| 1. |
- Kobetski, Avenir, 1977, et al.
(författare)
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Time-Optimal Coordination of Flexible Manufacturing Systems Using Deterministic Finite Automata and Mixed Integer Linear Programming
- 2009
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Ingår i: Discrete Event Dynamic Systems: Theory and Applications. - : Springer Science and Business Media LLC. - 0924-6703 .- 1573-7594. ; 19:3, s. 287-315
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Tidskriftsartikel (refereegranskat)abstract
- Automation and flexibility are often mentioned as key concepts in modern production industry. To increase the level of flexibility, deterministic finite automata (DFA) can be used to model, specify and verify the production systems. Often, it is also desirable to optimize some production criteria, such as for example the cycle time of a manufacturing cell. In this paper, a method for automatic conversion from DFA to a mixed integer linear programming (MILP) formulation is first presented. This conversion is developed for a number of DFA structures that have shown to be useful in practical applications. Special attention is paid to reducing the search region explored by the MILP solver. Second, a conversion from the MILP solution to a DFA supervisor is described. This allows to combine the advantages of DFA modeling with the efficiency of MILP and supervisory control theory to automatically generate time-optimal, collision-free and non-blocking working schedules for flexible manufacturing systems.
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| 2. |
- Kumar, Ratnesh, et al.
(författare)
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Maximally permissive mutually and globally nonblocking supervisors for discrete event systems
- 2004
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. ; 37:18, s. 69-74
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Konferensbidrag (refereegranskat)abstract
- A supervisor is said to be mutually nonblocking with respect to a pair of specifications if upon completing a task in any of the specifications , it can continue on to complete t he task in the other specificat ion, i.e. , the two specifications do not block each other. T he notion of mutually nonblocking supervisor was introduced by Fabian and Kumar (2000). In this paper we present an algorithm of polynomial complexity for computing a maximally permissive mutually and globally nonblocking supervisor. The algorithm is based on a notion of attmctability, and as a special case offers a new way of computing the maximally permissive nonblocking supervisors.
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| 3. |
- Kobetski, Avenir, 1977, et al.
(författare)
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Scheduling Algorithms for Optimal Robot Cell Coordination - a Comparison
- 2006
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Ingår i: Proc. of IEEE Conference on Automation Science and Engineering. - 1424403103 ; , s. 381-386
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Konferensbidrag (refereegranskat)abstract
- Flexibility is the keyword in the modern industrial world. Automatic generation of collision- and blocking free, time optimal schedules for industrial robot cells is thus motivated. While a lot of attention has been paid to the control of industrial systems, as well as to the development of general optimization algorithms, there is still a need to properly combine these two research areas. This paper discusses two scheduling algorithms, designed for industrial robot cells, in terms of performance. A novel heuristic to an A*-based algorithm, operating on Discrete Event Systems, is proposed and benchmarked against the well-known MILP algorithm.
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| 4. |
- Kobetski, Avenir, 1977, et al.
(författare)
-
Scheduling of Discrete Event Systems Using Mixed Integer Linear Programming
- 2006
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Ingår i: 8th International Workshop on Discrete Event Systems.
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Konferensbidrag (refereegranskat)abstract
- To remain competitive, the modern industry strivefor flexibility. Recently, a method for automatic generation of control code from a 3D simulation model of a flexible manufacturing system was developed. Finite automata and Supervisory Control Theory (SCT) was used to guarantee the required behaviour of the system. This paper moves one step further. A method for automatic conversion between deterministic finite automata and Mixed Integer Linear Programming (MILP) formulation is presented. This allows to efficiently combine SCT and MILP to automatically generate time-optimal, collision-freeand non-blocking working schedules.
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