ABSTRACT
The preceding chapter focused on topological and geometric properties of a product. While the process of deriving all the feasible disassembly sequences from an assembly drawing has more or less been automated and an efficient use of subset and superset rules results in minimum human interaction, some detachability analysis based on
visual inspection
remains indispensable. However, the extent of visual inspection can be reduced by the use of direction-oriented representations. Two different approaches can be distinguished here, surface-oriented analysis and direction-oriented analysis. The
surface-oriented analysis
starts with detailed information on product geometry, including the distinct surfaces of different components, thus analyzing the constraints in degrees of freedom of motion, which refer to infinitesimal relocations of components with respect to each other. This is called
movability analysis
. Translational or rotational movability is often required for the functionality of a product. Usually, this motion is constrained. The process of searching for the existence of a path along with a component or subassembly that can be detached from the rest of the product (implying motion to infinity) is called
detachability analysis
. Obstruction of the component or subassembly by components that are still present in the product might hinder the detachment. Infinity is usually approximated by the minimum distance of separation where the convex hulls of the two child subassemblies do not intersect (Oliver and Huang, 1994; Srinivasan et al., 1997). Prior to calculating this distance, the direction along which the dynamic subassembly is moved away from the static one has to be determined. This direction is called the
separation direction vector
.
