Partitioning An Assembly For Infinitesimal Motions In Translation And Rotation

The problem of partitioning an assembly into two subassemblies that can be separated arises in assembly planning. We consider assemblies of rigid parts whose contacts are equivalent, in terms of motion constraints, to finite sets of point-plane contact constraints. This type of contact includes all stable contacts between polyhedra as well as the large majority of contacts seen in industrial assemblies. For such assemblies, we describe a general algorithm to And a subassembly that is free to rotate and translate a small distance from the rest of the assembly. For assemblies with m contacts described as k point-plane constraints, the algorithm has a worst-case time bound of 0(~k5).