An integrated feedback for assembly auto-redesign system
Abstract
Producing high-quality products with reduced cost of assembly is a key factor to survive and compete in this competitive world. In this dissertation, an integrated feedback approach to achieve assembly-oriented product is proposed. The approach involves three phases, each aims to provide feedback from a different perspective, namely the geometric perspective, the functional perspective, and the tolerance perspective. For the geometric perspective, the strategy is to focus on three important areas: parallelism, assemblability, and redundancy. By cleverly formulating these three evaluation criteria, sufficient feedback information can be gathered to allow for automatic generation of redesign suggestions. These redesign suggestions, when properly implemented, will result in a new redesign that is more assembly-oriented: less time to assemble, less number of components and operations, and a higher degree of assemblability for the assembly tasks. For the functional perspective, the primary concern is on improving the modularity of a product's functional structure. A modular design is better for assembly, better for testing, and better for maintainability. Two measures, the interface complexity measure and the group homogeneity measure, are derived to measure the modularity of a given design. Once the analysis is completed, case-based reasoning is utilized to provide alternative redesign suggestions. Finally, for the tolerance perspective, a feedback paradigm for tolerance redesign is proposed which allows non-functional tolerance constraints to be specified as late as the assembly phase. At the same time, manufacturing cost considerations are taken into account. A tolerance representation based on fuzzy set theory is proposed. With this proposed representation, an assembly-driven fuzzy tolerance generation and assignment process is employed to derive the optimal tolerance assignments for a given design. To verify the feasibility, validity and performance of the proposed approach to product redesign, a prototype system called FANTASY has been implemented on a Sun Sparcstation with graphic simulation on an IRIS personal workstation. The system is implemented using C++ in an Unix environment.
Degree
Ph.D.
Advisors
Lee, Purdue University.
Subject Area
Electrical engineering
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