1993 / DB reference year
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Author Vandenbrande, Jan H. Requicha, Aristides A. G.
Source IEEE Transactions on Pattern Analysis & Machine Intelligence. v. 15, Dec. 1993, p. 1269-85.
Abstract The generation of correct and efficient plans for machining mechanical components requires the identification of features such as holes, slots and pockets, which are associated with distinctive manufacturing processes. This paper discusses an automatic feature recognizer that extends the state of the art in several directions. The recognizer decomposes the total volume to be machined into volumetric (i.e., solid) features that satisfy stringent conditions for manufacturability, and correspond to operations typically performed in 3-axis machining centers. Unlike most of the previous research, our approach is based on general techniques for dealing with features with intersecting volumes. Feature interactions are represented explicitly in the recognizer's output, to facilitate spatial reasoning in subsequent planning stages. The feature finder's architecture combines partial evidence from various sources such as nominal surface geometry, tolerances, attributes (e.g., threads), and design form f eatures. A generate-and-test strategy is used. OPS-5 production rules generate hints or clues for the existence of features, and post them on a blackboard. The clues are assessed, and those judged promising are processed to ensure that they correspond to actual features, and to gather information for process planning. An incompletely-specified solid feature, represented as a partially-filled frame, is associated with each promising hint. Computational geometry techniques are used to produce the largest volumetric feature compatible with the available data. The feature's accessibility, and its interactions with others are analyzed. Interactions are represented by segmenting the feature into "optional" and "required" volumes. Because some of the proposed features may rely on faulty hints, these are tested for validity in a verification phase. The validity tests ensure that the proposed features are accessible, do not intrude into the desired part, and satisfy other machinability conditions. The process
continues until it produces a complete decomposition of the volume to be machined into fully-specified features. The recognizer is implemented in a rapid prototyping test bed consisting of the KnowledgeCraft environment tightly coupled with the PADL-2 solid modeler, and running on Sun workstations. Rapid prototyping cuts time, costs to build finished parts.
Author Warner, Merlin C.
Source Modern Casting. v. 83, Oct. 1993, p. 25-7. XX