Reconfiguration of Industrial Embedded Control Systems

Abstract

This research work deals with the development of safety reconfigurable embedded control systems following the international industrial component-based standard IEC61499. According to this standard, a function block (FB) is a functional unit of software and a control application a FB network that has to meet functional and temporal properties described in user requirements. We define in the book chapter a new semantic of the reconfiguration where a crucial criterion to consider is the automatic improvement of the system performance at run-time. If a reconfiguration scenario is applied at run-time, then the FB network implementing the system is totally changed or modified. To handle all possible reconfiguration forms, we propose thereafter an agent-based architecture that applies automatic reconfigurations to adapt the system according to well defined conditions and we model this agent with nested state machines according to the formalism of net condition/event systems which is an extension of the Petri net formalism. In order to satisfy user requirements, we specify the functional and temporal properties with the temporal logic CTL (as well as its extensions ECTL and TCTL) and we apply the model checker SESA to check the whole system behavior. To assign this reconfigurable system into the execution environment, we define thereafter an approach based on the exploration of reachability graphs to construct feasible OS tasks that encode the FB network corresponding to each reconfiguration scenario. Therefore, the system is implemented with sets of OS tasks where each set is to load in memory when the corresponding scenario is applied by the Agent. We developed the tool X-Reconfig to support these contributions that we apply on the FESTO and EnAS benchmark production systems available in our research laboratory.