Desing and Formal Veri cation of Strategies in Flexible Manufacturing Systems

Rapid prototyping of complex systems and their control strategies is an important approach in system modeling. Naturally, these systems can be seen as a network of concurrently running communicating objects. One application eld are exible manufacturing systems (FMS) used in computer integrated manufacturing (CIM). A FMS consists of concurrently working machines which are connected by a computerized material handling system. This leads to well-known problems like scheduling and resource allocation. Concurrent objects as a modeling paradigm enable the designer to describe the system's structure and behavior naturally on a high abstraction level. In this contribution we argue that control strategies based on complex hierarchical strategies t nicely with the concurrent object based modeling view and, consequently, with a consistent design approach. Moreover, we introduce a suitable programming language (DFKI Oz) which supports the described modeling approach. Proving the correctness of the desired behavior of manufacturing systems is an important design step. Due to the complexity of each system component and their interaction the designer is not in the situation to overlook the whole systems behavior. In order to overcome this problem it is necessary to use formal methods to prove the satissability of system's properties given by a formal speciication. We use the formal hardware veriication method model-checking 4] to verify it. Validation of our approach is described by modeling and verifying a complex FMS in the eld of car production.