摘要
装配序列规划问题本质上是一个NP组合优化难题(Nondeterministic polynomial Problem),因此很难得到一个满足装配要求的装配序列,从而使装配序列规划成为提高产品精度、降低生产周期及成本的瓶颈环节。本文在分析飞机机翼装配特点的基础上,完成了虚拟装配系统中装配顺序规划模块的设计与实现,并对基于遗传算法及模糊集理论的装配序列规划技术进行了深入研究,主要研究内容包括:
1.调研并分析了装配关系、装配动作、装配方向等飞机装配的主要内容,总结了机翼装配的特点及流程;
2.对产品装配序列规划的内容进行了探讨,提出了本文所采用的装配序列生成方法——基于遗传算法的装配序列规划方法;
3.充分考虑在装配序列规划过程中所涉及到的装配动作、装配工夹具与装配方向等各方面因素,采用基因组的编码方法对装配信息进行编码;
4.提出基于模糊集的评价方法对生成的装配序列进行评价,使用模糊集的原理对适应度函数中的参数进行赋值,提高适应度函数的精确度,加快遗传算法的收敛速度;
5.基于CATIAV5和CAA FOR CATIA V5,设计了面向机翼的基于遗传算法的装配顺序规划模块,并完成了主要功能的开发。
The problem of assembly sequence planning (ASP) is a kind of NP optimization problems, so it is very difficult to find an assembly sequence which can achieve the assembly request. Therefore, assembly sequence planning had been becoming the bottleneck of reducing the cost and shortening the production time of a product. The technique of virtual assembly can quickly evaluate and optimize the assembly plan by simulating the assembling procedure; it also can achieve the product design, assembly process planning, functional analysis and quality testing adopting computer simulation and 3D interactive visual model. ASP is a key technique of virtual assembly. In this thesis, a system planning of assembly sequence planning module in Virtual Assembly system is proposed which is based on analyzing the characteristic of airfoil assembly and assembly design. The core techniques of assembly sequence planning which based on genetic algorithm and fuzzy set theory are investigated in detail. Main research work and achievements are as follows:
1. Researches and analyzes aircraft assembly design task, such as assembly methods, assembly action and assembly direction etc. Summarizes the characteristics and workflow of wing assembly design.
2. The assembly sequence planning of product is discussed. The paper presents the method - assembly sequence planning based on genetic algorithm, which is adopted by the module.
3. The genetic algorithm adopted the encode method of gene-group, expressed the assembly information of parts such as assembly actions, assembly tools, assembly fixtures and assembly directions, etc.
4. The method proposed fuzzy set-based fitness function, by which can judge and optimize the assembly sequence planning.
5. Based on CATIA V5 CAD Software and CAA FOR CATIA V5 Toolbox, designed and developed a module for airfoil's assembly sequence planning.
引文
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