Improving moving block railway system using fuzzy multi-agent specification language

Railway interlocking system is a distributed, safety, monetary and environmentally critical system and its failure may cause the loss of human life, severe injuries, loss of money and environmental damages. The complexity of this system requires formal modeling and step by step refinement for its construction and development. The formal specification-based languages, such as VDM, Z-notation and RAISE, have been used for its modeling using crisp (two-valued logic) theory. However, due to the continuous and inexact features, like speed, weight and moving block (breaking distance including length of a train), fuzzy distributed multi-agent approaches are required to capture the inexactness and uncertainty present in the existing system. In order to get a fuzzy distributed multi-agent environment, we have extended the Object-Z towards the fuzzy multi-agent specification language (FMASL) using an integration of fuzzy logic, multi-agent systems (MAS) and Object-Z to be applied for the railway interlocking system. Initially, our extended approach is applied for the specification of railway crossing, a critical component of interlocking system. We have supposed that a train is an autonomous intelligent agent and has fuzzy sub-agents: a moving block and a crossing intelligent agents.