A deadlock recovery approach for flexible manufacturing system
| Autor: | Kuo-Chiang Wu, 吳國江 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Generally, one can add monitors to problematic siphons to avoid deadlocks in a Petri nets, as these siphons seriously result in system performance degradation. This study proposes a novel approach that takes recovery action after detecting empty siphons rather than deadlocks and recovers the system from deadlock to its former live states. It can reach the same number of states as the original uncontrolled model and much higher than using traditional prevention methods. In addition, no new problematic siphons are generated due to added monitors. This study also proposes a recovery algorithm and proves its correctness. Nevertheless, this approach has the disadvantage that an interruption of some operation will cause material loss (low occurrence). In order to overcome such a disadvantage, we suggest a method of avoiding material loss by coloring the arcs (a new type colored Petri net). We also apply our approach to a complicated S3PR system to compare the effectiveness of control policies. The INA analysis indicates that the resulting controlled model is live and reaches 26750 states more than the 21581 states by Piroddi et al. (2008). Furthermore, this study proposes to combine ESCP (Elementary Siphons Controlled Policy) by Li et al. (2008) and our recovery methods into a hybrid approach. Under the same example of Li’s (Li et al. 2008), the hybrid approach is applied to Li’s sample. INA results indicate that 222 states can be reached, better than that of Li’s (216 states). In addition, only one monitor is employed but three monitors must be used in Li’s (2008). In consequence, all experimental results reveal the superiority of our approach. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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