Douglas A. Bodner

Research in object-oriented manufacturing simulations:an assessment of the state of the art

Object-oriented programming (OOP) has been revolutionizing software development and maintenance. When applied to simulation of manufacturing systems, OOP also provides an opportunity for developing new ways of thinking and modeling. In this paper, we identify existing large-scale, persistent OOP-based research efforts focusing on manufacturing system simulation, and present an integrating framework for discussing the associated modeling abstractions, implementation strategies, common themes, and distinctive features. The goal is to identify the fundamental research and application issues, assess the current state of the art, and identify key research needs.

A specification environment for configuring a discrete-part manufacturing system simulation infrastructure

A well-designed graphical environment that supports model specification has the potential of enabling the modeler to make better use of the modeling constructs and architecture. We describe on-going research in creating a graphical environment that supports model specification in OOSIM (Object-Oriented Simulation in Manufacturing), a high fidelity manufacturing system simulator.<<ETX>>

Models of Complex Enterprise Networks

This article describes the development of a modeling hierarchy for complex enterprise networks. Drawing on the extant modeling literature, these network models are elaborated in terms of 4 salient problem characteristics: conversions, flows, controls, and social/organizational relationships. The authors relate these 4 characteristics to phenomena, representations, micromodels, macromodels, and modeling tools. The roles of information and incentives in complex enterprises networks are considered. Examples of 2 domains, global manufacturing and healthcare delivery, are woven through these discussions of alternative representations and models. The authors conclude by providing a structured comparison of these 2 domains, discussing theoretical and practical implications, and presenting opportunities for future enterprise transformation research.

A distributed, event-driven control architecture for flexibly automated manufacturing systems

This paper presents a new distributed real-time control architecture for flexibly automated production systems. The modelling assumptions underlying the design are driven by, and abstract, the structure and operations of the emerging 300 mm semiconductor manufacturing fab, one of the most extensively automated environments in contemporary manufacturing. The key element of the controller design itself, which differentiates it from past efforts, is the distribution of the control function to the constituent components of the system shop-floor architecture, while maintaining both the logical correctness and the efficiency of the system behaviour. The architecture was designed to be easily implementable in the actual system shop-floor, and therefore is aligned with, and augments, current practices in these environments. From a theoretical perspective, the proposed design has employed, integrated and extended a series of theoretical results from the field of Discrete Event Dynamical Systems. It is our expectation that the proposed architecture will also provide a formal framework for further analytical studies on the performance evaluation and performance-oriented control/scheduling of the considered class of manufacturing systems.

Healthcare management through organizational simulation

Quality, affordable healthcare remains a contentious, complex and urgent societal problem. Given the scale and complexity of healthcare, systemic changes addressing emergent cost escalation and quality deficiencies are difficult to study, evaluate, and implement. In particular, it is difficult to empirically study alternative means of delivery that do not yet exist. To enable the study of such issues, we designed and developed Health Advisor, a web-based game using organizational simulation. Players are tasked to manage people through the healthcare system by making various information, cost, and quality of care trade-offs with score based on health outcomes and costs incurred. This paper reports on a series of evaluations of Health Advisor and the insights gained from these studies. In particular, results show that peoples perceptions of the usability and usefulness of information sources have a strong impact on the use of these sources, and a significant impact on their subsequent performance in diagnoses and referrals.

Object-oriented simulation to support operator decision making in semiconductor manufacturing

The authors describe research on the development of a high-fidelity simulator using the object-oriented programming paradigm. The simulator models the complex interactions in reentrant flow manufacturing facilities. In addition to potentially providing better estimates on throughput, work-in-progress levels, and bottleneck resources in the modeled system, the simulator serves as a platform to investigate issues of operator cross-training, decision aiding, and the effect of operator decisions in such manufacturing facilities. The authors describe the class hierarchy of objects required for modeling and analysis of semiconductor and thin films fabrication, and discuss their approach to modeling complex supervisory control decisions in reentrant flow lines.<<ETX>>

Object-oriented modeling and simulation of automated control in manufacturing

The object-oriented modeling of manufacturing systems as used in the development of a high-fidelity simulator is described. The separation of control and plant resources in the model allows explicit representation of the factory control system. Different control strategies can be readily tested within the simulation. The application of this approach to deadlock detection and resolution within a flexible manufacturing cell is discussed. The simulator also serves as a platform to investigate the integration of human resources and automated equipment in advanced manufacturing facilities, and to study supervisory control issues in automated systems.<<ETX>>

A high-fidelity, web-based simulator for 300 mm wafer fabs

Semiconductor fabs are capital intensive. The rate of capital return heavily depends on their productivity. Accordingly, simulation has been adopted in many cases as a viable design and analysis tool to achieve better productivity. However, the gap between the simplistic simulation models and real complex systems has limited the confidence to apply simulation results directly to real systems. Ideally, the simulator should support the rapid modeling and fast execution of high-fidelity fab models in order to be able to provide more realistic simulation results. In this paper, we present our current research effort to develop a high-fidelity web-based simulator for the 300 mm wafer fabs. We take a model-view-control approach that allows us to develop modular and reusable fab simulation objects. The proposed approach is implemented as a distributed system that uses a message-based event synchronization mechanism to coordinate the simulation objects as well as to support distributed simulation execution. The presented simulator also provides a high quality VRML animation for visualization of real time paced simulation execution.

Modeling control decisions in manufacturing systems simulation using objects

Control software is acknowledged as the biggest bottleneck in integrating modern manufacturing systems. We argue that understanding the interactions between parts, equipment, and supervisory control processes in the functioning of manufacturing enterprises is critical to the development of control software. We discuss a modeling environment which provides a platform for describing manufacturing control in terms of control entities and their interactions with their clients, and provides a rich representation of the manufacturing world in terms of object-oriented development of system components. The modeling environment is useful for rapidly prototyping manufacturing systems simulation. In this paper, we briefly describe the modeling architecture focusing on the concepts and implementation of the decision making controller entities in the architecture.<<ETX>>

Designing an Experiential Learning Environment for Logistics and Systems Engineering

Systems engineering increasingly addresses the system lifecycle, as opposed to its more traditional role focusing on design and development. This new situation results in part from the recognition that upstream design and deployment decisions have potentially significant cost and performance implications post-deployment. For military systems, the role that typically addresses post-deployment issues is the logistician. Over the system lifecycle, it is important that the traditional roles of systems engineer and logistician understand issues faced by one another, as well as joint cost and performance implications. This paper presents the design of a role-based experiential learning environment for logisticians involved in military sustainment. This design leverages the generic components of an existing single-learner technology base, the Experience Accelerator, for presenting and controlling the learner experience, plus simulating program outcomes resulting from learner decisions. This technology base has been used to create a learning experience for a lead systems engineer in charge of designing and developing a new unmanned aerial vehicle (UAV) system. In this new environment, the logistician learner interacts with systems engineers during UAV system acquisition and sustainment, learns about systems engineering issues and their effect on logistics, tries to influence upstream systems engineering decisions, and also performs logistics functions.