Archimedes 3.0:This effort has produced the present Archimedes 3.0 system. in which the application emphasis has shifted to design feedback, model validation, and assembly animation/documentation. Archimedes 3.0 has an easy-to-use graphical user interface, and allows a user to incorporate non-geometric constraints, including tool constraints. For example, see Example1 (requires an MPEG viewer in your browser) for an assembly sequence for a test device called a pattern wheel, such as is used in some Sandia stronglink designs. This assembly plan is geometrically correct, but unreasonable...one doesn't insert washers from the side as shown in this example. For a realistic assembly sequence for a different device, accomplished using the new constraint system, see Example2. (And click to see a snapshot of the current user interface.) Archimedes 3.0 has been demonstrated to a variety of potential customers and tested on a variety of industrial CAD models, and it has been generating considerable interest. Recently, an extensive article on Archimedes 3.0 was published in Assembly magazine. The following are excerpts from that article:
--------from ASSEMBLY magazine, October 1996-----------------------
The challenge for those who do research at the leading
edge of any discipline is how to bridge the gap between the
laboratory and the real manufacturing world, which is profit
motivated. The Intelligent Systems and Robotics Center laboratory
at Sandia National Laboratories (Albuquerque, NM) is
meeting the challenge with technology that may revolutionize
the traditional approach to planning and developing automated
assembly processes.
"The mechanical assembly planning problem is that of taking a model of a mechanical device, and computing one or more assembly sequences that will assemble the device from its piece parts," says [the Archimedes team.] A set of software programs called Archimedes has been developed at Sandia over the past six years to solve that problem. The current version, Archimedes 3.0, is a planning and visualization software tool used to generate, optimize, verify and examine sequences of assembly. Archimedes allows product and process engineers to define assembly process constraints, automatically determine alternative assembly sequences satisfying those constraints, optimize the assembly process according to a user-specified quality metric, and visualize and communicate the results quickly and graphically.
The traditional approach to solving the assembly planning problem starts with piece parts, joins them to make subassemblies, and combines these to make higher-level assemblies. At some point in the process, this can result in a part that has to be somewhere inside with no way to get in. Then an engineer has to backtrack and find the point in the process to get that part in. "But, if you start with the complete object [model] and then take it apart, you can't make the mistake of not installing one of the pieces. Each part comes off only when it is possible to take it off," says [previous project lead] Randy H. Wilson. ... Archimedes follows this procedure and determines multiple assembly sequences for a product. From the CAD model of the product, the program automatically finds part-to-part contacts, generates collision-free insertion motions and chooses assembly order.
Combined with a process engineer's knowledge of application- specific assembly process requirements, Archimedes allows systematic exploration of virtually all possible assembly sequences. The engineer uses a simple graphic interface to place constraints on the valid assembly sequences, such as defining subassemblies, requiring that certain parts be placed consecutively with or before other parts, and declaring preferred mating directions. Archimedes generates all of the collision- free assembly sequences satisfying the constraints, and ranks them according to the user's quality metric. Graphic visualization enables the engineer to easily identify process requirements to add as sequence constraints. And each assembly sequence is typically generated in minutes, so the user can go through as many iterations of the constrain-plan-view-constrain cycle as needed to achieve an acceptable plan.
Planning, visualization, and communication have been weak links in manufacturing for years. The standard procedure has been for a designer to design something and then "throw it over the wall" to manufacturing for them to build. One of the more valuable results that will ultimately come from using software systems like Archimedes is that it will bring the design and manufacturing groups together to address the fundamental problem of profitable production.
Excerpted from ASSEMBLY, October, 1996. By permission of the
Publisher (c) 1996. Hitchcock Publishing Co. All rights reserved.
By Donald E. Hegland, Editor.
Elaine Hinman-Sweeney, (845-2780) emhinma@sandia.gov
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Currently:Archimedes has been applied to some impressively large scale
assemblies, including a proposed missile subsystem by Hughes Aircraft with 474 parts.
A video of the assembly process produced by Archimedes contributed to the awarding
to Hughes of the contract for the AIM-9X system.
We are happy to have had a role in their success.
Currently the Archimedes Project is pursuing further research
into applying automated assembly planning technology to issues
of lifecycle costs for systems, and to documenting manufacturing
processes using graphics and text spun off automatically from Archimedes.
In addition, industrial collaborations and commerciallization of the existing code are
being considered.
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