A Grammar Driven Data Translation System for Computer Integrated Manufacturing

[+] Author and Article Information
Glen L. Niebur

Department of Aerospace and Mechanical Engineering, The University of Notre Dame, Notre Dame, IN 46556

Thomas R. Chase

Department of Mechanical Engineering, The University of Minnesota, Minneapolis, MN 55455

J. Mech. Des 124(1), 136-142 (Feb 01, 1999) (7 pages) doi:10.1115/1.1434268 History: Received February 01, 1999
Copyright © 2002 by ASME
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The data sharing architecture is built on a database management system. A translation program moves data from the central database to applications.
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Database methods are used to map the data between differing representations or to perform complex schema transformations. Thus, the translator need only reformat the data, which can be done based on simple grammar rules. The methods become part of the database management system, and can be used for all applications that require the same data transformations.
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Datatrans accesses the database and the application data files through interface programs. This isolates the translation process from the underlying data storage formats and schemas. The commands to the database interface and file interface are embedded in data description files, so that the interface commands to both the database manager and the data file are completely configurable for each application.
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The format of a data description file. Lines beginning with # are comments. Bold face words are Datatrans keywords. The control section defines the processing actions, the tokens section specifies regular expressions to be recognized by a lexical analyzer, and the rules section specifies a context free grammar to be recognized by a parser.
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(a) A two dimensional design of a retaining ring was created in the drafting program. (b) The geometry was imported into the FEA program and a finite element mesh was created.
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(a) The DXF representation of a circular arc (column 1). The lexical analyzer converts each of these to tokens to be passed to the parser (column 2). The progression of grouping the tokens to represent a circular arc, and finally a geometric entity in through the productions figure 6b is shown in columns 3 to 6. (b) The productions from the data description file that recognize the circular arc in the DXF file. Note that arcs are stored as circles in the database. (c) The query generated by Datatrans to store the circular arc from figure 6a, and the resulting data retrieved from the database. The entity level, line style, and color are stored in the entities table in Postgres, of which the circles table is a subtype. Querying the circle table does not retrieve this data unless it is specified explicitly.
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(a) The query from the data description file that is used to retrieve circles. Arc_start_point, and arc_angle are database methods that compute the location of a point on the arc, and the included angle of the arc, which are needed for the arc command in the FEA program. (b) The data retrieved by the query in a. (c) The productions from the data description file that recognize the data. (d) The FEA preprocessor commands that generate the arc. The preprocessor command language provides the capability to define the variables, kp1, kp2, and nextkp, which are used as identifiers for the keypoints used to create the circle. Alternatively, these could be generated within the database manager.




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