Fast global and partial reflective symmetry analyses using boundary surfaces of mechanical components

• An approach to global and local reflective symmetry analyses for B-Rep CAD models.
• Use of a divide-and-conquer principle over the B-Rep faces as atomic entities.
• The symmetry accuracy obtained is of the order of the CAD kernel modeling accuracy.
• The process time is very low, and compatible with user’s interactions.

Axisymmetry and planar reflective symmetry properties of mechanical components can be used throughout a product development process to restructure the modeling process of a component, simplify the computation of tool path trajectories, assembly trajectories, etc. To this end, the restructured geometric model of such components must be at least as accurate as the manufacturing processes used to produce them, likewise their symmetry properties must be extracted with the same level of accuracy to preserve the accuracy of their geometric model. The proposed symmetry analysis is performed on a B-Rep CAD model through a divide-and-conquer approach over the boundary of a component with faces as atomic entities. As a result, it is possible to identify rapidly all global symmetry planes and axisymmetry as well as local symmetries. Also, the corresponding algorithm is fast enough to be inserted in CAD/CAM operators as part of interactive modeling processes, it performs at the same level of tolerance than geometric modelers and it is independent of the face and edge parameterizations.

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