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Today’s product development processes rely on Mechanical Computer-Aided Design (MCAD) systems that implement a geometric-centered perspective in design. The development of long discussed feature-based MCAD has not yet led to systems that truly support semantic and functional representation of features, which hampers also the use of these models for functional reasoning. This paper investigates the present feature-based MCAD limitations. It illustrates, through simple examples, how to use ontological analysis and feature re-classification to introduce software extensions in existing MCAD that achieve a newer level of semantic representation of features, and enhance the cognitive understanding of the final model. The proposal also shows how to automatically validate these features from the functional viewpoint. 相似文献
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We consider the design of parametric curves from geometric constraints such as distance from lines or points and tangency to lines or circles. We solve the Hermite problem with such additional geometric constraints. We use a family of curves with linearly varying normals, LN curves. The nonlinear equations that arise can be of algebraic degree 60. We solve them using the GPU on commodity graphics cards and achieve interactive performance. The family of curves considered has the additional property that the convolution of two curves in the family is again a curve in the family, assuming common Gauss maps, making the class more useful to applications. Further, we consider valid ranges in which the line tangency constraint can be imposed without the curve segment becoming singular. Finally, we remark on the larger class of LN curves and how it relates to Bézier curves. 相似文献
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