Christine M. Mitchell

GT-MSOCC: A Domain for Research on Human - Computer Interaction and Decision Aiding in Supervisory Control Systems

Modeling and aiding operators in supervisory control environments are necessary prerequisites to the effective use of automation in complex dynamic systems. A research program is described that explores these issues within the context of the Georgia Tech-Multisatellite Operations Control Center (GT-MSOCC). GT-MSOCC is a real-time interactive simulation of the operator interface to a NASA ground control system for unmanned Earth-orbiting satellites. GT-MSOCC is a high fidelity domain in which a range of modeling, decision aiding, and workstation design issues addressing human-computer interaction may be explored. GT-MSOCC is described in detail. The use of high-fidelity domains as research tools is also discussed, and the validity and generalizability of such results to other domains are examined. In addition to a description of GT-MSOCC, several other related parts are included. A GT-MSOCC operator function model (OFM) is presented. The GT-MSOCC model illustrates an enhancement to the general operator function modeling methodology that extends the models utility for design applications. The proposed methodology represents operator actions as the lowest level discrete control network nodes. Actions may be cognitive or manual; operator action nodes are linked to information needs or system reconfiguration commands. Thus augmented, the operator function model provides a formal representation of operator interaction with the controlled system and serves as the foundation for subsequent theoretical and empirical research. A brief overview of experimental and methodological studies using GT-MSOCC is also given.

A Discrete Control Model of Operator Function: A Methodology for Information Display Design

Recent advances in computer technology and the changing rule of the human in complex systems require changes in design strategies for information displays. The use of discrete control models to represent the human operators cognitive and decisionmaking activities is described. The analytic procedures required to build a discrete control model show promise as a basis of a design methodology for the definition of an information display system for supervisory control tasks. The discrete control modeling procedures and their application for a simulated system is demonstrated.

OFMspert: inference of operator intentions in supervisory control using a blackboard architecture

The authors proposes an architecture for an expert system that can function as an operators associate in the supervisory control of a complex dynamic system. Called OFMspert (operator function model (OFM) expert system), the architecture uses the operator function modeling methodology as the basis for the design. The authors put emphasis on the understanding capabilities, i.e. the intent referencing property, of an operators associate. They define the generic structure of OFMspert, particularly those features that support intent inferencing. They also describe the implementation and validation of OFMspert in GT-MSOCC (Georgia Tech-Multisatellite Operations Control Center), a laboratory domain designed to support research in human-computer interaction and decision aiding in complex, dynamic systems. >

Use of Model-Based Qualitative Icons and Adaptive Windows in Workstations for Supervisory Control Systems

Model-based qualitative icons and adaptive window display interfaces may be valuable tools to enhance the effectiveness of operators in real-time data-intensive supervisory control systems. Qualitative icons may be used to integrate low-level quantitative data into high-level qualitative error detection mechanisms. Using windowing technology, multiple data sources that reflect different aspects of system state can be displayed simultaneously on a single screen. Both technologies were combined and implemented to design an operator interface to the Georgia Tech-Multisatellite Operation Control Center (GT-MSOCC). An operator function model for GT-MSOCC was used to derive workstation features, including hardware configuration, the function of qualitative icons for monitoring, fault detection and identification, and the contents and placement of computer windows. The model also determined sets of windows needed by the operator to undertake major operator control functions. An experiment was performed to evaluate the effectiveness of a workstation incorporating model-based qualitative icons and dynamic operator function window sets. Subjects controlled GT-MSOCC via either a conventional operator interface or the model-based interface. Eleven measures that reflected operator performance were analyzed. Subjects using the model-based workstation operated the system significantly better on nine of these measures. On all measures, performance with the model-based workstation was uniformly better on average and had less variability than performance with the conventional workstation.

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.

Using the operator function model and OFMspert as the basis for an intelligent tutoring system: towards a tutor/aid paradigm for operators of supervisory control systems

Training is a critical issue for operators responsible for the safe and efficient operation of large-scale complex dynamic systems. This paper proposes and articulates a set of requirements for an intelligent tutoring system. The requirements specify what (instructional content) and how (instructional strategies) to teach a novice operator to supervise and control a complex dynamic system. The instructional content teaches system structure and behavior (i.e., declarative knowledge), system procedures (i.e., procedural knowledge), and how to use this declarative and procedural knowledge to manage a complex dynamic system in real time (i.e., operational skill). Using the underlying representations of the operator function model (OFM) and OFMspert, the OFMs computational implementation. GT-VITA (Georgia Tech Visual and Inspectable Tutor and Assistant) realizes these requirements. As a proof-of-concept demonstration, an instance of the generic GT-VITA tutoring architecture was implemented for satellite ground controllers. The empirical evaluation, utilizing NASA satellite ground control personnel, showed that GT-VITA was a flexible and useful training system. In fact, NASA has adopted VITA as the foundation for required training for all satellite ground control personnel. In addition to an intelligent tutoring system architecture, by using and extending the operator function model and OFMspert, GT-VITA demonstrates a robust methodology for conceptualizing the tutor-aid paradigm. The tutor-aid paradigm defines a conceptual framework in which learning with a intelligent tutor gradually becomes collaboration with an intelligent associate. Using the same structures (i.e., OFM and OFMspert) and the same domain knowledge, GT-VITA specifies a tutor and GT-MOCA (Jones and Mitchell, 1995) specifies an aid. >

Human-computer cooperative problem solving: theory, design, and evaluation of an intelligent associate system

One approach to aiding the human supervisory controller of a complex dynamic system is to provide an intelligent operators associate. We propose a prescriptive theory of human-computer cooperative problem solving and describes the design and evaluation of a prototype system based on the theory. The theory consists of five principles: human-in-charge, mutual intelligibility, openness and honesty, management of trouble, and multiple perspectives. A prototype intelligent associate system, the Georgia Tech Mission Operations Cooperative Assistant (GT-MOCA), is an embodiment of these principles that provides a collection of context-sensitive resources for the human operator of a simulated satellite ground control system. These resources include an interactive visualization of current activities, an organized message lists of important events, and interactive graphics depicting the current state of the controlled system. An evaluation study utilizing actual NASA satellite ground controllers showed that GT-MOCA was perceived to be useful and provided performance benefits for certain portions of the control task. >

The effectiveness of supervisory control strategies in scheduling flexible manufacturing systems

The results of an experimental study of the supervisory control of a simulated flexible manufacturing system (FMS) are discussed. A real-time simulator of an FMS, (Georgia Tech-FMS (GT-FMS)) was implemented and configured with data from a real manufacturing system. An experiment was run in which humans interacted with the automatic control system of GT-FMS with the goal of improving overall system performance by meeting due data while simultaneously minimizing inventory. Experimental results show that with human supervision both due data and inventory performance of GT-FMS can be improved. The results strongly support the idea of actively integrating humans into operational controls of automated manufacturing environments. >

A methodology for human-machine systems research: knowledge engineering, modeling, and simulation

This paper proposes a methodology for carrying out human-machine systems engineering research and in particular focuses on the development of knowledge-based support for training and aiding. The process is characterized by the definition of knowledge requirements, a normative model structure of human-machine interaction, a knowledge architecture that implements the model, and an interactive real-time simulation environment. The knowledge requirements largely specify the model, knowledge architecture, and simulation. The model and the knowledge architecture are the basis for the design of intelligent systems. The simulation serves as an experimental testbed that provides a feasible, safe, and effective means for exploring alternative human-machine systems designs and also facilitates technology transfer. The aim is to create an understanding of a complex work domain that forms the context for ongoing research in human-machine interaction. A specific example from satellite ground control is described. >

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>>