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|Title:||Real-time, distributed scheduling of production resources|
|Author(s):||Tirpak, Thomas Michael|
|Doctoral Committee Chair(s):||Medanic, Juraj V.|
|Department / Program:||Electrical and Computer Engineering|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Engineering, Electronics and Electrical
|Abstract:||This thesis addresses the task of distributed production scheduling, especially for flexible manufacturing systems (FMS). Current mathematical programming and model-based approaches are considered, but are shown to inadequately manage the dynamic behavior, uncertainty, and large scale typical of such systems. Thus, a new unified framework for modelling and control is proposed that incorporates insights from Operations Research, Control Theory, Artificial Intelligence, and Software Engineering.
In this research, production scheduling is addressed in terms of the allocation of resources. The method of "resource allocation policy" scheduling is proposed and compared with the "event-time" schedules, which result from typical formulations of the production scheduling problem. Next, the technique of real-time simulation is introduced and applied to study the Automated Manufacturing Research Facility (AMRF). The proposed solution methodology for on-line production scheduling centers on a generic controller, which employs real-time simulation to evaluate the trade-offs existing among alternative production policies. The generic controller establishes a standard, parallel-processing architecture in which to perform the decision-making at any level in a hierarchically decomposed scheduling problem. The specification of the functional elements of the generic controller (GC), conceptualized by Davis, Jones, and Saleh (1991), has been further developed in this research work. Likewise, precise definitions have been enumerated for the types of data utilized in the GC, as well as the manner in which they are transmitted between the GC's elements.
The essential structure and functional content of the generic controller as well as the proposed resource-based, discrete-event model for production systems have been incorporated into the development of the Flexible Manufacturing Simulation Library (FMSL). The FMSL software provides a set of routines to model hierarchical production systems and perform the tasks required for on-line scheduling. Based on the preliminary studies with the AMRF model and the application of the FMSL for the modelling and simulation of the Motorola Grafted Multilayer process, conclusions are drawn regarding the importance of critical resources. Furthermore, the possibility to apply the proposed approach for true real-time monitoring and control in production systems is likewise considered.
|Rights Information:||Copyright 1991 Tirpak, Thomas Michael|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9211013|
This item appears in the following Collection(s)
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Electrical and Computer Engineering
Dissertations and Theses in Electrical and Computer Engineering