计算机辅助三维装配顺序规划

针对三维空间装配顺序推理问题,应用方向包围盒和分离轴定理,对装配几何约束分析方法进行了扩展完善,提出三维几何约束分析方法,并开发出相应的计算机辅助分析系统.通过实例表明,该方法可以在三维装配环境中自动推理出正确完备的装配优先关系和几何可行的装配顺序.     

Constraint ratio in product assembly planning

Assembly planning considers the product, process, and production system. The existence of constraints makes the assembly planning process difficult and time consuming. The planning degree of freedom (PDOF) for designers will be increased if the number of constraints is decreased on either the product or the other sides. A higher PDOF means that companies can be more flexible in responding rapidly to the assembly of parts. In this paper, a constraint ratio (C_R) has been defined to measure the influence of the product constraints on assembly planning. Some rules have been established to simplify the evaluation procedures of the constraint ratio of the product. Examples are illustrated and explained.     

面向拆卸的装配序列规划算法的实现

从装配模型中获取几何信息和配合关系 ,充分利用这些信息 ,引入优先拆卸方向的概念 ,通过局部配合约束表和干涉表的搜索 ,获得符合要求的装配序列。     

Integrated knowledge-based assembly sequence planning

This paper presents a novel approach and system for the automatic generation, selection and evaluation, optimisation, and simulation of assembly plans. The information and knowledge about a product and its assembly (e.g. assembly constraints, solid model and CAD database, heuristic rules) are described using a hybrid approach and model with numeric and symbolic representation. A new methodology is presented to generate all feasible assembly sequences of the product by reasoning and decomposing the feasible subassemblies, and representing them by the assembly Petri net modelling. Qualitative strategic constraints are then used to evaluate the feasible assembly sequences. In order to obtain a good assembly sequence, some quantitative criteria such as assembly time and cost, workstation number, operator number, and part priority index are applied to select the optimal assembly sequence. Based on DFA analysis, MTM time analysis, and assemblability analysis, estimates are made of the assembly time and cost of the product when each of these sequences is used. A knowledge-based system KAPSS has been developed to achieve the integration of generation, selection evaluation, and visualisation of the assembly sequences.     

An effective integration approach toward assembly sequence planning and evaluation

An integration strategy for assembly sequence planning and sequence scheme evaluation is proposed. This strategy can be used to plan a reasonable assembly sequence, to optimize a sequence scheme, and to predict whether a collision will occur between the assembly tool and assembled components by considering factors like target components and assembly resources. A hybrid method is presented for assembly sequence modeling that combines human-computer interactive operations to manually build a hierarchical assembly sequence main model and a hybrid graph method to automatically generate sub-assembly sequence schemes of the main model. An optimization algorithm based on time-cost is introduced to handle a best candidate components selection. This relieves the problem of limited capability found when handling large size assembly models with traditional methods. The essential issues involved in system implementation are discussed as well; these include a representation method for the assembly consequence model, an optimization model of assembly sequence planning, and an object-oriented system architecture model employed with multi-agent technology for visually evaluating the assembling process. This system, KM computer-aided assembly process planning, KMCAAPP, has been developed on the basis of our previous work, KMCAD3; KMCAAPP uses the presented approach. KMCAAPP can be integrated with CAD model from KMCAD3D. A case study shows that the presented approach can use large CAD assembly models and delivers a feasible and effective way to integrate the assembly sequence planning process with scheme evaluation by visually evaluating the assembling process. This allows the identification of design errors in a timely manner and mitigates economic loss.     

面向装配工艺规划与仿真的装配工具信息模型的研究

详细论述了装配工具信息模型建立的方法,研究了建立装配工具信息模型的相应策略,并以Pro/E为平台建立了相应的装配工具库系统并给出了搜索工具的算法流程.     

一种基于遗传算法的装配序列优化方法

基于遗传算法建立了装配序列生成模型,对装配序列进行优化生成。为提高优化效率,该算法将装配方向作为已知数据给出,并引入子装配体进行分层规划。最后,以蜗轮减速器装拆序列规划为实例验证该方法的有效性。     

基于减速器的装配序列规划方法研究

针对减速器产品分析出零件之间存在众多种装配序列,随着装配单元数量的增加,从而产生组合爆炸或大量的交互问答.为了解决这个问题,对减速器的结构进行了分析,并结合减速器的工作原理,提出了专家系统在解决问题具有的优势,根据关系数据库的特点,将装配知识存储在齿轮减速器知识库中并结合推理机及其推理算法,利用标准数据查询语言来对知识库进行正向推理.从而降低了装配序列规划的计算复杂度,保证规划所得装配序列的可行性和实用性.     

面向装配序列规划的装配成本评价研究

针对装配序列的特点提出了一个装配成本评价的模型,认为装配成本与产品装配过程中装配方向的变化次数,产品组成零件装配后的运动不确定度总和有关.提出了基于零件的装配方向矩阵确定装配方向变化次数的方法,并根据装配基础件确定零件装配后的运动不确定度.采用了基于优先关系矩阵的干涉推理方法检验装配序列的可行性,并计算装配序列中可能产生的装配干涉数目,最后用实例验证了所提模型的有效性.     

装配工艺规划后处理的研究与应用

装配工艺规划是产品装配活动中的一个关键环节 ,直接影响着产品的质量和装配费用。计算机辅助装配工艺规划 (CAAPP ,ComputerAidedAssemblyProcessPlanning)在一定程度上提高了装配工艺规划的效率 ,然而它并不能完成装配工艺规划中的所有活动。装配工艺规划后处理是装配工艺规划的重要组成部分 ,它作为CAAPP的有效补充 ,利用计算机辅助手段进一步提高了装配工艺规划的自动化水平。本文提出了装配工艺规划后处理的体系结构 ,并从装配信息建模、装配工艺文件的生成和装配资源共享与信息转换三个方面对其关键技术进行了较为系统的研究     

A hierarchical approach to disassembly sequence planning for mechanical product

An important aspect of design for the life cycle is assessing the disassemblability of products. This paper presents a novel approach to automatic generation of disassembly sequence from hierarchical attributed liaison graph (HALG) representation of an assembly through recursively decomposing the assembly into subassemblies. In order to increase the planning efficiency, the HALG is built according to the knowledge in engineering, design and demanufacturing domains. In this method, the boundary representation (B-Rep) models are simplified by removing the hidden surfaces to reduce the computational complexity of disassembly planning. For each layer of HALG, the subassembly selection indices defined in terms of mobility, stability, and parallelism are proposed to evaluate the extracted tentative subassemblies and select the preferred subassemblies. To verify the validity and efficiency of the approach, a variety of assemblies including some complicated products are tested, and the corresponding results are presented.     

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。     

基于Pro/E的三维辅助装配工艺规划系统研究

分析了现有计算机辅助装配工艺规划系统的不足,提出了三维辅助装配工艺规划系统的体系结构,并对其中装配模型信息表达、装配序列规划、路径规划、装配过程动画等关键技术进行了研究。基于Pro/E平台,建立修正的装配层次模型,并交互生成装配序列;通过确定装配路径上的关键点及关键点之间的位姿,进行装配路径规划和装配干涉检测。此提出的系统可以通过三维工艺简图和装配过程动画,形象、直观地指导现场装配。     

基于改进蚁群算法的装配序列规划研究

装配序列规划能解决装配过程中所出现的速度和质量问题,降低生产成本。通过考虑装配影响因素,对装配体零件之间关系进行数学建模,提出一种解决该问题的改进蚁群算法。算法提出用加强装配关系矩阵来表示零件之间存在的强约束关系;用加强随机状态转移规则,使蚂蚁能更快地寻找到最优或者近优解;完善信息素更新规则,使算法能更好的利用正反馈机制。通过实例证明,该改进型算法能实际有效地解决装配序列规划问题。     

A geometric constraint solver for 3-D assembly modeling

In this paper, we propose a geometric constraint solver for 3-D assembly applications. First, we give a new geometry and constraint expression based on Euler parameters, which can avoid singular points during the solving process and simplify constraint types. Then we present a directed graph based constructive method to geometric constraint system solving that can handle well-, over- and under-constrained systems efficiently. The basic idea of this method is that it first simplifies the constraint graph by pruning those vertices which have only in-arcs from the graph and then reduces the size of strongly connected components (SCCs) left in the graph by DOF-based analysis. The method can solve all kinds of configurations including closed-loops. After that, we apply a hybrid numerical method of Newton–Raphson and Homotopy to solve under-constrained systems. The hybrid method makes use of the high efficiency of the Newton–Raphson method as well as the outstanding convergence of the Homotopy method. Finally, we give a practical example and conclusion.     

产品装配顺序规划方法的研究

计算机辅助装配顺序规划是有关产品装配研究的重要内容。在提高装配顺序规划质量的条件下，综合拆分法与优先约束法的优点，提出了一种装配顺序规划的新方法。在子装配、组件预识别的基础上，采用割集法将产品进行拆分。基于装配城信息建立零件几何优先关系，基于产品共性特征及个性特征建立工艺优先关系，最终生成合理可行的装配顺序，并对实例进行分析。     

基于模型检验集成规划系统的机械装配序列规划

为探索机械装配序列规划的新技术,剖析了模型检验集成规划系统和规划领域定义语言,根据一般智能规划问题的形式化定义对机械装配序列规划问题进行了形式化描述;基于装配和拆卸可逆的前提假设,利用谓词逻辑公式和时态逻辑公式对机械装配过程中的硬约束和软约束进行了描述;根据装配序列规划问题的形式化描述,对装配序列规划领域及领域的具体问题进行了定义,给出了基于模型检验集成规划系统的装配序列规划问题的求解过程.实验结果表明,该系统可以正确、有效地实施机械装配序列规划.     

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.     

Integrated assembly and machining planning for electronic products using a genetic algorithm approach

To produce an electronic product, both assembly operations and machining operations are required in the process plan. In most cases, the assembly operations and machining operations need to be combined in a continued order with an integrated sequence. This is different from the traditional process planning approaches in which machining operations and assembly operations are separated as two independent tasks with no interactions. For an electronic product, the two types of operations and the associated costs may affect each other in an interactive way. Therefore, the sequence planning of assembly operations and machining operations must be analyzed with an integrated model. In this research, a graph-based model is presented to represent the assembly and machining operations in an integrated model. The related operation cost functions are developed to evaluate the costs for the integrated assembly and machining sequences. The integrated sequence planning problem is solved using a genetic algorithm approach with an objective of lowest operation costs. As a result, the assembly operations and machining operations can be planned in an integrated sequence suitable for producing electronic products. The result shows that the developed method using the genetic algorithm approach is efficient for solving the integrated sequence planning problem. Example products are demonstrated and discussed.     

水平井牵引机器人虚拟装配规划研究

快捷的装配工艺是水平井牵引机器人使用与维护的有力保障.结合机器人的结构特点,研究装配顺序与装配路径规划方法,并针对自主研制的水平井牵引机器人,开发虚拟装配规划系统,验证规划算法的有效性.