To Dana S. Nau or associates,
>From Thomas L. De Fazio
on 15 March 1995.
Abstract of Current Work:
Exploratory research into a design-specific approach to Design For Assembly (DFA) in the Concurrent Engineering (CE) environment:
The research addresses DFA for dense and complicated mechanical assemblies, for which it is felt that current DFA methods are inadequate. Currently, DFA comprises generic checklists, is based on experience with a wide range of products, and is effective if a product functional design engineer has substantial design, material, and process freedoms. Our recent successful product-specific DFA efforts in industry have addressed concurrent engineering of automotive power-transmission units and other dense, complicated mechanical assemblies, with both tight design constraints and dimensional tolerances. These efforts resulted in successful paradigms that would not be suggested by current DFA guidance, and some that would run counter to, or even violate current DFA guidance. Objectives of the research are to explore this realm in a systematic way, and to develop more rational bases for collaboration of product design engineers concerned with function, and production engineers c!
oncerned with assembly, in the realm of concurrent engineering of dense, complicated, or tightly specified and constrained mechanical assemblies.
The research uses the logic of Assembly Sequence Analysis (ASA) as structure, tool, and a basis for measure of results. The use of ASA differentiates our work from current DFA means. ASA is a design-specific logical means of relating product design geometry to assembly choices. Both design geometry and assembly choices offer new metrics and support conventional ones: parts-count, assembly-line topology, count of non-productive assembly tasks, for example. To date ASA has been used in one direction; from product design to assembly choice. Part of the work is to explore possibilities of using ASA in the other direction; to flag awkward assembly constraints, and to suggest areas for design reconsideration. Among the implied research questions are:
How may one use ASA to look back from assembly sequence to design geometry?
What useful information may move from assembly consideration to product design?
What are means for postponing imposition of assembly constraints during preliminary design?
Our current and recent work seems relevant to your categories 1, 3, 4, 6, 7, 8(?), 10, 12. That is, our work seems, more or less, to read on the descriptions of the above-cited categories.
List of relevant references:
T. L. De Fazio, & D. E. Whitney, "Simplified Generation of All Assembly Sequences," IEEE Jnl. Robotics & Automation, Vol. RA-3, No. 6, pp. 640-658, Dec. 1987.
D. F. Baldwin & al., "An Integrated Computer Aid for Generating & Evaluating Assembly Sequences for Mechanical Products," IEEE Jnl. Robotics & Automation, Vol. 7, No. 1, 78-94, Feb. 1991.
T. L. De Fazio & D. E. Whitney, "Computer Aids for Finding and Evaluating Assembly Sequences: What is now Done, and what are Some Gaps in Current Application," Invited Paper, Workshop S1, 1992 IEEE Int'l Conf. on Robotics & Automation, Nice, France, May 1992.
T. L. De Fazio & al., "A Prototype of Feature-Based Design for Assembly," Trans. ASME, J. of Mechanical Design, Vol. 115, No. 4, Dec. 1993.
D. E. Whitney, & al., "Problems and Issues in Design and Manufacture of Complex Electro-Mechanical Systems," Final Report for ARPA Contract No. N00030-91-G-0110, Jan. 1994.
J. L. Nevins & D. E. Whitney, Ed's, & T. L. De Fazio, & al., "Concurrent Design of Products and Processes: A Strategy for the Next Generation in Manufacturing." McGraw-Hill, New York, 1989.
T. E. Abell & al., "Computer Aids for Finding, Representing, Choosing Amongst, and Evaluating the Assembly Sequences of Mechanical Products," (Ch. 15) in "Computer-aided Mechanical Assembly Planning," L. S. Homem de Mello & S. Lee, Editors. Kluwer Academic Publishers, June 1991.
What is a URL?
--------------------------------------
Date: 3/14/95 5:44 PM
To: Thomas De Fazio
From: virtual@frabjous.cs.umd.edu
We are doing a study of Virtual Manufacturing technologies. Our
conclusions will appear in a report to the Air Force Mantech program.
We have the following goals:
- to assess what research and applications are relevant to key aspects
of virtual manufacturing;
- to build an internet repository of virtual manufacturing information
on the World-Wide Web;
- to identify gaps in these research and application efforts, and
present our outlook for the future of virtual manufacturing
technologies.
If any of your work is relevant to virtual manufacturing, then this is
an invitation to send us information about it, for possible inclusion
on the Web site and in the report.
At the end of this message is a list of 13 areas that are relevant to
our study. If you are doing work on one of these areas, please send
email to the following address, before the end of March:
virtual@frabjous.cs.umd.edu
In your email, include the following information:
- a 150- to 200-word abstract of your work and how it is relevant to
the areas listed below;
- a list of relevant references;
- if possible, a URL for a world-wide-web or anonymous ftp site where
interested parties can retrieve more detailed information about your
work.
Also, please forward this message to anyone else whom you think might
be interested.
Thanks!
Dana S. Nau, nau@cs.umd.edu
Computer Science Department and
Institute for Systems Research
University of Maryland
Here are the other members of the team that is doing this study:
Thom Hodgson, North Carolina State University, hodgson@eos.ncsu.edu
Hank Grant, University of Oklahoma, hgrant@mailhost.ecn.uoknor.edu
Ioannis Minis, University of Maryland, minis@eng.umd.edu
Radharamanan (Radha), Marquette University, 6233radharam@vms.csd.mu.edu
Here are the areas that are relevant for our study:
1. VISUALIZATION: The representation of information to the user in a way
that is meaningful and easily comprehensible. In addition to graphical
user interfaces (GUIs) and virtual reality technologies, this technical
area includes information distillation, aggregation and autointerpretation.
2. ENVIRONMENT CONSTRUCTION TECHNOLOGIES: A computer based environment which
facilitates the construction and execution of VM systems. The tools are used
to extract information, to create models supporting simulation, to properly
configure the virtual environment, to analyze the ``fit'' of the virtual
environment to the real production environment, to link real and virtual
processes, and to link to the manufacturing control systems.
3. MODELING TECHNOLOGIES: Since simulations are based on models, modeling
technologies are key technologies for VM. Significant modeling issues are:
representation, representation languages, abstraction, federation,
standardization, reuse, multi-use, and configuration control.
4. REPRESENTATION: The technologies, methods, semantics, grammars and
analytical constructs required to represent all of the types of information
associated with designing and manufacturing a product in such a way that the
information can be transparently shared between all software applications
that support the representation technologies, methods, semantics, etc.
5. META-MODELING: This area refers to modeling about modeling, in essence,
constructing, defining and developing models that accommodate inter-model
interaction. The area involves standards and integration issues.
6. INTEGRATING INFRASTRUCTURE & ARCHITECTURE: The underlying infrastructure
(e.g. network, communications) that supports the ability to share models
and integrated product and process development across geographically
distributed enterprises (e.g. global co-location). The area also includes
creating a framework for the interoperation of all VM technologies.
7. SIMULATION: The ability to represent a physical system or environment
in a computer. This area includes a wide range of computer software
applications and, in the long term, links to real world systems that
enable simulation-based control. Includes model optimization and validation.
8. METHODOLOGY: The methodology for developing, deploying and using VM
systems, including ``simulation-based reason.'' The latter refers to
``problems'' that are defined in such a way that ``simulation'' will generate
insights (i.e., alternatives, potential solutions, problem
definition/refinement). Problem solutions will likely require more than
just ``simulation''. This methodology cannot be identical during the different
phases, however, it should be consistent across all phases.
9. INTEGRATION OF LEGACY DATA: This technical area primarily deals with
data and the many aspects of dealing data in general. Also, corporate
culture and multiple platforms were identified.
10. MANUFACTURING CHARACTERIZATION: This ara involves the capture,
measurement and analysis of the variables that influence material
transformation during manufacturing. It also involves the techniques
and methods for creating generic models of these processes based on actual
shop floor data.
11. VERIFICATION, VALIDATION & MEASUREMENT: For VM, this area refers to the
methodologies and tools to support the verification and validation (V&V) of
a VM system. Making decisions on a VM ``simulation'' of manufacturing
demands a confidence that the impacts of those decisions on physical
manufacturing will be realized as predicted. The methodologies and tools
are developed to provide the confidence. Measurement is included in this
technical area because its central role in maintaining a mapping between
the physical and the virtual is necessary for the V&V methodologies.
12. WORKFLOW: The work of an organization follows a path called the
workflow. This technical ara encompasses the capture, evaluation and
continuous improvement of the processes that are associated with workflow.
The workflow area processes primarily involve information, whereas the
manufacturing characterization area primarily involves physical material
transformation processes.
13. CROSS-FUNCTIONAL TRADES: The essence is multi-discipline optimization
applied to large grain (specifically Life Cycle Cost disciplines) problems.
These trades will be general across organizations at a high level, but will be
organization specific at a lower level as with factory floor operations, etc.
This has big technology transfer impacts. Many people had a hard time dealing
with the specific labels of the underpinnings, however, they were adamant
that it described what was really needed (e.g. requirement). Figure 3-1
in the final report of the user's workshop (presented here as Figure 3-1)
provides the context of this issue.
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To: de-fazio@draper.com
From: virtual@frabjous.cs.umd.edu
Subject: [nau@cs.umd.edu: virtual manufacturing survey]