Precedence knowledge in feature mating operation assembly planning

The authors discuss the representation and acquisition of the precedence knowledge of an assembly, which plays an important role in the generation of assembly sequences and the planning of assembly. An efficient and complete symbolic representation has been developed to express the precedence knowledge clearly and precisely. This symbolic representation makes it possible to perform reasoning and manipulation of the precedence knowledge. Furthermore, the representation is complete in the sense that it can represent the assembly precedence knowledge as well as the disassembly precedence knowledge and these two forms of knowledge can be transformed from one to another. A geometric mating graph is developed to include all the necessary geometric and topological information for the precedence knowledge acquisition. Two algorithms are developed to obtain the precedence knowledge from the geometric mating graph systematically. The disassembly precedence knowledge thus obtained is equivalent to the assembly precedence knowledge and can be used to generate all the possible sets of assembly sequences