Machine interpretation of CAD data for manufacturing applications

Abstract

Machine interpretation of the shape of a component from CAD databases is an important problem in CAD/CAM, computer vision, and intelligent manufacturing. It can be used in CAD/CAM for evaluation of designs, in computer vision for machine recognition and machine inspection of objects, and in intelligent manufacturing for automating and integrating the link between design and manufacturing. This topic has been an active area of research since the late '70s, and a significant number of computational methods have been proposed to identify portions of the geometry of a part having engineering significance (here called "features").1 However, each proposed mechanism has been able to solve the problem only for components within a restricted geometric domain (such as polyhedral components), or only for components whose features interact with each other in a restricted manner. The purposes of this article are to review and summarize the development of research on machine recognition of features from CAD data, to discuss the advantages and potential problems of each approach, and to point out some of the promising directions future investigations may take. Since most work in this field has focused on machining features, the article primarily covers those features associated with the manufacturing domain. In order to better understand the state of the art, methods of automated feature recognition are divided into the following categories of methods based on their approach: graphbased, syntactic pattern recognition, rule-based, and volumetric. Within each category we have studied issues such as the definition of features, mechanisms developed for recognition of features, the application scope, and the assumptions made. In addition, the problem is addressed from the perspective of information input requirements and the advantages and disadvantages of boundary representation, constructive solid geometry (CSG), and 2D drawings with respect to machine recognition of features are examined. Emphasis is placed on the mechanisms for attacking problems associated with interacting features.

Relation between part position and kinematic freedom: An expository survey

“…The specific characteristics of the regions in contact, called assembly feature, help in achieving the assembled configuration [45]. There is a large number of papers available in literature on feature recognition [46] almost all of which concern characterisation and identification of machinable features on a single mechanical part; the methods cannot be applied for automatic identification of assembly features [47]. Chang and Perng [6] used high-level entities of mating features and mating relations to describe the composed state of parts in an assembly.…”

A Novel Knowledge-Based System for Interpreting Complex Engineering Drawings: Theory, Representation, and Implementation

“…Existing engineering interpretation methods may be roughly classified into five categories, depending on the basic technique they rely on: pixel-level knowledge-independent [6], [7], [9], [10], [11], [22], [23], pixel-level knowledge-dependent [13], [16], [17], [18], [20], [24], [25], [26], [27], [28], [29], vectorial-level knowledge-independent [30], [31], [32], [33], vectorial-level knowledge-dependent [34], [35], [36], [37], [38], [39], and hybrid systems [8], [40], [41].…”

Resolving non-uniqueness in design feature histories

“…An object is represented as a set of convex components with alternating addition and subtraction of volumes. The convex decompositions are sometimes known as alternating sum of volutnes (ASV) [9]. The technique first finds the convex hull of the object and then finds the set difference between the object and its convex hull.…”