Knowledge driven verification of positional tolerances

Geometrical specification and verification of products is achieving a more and more important role in Industry . In case of specifications associating modifiers to positional tolerances and datums, the direct conformance verification of a workpiece is not immediate. Besides advanced functions of CMM software, which usually only indicate conformance or non-conformance to specifications, a more detailed analysis of a specific workpiece can be performed using manual or graphical computations as e..g. in “paper gaging” techniques. Aim of this work is to present a prototypal knowledge based module implementing the tolerance analysis procedure and the conformance verification rules. This module, implemented in Java, automatically generates a graphical representation of the tolerance zones on which a rule based tolerance analyzer infers the conformance/non-conformance conditions, allowing the operator to identify and possibly improve the fabrication process. The software module uses a design patterns approach to structure the overall architecture in order to simplify knowledge reuse and promote modularization.