Institute for Systems Research

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Author: search.filters.author.Karinthi, Raghu R.Subject: search.filters.subject.Systems Integration

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    Evaluating Product Machinability for Concurrent Engineering
    (1992) Nau, D.S.; Zhang, G.M.; Gupta, Satyandra K.; Karinthi, Raghu R.; ISR
    Decisions made during the design of a machined part can significantly affect the product's cost, quality, and lead time. Thus, in order to address the goals of concurrent engineering, it is important to evaluate the machinability of the proposed design, so that the designer can change the design to improve its machinability, To determine the machinability of the part, all of the possible alternative ways to machine the part should be generated, and their machinability evaluated. This chapter describes the techniques we have developed to do this automatically.

    The information provided by these techniques will prove useful in two ways: (1) to provide information to the manufacturing engineer about alternative ways in which the part might be machined, and (2) to provide feedback to the designer identifying problems that may arise with the machining.

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    A Simple Approach to Performing Set Operations on Polyhedra
    (1991) Vanecek, G., Jr.; Nau, D.S.; Karinthi, Raghu R.; ISR
    In performing regularized set operations on two solids, the most difficult step is boundary classification, in which the boundaries of each solid are split into portions that are inside, outside, or on the surface of the other solid. In this paper, we present a method for doing boundary classification on polyhedra solid. The approach is based on recursively decomposing space based on the boundaries of the solids being classified.

    This approach has several appealing properties: it is simple to describe, efficient (tests indicate O (n log n) complexity in a variety of cases), and can handle both manifold and non-manifold 3-D solids. This approach serves as the basis for set operations in the Protosolid solid modeler.

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    An Algebraic Approach to Feature Interactions
    (1990) Karinthi, Raghu R.; Nau, D.; ISR
    Planning the manufacture of machined parts requires a great deal of geometric reasoning. One of the key steps in this task is the derivation of machinable features from a solid model of the part. Regardless of the approach used for obtaining the features, geometric interactions among the features can create situations where there are several possible feature representations for the same part. This presents a problem in planning the manufacture of the part, since some of these representations may be manufacturable and some may not. This dissertation presents an automatic way of computing alternate feature interpretations using an algebra of feature interactions. The algebra is intended to enable automated process planning systems to decide whether various interpretations of a part as a collection of machinable features are feasible for manufacturing, and among the feasible ones, which is the most appropriate one for manufacturing. Alternate feature interpretations are computed by performing operations in the algebra. Furthermore, various provable properties of the feature algebra aid in resolving several of the feature interactions without even applying the operations in the algebra. The operations in the algebra are defined on the set of all compact, regular, semi-analytic solids. A restricted subset of the algebra has been implemented in a geometric reasoning system, for use with the Protosolid solid modeler and the EFHA process planning system (which were developed earlier at the University of Maryland). We have shown through experiments that computing the operations of the feature algebra as developed in this dissertation is much more efficient than computing them by converting them to quiries to solid modeler.