面向协同装配规划的装配单元规划方法

作为复杂产品装配规划的有效求解策略,协同装配规划将复杂产品的装配规划结构按照装配要求分解为简单的子装配规划结构,子装配规划结构的最优或次优装配序列采用成熟的装配规划方法求解,通过装配序列合并得到产品的整体装配序列。协同装配规划所要解决的首要问题是装配规划结构分解,针对这个问题,提出装配单元规划方法。首先从产品可装配性的角度分析了影响装配单元规划的装配设计和装配工艺约束,并对归类的部分装配约束进行量化;进而基于模糊层次分析法生成装配单元决策图,采用最小生成树算法生成候选装配单元。同时,建立装配关系干涉矩阵对候选装配单元进一步验证,生成装配过程中互不干涉的装配单元。以一款电动机装配体为例验证提出的方法,结果表明该方法是一种求解装配规划结构分解问题的有效方法。     

基于遗传退火算法的复杂产品装配序列规划方法

分析了可行装配序列的推理约束条件,建立了考虑装配体稳定性的优化评价模型。采用带记忆的遗传模拟退火算法进行复杂产品的装配序列规划,并通过大量试验分析确定了算法近优运行参数。最后以8E150ZLC柴油机机油泵为例验证说明该方法是一个行之有效的具有工程实际意义的产品装配序列规划方法。     

Efficient method of assembly sequence planning based on GAAA and optimizing by assembly path feedback for complex product

In the process of complex product assembly, assembly resources (fixtures, tools, operations, and so on) must enter assembly environment with parts together to rapidly finish product assembly. Assembly planning must take assembly resources into account fully. But, designer cannot plan every assembly procedure because of the lack of assembly resources during assembly design. Then, it will cause assembly failures and redesign for assembly easily. This paper investigates an efficient method of assembly sequence planning based on genetic algorithm and ants algorithm (GAAA) and optimizing by assembly path feedback to assembly process planning including assembly resources for complex products. Firstly, a new GAAA is investigated to rapidly plan assembly sequence in order to solve the nondeterministic polynomial-bounded problem in high searching and solving efficiency. Secondly, on the basis of the assembly sequence, a B-Rep filling algorithm which can form a swept volume between the part and its kinetic orientation is developed to plan assembly path interactively. Thirdly, the performance of the assembly path according to the assembly sequence is analyzed and sent back to avoid the most of assembly collisions and interventions during product assembly design. Lastly, we develop a simulating system to simulate assembly sequence and path based on component application architecture for CATIA V5. The simulating result proved that the proposed method of assembly sequence planning based on GAAA and optimizing by assembly path feedback for complex products is efficient. Assembly optimal design including assembly resources can work well.     

INTEGRATED APPROACH TO ASSEMBLY SEQUENCE PLANNING OF C0MPLEX PRODUCTS

Assembly sequence planning will be more difficult due to the increasing complexity ofproducts. An integrated approach to assembly sequence planning of complex products applying de-composition-planning-combination strategy is presented. First, an assembly is decomposed into a hier-archical structure using an assembly structure representation based on connectors. Then, an assemblyplanning system is used to generate the sequences that are locally optimal for each leaf partition in thestructure hierarchy. By combining the local sequences systematically in a bottom-up manner andchoosing suitable ones from the merged sequences, the assembly sequence of each parent structureincluding the whole assembly is generated. An integrated system has been completed. A complexproduct is given to illustrate the feasibility and the practicality of the approach.     

INTEGRATED APPROACH TO ASSEMBLY SEQUENCE PLANNING OF COMPLEX PRODUCTS

Assembly sequence planning will be more difficult due to the increasing complexity of products. An integrated approach to assembly sequence planning of complex products applying decomposition-planning-combination strategy is presented. First, an assembly is decomposed into a hierarchical structure using an assembly structure representation based on connectors. Then, an assembly planning system is used to generate the sequences that are locally optimal for each leaf partition in the structure hierarchy. By combining the local sequences systematically in a bottom-up manner and choosing suitable ones from the merged sequences, the assembly sequence of each parent structure including the whole assembly is generated. An integrated system has been completed. A complex product is given to illustrate the feasibility and the practicality of the approach.     

产品装配顺序的层次化推理方法研究

提出一种装配优先关系分类模型，将装配顺序规划过程中的各种装配优先关系分为几种优先关系，确定性工艺优先关系和模糊性工艺优先关系3类。并在此基础上，提出层次化装配顺序推理方法，分别从装配顺序的几何可行性、工艺可行性和工艺优良性3个层次，对装配顺序进行递进推理，最终得到性能优良的装配顺序。开发的产品装配分析软件原型系统－－PAAS可以对复杂产品的装配顺序规划进行有效的分析和优化。     

Subassembly identification for assembly sequence planning

Assembly sequence planning is a typical of NP-complete problem which will spend a large amount of computation time or disk memory once the assembly becomes complex. The complex product or assembly is composed of many parts and the number of assembly relationships between them is numerous. To decrease the difficulty of assembly sequence planning of complex products, the subassembly identification methods are focused on. It aims to decompose a complex assembly into a limitative number of subassemblies. Each subassembly contains a relatively smaller number of parts and the assembly sequence planning tasks of them can be handled efficiently. The subassembly identification methods for assembly sequence planning are summarized with respect to assembly constraints. The assembly constraints including the topological, geometrical, and process constraints are considered and merged into the assembly models for subassembly identification. The assembly models are generally represented as directed or undirected assembly diagrams including these considered constraints. It is generally taken as the input information to generate appropriate subassemblies complying with the requirements. The graph theories and graph search algorithms, integer programming methods and the emerging techniques, such as the knowledge-based methods, the intelligent algorithms and the virtual technology, etc. are advocated to resolve the subassembly identification problem with respect to the assembly models. The hierarchical assembly tree is widely used to represent the results of subassembly identification. These useful methods are not only used to subassembly identification for assembly sequence planning, but also successfully referred to by product disassembly.     

Computer aided geometric feasible assembly sequence planning and optimizing

Assembly sequence planning (ASP) is the foundation of the assembly process planning and design for assembly (DFA). In ASP, geometric feasibility is the prerequisite in the valid assembly sequences searching. The assembly precedence relations’ (APRs) deriving and fulfilling are the essential tasks in the geometric feasible assembly sequence planning. In this paper, a systematical approach called geometric constraint analysis (GCA) is proposed and the corresponding software system is developed and integrated with CAD system. Using this system, only with a few mouse clicks on CAD draft, assembly precedence relations (APRs) can be derived correctly and completely. Then, all the geometric feasible assembly sequences can be inferred out automatically. Moreover, an optimal algorithm is designed and realized in the GCA method, by which, the most optimal assembly sequence in terms of the operation convenience can be found out from the immense geometric feasible sequences. An erratum to this article can be found at     

粒子群算法在装配顺序规划中的应用

装配顺序规划是计算机辅助工艺设计的一个重要环节,影响着轿车车身的装配质量和效率.针对当前装配顺序规划易产生组合爆炸等问题,提出了基于粒子群算法的装配顺序规划算法.装配偏差是影响装配质量的重要因素,因此应用装配体的装配偏差评价装配顺序.在装配顺序规划过程中,首先将装配顺序编码为粒子,根据所建立的判断规则进行识别粒子的可行性,并通过装配偏差评估可行粒子的适应度值,然后根据粒子群算法过程规划装配顺序,最后采用前翼子板案例阐述装配顺序的生成和优化过程.     

Design automation and optimization of assembly sequences for complex mechanical systems

Assembly sequence design for a mechanical system can have significant impact on manufacturing cost and product quality. Traditionally, such a design process is largely based on experience and best practices, often ineffective and non-optimal as the system becomes complex. This paper proposes a new, systematic method for automatic assembly sequence design and optimization. Key elements include assembly modeling, sequence planning, locating scheme optimization, dimensional quality evaluation, and optimization. First, a directed graph and an assembly matrix are employed to describe the assembly relation of a system. Then, the feasible assembly sequences are generated through layered subassembly detection of adjacency matrices, filtered by engineering constraints. To evaluate quickly the assembly quality and compare the influences of different locating point schemes, a linear 3D variation propagation analysis model with deterministic locating principle is introduced. The optimal locating scheme is then selected using a genetic algorithm with the least variation propagation. Finally, the assembly dimensional quality for different sequences is evaluated and the optimal assembly sequences are achieved through genetic algorithms. A case of automotive body side assembly is presented to illustrate the whole methodology.     

基于递归循环的层次化爆炸图自动生成方法

提出以递归循环和深度优先搜索层次化装配序列的策略自动生成复杂产品层次化爆炸图的方法。为使设计结构符合装配规划的要求,设计了可方便定义子装配体和编辑装配树的装配结构重构功能。为避免重复的干涉检测,研究干涉矩阵合成方法,通过对原始装配关系信息的整合,柔性化生成面向层次化结构的装配关系矩阵。为降低大规模序列规划问题的复杂性,将整体规划任务分解为若干个及若干层级子任务,子任务内采用多规则筛选算法,以基于干涉矩阵的几何可行性为前提,并行性、连续性、稳定性和方向性等为优化筛选指标,循环构建序列。提出递归爆炸算法,循环对层次化装配序列进行深度优先搜索,实时计算已爆炸零部件的累积包围盒,从而确定待爆炸零件位移矢量,自动生成间隔均匀有序、结构紧凑且空间层次感强的爆炸图。开发了基于Siemens NX的装配规划系统Auto Assem,以减速器及汽车部件实例验证了方法的有效性。     

基于虚拟现实和仿生算法的装配序列优化

针对自动装配规划和交互式规划都存在不足,将虚拟现实和仿生算法结合起来,提出一种生成优化装配序列的新方法.建立基于几何约束的虚拟装配环境,在该环境中根据经验和知识进行交互式拆卸,定义优先约束表来表达零件间的优先约束关系.应用蚁群算法规划出初始优化的装配顺序,再在虚拟环境下进行仿真、评价和优化,考虑装配位置可达性和工具操作等因素,识别新的优先约束和评价准则,重新规划出更优的装配顺序,不断反复和完善,直到得到满意的最佳装配顺序为止.通过实例验证该方法有效性.     

基于零件约束的装配规划技术研究

装配规划是虚拟装配中的关键技术。这里将装配序列的分层规划方法和拆卸法求解装配序列的方法相结合，在研究产品装配层次结构的基础上，以子装配体为研究对象，利用零件之间的装配约束信息求解零件的拆卸方向和顺序，进而实现产品的装配顺序和路径规划。     

面向装配仿真的装配序列规划方法的研究

从装配仿真的角度对装配序列规划进行了详细分析,建立了一个层级关联关系模型描述机械产品零部件的层次关系,装配关联关系,并利用该模型实现了装配仿真与计算机辅助装配序列规划的集成。     

基于复合装配图进行装配序列规划的研究

为了构建一个有效且便于使用的装配序列规划系统,给出了一个开放式装配模型———复合装配图,以有向装配连接图表述零件之间的优先关系,利用检查有向圈、删除冗余有向边确保该图正确、简洁。在此基础上,用无向边连接没有优先关系的零件,并根据装配代价和装配可行性对有向边、无向边赋权值,得到复合装配图。将装配序列规划描述为在复合装配图中求解特殊的最优H回路,并且基于分支定界法给出了满足优先关系、装配可行性、装配代价优化的装配顺序规划算法。最后通过实例验证了算法的有效性。     

基于配合约束的装配序列规划的遗传算法研究

为提高装配序列规划问题的寻优效率,提出了一种将装配约束条件和遗传算法相结合的求解方法.对配合约束进行了分类并给出每种类型特征尺寸的定义.在此基础上,引入特征标签的概念,用于描述零件的装配特征信息和配合约束关系.根据零件间特征标签的相似程度设计了可装配度函数,以度量装配的可行程度,并以该函数为基础构建了遗传算法的适应度函数.另外,为减少无用个体的数目,提出了基于配合约束的子代个体的保留策略,并以此为指导进行子代的有效性检验.最后,通过实例说明了该算法的有效性.     

A converse method-based approach for assembly sequence planning with assembly tool

In order to improve the quality and efficiency of assembly sequence planning for complex mechanical product, a converse method-based approach for assembly sequence planning is proposed. Firstly, the disassembly interference matrix of product and the disassembly constraint degree of part are defined. Product disassembly sequence is obtained through geometry reasoning algorithm and the searching work of disassembly sequence is simplified by the contact constraint set. Secondly, the maneuverability of tool is inspected through the using matrix and interference matrix of assembly tool. The infeasible disassembly sequence is excluded and product assembly sequence is obtained by reversing the order of disassembly sequence. Thirdly, the evaluation mechanism for assembly sequence is established to get the optimal assembly sequence and the optimal assembly sequence is selected by calculating the value of evaluation function. Finally, a vibration generator is illustrated to verify the validity and feasibility of the proposed approach.     

装配序列生成的有序二叉决策图技术研究

为提高装配序列规划求解效率,在图论割集法的基础上,引入有序二叉决策图描述装配关联图、装配操作、装配几何可行性和装配稳定性.利用装配优先约束关系,简化装配关联图,设计了基于符号有序二叉决策图技术的装配序列生成算法,分析了该算法的时间复杂度.在每一次割集分解之后,检验子装配体的几何可行性和稳定性,实现装配序列生成过程中状态空间的隐式表示和搜索.研究实例验证了基于符号有序二叉决策图技术的装配序列生成算法的可行性和有效性.     

Assembly Auxiliary System for Narrow Cabins of Spacecraft

Due to the narrow space and complex structure of spacecraft cabin, the existing asssembly systems can not well suit for the assembly process of cabin products. This paper aims to introduce an assembly auxiliary system for cabin products. A hierarchical-classification method is proposed to re-adjust the initial assembly relationship of cabin into a new hierarchical structure for efficient assembly planning. An improved ant colony algorithm based on three assembly principles is established for searching a optimizational assembly sequence of cabin parts. A mixed reality assembly environment is constructed with enhanced inforamtion to promote interaction efficiency of assembly training and guidance. Based on the machine vision technology, the inspection of left redundant objects and measurement of parts distance in inner cabin are efficiently performed. The proposed system has been applied to the assembly work of a spacecraft cabin with 107 parts, which includes cabin assembly planning, assembly training and assembly quality inspection. The application result indicates that the proposed system can be an effective assistant tool to cabin assembly works and provide an intuitive and real assembly experience for workers. This paper presents an assembly auxiliary system for spacecraft cabin products, which can provide technical support to the spacecraft cabin assembly industry.     

面向航天器舱体的智能装配系统研究

针对航天器舱体的装配,运用计算智能、人类智能和机器智能构建了一个智能装配系统。采用蚁群算法对舱体内零件的装配顺序进行了规划和优化,降低了复杂结构体的装配规划难度。采用混和现实技术给出了虚拟装配验证和训练的解决方案,从视觉、信息和操作三个方面来提高装配的人机交互效率;基于视觉的装配质量检测方法可为检查人员提供有效的提示信息,协助检查人员快速发现多余物,减小遗漏多余物的几率。