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- Flordal, Hugo, 1977, et al.
(författare)
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Automatic Multi Robot Coordination
- 2003
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Ingår i: Konferensprogram för Mekatronikmötet 2003, Göteborg, Sweden.
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Konferensbidrag (refereegranskat)
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- Flordal, Hugo, 1977, et al.
(författare)
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Supervision of Multiple Industrial Robots - Optimal and Collision Free Work Cycles
- 2004
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Ingår i: Proceedings of the IEEE Conference on Control Applications, Taipei, Taiwan, 2-4 Sept. 2004. ; 2, s. 1404 - 1409
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Konferensbidrag (refereegranskat)abstract
- A method for automatic generation of collision free, blocking free and work cycle time optimized supervisors for industrial robot cells has been implemented. The individual robots' tasks are specified as a set of targets that the robot should visit in arbitrary order. Finite automaton models of allocation and release of critical spatial volumes that the robots share, as well as models of the robots' possible movements are automatically extracted from a 3D simulation environment. This includes explicitly calculating the intersection between the robots' work envelopes, the spatial volumes where collisions may occur, and simulating the robots' collisions with these. Each robot's different sequences of operations of factorial complexity in the number of states are efficiently represented as a set of automata using a polynomial number of states. The automatically generated system model is analyzed using the Ramadge-Wonham supervisory control theory to verify nonlocking and to synthesize supervisors. The method guarantees collision freeness, nonblocking and a flexible coordination function. The model is also used to find the time optimal work cycle for completion of the robots' tasks. To meet market demands of mass customization and shorter time to market, more flexible manufacturing systems are needed. The method presented here aims to automatize robot coordination programming which, being a tedious manual task in today's industry, is a bottleneck in the development of old and new production lines.
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- Åkesson, Knut, 1972, et al.
(författare)
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Hybrid Computer-Human Supervision of Discrete Event Systems
- 2002
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Ingår i: proc. of 2002 IEEE International Conference on Robotics and Automation, Washington DC, MAY 11-15,, USA. ; , s. 2321-2326
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Konferensbidrag (refereegranskat)abstract
- This paper presents a framework for accommodating human intervention in a computer supervised discrete-event system. The basic mechanism for allowing such hybrid supervision by a computer and a human operator is by switching priorities between events controlled by each according to some specified schedule. To synthesize a computer supervisor under such conditions, a transformation that maps the problem to one that satisfies the model stipulations of the Supervisory Control Theory is presented. The aforementioned framework introduces a parameter that can be tuned to provide for different levels of co-operation between the human and computer supervisors. Several important properties of the resulting supervisors are presented.
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- Åkesson, Knut, 1972
(författare)
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Methods and Tools in Supervisory Control Theory: Operator Aspects, Computational Efficiency, and Applications
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a tool together with efficient algorithms for verification and synthesis of discrete-event supervisors that might share responsibilities with human operators. It is also shown how the supervisory control theory can be used to solve resource allocation problems for flexible manufacturing systems. The supervisory control theory is a formal methodology for analyzing properties of discrete-event systems and also for generating supervisors that enforce that a system behaves according to given specifications. The supervisory control theory shows great promise to help developers to create correct control functions for discrete event systems. Unfortunately, industrial acceptance has been limited so far. In this thesis we try to identify the major factors that prevent the supervisory control theory from becoming an industrial success. Four major limiting factors are identified. First, we note that supervisory control problems are inherently hard to solve. This implies that brute-force algorithms will only be able to solve relatively small problems, thus there is a need for more intelligent algorithms that will take advantage of the structure present in many systems. Second, control systems that interact with humans are becoming more widely used. In this thesis a framework for analysis and synthesis of discrete event supervisors that need to interoperate with human users is developed. Third, the lack of efficient tools is an important factor that limits the industrial acceptance of the supervisory control theory. An efficient tool for supervisor synthesis, verification, simulation, and code-generation has been developed as part of this work. Fourth, the lack of industrial success stories is holding back the acceptance of the supervisory control theory. We show how a large class of resource allocation systems can be easily solved by the supervisory control theory. A commercial chemical batch control system has been extended with resource allocation capabilities where a supervisor is automatically synthesized according to the supervisory control theory. The supervisor guarantees that the concurrently running batches never run into circular waits for shared resources. The supervisor handles flexible batch recipes with sequential, parallel, and alternative operations, where each operation might be produced in a number of resources. Alternative operations are used to handle errors that emerge during the production of a batch.
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