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

目前，机械设计图的很大一部分都是利用CAD系统生成的。由于设计信息是由设计人员输入的，因此CAD图纸存在与传统手工图纸类似的各种绘图错误。因此，建立一套计算机辅助图样校核的方法是非常必要的。机械图样表达了关于设计对象的各种信息，这些信息大致可以分为1)形状和尺寸等几何信息，2)公差、表面特征和装配等功能信息，3)生产信息。作为计算机辅助图样校核系统研究的第一阶段，我们处理几何信息和功能信息。对于几何信息误差的校核，我们引入了一个由两个数学模型组成的基于知识库的尺寸误差处理模型。利用该处理模型，我们开发了一个原型系统，它可以检查(A)尺寸不足，(B)尺寸过大或多余尺寸(C)尺寸图形与图纸中对应的几何尺寸不匹配，(D)尺寸符号或局部几何特征的输入错误，如孔。对于功能信息错误的检查，我们考虑了几种局部几何特征相对于功能信息的识别方法，但尚未开发出图形中功能信息错误检查系统。

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.