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基于关联矩阵消元法的机构自动搜索算法 总被引:1,自引:0,他引:1
为解决仿真环境下运动机构的自动搜索及机构信息的提取问题,提出了一种基于关联矩阵消元法的机构自动搜索算法.该算法建立零部件关联矩阵,通过对关联矩阵中非零元素的消元处理,实现了对所有已装配零部件和运动副的遍历,进而实现了装配体中运动机构的自动搜索和机构数量的计算,以及属于同一机构的零部件和运动副等机构信息的识别和提取,为机构运动仿真分析提供了条件,提高了自动化程度.开发了原型系统虚拟装配工艺规划软件,对所提算法进行了验证. 相似文献
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基于物理属性的虚拟装配过程 总被引:4,自引:0,他引:4
针对虚拟装配系统中存在仿真程度不够高的缺点,提出基于物理属性的虚拟装配过程研究。通过分析虚拟装配过程对零部件物理属性的需求,建立零部件物理属性模型,给出确定零部件各物理属性以及自由运动状态的方法,分析碰撞响应对运动状态的影响。研究虚拟装配系统中装配对象间的交互过程,使用多刚体系统动力学分析方法对零部件装配过程中的动力学以及运动学进行分析,给出装配对象的运动学与动力学方程。通过把抽象的约束关系转换为基本约束方程表达运动副约束,并把运动副约束用于装配对象的运动分析。提出基于碰撞与静力学的稳态分析方法研究零部件达到稳定状态的条件。应用实例表明上述方法有效可行。 相似文献
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探讨了在虚拟环境中进行复杂机械产品运动分析时CAD装配模型向机构模型转化的信息识别。首先在总结CAD装配系统提供的各种装配约束类型与其相对应的运动几何元素基础上,给出了平移和旋转自由度的归约规则,根据简单运动副约束与运动自由度及运动几何元素的映射关系,实现从零部件装配信息到运动分析用的构件和简单运动副信息的转换。 相似文献
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通过分析虚拟装配环境的结构及性能,针对场景图数据结构在虚拟装配应用中的不足,定义了一种基于知识的层次对象时间Petri网,并用于建立虚拟装配环境的应用层模型。该模型以虚拟手的位姿作为输入,运行后输出具体的操作事件更新场景图,完成装配活动,以满足虚拟装配环境的实时和并发等动态性能要求,实现了虚拟装配大量离散事件的处理及装配意图的响应。给出了基于知识的层次对象时间Petri网的产品装配模型表达,不仅表达了产品结构及装配关系,同时记录零部件在装配过程中的方位及约束状态等动态信息,从而在虚拟装配环境中实现了装配与拆卸并存的实际装配活动。此外,还给出了由产品装配层次图生成的基于知识的层次对象时间Petri网装配模型的算法,说明了基于应用层模型的装配、拆卸操作以及装配过程仿真,开发了原型系统。 相似文献
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支持虚拟装配的装配约束关系信息动态生成 总被引:3,自引:0,他引:3
分析了虚拟装配规划中装配模型重构对装配约束关系信息的需求,提出了装配约束关系信息动态生成的处理技术.通过分析装配特征及装配特征信息,建立了基于装配特征的装配关系模型.将装配约束关系信息以零件为单位构建零件装配约束关系集,以子装配体内所有零件装配约束关系集为集合元素,构建子装配体装配约束关系集族.通过子装配体装配约束关系集族的"广义并集"与"广义交集"的差运算,获取子装配体与其外部零件之间的装配约束关系信息;通过子装配体或装配体的装配约束关系集族的"广义交运算",并利用装配约束二元关系的传递性,获得零件之间未定义的装配约束关系信息,从而实现装配关系模型信息的动态生成,以支持虚拟装配中装配模型的重构、装配规划和装配仿真. 相似文献
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针对商品化CAD系统与虚拟装配系统之间装配信息的转换问题,根据CAD系统中装配信息的表达形式,提出了一种获取装配信息的算法,实现了Pro/E中装配信息的自动提取,并依据Pro/E中装配信息的数据结构和虚拟装配系统的功能要求,设计了一种适用于虚拟装配系统的装配数据结构,较好解决了Pro/E与虚拟装配系统之间的装配信息集成问题,提高了虚拟装配的效率。 相似文献
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为保证虚拟装配操作的精度和效率,提出了一种准确高效的用户装配意图捕捉算法.给出了虚拟装配环境中约束模型的表达和建模方法,引入约束元素包围盒的概念,并提出了其构造原则及方法.将约束元素包围盒的相交测试作为装配意图捕捉算法的入口,根据约束元素和自由度之间的映射关系,提出了约束多层识别算法来判断约束元素之间的装配约束类型,并通过设置约束元素优先级和利用约束元素间的进给增量比较策略来实现约束的智能确认.最后,使用时间花费代价函数表征装配意图捕捉算法的计算效率.通过某航天产品中的装配实例验证了所提算法的有效性. 相似文献
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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. 相似文献
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《机械工程学报(英文版)》2010,(6)
Currently,virtual assembly technology has attracted increasing attention due to considerations of solving assembly problems in virtual environment before actual assembly in manufactory.Previous studies on kinematic analysis of mechanism only aim at analyzing motion law of single mechanism,but can not simulate the multi-mechanisms motion process at the same time,let alone simulating the automatic assembly process of products in a whole assembly workshop.In order to simulate the assembly process of products in an assembly workshop and provide effective data for analyzing mechanical performance after finishing assembly simulation in virtual environment,this study investigates the kinematics analysis of mechanisms based on virtual assembly.Firstly,in view of the same function of the kinematic pairs and the assembly constraints on restricting the motion of components(subassembly or part),the method of identifying kinematic pairs automatically based on assembly constraints is presented.The information of kinematic pairs can be obtained through calculating the constraint degree of the assembly constraints.Secondly,the incidence matrix eliminating element method is proposed in order to search the information and establish the models of mechanisms automatically after finishing assembly simulation in virtual environment.Both methods have important significance for reducing the workload of pretreatment and promoting the level of automation of kinematics analysis.Finally,the method of kinematics analysis of mechanisms is presented.Based on Descartes coordinates,three types of kinematics equations are formed.The parameters,like displacement,velocity,and acceleration,can be obtained by solving these equations.All these data are important to analyze mechanical performance.All the methods are implemented and validated in the prototype system virtual assembly process planning(VAPP).The mechanism models are established and simulated in the VAPP system,and the result curves are shown accurately.The proposed kinematics analysis of mechanisms based on virtual assembly provides an effective method for simulating product assembly process automatically and analyzing mechanical performance after finishing assembly simulation. 相似文献
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基于约束的虚拟装配技术研究 总被引:1,自引:3,他引:1
为了实现基于约束的虚拟装配操作,给出了虚拟环境中装配约束的统一表达方法,以及约束与自由度的等价关系和运动自由度的归约等,提出了一套虚拟装配中的约束处理算法。首先,利用装配关系自动识别算法,判断两个零件几何约束元素之间的位姿关系是否在给定的误差范围内;其次,使用定位求解算法,使主动体零件在满足已经确认约束的基础上,以最小的位姿调整量满足新约束;最后,提出了基于广义坐标系的运动导航算法,根据装配零件满足的约束对其运动进行引导。这些算法已经应用于集成虚拟装配环境的系统中,实践证明它们能很好地支持集成虚拟装配环境的约束处理,实现了虚拟装配过程与实际装配过程的高度统一。 相似文献
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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。 相似文献
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Yang Rundang Wu Dianliang Fan Xiumin Yan Juanqi 《Frontiers of Mechanical Engineering in China》2007,2(2):243-249
To realize a constraint-based virtual assembly operation, the unified representations of the assembly constraint, the equivalent
relation between the constraint and the degree of freedom (DOF), and the movement DOF reduction in a virtual environment are
proposed. Several algorithms about the constraint treatment are submitted. First, the automatic recognition algorithm based
on the assembly relation is used to determine the position and orientation relation between two geometry elements of constraint
whether they meet the given errors. Second, to satisfy the new constraint, according to the positing solving algorithm, the
position and orientation of an active part are modified with minimal adjustment after the part has satisfied the affirmed
constraints. Finally, the algorithm of movement navigation based on the generalized coordinate system is put forward, and
the part movement is guided. These algorithms have been applied to the integrated virtual assembly environment (IVAE) system.
Experiments have indicated that these algorithms have well supported constraint treatments in the IVAE and realized the closer
combination of the virtual and the real assembly processes.
Translated from Computer Integrated Manufacturing Systems, 2006, 12(3): 413–419 [译自: 计算机集成制造系统] 相似文献
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基于约束解除的装配序列并行化优化 总被引:1,自引:0,他引:1
为了提高产品装配的效率,提高装配序列的并行性,提出了基于约束解除和简化配合关联图的装配序列并行优化方法。给出了装配效率的评价指标一并行性评价因子的数学模型。将模糊逻辑用于装配约束的量化过程,通过约束归约方法将无约束条件下可自由运动零件的自身约束与零件间通过点、线、面之间几何约束关系所表达的装配约束进行求交,建立零件间的等价约束评价值即联接度,联接度概念的提出清晰地表达了配合关联图中的薄弱环节;在此基础上,建立装配体的赋权配合关联图,并根据联接度值的大小对零件间的虚联接进行简化,给出了一个基于阈值的追求装配最高并发度的配合关联图分解与重组策略,实现了装配序列并行优化,并通过实例说明了该算法的有效性。 相似文献
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针对传统装配序列规划方法解空间大、模型简单的问题,提出了应用虚拟现实技术解决船舶装配序列规划问题的方法。该方法分为虚拟拆卸和方案评价两个阶段,分析了虚拟装配平台上进行虚拟拆卸的基本流程和关键技术——虚拟环境下的实体模型表达和基于装配约束的运动导航。建立了船舶装配序列评价模型,确定了零件重量、装配时间、装配稳定性和装配过程难度等面向手工装配的评价指标。最后,用某船舶机舱区域的规划实例进行了验证,结果表明该方法生成的装配序列对实际船舶装配生产具有指导作用。 相似文献