| 251. |
- Pettersson, Stefan, 1969, et al.
(författare)
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Hybrid Modelling Focused on Hybrid Petri Nets
- 1995
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Ingår i: Proc. of the 2nd European Workshop on Real-time and Hybrid systems, Grenoble, France. ; , s. 303-309
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Konferensbidrag (refereegranskat)
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| 252. |
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| 253. |
- Pettersson, Stefan, 1969, et al.
(författare)
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LMI for Stability and Robustness of Hybrid Systems
- 1997
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Ingår i: Proc. 1997 American Control Conference, Albuquerque, New Mexico,JUN 04-06. ; , s. 1714-18
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Konferensbidrag (refereegranskat)abstract
- This paper presents results for stability and robustness of hybrid systems consisting of nonlinear subsystems. Present stability results that are extensions of classical Lyapunov theory are restricted to certain kinds of hybrid systems. For example, it is required that all subsystems have the same equilibrium point. In this paper these results are generalized, but more importantly, it is shown how Lyapunov functions for hybrid systems can be solved by linear matrix inequalities (LMI). Furthermore, it is shown how uncertainties around the nominal switch sets can be handled by introducing acceptable switch regions as additional stability conditions. The theory is illustrated by an example.
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| 254. |
- Pettersson, Stefan, 1969, et al.
(författare)
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Stability and robustness for hybrid systems
- 1996
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Ingår i: Proc. of the 35th IEEE Conference on Decision and Control, Kobe, Japan, DEC 11-13. ; , s. 1202-1207
-
Konferensbidrag (refereegranskat)abstract
- Stability and robustness issues for hybrid systems are considered in this paper. Present stability results, that are extensions of classical Lyapunov theory, are not straightforward to apply in general due to two reasons. First, existing theory do not unveil how to find needed Lyapunov functions. Secondly, at some time instants it is necessary to know the values of the continuous trajectory. Because of these drawbacks, stronger conditions for stability are suggested. The search for Lyapunov functions can then be formulated as a linear matrix inequality problem. Additionally; it is shown how to obtain robustness properties. An example illustrates the results.
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| 255. |
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| 256. |
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| 257. |
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| 258. |
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| 259. |
- Provost, Julien, 1984, et al.
(författare)
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Human operator and robot resource modeling for planning purposes in assembly systems
- 2012
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Ingår i: 4th CIRP Conference on Assembly Technologies and Systems (CATS 2012), Ann Arbor, 21-22 May 2012.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents how robot and human resources can be modeled for planning purposes. Instead of using simplistic models such as available or unavailable resources, the method for modeling resources presented in this paper integrates parameters that are realistic and relevant for the considered assembly system. For example, a robot resource model can take into account maintenance tasks and ramp-up parameters. The framework of this modeling is based on the definition of Sequences of Operations (SOPs) and includes a formal relation between product operations and resources abilities. The main idea is to avoid the representation of long and static sequences of operations, since this typically reduces flexibility and is even intractable for large systems. To tackle this issue, relations between operations and resources are defined using only strictly necessary pre-conditions and post-conditions for each individual operation. The Sequences of Operations that permit to express the minimally restrictive behavior of an assembly system are automatically generated. Finally, the SOPs can be viewed from different angles, e.g. from a product or a resource perspective. These multiple views increase the interoperability between different engineering disciplines. Experiments have shown that, even for simple examples, obtaining the optimized assembly sequence is not an easy task. That is why a sequence planning software associated to realistic resource models, including both humans and robots, as presented in this paper, is a crucial help to increase flexibility in assembly systems that require different Levels of Automation.
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| 260. |
- Provost, Julien, 1984, et al.
(författare)
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Planning in assembly systems – A common modeling for products and resources
- 2012
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Ingår i: Emerging Technologies & Factory Automation (ETFA). - 9781467347372
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method for modeling robot andhuman resources in the context of assembly systems planning.In assembly systems, several redundant resourcescan be used to increase system flexibility. However, the“quality” of a sequence planning strongly depends on the“quality” of the system modeling. Furthermore, occurrenceof unexpected events or variations in availability ofresources may have significant impact on the actual planning.Instead of using simplistic models such as availableor unavailable resources, the method presented in this paperproposes a more detailed modeling of resource abilities.Products and resources are considered on the samelevels and matched together on a final step. The aim ofthis modeling is to permit analyses and to increase systemflexibility.
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