INTELLIGENT WORKSTATION CONTROLLER FOR COMPUTER-INTEGRATED MANUFACTURING - PROBLEMS AND MODELS

A shop floor control system (SFCS), an integrated part of computer-int egrated manufacturing, oversees the production required to fill orders . To effectively control these activities, it is necessary to define a control architecture and functional perspective of how a SFCS operate s. In this paper, a hierarchical SFCS (shop, workstation, equipment) i s adopted. The paper presents the problems and models necessary to dev elop an intelligent workstation controller (IWC) at the middle level o f a SFCS. The IWC is responsible for selecting a specific process rout ing, allocating resources, scheduling and coordinating activities acro ss the equipment, monitoring the progress of activities, detecting and recovering from errors, and preparing reports. The IWC fulfills this responsibility using three functions - planning, scheduling, and execu tion. Requirements for the development of the IWC are to create a proc ess plan representation model, specify the evolution of a process plan from the shop down to the equipment, and define all of the functions to be integrated into an intelligent controller. A deadlock detection and resolution model is also presented to maintain the system in a dea dlock-free state. Finally, the IWC software is created to demonstrate the architectural linkages with other controllers. As a result, the de velopment of the IWC will save cost and time in developing control sof tware for automated manufacturing systems.