The development of a hybrid hierarchical/heterarchical shop floor control system applying bidding method in job dispatching

Advancement in computer technology has brought shop floor control into a new era. Hierarchical and heterarchical control structures are two of the most popular control frameworks applied by industries and academics. However, the loading on the central controller may be very heavy in a hierarchical control structure, as the number of equipment in the shop floor increases. On the ether hand, in a heterarchical configuration, the inter-cell communication will be very busy making control strategies to achieve. In this research, a hybrid hierarchical/heterarchical structure is proposed. This approach reduces the loading on the shop floor controller by empowering each cell controller to determine the production schedules of its corresponding equipment. However, the shop floor controller still is responsible for the global conditions of the shop such as deciding the job finishing time and balancing the utilization rate of equipment. A bidding method based on the required production costs is also proposed and implemented under the developed control structure. (C) 1998 Elsevier Science Ltd. All rights reserved.