【作者】 毛秉毅；

【导师】 路懿；

【作者基本信息】 燕山大学 ， 机械电子工程， 2015， 博士

【摘要】 机构拓扑结构是机构创新和机构概念设计所要解决的关键问题,现代机构学的主要任务是为创造现代机械系统的新机构提供理论和实际有效的方法,并在此基础上产生满足特定要求的新机构。并联机构的广泛应用促使并联机构的创新研究不断发展。作为机构设计主要手段的机构拓扑图型综合,近年来也成为了十分重要的研究课题和方向。提出并研究了利用特征数组对并联机构进行型综合的方法。在合理的关联杆组的基础上,对于拓扑胚图和拓扑图综合过程中的同构判断的难题,提出了解决方案。用先进CAD软件编写了实现数、图、型综合过程自动化的程序。研究了闭环机构中关联杆组、冗余约束、自由度和被动自由度之间的关系。首先,用串联连接的单自由度基本连杆构成各种运动副,推导出计算关联杆组自由度、基本运动副数、关联杆组中有效基本连杆数的公式。其次,导出不同的关联杆组,分析关联杆组、冗余约束、自由度和被动自由度之间的内在关系。再次,导出拓扑图,综合出相关的含冗余约束和被动自由度的闭环机构。最后,确定含冗余约束和被动自由度的闭环机构的冗余约束和被动自由度数。提出并研究了用加边法由简单拓扑胚图推导有效拓扑胚图,并识别拓扑胚图的同构的方法。解释了拓扑胚图以及拓扑胚图中边和顶点的概念,确定了边、顶点在拓扑胚图中的数量。先由关联杆组构造出不同的拓扑胚图。再根据不同边数,针对相同关联杆组将拓扑胚图进行分组,识别同构拓扑胚图和无效拓扑胚图。然后用加边法由简单拓扑胚图和虚拓扑胚图推导出有效拓扑胚图。推导出五副杆、四副杆和三副杆的有效拓扑胚图。用数组排列方式,表示拓扑胚图中基本连杆点的数量和边的数量关系。确定了表示胚图和识别同构及无效的拓扑胚图的相关标准,描述了含五副杆关联杆组的一些简单的拓扑胚图,识别了同构。提出基于特征字符串的方法来表示含六副杆及其它基本连杆的有效拓扑胚图。解释了拓扑胚图与特征字符串的概念,确定了拓扑胚图中顶点和边的数量关系;定义了由特征字符串表示拓扑胚图及判别同构和无效拓扑胚图的相关准则;通过特征字符串表示了由六副杆和其它基本连杆的简单拓扑胚图,并根据特征字符串和连杆的同构排列关系判别出了同构及无效的拓扑胚图;列举了一些简单的拓扑胚图的应用实例,进一步证实所提出的判别准则的合理性和正确性。在对拓扑胚图研究的基础上,提出用特征字符串推导1-2自由度平面闭环机构拓扑图的方法。通过有效拓扑图生成模拟机构,确定并验证了特征字符串与机构拓扑图之间的等价条件。更多还原

【Abstract】 Determining the mechanism topology is the key issue of mechanical innovation and mechanical conceptual design to be resolved, the main task of modern mechanisms is to provide theoretical, practical and effective way for the creation of new mechanisms of modern mechanical systems and create new mechanisms to meet the specific requirements. Extensive use of parallel mechanism promotes the continuous development of innovative research. As the primary means of mechanism design, mechanism topology type synthesis, has become a very important research topic and direction in recent years.The type synthesis of parallel mechanism is studied using feature arrays. On the basis of the reasonable associated linkages, the solution of contracted graphs type synthesis and contracted graphs isomorphism identification is proposed. With advanced CAD software, the procedure that can achieve number, graph, type synthesis process automatically.The relations among the associated linkages, redundant constraints, degrees of freedom and passive degrees of freedom of the closed mechanisms are studied. Firstly, the formula that can calculate the degree of freedom, the number of joints and the number of effective basic link is deduced. Secondly, the intrinsic relations among the associated linkages, redundant constraints, degrees of freedom and passive degrees of freedom are analyzed. Thirdly, several topology graphs are derived and the relevant closed mechanisms containing redundant constraints and passive degrees of freedom are synthesized. Finally, the numbers of redundant constraint and passive degree of freedom of the closed mechanisms including redundant constraints and passive degrees of freedom are determined.This paper focuses on the derivation of valid contracted graphs from simpler contracted graphs by adding edge and the identification of their isomorphism. The concepts of contracted graphs are explained, and the numbers of vertices and edges in contracted graphs are determined. First, many different contracted graphs are constructed from associated linkages. Second, based on the numbers of different edges, many contracted graphs corresponding to the same associated linkage are grouped and the isomorphic and invalid contracted graphs are identified and deleted. Finally, many complex valid contracted graphs are derived from simpler valid contracted graphs or virtual contracted graphs by adding edge.The derivation of the valid contracted graphs with pentagonal links, quaternary links and ternary links is studied for the type synthesis of closed mechanisms. By means of the arrays, the relations between the number of points and edges in the contracted graphs are indicated. At the same time, the relevant standards used to identify isomorphic and invalid contracted graphs are determined. Some simple contracted graphs containing pentagonal links are described, and the isomorphic contracted graphs are identified. This paper focuses on the derivation of the valid contracted graphs with hexagonal links plus other links using the characteristic strings. First, the concepts on the contracted graphs and characteristic strings are explained, and the numbers of vertices and edges in the contracted graphs are solved. Second, the relative criterion is determined for representing/deriving contracted graphs and identifying isomorphic/invalid contracted graphs by characteristic strings. Third, some simple contracted graphs are derived from some associated linkages with hexagonal links plus more other links, are represented by characteristic strings, and the isomorphic/invalid contracted graphs are identified using the characteristic strings and the isomorphic queues of the links. Finally, some examples are given for illustrating their applications.A characteristic string approach is presented for derivation and isomorphism identification of valid topological graphs for some 1, 2 degree of freedom planar closed mechanisms from the contracted graphs. The equivalent conditions between the characteristic string and the topology graph with digits are determined and verified by some created simulation mechanisms of valid topology graphs.更多还原