Alan Jones
Boeing Information and Support Services
CAD Geometry Algorithms in a Large Industrial Enterprise
We survey CAD geometry algorithms currently in use at the Boeing
company. Geometry creation, NC tool path generation, visualization and
interference detection are well represented. Other areas, for example
path planning for assemblability or maintainability, and tolerance
stackup analysis, are not so widely used. We extract a few basic
principles from this survey. The most important is that each design or
manufacturing process, together with the algorithms that support it, is
embedded in a network of upstream and downstream processes. Thus, each
algorithm imposes constraints on, and is constrained by, many others.
This is illustrated on a finer level of granularity by the current
controversy over robust solid modeling. How can the maze of algorithms,
tolerances and stopping criteria inside a typical CAD system be
designed so that everything works reliably together? And can geometry
be shared between different CAD tools without dragging along the
tolerances, algorithms and methods involved in its creation? These are
crucially important open issues.