Representation and Programming for a Robotic Assembly Task Using an Assembly Structure

This paper describes a knowledge representation and programming method for a robotic assembly task. The methodology is explained using a robotic assembly task involving position and force controls. The action sequence is defined based on a control hierarchy which consists of four levels (Control primitive level, Control skill level, Skill level, and Task level). A complicated assembly task can be represented by the product and concatenation of control primitives in the lower levels, and various tasks can be defined by adding new control primitives. The parts to be assembled are represented by the built-up structure that we propose. In this paper, the concept of a CRS (Constraint Reduction System) is introduced for creating a robot task program. The CRS is realized through the use of an extended "prolog" programming language. All the actions and primitives are considered processes and can be uniformly described by the reduction rule of the CRS.