Representation and interpretation of geometric tolerances for polyhedral objects. II. Size, orientation and position tolerances

This article presents a computational scheme for representing and interpreting the geometric tolerances (mainly size, orientation and position tolerances) assigned to polyhedral objects. The proposed representational scheme is based on a surface-based variational model. Variations are applied to a part model by varying each surface's model variables. Those model variables are constrained by relations derived from tolerance zones. This article addresses two questions: (i) how to describe the tolerance zones according to different tolerance specifications? and (ii) how to vary the model variables when the variational models (of the part) are instantiated? The scheme has been fully implemented in an object-oriented programming environment.