Tuesday, November 2

Dimensional Constraints in CAD -- Now and in the Future

9:15 AM-10:00 AM
Room: Rio Grande Ballroom
Chair: Rida T. Farouki, University of California, Davis

Almost all mechanical CAD systems are now using some form of dimensional constraint solving. Although this is commonly restricted to two dimensional sketches, it is spreading rapidly into three dimensions.

The speaker will review a variety of commercial uses for 2D constraints, including dynamic profile modification, constraint deduction, tightening geometric accuracy, automatic dimensioning and planar mechanisms. Many of these applications have counterparts in three dimensions, which are being searched, developed and released by leading CAD companies. The speaker will describe some of these new technologies, such as the dynamic positioning of the parts in an assembly seamlessly integrated with the simulation of their motion, direct constraint based part shape modification without recourse to a design history, and the correction of geometric inaccuracies to provide the tolerances required for optimum reliability in solid modelling applications.

The speaker predicts that the use of 3D dimensional constraints will grow rapidly in assembly and motion simulation applications, but will be hindered in the part modelling field by the limitations of existing solid model data-structures, which have undergone little fundamental change since the 1970s. A new generation of solid modellers will have to be developed to fully accommodate 3D dimensional constraints.

John C. Owen
D-Cubed Ltd., United Kingdom


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Created TJF, 5/20/99;Last Updated MMD, 6/21/99