Effectiveness of dynamic rescheduling in agent-based flexible manufacturing systems

This work has been developed within the framework of agent-based decentralized scheduling for flexible manufacturing systems. In this framework;, all workcells comprising the manufacturing system, and the products to be generated, are modeled via intelligent software agents. These agents interact dynamically using a Bidding Production Reservation (BPRS) scheme, based on the Contract Net Protocol, to devise the production schedule for each product unit. Simulation studies of a job shop have demonstrated the gains in performance achieved by this approach over heuristic dispatching rules commonly used in industry. Manufacturing environments are also prone to operational uncertainties such as variations in processing times and machine breakdowns. In order to cope with these uncertainties. the BPRS algorithm has been extended for dynamic rescheduling to also occur in a fully decentralized manner. The resulting multi-agent rescheduling scheme results in decentralized control of flexible manufacturing systems that is capable of responding dynamically to such operational uncertainties, thereby enhancing the robustness and fault tolerance of the proposed scheduling approach. This paper also presents the effects of the proposed agent-based decentralized scheduling approach an the performance of the underlying flexible manufacturing system under a variety of production and scheduling scenarios, including forward and backward scheduling. Future directions for this work include applying the proposed scheduling approach to other advanced manufacturing areas such as agile and holonic manufacturing.