Knowledge-Base Processing Model of Checking of Mechanical Design Drawings and Its Applications to Computer-Aided Drawing Check System for CAD Drawings

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Recently the great part of mechanical design drawings are produced by using CAD systems. The CAD drawings have various drawing errors similar to traditional manually-produced drawings, because of design information being input by designers. Hence, establishment of a methodology of computer-assisted drawing checks is very much needed.A mechanical drawing expresses a great diversity of information about a design object which are roughly classified as1) geometric information such as shapes and sizes,2) functional information such as tolerances, surface features and assembles, and3) production information.As the first stage of the studies for computer-aided drawing check systems, we deal with the geometric information and the functional information.For checking of geometric information errors we introduce a knowledge-base processing model for dimensional errors which consists of two mathematical models. By using the processing model, we develop a prototype system which checks(a) deficiency of dimensions,(b) over-dimensions or redundant dimensions(c) incompatibility between dimension figures and the corresponding geometric size in the drawing, and(d) input-error of dimension symbols or numbers of local geometric features such as holes.For checking of functional information errors, we consider several methods of recognition of local geometric features with respect to functional information, however, a checking system for the functional information errors in a drawing has not been developed yet.