Automated sequence generation and selection for mechanical assembly and part replacement.

摘要

Increasing productivity through automation has been known to be one of the most important thrusts for achieving competitiveness in the market. In manufacturing, especially, assembly is a significant cost item and is often the most labor intensive one. Thus, the field of automatic assembly to reduce this substantial assembly cost is a highly attractive area of research. One effort to further reduce the assembly cost and time concentrates on the assembly/disassembly sequence generation.;Even though considerable research has been accomplished in this area, its application to real life problems is known to be in the early stages. This thesis presents a formal logic-based scheme and a set of algorithms for mechanical assembly/disassembly sequence generation and selection. The overall procedure is implemented through an integrated computer system called SADAS (System for Assembly and DisAssembly Sequence generation). The proposed approach deals with the general nature of the problem domain. The important characteristics considered are: (1) There exist a large number of alternatives of assembly/disassembly, (2) Minor design changes can drastically affect the assembly/disassembly sequences, and (3) Because of (1) and (2), the problem could become computationally intractable.;A new concept, "Freedom and Interference Space", is proposed in this research to develop the algorithms. Based on this concept, sequences are generated for the cases of (1) Full Disassembly, (2) Part Replacement by Individual Disassembly, (3) Part Replacement by Group Disassembly, (4) Hierarchical Assembly, and (5) Alternative Assembly Sequences. Group disassembly which is based on the concept called "Carpenter's Approach" makes the disassembly work more efficient, and a complex assembly can be analyzed through the hierarchical assembly sequence generation scheme. Sequences generated are fed into the sequence selection module in which one or few sequences are selected.;The possibility of applications of the approach to practical assemblies is verified through the implementation with three practical examples: Toner Cartridge, Transformer, and Governor in a Diesel Engine. The performance is also analyzed by comparing it with the previous works from the viewpoint of practical applications.