Uses assembly sequence analysis (ASA) to explore design for assembly (DFA), subassembly partitioning, and assembly sequence choice for two complex assemblies. Complex assemblies have very high parts-counts, a final assembly organized as an assembly of subassemblies, and offer limited redesign options. ASA addresses combinatorial aspects of complex assemblies that conventional DFA ignores: choice and partitioning of subassemblies, and assembly sequence choice. The paper describes criterion-based searches for favorable subassembly partitioning and assembly sequences that use genetic algorithm techniques to spread assembly move difficulty across entire final assembly sequences while satisfying all logical constraints imposed on the assembly sequence by part geometry. The measure of assembly move difficulty, a count of kinematic degrees of freedom secured during each final assembly step, is measured on an absolute scale. We find that ASA can pinpoint candidate DFA-related redesigns and can suggest assembly issues to designers. Logical assembly issues dominate quantitatively-characterized issues when selecting assembly sequence or subassembly partitioning. After logical issues are addressed, the sequence choice criterion defined here often duplicates choices made by experienced analysts. Finally, the sequence choice criterion favors in-line over branched final assembly lines.

This work addresses development of winding technique and technology, to automate winding of optical fiber in a quadrupole pattern, for interferometric fiber-optic gyros (IFOG's). An emphasis of this work is developing winding processes that can proceed under tension, stably, without hands-on manual efforts. A quadrupole winding pattern requires handling two supply spools and one product spool; the supply spools takes turn being active, and tension control must be maintained during changes of spools. Typical coil-winding machinery has significant elasticity, backlash, and inertia. Another emphasis of this work is the development of winding-machine-specific controls, capable of maintaining controlled tension, at all times, and for any winding-machine dynamics.>

An integrated computer aid that is useful for assembly-line design and for concurrent design of mechanical products is described. Recognizing that early consideration of assembly sequence is important for producibility, quality control, flexibility, and market responsiveness, the authors have built an integrated set of user-interactive computer programs that generates all feasible assembly sequences for a product and then aids the user in judging their value based on various criteria. The programs use a disassembly analysis for generating sequences and provide online visual aids during generation and evaluation. During evaluation, matters such as avoiding difficult assembly states or moves, stability, fixturing, orientation, refixturing and reorientation count, and inclusion of favorable states are considered to highlight desirable or undesirable sequences. The designer edits the set of sequences according to these criteria, leading to an informed sequence choice or to needed design refinement. The interactive programs provide a rapid means for sequence selection, encouraging their use during early design.>

The authors discuss computer aids for assembly sequence choice and design during product design. Implementations include adapting A. Bourjault's (1984) method for finding physically possible assembly sequences, using a solid modeler during this step, representing sequences in a state transition space, and reducing the sequence count to a small set of desirable ones by computer-interactive editing of the state transition space.>

Bourjault has presented a method which will generate all valid assembly sequences for the set of parts that constitute an assembly. A modification of Bourjault's method is presented which makes practical the application of this technique of assembly analysis to assemblies with greatly increased part count. The salient difference between the two methods is in the form and number of the questions whose answers yield the relations that allow algorithmic generation of assembly sequences. Bourjault's method requires 2l^{2} questions plus an often-large number of subsequent questions whose existence depends on answers to part of the former question set; all have yes or no answers. (Here l is the number of relations between parts.) The modified method requires 2l questions that are answered in a precedence-logical form; the questions are similar to those asked by an engineer contemplating assembly of a set of parts. Applications and techniques for use are presented, and examples are shown for l as great as 18.