fast-time outputs to real-time events, it is possible that Micro Saint models could even be used directly in virtual simulations.

Man Machine Integrated Design and Analysis System (MIDAS)

MIDAS is a system for simulating one or more human operators in a simulated world of terrain, vehicles, and other systems (Laughery and Corker, 1997; Banda et al., 1991; see also Chapters 7 and 8).

Purpose and Use

The primary purpose of MIDAS is to evaluate proposed human-machine system designs and to serve as a testbed for behavioral models.

Assumptions

MIDAS assumes that the human operator can perform multiple, concurrent tasks, subject to available perceptual, cognitive, and motor resources.

Architecture and Functionality

The overall architecture of MIDAS comprises a user interface, an anthropometric model of the human operator, symbolic operator models, and a world model. The user interface consists of an input side (an interactive GUI, a cockpit design editor, an equipment editor, a vehicle route editor, and an activity editor) and an output side (display animation software, run-time data graphical displays, summary data graphical displays, and 3D graphical displays).

MIDAS is an object-oriented system consisting of objects (grouped by classes). Objects perform processing by sending messages to each other. More specifically, MIDAS consists of multiple, concurrent, independent agents.

There are two types of physical component agents in MIDAS: equipment agents are the displays and controls with which the human operator interacts; physical world agents include terrain and aeronautical equipment (such as helicopters). Physical component agents are represented as finite-state machines, or they can be time-script-driven or stimulus-response-script-driven. Their behaviors are represented using Lisp methods and associated functions.

The human operator agents are the human performance representations in MIDAS—cognitive, perceptual, and motor. The MIDAS physical agent is Jack™, an animated mannequin (Badler et al., 1993). MIDAS uses Jack to address workstation geometry issues, such as the placement of displays and controls. Jack models the operator's hands, eyes, and feet, though in the MIDAS version, Jack cannot walk.

The visual perception agent computes eye movements, what is imaged on the



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