In this paper we develop a systematic approach to mechanical assembly which allows rigorous reasoning and is sufficiently general so that it is applicable to different kinds of assemblies. The paper presents a representation scheme based on attribute graphs for describing assembly parts and an algebra to model assembly tasks. Any task is modelled as a merging of two attribute graphs to produce a single attribute graph which represents the merged or assembled object. The paper introduces a number of different types of merging operations and their mathematical properties are of particular interest in the assembly context. These two aspects of assembly, namely the representation scheme to describe assembly objects and the framework to model assembly tasks, form major components of an assembly planner. Due to its generic, formal and systematic nature, the framework is applicable to the assembly of different kinds of products, thus making the proposed scheme particularly attractive for flexible assembly systems.
