lisa, et al.
(författare)
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A Reference Architecture for Service-oriented Control Procedures and its Implementation with SysML and Grafchart
- 2013
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Ingår i: IEEE 18th Conference on Emerging Technologies & Factory Automation (ETFA), 2013. - 1946-0759 .- 1946-0740. - 9781479908622 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- Innovative engineering methods are needed to enhance the adaptability and agility of industrial control procedures and concurrently manage their rising complexity. Service-oriented Architecture (SOA) constitutes a promising paradigm to meet these challenges. To apply the rather abstract SOA principles to industrial automation, a model-driven engineering method is presented in this paper. Therefore, a reference architecture is introduced providing a framework to structure and define services for control tasks in a convenient way. The application of the engineering method is supported by an implementation concept. It uses SysML during the design phase and the process modeling and control language Grafchart for the execution of service-oriented control procedures.
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| 4. |
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| 5. |
- Shoaei, Mohammad Reza, 1983, et al.
(författare)
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Reduced-order synthesis of operation sequences
- 2011
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 1946-0759 .- 1946-0740. - 9781457700170 ; , s. 8-
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Konferensbidrag (refereegranskat)abstract
- In flexible manufacturing systems a large number of operations need to be coordinated and supervised to avoid blocking and deadlock situations. The synthesis of such supervisors soon becomes unmanageable for industrial manufacturing systems, due to state space explosion. In this paper we therefore develop some reduction principles for a recently presented model based on self-contained operations and sequences of operations. First sequential operation behaviors are identified and related operation models are simplified into one model. Then local transitions without interaction with other operation models are removed. This reduction principle is applied to a synthesis of non-blocking operation sequences, where collisions among moving devices are guaranteed to be avoided by a flexible booking process. The number of states in the synthesis procedure and the computation time is reduced dramatically by the suggested reduction principle.
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| 6. |
- Sundström, Nina, 1980, et al.
(författare)
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Event- and time-based design of operation sequences with uncertainties in execution times
- 2013
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 1946-0759 .- 1946-0740. - 9781479908646 ; 18
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Konferensbidrag (refereegranskat)abstract
- In this paper, we introduce a complete framework for integrating the design of the manufacturing process and control system. We show how operation sequences can be designed in a modeling tool, Sequence Planner (SP), and how relations between operations may be expressed using logical conditions. An approach to convert the SP model into a constraint programming model for optimization is presented. The time-based solution is transformed to an event-based description. Due to uncertainties in execution times, some logical restrictions based on the optimal schedule are relaxed to avoid unnecessary delays. The control logics to achieve the desired operation sequences are added to the SP model. Hence, the process designer can revise the sequences if necessary, and the control designer retrieves a logical description of the optimized process that can be automatically converted to control code.
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