به سوی یک پیاده سازی از روش های بازیابی برای نظارت بر سیستم های تولید انعطاف پذیر

This paper first specifies Recovery and gives some trends about Recovery strategies. Then, it focuses on Reconfiguration. Several reactivity levels are defined according to the failure impact, flexibilities reserved during the exploitation phase, and flexibilities corresponding to the whole potentialities of the architecture. These enable to know if the FMS can react with its current configuration, or if its configuration has to be changed to go on with the production, or if the production has to be changed to maintain FMS availability. The Recovery procedures are implemented through a model named Operational Accessibility Graph, which has been emphasized by the definition of new attributes and methods. Some algorithms, based on the graph theory, are presented.

Flexible manufacturing systems (FMS) are specific manufacturing systems. They are discrete event systems (DES) that include flexibility notion, which is characterized by the capability and the speed of adapting to new situations [1]. Our Supervision approach is different from the Supervisory Control [2], [3] and [4]. Supervision is independent of Control Part. The aim of Supervision is to give parameters to the Control Part in order to perform, in the best conditions, production-planning [5]. Supervision fulfils functions like Monitoring, Piloting, and Working Modes’ Management. The architecture is supposed to be tolerant [6]. So, FMS has the potentiality to be reconfigurable. Control Part takes into account FMS flexibilities that are considered as potentialities in the set of possible controls. But the Control Part remains non-deterministic and does not decide about FMS configurations. This paper focuses on Recovery and, especially, on Reconfiguration based on the hypothesis of complete failures.

The Recovery strategies presented in this paper take into account some criteria such as product priority and availability priority. This enables to define four levels of reactivity for Recovery procedures, according to the failure impact, the potentialities of FMS resources and configurations’ options considered during the FMS normal working mode. The implementation of these procedures is based on a model named OAG. The modeling takes now into account, not only the flexibilities corresponding to the whole potentialities of the architecture, but also a restriction of this set that is: the flexibilities reserved during the exploitation phase. The information is stored through attributes ‘Reserved’ and ‘Used’ of OAG elements. Some methods are defined to collect information about ‘Potential operations’, ‘Possible operations’, ‘Reserved operations’ and ‘Used operation’. Algorithms presented enable to know if: • the FMS can react with its current configuration. • its configuration has to be changed to go on with the current production. • the production has to be changed in order to maintain FMS availability.