产品装配分析环境的构建

采用Visual C 编程语言，在现有CAD系统的基础上，以Object ARX为开发工具，建立了产品装配分析系统基本结构，可直观演示人机交互拆、装过程，分析装配几何体设计中的缺陷，提取相关装配特征信息，进行装配顺序分析和工艺规划。在Open Inventor虚拟现实软件开发包的基础上，开发了虚拟装配环境，构建了虚拟装配系统的结构框架，实现了从CAD环境到虚拟装配环境产品几何模型数据的传递，演示了产品在虚拟环境下的拆卸过程。     

A green assembly sequence planning model with a closed-loop assembly and disassembly sequence planning using a particle swarm optimization method

In a green product life cycle, it is necessary to determine how to disassemble a product before the product is planned to be assembled. In this research, a green assembly sequence planning model is developed. A closed-loop assembly sequence planning model is presented by integrating assembly and disassembly sequence planning models. For an assembled product, an assembly sequence planning model is required for assembling the product at the start, while a disassembly sequence planning model is performed for disassembling the product at the end. In typical assembly and disassembly sequence planning approaches, the two sequences are independently planned and evaluated. In this paper, a closed-loop model is presented to concurrently generate and evaluate the assembly and disassembly sequences. First, a graph-based model is presented for representing the feasible assembly sequences and disassembly sequences. Next, a particle swarm optimization (PSO) method with a new encoding scheme is presented. In the PSO method, the assembly and disassembly sequences can be simultaneously represented and evaluated with an objective of minimizing the total of assembly costs and disassembly costs. The test results show that the presented method is feasible and efficient for solving the integrated assembly and disassembly sequence planning problem. An example product is illustrated and discussed.     

A multi-plant assembly sequence planning model with integrated assembly sequence planning and plant assignment using GA

In a multi-plant collaborative manufacturing system, the manufacturing operations and assembly operations for producing a product can be distributed at different plants at various locations. The components are assembled with assembly operations performed in a multi-plant assembly sequence. In this research, a multi-plant assembly sequence planning model is presented by integrating (1) assembly sequence planning, and (2) plant assignment. In assembly sequence planning, the components and assembly operations are sequenced according to the assembly constraints and assembly cost objectives. In plant assignment, the components and assembly operations are assigned to the suitable plants to achieve multi-plant cost objectives. The feasible assembly sequences are generated using the developed graph-based models of assembly precedence graphs and matrices. A genetic algorithm (GA) method is presented to evaluate the multi-plant assembly sequences with an objective of minimizing the total of assembly operational costs and multi-plant costs. The main contribution lies in the new model for multi-plant assembly sequence planning and the new GA encoding scheme for simultaneous assembly sequence planning and plant assignment. Example products are tested and discussed. The test results show that the presented method is feasible and efficient for solving the multi-plant assembly sequence planning problem.     

基于虚拟技术的装配工艺设计系统研究

介绍了基于虚拟技术的三维计算机辅助装配工艺设计系统,提出了3D-VAPP系统的体系结构;并对CAD模型的数据转换、可视化装配顺序和装配路径规划、装配过程动态模拟验证、装配工艺知识维护、装配工艺文件管理等一系列关键技术及解决方案进行了论述;尤其提出了一种基于多层次面片机械模型的精确碰撞检测算法及装配过程多角度观察镜头自动切换算法流程。最后,给出了系统进一步研究的趋势。     

A pragmatic system to support interactive assembly planning and training in an immersive virtual environment (I-VAPTS)

Assembly planning for complex products is a difficult task requiring both intensive knowledge and experience. Computer aided assembly planning (CAAP) systems have been the subject of considerable research in recent years without achieving a wide application in manufacturing industry. In this paper an alternative approach to the generation of an optimal assembly planning scheme is presented based on the adoption of immersive virtual reality. A product is assembled from CAD models by providing a CAD interface to transfer assembly constraint information from the CAD system to a virtual environment. In the virtual environment an efficient dynamic recognition and management method based on surface geometry is employed, and a process-oriented assembly task model is established to support interactive assembly planning and evaluation. The system is implemented using an object oriented methodology, and has been successfully applied to train and guide the assembly workers in a pump assembly process.     

A model-based approach to assembly sequence planning

This paper presents a systematic approach for automatic assembly sequence planning (ASP) by using an integrated framework of assembly relational model (ARM) and assembly process model (APM), which are established by object-oriented method. ARM, consisting of assembly, components and liaisons, is the static model of assembly to describe the geometric relationships between components in terms of contact, constraint and interference matrixes. APM, containing states and sub-processes, is the dynamic model of assembly to represent all potential alternatives in assembly process. An algorithmic procedure is also presented by which APM of an assembly can be constructed systematically by analyzing states from lower levels to higher levels. Through the procedure, all feasible sequences of a product can be generated, and the optimum one can be determined by further evaluating each sequence. To explain the approach more clearly, a practical assembly with five components is used as an illustration in the paper.     

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.     

集成三维设计模型的装配顺序规划

装配顺序规划是研究和开发计算机辅助装配工艺设计系统,实现产品装配设计过程和装配工艺设计过程有效集成的关键技术。研究了CAD模型中装配设计信息提取、子装配体识别法和拆卸法综合应用的装配顺序规划、基于装配结构树的装配设计与工艺集成数据接口的定义等相关技术。在这些研究的基础上,借助国产三维CAD平台CAXA的二次开发平台和XML技术,对以上技术进行了实现。最后,以电机产品为研究对象,给出了相关实例。     

在EMPOWER中实现雷达的虚拟装配

虚拟装配技术是虚拟制造技术在设计和制造业中的重要应用领域之一。文中阐述了虚拟装配的原理和过程,以雷达产品中的天线座系统为对象,对其装配顺序进行规划,实况装配零件和部件,实现装配过程仿真。为虚拟装配技术在雷达产品中的应用做了初步的尝试和探索。     

A flexible microassembly system based on hybrid manipulation scheme for manufacturing photonics components

In this paper, a flexible microassembly system based on hybrid manipulation scheme is proposed to apply to the assembly of photonics components such as lensed optical fiber ferrules and laser diode (LD) pumps. In order to achieve both high precision and dexterity in microassembly, we propose a hybrid microassembly system with sensory feedbacks of vision and force. This system consists of the distributed six degrees of freedom (DOF) micromanipulation units, the stereomicroscope, and haptic interface for the force feedback-based microassembly. A hybrid assembly method, which combines the vision-based microassembly and the scaled teleoperated microassembly with force feedback, is proposed. The feasibility of the proposed method is investigated via experimental studies for assembling micro-optoelectrical components. Experimental results show that the hybrid microassembly system is feasible for applications to the assembly of photonic components in the commercial market with better flexibility and efficiency.     

计算机辅助创新技术驱动的产品概念设计与详细设计集成研究

针对计算机辅助创新(Computer-aided innovation,CAI)技术提出的创新概念方案不能顺利地输出给CAD系统的问题,从分析具备产品的功能信息及结构信息的CAD装配结构模型入手,通过建立产品装配结构的信息模型图,分析并确定装配模型存在的问题和冲突,然后应用计算机辅助创新(CAI)技术驱动的知识工程(Knowledge based engineering,KBE)及语义处理技术集成的创新技术进行解决,进而驱动产品结构设计,创新性地解决装配结构中存在的问题,形成从构思创新方案产生-形成知识-驱动结构设计的有机创新过程,初步实现了概念设计与详细设计的集成。进而建立了计算机辅助创新(CAI)技术驱动的产品概念设计和详细设计的集成过程模型,通过无磨损蝶阀产品的创新案例验证了该模型的可行性。     

基于结构造型技术的三维CAD系统的研究

结构造型技术通过改进现有特征造型方法和产品模型表示法,实现了装配模型与零件模型的统一.论述了结构造型技术的基本概念、性质和设计原则,提出了基于结构造型的CAD软件架构和建模方法,并详细讨论了产品模型的维护策略和流程控制方法.该方法已用于KMCAD3D系统,实践证明该系统可以有效地维护设计意图,简化模型维护算法;人机交互操作步骤少,避免了重复数据输入,与传统特征造型系统相比,设计效率提高2～3倍.     

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.     

机器人装配状态变迁控制的同步Petri网模型

采用同步Petri网对机器人自动化装配过程进行建模 ,更加全面地反映了装配状态变迁过程中的力 /位姿信息特征 ,在此基础上研究了任务级上装配状态变迁路径的评价方法及优化算法 ,该方法可用于指导产生具体的装配命令并可在不确定性存在时收敛到最终装配状态。     

车床主轴箱装配工艺自动设计的研究

介绍了对车床主轴箱进行计算机辅助装配工艺设计（ＣＡＡＰＰ）的研究。文中分析了装配工艺自动设计系统的结构，提出了装配信息的描述方法，讨论了装配顺序自动决策的原理及具体实现方法。     

基于分层有向图的装配顺序规划方法

航空产品装配结构复杂,装配单元繁多,其装配顺序规划的难度较大.基于割集法对航空产品进行规划易产生图爆炸现象,因此,采用分层有向图表示装配模型,提出一种将装配模型逐层拆解,逐步规划,组合形成产品装配顺序的方法.并以某型机翼为实例予以应用验证.     

Unification of the a priori inconsistencies checking among assembly constraints in assembly sequence planning

Sequence planning generation is an important problem in assembly line design. A good assembly sequence can help to reduce the cost and time of the manufacturing process. This paper focuses on assembly sequence planning (ASP) known as a hard combinatorial optimization problem. Although the ASP problem has been tackled via even more sophisticated optimization techniques, these techniques are often inefficient for proposing feasible assembly sequences that satisfy the assembly planners’ preferences. This paper presents an approach that makes easier to check the validity of operations in assembly process. It is based on a model of the assembly planners’ preferences by means of strategic constraints. It helps to check a priori the consistency of the assembly constraints (strategic and operative constraints) given by the assembly system designers before and while running an assembly plan generation algorithm. This approach reduces the solution space significantly. A case study is presented to demonstrate the relevance of the proposed approach.     

装配序列评价研究

以同层装配单元的几何可行装配序列为评价对象,提出了装配序列评价指标体系,分析了指标因素的内涵;在实现评价序列对基于单因素装配性能优良的隶属度计算的基础上,通过二级模糊综合评价,获得装配序列总体评价结果。该评价方法的实现,提高了装配序列优选的自动化水平。     

面向大型产品装配序列规划的分类方法研究

讨论了在对大型产品进行装配序列规划时 ,为了简化装配序列产生过程 ,需要对待装配大型产品按操作复杂度分成两类 ,即复杂装配部分和简单装配部分 ,复杂部分进行虚拟装配规划 ,简单部分进行自动装配规划。分类时 ,首先对装配产品进行子装配体识别以得到组件 ,然后利用分类算法将组件分为两类。     

Mechanical Product Disassembly Sequence and Path Planning Based on Knowledge and Geometric Reasoning

A feature-based assembly model is proposed for disassembly sequence planning, and establishing a correct and practical disassembly path for the part in the product, based on geometric reasoning and knowledge. The fundamental assembly modelling strategy for a product is based on the mating features of its parts. An algorithm is introduced which uses the information provided by the mating features of parts in the product to find the candidate parts for disassembly and to carry out disassembly path planning. A complete and accurate interference checking approach is used to ensure no global collision while disassembling a part. In some cases, it cannot be implemented by geometric reasoning alone, so a set of criteria and heuristic rules based on knowledge, constraints, relationships among parts, and quantitative disassemblability assessment are used. It can also be carried out interactively by the user when necessary. The proposed method is integrated with the CAD model of the product. The user can visually disassemble the product while planning, so it is easier to carry out the disassembly planning and generate an optimal sequence.