Assembly knowledge representation for assembly motion planning and execution

A feature-based representation for describing assemblies is introduced. The representation is such that the system has the ability to generate automatically CAD models of assemblies and parts, which are allowed to be articulated. The representation also permits automatic computation of spatial relations among assembled parts. The uncertainty information, such as the various tolerances involved and uncertainties in the initial positions of the parts, is easily incorporated in the representation. Built around this representation is an assembly motion planner, which works in two stages. In the first stage, it ignores the uncertainties present in the system and develops a motion plan that is later modified in the second stage by the incorporation of force/torque-guided motions. The force/torque-guided motions are automatically introduced only in those segments of the plan where there exist possibilities of collision on account of the various uncertainties