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- Bengtsson, Kristofer, 1979, et al.
(författare)
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Sequence Planning Using Multiple and Coordinated Sequences of Operations
- 2012
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Ingår i: IEEE Transactions on Automation Science and Engineering. - 1558-3783 .- 1545-5955. ; 9:2, s. 308-319
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Tidskriftsartikel (refereegranskat)abstract
- The sequential behavior of a manufacturing system results from several constraints introduced during the product, manufacturing, and control logic development. This paper proposes methods and algorithms for automatically representing and visualizing this behavior from various perspectives throughout the development process. A new sequence planning approach is introduced that uses self-contained operations to model the activities and execution constraints. These operations can be represented and visualized from multiple perspectives using a graphical and formal language called Sequences of Operations (SOPs). The operations in a manufacturing system are related to each other in various ways, due to execution constraints expressed by operation pre- and post-conditions. These operation relations include parallel, sequence, arbitrary order, alternative, and hierarchy relations. Based on the SOP language, these relations are identified and visualized in various SOPs and sequences. A software tool, Sequence Planner, has been developed, for organizing the operations into SOPs that visualize only relevant operations and relations. Note to Practitioners-This paper proposes methods and algorithms for a new sequence planning approach in which sequences are automatically created based on the relations among operations instead of having to be manually constructed. Using various views, the sequences of operations related to, for example, part flow, robot operations, and operator tasks, can be visualized. The use of various views helps the user better understand the relations between cell control and mechanical design, and between product design and total system behavior.
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| 2. |
- Bergagård, Patrik, 1984, et al.
(författare)
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Deadlock avoidance for multi product manufacturing systems modeled as sequences of operations
- 2012
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Ingår i: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. - 9781467304290 ; , s. 515 - 520
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Konferensbidrag (refereegranskat)abstract
- This paper demonstrates how industrial models of the sequential order between manufacturing operations may be connected with academic resource deadlock avoidance policies. Given a set of product types each modeled as a sequence of operations, the operations can be adapted to control concurrent manufacturing of multiple product instances, without resource deadlocks and with maximal flexibility. The given sequences of operations may contain routing flexibility, conjunctive and/or disjunctive resource requirements, and product assembly. Using a known deadlock avoidance approach, this paper presents how to transform the given operations into models required for the deadlock avoidance approach and how the calculated policy may be retransformed back into the operations.
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| 3. |
- Bergagård, Patrik, 1984
(författare)
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Modeling and analysis of restart, transport, and resource allocation in manufacturing systems using sequences of operations
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Highly automated and flexible manufacturing systems have gained industrial popularity for their ability to combine high product volumes with high product quality. However, the process planning, the process to design and plan thetasks and actions, the operations, that constitute the manufacturing process, is a complex and time consuming process. The process planning struggles with continuouslychanged requirements from the products to be produced and demands and capabilities of the manufacturing system itself.The high cost of investment of a manufacturing system in combination with many interlaced manufacturing systems in a factory, requires that the manufacturing process is running smoothly with high utilization of the resources and thatstoppages are avoided. To reach a high resource utilization, multiple products may be concurrently produced in a manufacturing system. In systems where several product routes are possible, the design of operations that combine concurrent manufacturing and high utilization is a difficult task. One major reason for stoppages is the occurrence of unforeseen errors that cause the manufacturingsystem to halt. The succeeding error recovery is often a complex and thereby time consuming process that typically requires manual involvement. To plan for restart after errors already during the process planning would therefore shorten the time the system is halted.To accomplish a useful process plan that faces the presented problems and is adaptive to (late) requirement changes, it is favorable to base the analyses and activities during the process planning on mathematically well defined methods, formal methods, well-suited for computerized calculations but heavily depended on precise models to calculate useful results.To support the process planning, this thesis presents how to use formal methods to analyze transport, resource allocation for concurrent manufacturing, and restart in manufacturing systems. To overcome the modeling issue, the required formal models are automatically generated from the operations that model the manufacturing processes and the result of the methods are given as additional operations and extensions to existing operations.
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