集成环境下基于割集的装配顺序生成算法研究

在分析总结以往学者对装配顺序规划研究的基础上,综合拆卸法和优先约束法的特点,探讨了一种新的装配顺序分析方法,该方法利用产品的装配域信息,根据图论的割集法对产品进行拆分,建立几何优先约束关系,然后通过人机交互的方式建立工艺优先约束关系,最终得到可行的产品装配顺序。实现了集成环境下基于割集的装配顺序规划。给出了割集的生成算法框图以及装配顺序规划的算法框图,最后通过实例验证。     

集成环境下基于CAD产品装配顺序规划

在分析总结以往学者对装配顺序规划的研究基础上，综合拆卸法和优先约束法的特点，探讨了一种新的装配顺序分析方法，该方法利用产品的装配域信息，根据图论的割集法对产品进行拆分，建立几何优先约束关系，然后通过人机交互的方式建立工艺优先约束关系，最终得到可行的产品装配顺序。实现了集成环境下基于CAD产品装配顺序规划。本文给出了割集的生成算法框图以及装配顺序规划的算法框图，最后通过实例验证。     

计算机辅助几何可行装配顺序推理及其优化分析

针对装配优先关系分析、几何可行装配顺序推理以及最优几何可行装配顺序选择3个层次的问题,提出了一种系统化的分析方法——几何约束分析方法。该方法从装配体中各个零件之间的约束方向分析出发,可以自动求解出正确和完备的装配优先关系在装配优先关系的约束下,可以计算出所有的几何可行装配顺序规划;并从操作空间大、装配方便角度出发,设计出几何可行装配顺序优选算法,可以从大量的几何可行装配顺序中求解出几何性能最佳的装配顺序规划。应用具体实例分析演示了几何约束分析方法在计算机中的实现过程,并证实了该方法的实用性和有效性。     

计算机辅助几何可行装配顺序推理及基优化分析

针对装配优先关系分析,几何可行装配顺序推理以及最优几何可行装配顺序选择3个层次的问题,提出了一种系统化的分析方法-几何约束分析方法,该方法从装配体中各个零件之间的约束方向分析出发,可以自动求解出正确和完备的装配优先关系;在装配优先关系的约束政下,可以计算出所有的几何可行装配顺序规划;并从操作空间大、装配方便角度出发,设计出几何可行装配顺序优选算法;可以从大量的几何可行装配顺序中求解出几何性能最佳的装配顺序规划,应用具体实例分析演示了几何约束方法在计算机中的实现过程,并证实了该方法的实用性有效性。     

装配顺序规划中的几何约束分析方法

针对目前计算机辅助装配顺序规划中存在的问题，提出了一种几何约束分析方法。该方法根据装配结构设计ＣＡＤ信息，利用ＧＣＡ最小约束装配状态算法，能够计算出正确、完备的装配优先关系，为进一步提高装配顺序规划的自动化水平和分析效率提供了一种有效途径。     

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.     

几何可行装配顺序推理方法及实现技术

在系统分析相关文献的基础上，重点针对装配优先关系推理和几何可行装配顺序计算，提出了一种系统化的分析方法－“几何约束分析”方法。该方法从装配体中各个零件之间的约束方向计算出发，可以自动求解出装配结构本身所固有的、隐含的装配优先关系，而且能够保证推理结果的正确性和完备性。在此基础上，设计出几何可行装配顺序的反向推理算法，并结合实例分析了基于几何约束分析方法的装配优先关系推理，及几何可行装配顺序推理的计     

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.     

装配规划中基于割集的装配顺序生成方法

针对装配规划提出一种新的装配零件关系的描述方法，该方法应用改进的关联图－优先约束关联图，描述装配零件间的连接关系、优先关系及约束关系。在生成产品装配顺序时，充分地把装配优先关系与割集法副合到装配顺序搜索中，有效地生成产品所有满足装配条件的装配顺序，为装配规划提供参考的装配工艺路径。     

计算机辅助装配顺序规划研究综述

首先对装配顺序的分类进行了综述,然后基于装配顺序规划的系统结构,从产品装配建模方法,装配顺序的产生,表示,评价及优化等角度,对目前该领域的国内外研究现状进行了分类和剖析,最后总结出今后计算机辅助装配顺序规划的研究发展方向。     

虚拟装配工艺规划实现技术研究

对虚拟环境下的产品装配工艺规划进行了研究,分析虚拟环境下面向集成的装配工艺规划系统结构。对虚拟装配工艺规划的三个核心问题(装配模型、装配序列规划和装配路径规划)进行描述,提出虚拟环境下面向工艺设计的产品装配模型总体结构。给出虚拟环境下装配约束关系的识别方法,实现了零部件基于约束的三维空间导航运动。建立原型系统,能够为虚拟环境下的装配工艺规划奠定基础。     

面向印刷机械的虚拟装配系统研究与开发

分析了虚拟装配系统的功能结构，建立了基于配合特征的集成装配模型，采用几何推理和装配知识相结合的方法进行装配序列规划，实现了三维环境下的交互式装配工艺规划与仿真。最后，给出了该系统在某输纸机构装配中的应用实例。     

多工位装配序列粒子群优化算法

针对传统单工位装配序列求解上的不足,将粒子群算法应用于多工位多目标装配序列优化的求解,提出一种面向复杂多工位产品的装配序列优化方法。采用优先序列图(Assembly precedence graph,APG)来描述零件间的优先约束关系,构建优先关系矩阵、装配干涉矩阵、工位能力表和装配信息表,描述装配部件干涉及工位之间的关系;给出粒子群算法编码体系和装配关系算法模型表达方法;综合考虑装配操作成本、装配工具更换成本和装配夹装变更成本和运输成本的影响,提出有工程意义的适应度函数的表达式;根据APG生成随机的可行初始装配序列,并利用粒子群算法(Particle swarm algorithm,PSO)对装配序列和装配工位进行优化。以飞机起落架装配序列规划实例验证多工位粒子群装配序列优化算法有效性。     

Assembly sequences merging based on assembly unit partitioning

Assembly sequence planning is a typical of combinatorial optimization problem which is difficult to be tackled when the number of parts of assembly becomes large. To reduce the searching space of assembly sequence planning of complex products, assembly sequences merging based on assembly unit partitioning is suggested. Assembly unit partitioning is presented to decompose the complex products into a group of assembly units containing a reduced number of parts or components, and the assembly design constraints and the assembly process constraints are comprehensively taken into account. The global optimal assembly sequences can be acquired through three steps. Firstly, the assembly units and decision graph of assembly unit are generated utilizing fuzzy analytical hierarchy process approach. Secondly, the optimal or near-optimal subsequences of assembly units can be obtained with current efficient methods of assembly sequence planning. Thirdly, under the assembly interference of assembly relations (geometrical constraints) of the whole products and the assembly precedence concluded by subsequences of assembly units, the assembly sequence merging is implemented to generate the global assembly sequences, and the optimal sequence is obtained through assembly sequences evaluation. The assembly constraints considered at the two previous steps is represented by the evaluation function. The effectiveness of the method is verified by an illustrative example and the results show that the searching space of assembly sequence merging of complex products is reduced remarkably and the optimal assembly sequence of the whole produces is obtained.     

Universal mechanism modeling method in virtual assembly environment

Motion simulation and performance analysis of mechanism are important methods for analyzing assembly quality after finishing assembly simulation in virtual assembly environment. However, most simulation systems have no function of mechanism motion simulation due to the randomicity of mechanism and lack of universal mechanism modeling method. In order to realize the simulation of any mechanism after finishing assembly simulation in a virtual environment, a new universal mechanism modeling method is presented. Two main models are contained in the mechanism model: information model and mathematical model. Firstly, the information model of mechanism is proposed to describe the data structure of mechanism which contains bottom geometry data, information of constraint, link, kinematic pair and physical data. Because the object of mechanism simulation is the assembly, which is assembled during the process of assembly simulation, the information of mechanism can be obtained automatically through mechanism automatic search method. Secondly, mathematical model of mechanism is presented. The mathematical model uses mathematical method to express the mechanism. In order to realize the automatic expression of any random mechanism, basic constraint library is presented, consequently random mechanism can be described based on the basic constraint library. Finally, two examples are introduced to validate the method in the prototype system named VAPP(Virtual Assembly Process Planning). The validation result shows that the mechanism modeling provides a universal modeling method for mechanism motion simulation in virtual assembly environment. This research has important effect on the development both of mechanism motion simulation and virtual assembly.     

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     

A systematic approach for automatic assembly sequence plan generation

This paper presents a systematic approach for automatic assembly sequence plan generation (ASPG) by using an integrated framework of the part liaison matrix and precedence Boolean relations. The objective of this study is to propose a unified and integrated mathematical representation, manageable by computer programs, that allows an optimal assembly sequence be generated for various different production conditions and environment. To meet the aforementioned objective, a five-step modelling procedure is presented. In the first step, the product design and production information associated with part allocations and assembling sequences are logically arranged, simplified and systematically coded into the liaison matrix and precedence Boolean algebraic expression. In the second step, the position and assembly sequence relations of the original product are simplified into the so-called sub-assembly by using a group-like technology method. By doing so, the liaison matrix and precedence Boolean relation of the grouped sub-assemblies can then be easily obtained in the third modelling step. In the fourth modelling step, the constrained precedence Boolean relations of the grouped sub-assemblies are characterised and generalised for use in the proposed model. By simultaneously solving the aforementioned general and constrained position and precedence Boolean relations, the optimised assembly sequence of the underlying product can be quickly obtained in the fifth modelling step. A product assembly example is presented to illustrate the effectiveness of the proposed modelling approach. The enhancement of assembly efficiency and quality are also carefully evaluated .     

RESEARCH OF MOVEMENT NAVIGATION BASED ON ASSEMBLY CONSTRAINT RECOGNITION

0 INTRODUCTIONThe traditional assembly design stresses the final result of assembly modeling, but pays little attention to the process of assembly simulation. Nonetheless, the procedure of assembly is a cardinal element that determines the quality of assembly modeling. These drawbacks hinder the advancement of the speed and quality of assembly design. Moreover, in the traditional mode of product development, designers make prototypes to evaluate the function and appearances of products. P…