Steps towards advanced cell control systems: An application in Flexible Assembly Systems

This paper presents an advanced cell control system which integrates design , modelling control and monitoring capabilities and demonstrates its use in a class of Flexible Assembly System (FAS). From this research work a Timed Colour Petri Net (TCPN) based model for the design and modelling of FAS is proposed. Furthermore, through the adoption of a Manufacturing Message Spe cifications (MMS) based open network communication scheme, a realtime distr ibuted client/server control methodology is formulated. These techniques am integrated within an advanced cell control architecture which is demonstra ted through the implementation of a class of FAS using multiple robotic wor kstations and a conveyor based materials handling system for concurrent man ufacture of products in small batch quantities. Operational flexibility is enhanced by the introduction of a flexible process planning scheme and a ge netic algorithm for real-time searching of near-optimal production sequence s and operation assignments. Such an architecture can facilitate some fault recovery capabilities within the cell control system.