Issues in Fine Motion Planning for Assembly

A common problem in robotic assembly is that of mating tightly fitting parts when the locations and the dimensions of the parts are somewhat uncertain. Because the clearances allowed between mating features of parts are likely to be smaller then the aggregate uncertainties, it is often necessary to use sensoryguided motions, as opposed to point-to-point motions, for carrying out portions of an assembly operation. In this paper we will discuss a fine motion planner that develops motion plans for assembly operations where force/torque guided motions are incorporated into the plan as needed. While much work in fine motion planning has focused on dealing with the uncertainties involved, this paper will expose equally important issues that arise in assembly motion planning due to the complicated geometry of assembly parts and the tight clearances allowed between mating features of assembly parts.