Automatic generation of goal regions for assembly tasks in the presence of uncertainty

Abstract

This paper presents a systematic procedure for generating the goal region of a mating action from a model of assemblies. The goal region of a mating action is defined as the acceptable destination of the moving object and is used to identify the successful situation of the mating action. Previous work always assumed the existence of the goal region in a mating action. In this paper, goal regions are constructed by using the mating features and the constraint types residing in the model of assemblies. The mating features identify the important variables between which the interdependencies are considered, and the constraint types identify the necessary constraints that mating features cannot provide. Assuming convexity and similarity of mating features, an analytical solution for C-space interior is developed to construct the goal region from 2-D features. This method provides a well-defined goal region which can enable the computation of the corresponding success probability. The effects of interference and fine-motion planning on success probabilities are also taken into consideration to define theoretical goal regions. Finally, due to the uncertainties arising in object representation, goal regions are also subject to uncertainties. An approach that shrinks the nominal boundary of a goal region is also proposed to compute the expectation of success probabilities. © 1996 IEEE.