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These proceedings contain lectures presented at the NATO Advanced Study Institute on Concurrent Engineering Tools and Technologies for Mechanical System Design held in Iowa City, Iowa, 25 May -5 June, 1992. Lectures were presented by leaders from Europe and North America in disciplines contributing to the emerging international focus on Concurrent Engineering of mechanical systems. Participants in the Institute were specialists from throughout NATO in disciplines constituting Concurrent Engineering, many of whom presented contributed papers during the Institute and all of whom participated actively in discussions on technical aspects of the subject. The proceedings are organized into the following five parts: Part 1 Basic Concepts and Methods Part 2 Application Sectors Part 3 Manufacturing Part 4 Design Sensitivity Analysis and Optimization Part 5 Virtual Prototyping and Human Factors Each of the parts is comprised of papers that present state-of-the-art concepts and methods in fields contributing to Concurrent Engineering of mechanical systems. The lead-off papers in each part are based on invited lectures, followed by papers based on contributed presentations made by participants in the Institute.



Basic Concepts and Methods


World-Class Concurrent Engineering

World-class concurrent engineering is the modern way to develop new products. It features basic concurrent engineering (improved process and teamwork), enhanced quality function deployment (enhanced QFD), and quality engineering using robust design (Taguchi methods). This replaces the many dysfunctions, some of which are elegant, of traditional practice. The result is much better functionality, lower costs, and shorter development time.

Don P. Clausing

Virtual Team Framework and Support Technology

This paper first discusses the motivation for the concept of a Virtual Team and outlines its essential features. The merits of implementing such a concept on the computer network to support Concurrent Engineering between distributed team members are then highlighted. In the second part of the paper the efforts in the DICE (DARPA Initiative in Concurrent Engineering) project to realize virtual teams through a set of generic software services are reviewed.

K. J. Cleetus

Integrated Tools and Technologies for Concurrent Engineering of Mechanical Systems

Computer Aided Engineering tools and technologies that hold the potential for creating a simulation based Concurrent Engineering environment in the near-term and a design optimization based capability for the future are analyzed. Technical challenges and opportunities associated with integrating these tools into a software environment that can support multidisciplinary engineering teams are defined and illustrated. A road map for evolutionary creation of a simulation based Concurrent Engineering design environment in the near-term and a design optimization environment in the longer term is presented. Projects underway to create the capability advocated by the road map are presented, to illustrate technical considerations peculiar to Concurrent Engineering of mechanical systems and challenges associated with network based multidisciplinary CAE system integration for Concurrent Engineering.

Edward J. Haug

The Emerging Basis for Multidisciplinary Concurrent Engineering

Some industry perspectives on Concurrent Engineering are examined as a background for discussing the technology basis and level of maturity. Integrated multidisciplinary analysis tools are presented as a major contributor to concurrency. Key islands of integrated technology are identified and the potential for connecting these islands is discussed.

Robert G. Vos

Presentation and Evaluation of New Design Formulations for Concurrent Engineering

Design is an important activity which drives many other disciplines. To insure future competitiveness in a world wide market place, reliable design processes and products must be understood. To develop this understanding, design must be studied so that in the future it can become a reliable science. To begin this study, as with other sciences, design formulations must be developed and laboratories constructed. To begin a Ph.D. research program, a survey of design directed activities was conducted, a new formulation for design conceived, and a design laboratory proposed. This paper summaries the initial phase of this research.

Eric R. Stephens

Data and Process Models for Concurrent Engineering of Mechanical Systems

This paper presents a framework for computer aided engineering (CAE) that has been developed for Concurrent Engineering of mechanical system design and analysis. The framework integrates engineering software systems in a tool-workspace-subenvironment-environment hierarchy. A workspace or a subenvironment represents an engineering application or discipline. The paper discusses (1) an object-oriented tool integration method to integrate engineering applications, (2) global and local data models that are used to integrate product information at different hierarchical levels, and (3) an engineering process modeling method that expresses engineering activities as tool or workspace runstreams. The developments in these three aspects of the framework build a basis to develop activity coordination capabilities. Some considerations that are related to engineering activity coordination are discussed at the end of the paper. The CAE framework presented can be extended for computer aided manufacturing (CAM) applications also.

J. K. Wu, F. N. Choong

Storage and Retrieval of Objects for Simulations in Mixed Application Areas

Concurrent Engineering of products can benefit from the use of simulation at every stage from the requirements phase through to production, maintenance and update. This paper explores the adaptation of iconic graphical user interface based systems to achieve the necessary rapid prototyping required for parallel product development. To achieve this model definition, interfaces standards and storage in a set of discipline related object oriented databases is proposed.

Richard N. Zobel

Analysis of Structural Systems Undergoing Gross Motion and Nonlinear Deformations

Recent developments in flexible multibody dynamics provided new tools for the analysis of structural systems undergoing geometric and material nonlinear deformations. The restrictions that some of the most popular methods present for the analysis of multibody system with flexible components are discussed within the framework of a general methodology. The equations of motion for a flexible body undergoing large overall motion are obtained based on the principles of continuum mechanics and employing nonlinear finite elements. These equations are then simplified based on a lumped mass formulation and referring the nodal accelerations to the inertial reference frame. The resulting equations, which describe completely the coupling between the nonlinear gross motion and the deformation of the flexible components of the system, present a mass matrix that is diagonal and constant. These equations can be further simplified for cases where the level of deformations lies within the elastic range and the geometric nonlinearities are not important. Under these assumptions the modal superposition method can be used to reduce the number of nodal degrees of freedom of the flexible components. If the assumptions of material and geometric linearity are not met the number of nodal degrees of freedom can still be reduced using a static condensation technique. The equations obtained in this manner are implemented in a general purpose program and solved numerically. The study of a light space structure is presented in order to show the effects of the nonlinear geometric deformations in behavior of the system. The application of the methodology described here to crashworthiness and structural impact is illustrated with the study of the rollover of an off-road vehicle.

Jorge A. C. Ambrósio

Multidisciplinary Simulation

A new approach is described for multidisciplinary simulation, i.e., the simulation of models, which consist of components from different engineering disciplines. The central part of this approach consists of the definition of a neutral (low level) interface for general event-driven ordinary differential equations and differential algebraic equations, called DSblock (= Dynamic System block). Several preprocessors have been realized that generate DSblocks from models of existing modelling environments from different domains. Furthermore a run time environment is available to simulate DSblocks in an interactive way.

Martin Otter

Dynamic Analysis of Rigid-Flexible Mechanisms

Recent developments in the field of computer methods in rigid-flexible multibody dynamics have been considerable, and have evolved due to the progress of numerical methods and computer technologies.In this paper, formulations for the dynamic analysis of mechanical systems composed of rigid and flexible bodies are reviewed. Reference and relative kinematics are discussed. The equations of motion are derived using Lagrange multipliers techniques and relative joint velocity methods in order to reduce the number of rigid body and elastic coordinates of the system. An integrated simulation methodology is proposed where all the necessary interface data is generated to carry out a static stress model analysis of the individual bodies using inhouse software or commercially available codes. Additional functions of stress history evaluation or stress detailing for fatigue design of complex geometries are presented.One example of an off-road vehicle is presented where the main body is assumed to be flexible.

M. S. Pereira, P. L. Proença

Decoupling Method in Control Design

In the scope of Concurrent Engineering activities, this report introduces a control strategy which allows the systematic construction of controlled multibody systems. The feedback-law derivation is based on the Nonlinear Decoupling Method. This eases the design of hardware and software control loops of mechanical controllers with high-reliability features.

M. Cotsaftis, C. Vibet

Application Sectors


Implementation and Applications of Multidisciplinary Concurrent Engineering

Multidisciplinary concurrent implementation is presented from the perspective of practical software development. Model types from several disciplines are described, along with consideration of interfacing models for greater concurrency within an overall CAE integrated system. Supporting tools presented include integrated system simulation; multidisciplinary optimization; model synthesis and reduction; and sharing of tasks and data across a distributed computing network.

Robert G. Vos

Simulation Based Design of Automotive Systems

The design of automotive systems using simulation tools features cost reduction and quality enhancement. This paper presents two basic approaches. The first approach deals with the application of CAD data bases to the evaluation of input data for multibody system formalisms, most adequate for automotive system modeling. An object oriented data model for multibody systems is presented. The second approach covers the development of an integrated simulation tool for automotive vehicles and the corresponding animation facilities. Driving comfort is related to the human perception of mechanical vibration. A companion paper deals with the optimization of automobile parameters using the multibody systems approach.

Werner O. Schiehlen

Simulation-Based Design of Off-Road Vehicles

Analytical and physical simulation tools and technologies for the design of off-road wheeled and tracked vehicles are presented. Advanced Computer-Aided Design (CAD) and supercomputer-based analytical tools for off-road vehicle design and evaluation are illustrated via applications. High-capacity hardware-in-the-loop real-time simulators are discussed, with illustrative applications in off-road vehicle development and evaluation. The basic theme of this paper focuses on how the application of simulation technology is becoming an integral part of the Army’s combat and tactical vehicle research, development and acquisition process. This paper presents two basic goals to form the basis for simulation-based Concurrent Engineering. The first is use and creation of simulation tools that not only predict vehicle performance, but also subsystem and component reliability. The second is the development of an integrated simulation capability and military vehicle design and performance data base to form the basis for simulation-based Concurrent Engineering.

Ronald R. Beck

Modeling and Optimization of Aero-Space and Naval Structures

After being able to determine structural behavior by means of finite methods, an important goal of engineering activities is to improve and to optimize technical designs, structural assemblies and structural components. The task of structural optimization is to support the engineer in searching for the best possible design alternatives to specific structures. The “best possible” or “optimal” structure is the structure which closely correspond to the designer’s desired concept and his objectives while at the same time meeting the functional, manufacturing, and application demands. In comparison to the “trial and error” method generally used in the engineering environment and based on an intuitive empirical approach, the determination of optimal solutions by applying mathematical optimization procedures is more reliable and efficient if correctly applied. These procedures are increasingly entering industrial practice [1].

H. A. Eschenauer

Teleoperation of a Redundant Manipulator

For an interactive real-time simulation of teleoperation, this paper describes an iterative form of resolved motion rate control in which the constraint Jacobian is constructed on-line in real time and is used in the pseudoinverse method, as the manipulator is teleoperated. The operator’s command is interpreted as a series of increments in Cartesian space, and then the constraint Jacobian is developed between two successive increments by viewing the predecessor as the initial configuration and the successor as the target configuration. The Jacobian constructed in this way enables us to treat both free motion and environmental contact in the same way. Although this method requires numerical iterations, its convergence is fast enough to allow real-time control.

K. Harold Yae



Relationship Between Design for Manufacturing, a Responsive Manufacturing Approach, and Continuous Improvement

Low volume and custom designed products cannot realistically be designed and produced with static or “frozen” design definitions. Rather, design refinement continues throughout the development and production life of the product. Design changes and iterations are a way of life in such an environment, and can be (and should be) a powerful part of “continuous improvement”. To take advantage of this powerful potential, design changes must be introduced in a controlled manner, and should be introduced rapidly and efficiently.In most system job shop environments, the excessive work-in-process inventories and poor in-process quality result in very long times from engineering release through product delivery. These long times and the resulting disruptive effects of engineering changes lead to a variety of “workaround” approaches, including special prototype shops, “skunkworks,” and outside fast-turnaround shops. However, dramatic reductions in work-in-process and cycle times can be achieved through aggressive application of just-in-time and total quality management principles. In turn, the much more responsive manufacturing environment greatly facilitates change implementation, which in turn allows direct use of the production shops instead of “special” arrangements or shops. In turn, the iterative learning between design, manufacture, and use can be utilized as a powerful aspect of Continuous Improvement. The approach and results are illustrated with a case example.

J. E. Ashton

Defect Preventive Quality Control in Manufacturing

Quality control techniques are reviewed, including inspection oriented QC, statistical process control, and design oriented QC. Statistical methods and engineering technologies for next generation quality control methodology — real-time defect prevention during manufacturing — are presented, including (1) real-time sensing to allow the QC system to monitor a process, (2) real-time analysis of process status, and (3) real-time corrective action.

S. M. Wu, S. J. Hu

An Approach for PDES/STEP Compatible Concurrent Engineering Applications

An object-oriented approach to implement PDES/STEP compatible applications is proposed. To demonstrate the approach, a computer processable Assembly Application Protocol (AAP) is developed and documented as an object class structure and implemented in the form of a class library. The approach shows how (1) the PDES/STEP entities are used as building blocks of engineering information, (2) the EXPRESS language is used to model the PDES/STEP compatible data model, and (3) the application oriented data semantics can be embedded in a computer system. The AAP acts as a feature-based information model and persistent object data schema for CE assembly applications. The software tools used to implement the AAP are EXPRESS2C++ translator, C++ programming language, and ROSE database. The use of standard tools are shown to enhance the CE communication and research opportunities, based on the experience with the new generation international product definition and exchange standard, are suggested.

Thu-Hua Liu, Gary W. Fischer

Concurrent Engineering Tools for Forging Die and Process Design

This paper discusses the development of engineering tools for die shape design in the forging process and the utilization of this information for determining optimal operating conditions. The tools discussed here are based on computer graphics, finite element modeling, design optimization and optimal control strategies, and can be run on personal computers, work stations and main frame computers, to meet a variety of customer needs and to provide user friendly tools for conducting “what if” studies. The methods developed here are applicable to several unit processes like extrusion, shape rolling, etc., besides forging. Details about the design variables, design constraints, objectives, analytical sensitivity calculations, condensed states, satisfaction of behavior constraints, and the optimal tracking algorithm are presented here with engineering case studies.

Ramana V. Grandhi, Raghavan Srinivasan

Effects of Structural Dynamics on Chatter in Machine Tools and Its Evaluation at Design Stage

Chatter can be defined as violent vibrations between the workpiece and the cutting tool in machine tools. Its importance in the design of machine tools is discussed in this research. Instead of investigating the chatter probabilities on machine tools of which the prototype has already been developed, these probabilities should be evaluated at the design stage. To do this, a mathematical model has been developed to analyze the structural dynamics of a radial drilling machine. The effects of structural dynamics are pointed out in terms of point and transfer receptances. The receptance properties determine the important factors for design.

Mehmet S. Tekelioglu

Design Sensitivity Analysis and Optimization


Concurrent Engineering Design Optimization in a CAD Environment

Concepts, methods and tools for interactive CAD-based concurrent engineering design optimization of mechanical products, systems and components which are critical in terms of cost, development time, functionality and quality, are presented. The emphasis is on formulation, development and implementation of methods and capabilities for finite element analysis, design sensitivity analysis, rational design, synthesis and optimization of mechanical systems and components, and the integration of these methods into a standard CAD modeling environment with a view to develop a concurrent engineering design optimization system. Methods for optimizing the topology of mechanical components are integrated into the system and used as a preprocessor for subsequent shape and sizing optimization. Use of the system for concurrent engineering design of mechanical components is illustrated by examples.

Niels Olhoff, Erik Lund, John Rasmussen

Design Sensitivity Analysis and Optimization Tool for Concurrent Engineering

This paper together with the following two papers present emerging technologies for development of design sensitivity analysis (DSA) and optimization that can be used for concurrent engineering. A summary of recently developed unified continuum DSA methods for linear and nonlinear structural systems is presented. Design sensitivities of static and dynamic responses of elastic solids and built-up structures with respect to material property, sizing, shape, and configuration design variables are considered. For DSA of acoustic response, acousto-elastic systems are treated. For DSA of nonlinear structural systems, both geometric and material nonlinearities are considered. The adjoint variable and direct differentiation methods are used to derive explicit design sensitivity expressions that can be evaluated numerically using analysis results from established finite element analysis (FEA) codes. It is demonstrated that the continuum based DSA method allows design sensitivity computations to be carried out using established FEA codes with respect to geometric design parameters that are employed in computer-aided design (CAD) tools, so that industry standard tools can be exploited in concurrent engineering. A DSA and optimization (DSO) tool with a visually driven user interface is developed to allow design engineers to easily create geometric, design, and analysis models; define performance measures; perform DSA; and carry out a four-step interactive design process that includes visual display of design sensitivity, what-if study, trade-offs, and interactive design optimization.

Kyung K. Choi, Kuang-Hua Chang

Concurrent Engineering Design with and of Advanced Materials

Advanced materials are now used frequently in engineering design and that has opened for the possibility of material design. A general characteristic of these materials is that they are anisotropic, and this puts new demands on the analysis capabilities and optimization methods. In recent years a number of questions have been clarified, and the intention of the present notes is to distribute the knowledge gained. Active research areas are also commented on, and the concurrent design with a number of different design parameters is put forward.

Pauli Pedersen

Optimization of Automotive Systems

As an example for the optimal design of automotive systems, the problem of suspension systems with passive and actively controlled elements is formulated as an integrated modeling and design problem. For the modeling part, multibody formalisms are applied; the resulting nonlinear programming problem is solved by standard optimization algorithms. The missing link is an efficient and reliable procedure for computing gradients. Advantages and drawbacks of three different approaches are discussed in detail. Optimization of a vehicle with active and passive suspension is performed with respect to riding comfort, riding safety, and relative displacements between the wheels and the car body.

Dieter Bestle

Multicriterion Optimization of Large Scale Mechanical Systems

The paper deals with discussion of optimization problems in engineering structural design. The following questions are discussed: continuous or discrete optimization, single-or multicriteria optimization, one-or multilevel optimization. The paper is illustrated with example of multicriterion discrete optimization of large scale truss systems.

Stefan Jendo, Witold M. Paczkowski

Design Sensitivity Analysis for Coupled Systems and Their Application to Concurrent Engineering

Design sensitivities are derived via the direct and adjoint methods for fully coupled nonlinear systems. These sensitivity derivations may then be used to create a concurrent engineering design environment where the individual systems are the product analyses and manufacturing process analyses. The sensitivity information, in turn, may be used in a trade-off study to quantify how product or manufacturing design changes affect any performance functional, e.g. cost, mass, stress, or cooling rate. Finally, it is noted that the necessary operator required for the sensitivity analyses is, in fact, the tangent operator of the coupled system analysis; and that this operator may be partitioned to take advantage of existing software capabilities.

Daniel A. Tortorelli

Configuration Design Sensitivity Analysis for Design Optimization

A unified configuration design sensitivity analysis (DSA) is developed for built-up structures that include truss, beam, plane elastic solid, and plate design components. Taking the total variation of the energy equation and using an adjoint variable or direct differentiation method, configuration design sensitivity results for static and eigenvalue response are formulated in terms of the design velocity fields. Displacement, stress, and eigenvalue performance measures are considered. A computational procedure for configuration design optimization is presented, using an established finite element analysis (FEA) code, the continuum DSA method, and an optimization code. A domain displacement method is presented to compute both the domain velocity and the angular velocity. A configuration design optimization of a crane structure is demonstrated using the FEA code ANSYS, continuum DSA, and Pshenichny’s linearization method.

Sung-Ling Twu, Kyung K. Choi

Shape Design Sensitivity Analysis and What-if Tool for 3-D Design Applications

Shape design parameters that govern the geometric shape of a structural component are the most effective way to improve design of 3-D elastic solid components. Four major characteristics, however, that are unique to the shape design problem make it more complicated than the traditional sizing problem; (1) it is difficult to retain the accuracy of finite element analysis results for a design model whose geometry changes during the design process, (2) it is difficult to handle the sophisticated shape design parameterization and update geometric shape, (3) efficient computation of shape design sensitivity information for a large scale problem is difficult to achieve, and (4) visualization of important design sensitivity information and automation of shape design processes to provide an effective design environment is not available.To support Concurrent Engineering activities, design parameters defined in the CAD model are the most important common data shared by various engineering disciplines. Design sensitivity analysis that computes structural responses with respect to design parameters defined in the CAD model is a critical step to support Concurrent Engineering activities.This paper presents a methodology to support structural shape design for 3-D elastic solid components, using the geometric modeler PATRAN [1]. The proposed methodology overcomes four major difficulties of shape design; accuracy, integration, efficiency, and effectiveness. A clevis and a turbine blade examples are given to demonstrate capabilities of the design tool.

Kuang-Hua Chang, Kyung K. Choi

Optimal Design of Vibrating Structures

The problem of optimal design of vibrating elastic systems with damping is discussed. Linear constitutive relations in differential form for viscoelastic materials are cited with remarks concerning some experimental results of optimal identification of material damping. These relations are used in the derivation of selected variational principles in complex formulation, together with analysis of forced vibrations and eigenproblems. It is demonstrated that material damping, described in commonly used linear models of viscoelastic materials, significantly changes mechanical properties of a system with even an arbitrarily small amount of dissipated energy. It is shown that a continuous viscoelastic system, in contrast to a perfectly elastic one, may have a finite number of eigenfrequencies and resonant frequencies. Moreover, some of the eigenfrequencies associated with high order eigenmodes may be shifted down, due to dissipation of energy. Therefore the eigenvalue optimization problem is directly related to material characteristics and frequently cannot be formulated in such a manner as for perfectly elastic systems. The formulation of sensitivity analysis and optimization of structures for two important classes of problems, namely forced steady state harmonic vibration and eigenproblems, are presented and discussed.

Tomasz Lekszycki

The Problem of Additional Load of Minimum Work in a Thin Plate

A rectangular elastic plate is simply supported along its boundary. A flexural couple is exerted on one of its sides, while the others remain unloaded. The question is posed, assuming the ability to produce couples along the side opposite the already loaded one, of determining the values of these latter couples which would minimize the elastic strain energy of the system.The solution is obtained in explicit form by representing the transverse displacement in the form of a Fourier series and directly calculating the minimum of the strain energy.

Salvatore Sergio Ligaró

Layout Optimization of Large FE Systems by New Optimality Criteria Methods: Applications to Beam Systems

The aim of this paper is to demonstrate the optimization capability of recently developed optimality criteria methods (COC, DCOC) by solving layout problems for beam systems (grillages) involving many thousand potential members. Although the method presented can include all practical design constraints, its validity and accuracy is also verified by comparing the numerical output with closed form analytical solutions for some layout problems.

O. Sigmund, M. Zhou, G. I. N. Rozvany

Analysis and Design of Structural Sandwich Panels Against Denting

The problem of local bending often encountered in laterally loaded sandwich panels is analyzed by considering the deflection of the loaded facing against the not loaded facing as being governed by an elastic foundation model. This is achieved by the development of a two-parameter elastic foundation formulation which takes into account the existence of shear interactions between the loaded facing and the supporting medium (core material). The results obtained by application of the developed approximate solution procedure, i.e., the local stress field in the near vicinity of the area of application of the external load, are compared with finite element solution results and very good comparative results are obtained.

Ole Thybo Thomsen

Virtual Prototyping and Human Factors


Virtual Prototyping for Mechanical System Concurrent Engineering

The emergence of high-speed computers, new mechanical system dynamic simulation formulations, and a broad range of operator-in-the-loop simulators is shown to provide a revolutionary new virtual prototyping tool to support Concurrent Engineering of mechanical systems. The state-of-the-art of operator-in-the-loop simulation and projections regarding its refinement for use in a broad range of engineering applications is outlined, with emphasis on providing a virtual prototyping capability that accounts for the operator-machine interaction, prior to fabrication and test of prototypes. Examples of advanced ground vehicle simulators, telerobotic simulators, and construction equipment simulators are used to illustrate virtual prototyping applications that hold the potential to revolutionize the process of mechanical system design for the human operator. The potential now exists to routinely investigate trade-offs involving mechanical system design and operator effectiveness that will permit the engineering community to optimize the design of mechanical systems for the human operator, beginning early in the design and development process and continuing through commercialization and product improvement. Bringing the human factor into design consideration using virtual prototyping before design decisions are finalized is projected to be one of the greatest advances in Concurrent Engineering of Mechanical Systems to occur in the decade.

Edward J. Haug, Jon G. Kuhl, Fuh Feng Tsai

An Open Software Architecture for Operator-in-the-Loop Simulator Design and Integration

This paper describes the design and implementation of an open software architecture for operator-in-the-loop simulators to support virtual prototyping applications. This framework provides properties that are critical to the cost-effective design of complex simulators, including uniform software specification techniques, modular design methodologies, enhanced reliability and maintainability, ease of reconfigurability, and reusability of simulator subsystems. The open architecture has already served as a basis for development of the Iowa Driving Simulator (IDS) and will, with further enhancement, be used to support development of tracked vehicle virtual prototyping simulation under support from the Defense Advanced Projects Research Agency (DARPA). The architecture is suitable for general application to the design and integration of a wide variety of simulation systems.

Jon G. Kuhl, Yiannis E. Papelis, Richard A. Romano

Man/Machine Interaction Dynamics and Performance Analysis

The Man/Machine Interaction Dynamics and Performance (MMIDAP) analysis project, lead by NASA’s Goddard Space Flight Center (GSFC), seeks to create an ability to study the consequences of machine design alternatives relative to the performance of both the machine and its operator. The MMIDAP problem highlights the conflicting needs and views of groups that focus on machine design and groups that focus on human performance, ergonomics, and cumulative injury potential. There is a critical need to integrate associated design and simulation tools and to establish multidisciplinary lines of communication. This will enable engineers to design mechanical systems and concurrently perform the system design trade studies needed to assess resultant machine-operator performance. Basic need within industries that design and manufacture human operated machinery, and the underlying complexity of cross disciplinary communication provide the motivation to closely coordinate evolving MMIDAP capability with the Concurrent Engineering community. This chapter outlines ongoing efforts by the GSFC and its university and small business collaborators to integrate both human performance and musculoskeletal databases with the host of analysis capabilities necessary for early design analysis and trade studies relative to the dynamic actions, reactions, and performance assessment of coupled machine-operator systems.

Harold P. Frisch

Simulated Humans, Graphical Behaviors, and Animated Agents

A variety of issues involved in visualizing human task behavior will be examined, focusing on the broad, yet vertically-integrated, effort at the University of Pennsylvania. Computer graphics visualization of the appearance, capabilities and performance of humans is a challenging task. From modeling reasonable body size and shape, through control of the highly redundant body linkage, to simulation of plausible motions, human figures offer numerous computational problems and constraints. Our research has produced a system, called Jack, for the definition, manipulation, animation, and human factors performance analysis of simulated human figures. Human motion can be visualized by interactive specification and simultaneous execution of multiple constraints. Enhanced control is provided by natural behaviors such as looking, reaching, balancing, lifting, stepping, walking, grasping, and so on. As an alternative to interactive specification, a simulation system allows a convenient temporal and spatial parallel “programming language” for behaviors. At an even higher level, we have been exploring the possibility of using Natural Language instructions, such as are found in assembly or maintenance manuals, to drive the behavior of our animated human agents.

Norman I. Badler

Human Factors in Vehicle Driving Simulation

In considering operator-in-the-loop simulation much concern is rightly directed to the response of the human controller whose actions are vital with respect to performance of the overall system. Operator-in-the-loop simulation provides a cost-effective approach to understanding the performance envelope of any proposed system and is particularly relevant to the investigation of vehicles. However, the growth of full-fidelity manipulable simulation ‘worlds’ has reflexively begun to provide a new and exciting window from which to frame innovative and critical questions about how we can understand behavior itself. In the first of the present synopses, Flach argues that just such capabilities are central to a full evaluation of a control-theoretic approach to evaluating operator performance. In the second paper, Hancock argues that it is only through the use of such facilities that the design, test, and evaluation of prototype in-vehicle collision avoidance warning systems can be accomplished. As a critical component of the general IVHS effort, the safety gains potentially associated with an effective collision warning system clearly make the investment worthwhile. Hancock further argues that, exactly how such tests are to be conducted and such systems are to be designed relies heavily upon real-world application of perceptual field theories associated with ecological views of the coupling between driver perception and action.However, full fidelity simulators are expensive systems and their cost/effectiveness has been questioned. Green explores ways in which many questions may be answered with reduced fidelity simulation. He develops a number of principals, which although simple in themself, have been largely ignored in previous interface developments. In citing a sequence of his own and others findings, Green indicates exactly how preferred design can be transferred from the realm of speculation to actual instantiation. In returning to the use of simulation, Caird points to a number of real and potential perceptual questions that might act to distort graphics worlds that the naive user may consider viable simply because they match in terms of metrical structure. He points to the lack of psychological knowledge and information that might resolve such issues. The general point that physical worlds are not simply equatable with perceptual worlds is one that has to be taken most seriously by graphic world designers and anyone hoping to extrapolate from high-fidelity simulation to real-world performance. In the final component, Andre also examines problem issues in simulation. He emphasizes the need to ‘know’ the simulation environment as well as the real-world performance environment and illustrates his argument with a number of traps ready to snare the unwary investigator. Finally, he points to a sequence of contemporary problems in design which could have been obviated if simulation had been used early in the design sequence.The overall message from the collective presentations is clear. If concurrent engineering requires parallel consideration of multiple components of system design and manufacture, human factors issues should be given early prominence in any system that a human has to operate or maintain. Failure of early and adequate consideration of human factors will result in the spectacular failures that regale the news media. Although there are questions yet to be answered, the consensus of the present offering is that high-fidelity simulation is a vital tool in this process and is a central pillar of concurrent engineering approaches. While cost-effective in most environments, there are some systems that simply cannot be evaluated except using this form of assessment. The contemporary developments in computer capability to accomplish such simulation now make the widespread use of this approach a viable and advised strategy and is a facility especially welcome in the study of complex human behavior.

P A. Hancock

Evaluating In-Vehicle Collision Avoidance Warning Systems for IVHS

Pursuant to the recent Intermodal Surface Transportation Efficiency Act (ISTEA), there has been a considerable apportionment of resources for developments in the area of Intelligent Vehicle Highway Systems (IVHS). IVHS promises, both here in the United States and in its various international forms, to address the questions of improved safe and efficient transportation. Such developments are mandated by the unacceptable levels of urban traffic congestion in most global conurbations and the epidemic level of traffic accidents which serve to rob society of human life and incur unsupportable burden on financial resources in the form of medical and insurance costs. IVHS can be divided into two major elements with respect to driver behavior. The first element, and one not dealt with in detail here, is assistance to navigation and congestion avoidance. The second, which is of central concern here, is collision avoidance. Collision avoidance systems seek to inform the driver of imminent or impending collision and to present assistance in conflict resolution. Just how such conflict resolution is to be enacted has yet to be determined. Various tactics have been suggested. They range from usurpation of control by some automatic system to messaging systems for preferred avoidance maneuvers. While the design and operational ramifications of these options are considered briefly here, the central theme is the critical use of simulation as a method for investigating and evaluating such alternatives. It is proposed that testing in high-fidelity simulation is currently the most, if not the only, viable option by which such technology can be safely instantiated. In examining this issue I contrast the situation specific approaches that appear to be favored in current research with an envelope approach based on the ecological analysis first posited by Gibson some fifty years ago. How simulation informs such design becomes a critical link if the safety aspects of IVHS are to reach fruition.

P. A. Hancock

Tools and Methods for Developing Easy to Use Driver Information Systems

This chapter describes approaches that can be used to determine if systems are safe and easy to use. Examples are given from the author’s research for a variety of driver information systems, particularly warning systems, traffic information systems, and navigation displays, as well as conventional instrumentation such as speedometers. Methods are needed to provide for an early focus on users and their tasks, to provide for empirical measurement, and to support iterative design. Approaches examined include focus groups, paper and pencil studies at a driver licensing office, response time experiments, rapid prototypes using HyperCard and SuperCard, procedures involving driving simulators, and on-the-road experiments in instrumented vehicles. Simple driving simulators (task loaders) have proven to be particularly useful over the years. Application of these approaches varies with the design phase, and with the personnel, facilities, and funding available.

Paul Green

The Perception of Visually Simulated Environments

The perception of simulated environments by the operator in-the-loop is examined. One objective of simulation is to provide realistic visual scenes for an operator to navigate through. While the physical re-creation of these synthetic environments has received considerable activity, less attention has been given to the perceived information conveyed by a simulated scene to an operator. In general, how perceptual differences between simulated and real scenes affect perception and subsequent action is not completely understood. To the extent it is understood, previous research done on the visual characteristics of flight and driving simulation is highlighted. The key issues of visual realism and fidelity, and distortion of spatial layout are elaborated.

J. K. Caird

Effective Vehicle Driving Simulation: Lessons from Aviation

Recent advances in computer and display systems technology have made vehicle driving simulators a viable training and evaluation resource for both civilian and military operations. Such computer-aided simulation has unlimited human factors applications for improving the safety, efficiency, and cost of a wide variety of mechanical vehicle systems. However, technological capabilities do not, by themselves, improve the design or training process. For simulators to be effective, users must understand the complexities of the simulation system, exercise control over the simulator’s technological capabilities, and determine relevant criteria for simulation fidelity. Drawing on the experiences of the aviation community, this paper focuses on four important issues/applications for vehicle driving simulation: 1) modeling the simulation environment, 2) simulator fidelity and design, 3) automotive design evaluation (displays and controls), and 4) driver education and training.

Anthony D. Andre

Active Psychophysics: A Psychophysical Program for Closed-Loop Systems

Concurrent Engineering requires a creative blend of basic research with design. This is particularly true for human-machine systems. Simulators provide both an opportunity and a challenge for basic research on human performance. Simulators provide an opportunity where researchers can manipulate goals, dynamics, and information in a way that will allow direct generalizations to operational environments. Simulators provide a challenge where human performance researchers must provide information with regard to critical design decisions — How much realism is necessary? How can the simulator be used most effectively in training?

John M. Flach


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