闭环和并联机构拓扑胚图理论与应用

发布时间：2019-04-27 21:39

【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。
[Abstract]:The topological structure of mechanism is the key problem to be solved in the innovation of mechanism and the conceptual design of mechanism. The main task of modern mechanism science is to provide theoretical and practical effective methods for the creation of new mechanism of modern mechanical system. And on this basis to produce new institutions to meet specific requirements. The extensive application of parallel mechanism promotes the innovation research of parallel mechanism to develop continuously. As the main means of mechanism design, mechanism topology synthesis has become a very important research topic and direction in recent years. A method of progressive synthesis of parallel mechanisms based on characteristic arrays is proposed and studied in this paper. On the basis of reasonable association bar group, a solution to the difficult problem of isomorphism judgment in the process of synthesis of topological embryogram and topological graph is put forward. With the advanced CAD software, the program to realize the automation of digital, graphic and integrated process is compiled. In this paper, the relationship among associative bar group, redundant constraints, degrees of freedom and passive degrees of freedom in closed-loop mechanisms is studied. Firstly, all kinds of motion pairs are composed of single-degree-of-freedom basic connecting rod connected in series. The formulas for calculating the degree of freedom, the number of basic motion pairs and the number of effective basic connecting bars in the associated rod group are derived. Secondly, different associative bar groups are derived, and the internal relationships among associative bar groups, redundant constraints, degrees of freedom and passive degrees of freedom are analyzed. Thirdly, the topology diagram is derived and the related closed-loop mechanisms with redundant constraints and passive degrees of freedom are synthesized. Finally, the redundant constraints and the number of passive degrees of freedom of closed-loop mechanisms with redundant constraints and passive degrees of freedom are determined. In this paper, we propose and study the method of deducing an effective topological embryogram from a simple topological embryogram by the edge-adding method, and identify the isomorphism of the topological embryogenic graph. In this paper, the concepts of edge and vertex in topological primitive graph and topological primitive graph are explained, and the number of edges and vertices in topological primitive graph is determined. First of all, different topological diagrams are constructed from the association bar group. Then, according to the number of different edges, the topological embryogram is grouped for the same associated rod group, and the isomorphic topological embryogram and the invalid topological embryogram are identified. Then the efficient topological embryogram is derived from the simple topological embryogram and the virtual topological embryogram by the method of adding edges. The effective topological diagrams of five, four and three pairs are derived. The relationship between the number of basic connecting points and the number of edges in topological graph is expressed by array arrangement. The related criteria of representing embryogram and recognizing isomorphism and invalid topological embryogram are determined. Some simple topological embryogram with five-member association bar group are described and isomorphism is recognized. A method based on characteristic string is proposed to represent an efficient topological graph with six couplets and other basic links. In this paper, the concepts of topological germ graph and characteristic string are explained, and the quantitative relationship between vertices and edges in topological germ graph is determined, and the related criteria of representing topological germ graph by feature string and distinguishing isomorphism and invalid topological germ graph are defined. The simple topological embryogram of six pairs and other basic links is represented by the characteristic string, and the isomorphism and invalid topological embryogram are distinguished according to the isomorphism arrangement relation between the characteristic string and the connecting rod. Some simple application examples of topological embryogram are given, and the rationality and correctness of the proposed criteria are further verified. Based on the study of topological embryogram, a method is proposed to derive the topological diagram of a planar closed-loop mechanism with 1 ~ 2 degrees of freedom by means of the characteristic string. The equivalent conditions between the characteristic string and the topology diagram of the mechanism are determined and verified by generating the simulated mechanism by the effective topology diagram.
【学位授予单位】：燕山大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH112

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