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閉環(huán)和并聯(lián)機構(gòu)拓撲胚圖理論與應(yīng)用

發(fā)布時間:2019-04-27 21:39
【摘要】:機構(gòu)拓撲結(jié)構(gòu)是機構(gòu)創(chuàng)新和機構(gòu)概念設(shè)計所要解決的關(guān)鍵問題,現(xiàn)代機構(gòu)學(xué)的主要任務(wù)是為創(chuàng)造現(xiàn)代機械系統(tǒng)的新機構(gòu)提供理論和實際有效的方法,并在此基礎(chǔ)上產(chǎn)生滿足特定要求的新機構(gòu)。并聯(lián)機構(gòu)的廣泛應(yīng)用促使并聯(lián)機構(gòu)的創(chuàng)新研究不斷發(fā)展。作為機構(gòu)設(shè)計主要手段的機構(gòu)拓撲圖型綜合,近年來也成為了十分重要的研究課題和方向。提出并研究了利用特征數(shù)組對并聯(lián)機構(gòu)進行型綜合的方法。在合理的關(guān)聯(lián)桿組的基礎(chǔ)上,對于拓撲胚圖和拓撲圖綜合過程中的同構(gòu)判斷的難題,提出了解決方案。用先進CAD軟件編寫了實現(xiàn)數(shù)、圖、型綜合過程自動化的程序。研究了閉環(huán)機構(gòu)中關(guān)聯(lián)桿組、冗余約束、自由度和被動自由度之間的關(guān)系。首先,用串聯(lián)連接的單自由度基本連桿構(gòu)成各種運動副,推導(dǎo)出計算關(guān)聯(lián)桿組自由度、基本運動副數(shù)、關(guān)聯(lián)桿組中有效基本連桿數(shù)的公式。其次,導(dǎo)出不同的關(guān)聯(lián)桿組,分析關(guān)聯(lián)桿組、冗余約束、自由度和被動自由度之間的內(nèi)在關(guān)系。再次,導(dǎo)出拓撲圖,綜合出相關(guān)的含冗余約束和被動自由度的閉環(huán)機構(gòu)。最后,確定含冗余約束和被動自由度的閉環(huán)機構(gòu)的冗余約束和被動自由度數(shù)。提出并研究了用加邊法由簡單拓撲胚圖推導(dǎo)有效拓撲胚圖,并識別拓撲胚圖的同構(gòu)的方法。解釋了拓撲胚圖以及拓撲胚圖中邊和頂點的概念,確定了邊、頂點在拓撲胚圖中的數(shù)量。先由關(guān)聯(lián)桿組構(gòu)造出不同的拓撲胚圖。再根據(jù)不同邊數(shù),針對相同關(guān)聯(lián)桿組將拓撲胚圖進行分組,識別同構(gòu)拓撲胚圖和無效拓撲胚圖。然后用加邊法由簡單拓撲胚圖和虛拓撲胚圖推導(dǎo)出有效拓撲胚圖。推導(dǎo)出五副桿、四副桿和三副桿的有效拓撲胚圖。用數(shù)組排列方式,表示拓撲胚圖中基本連桿點的數(shù)量和邊的數(shù)量關(guān)系。確定了表示胚圖和識別同構(gòu)及無效的拓撲胚圖的相關(guān)標準,描述了含五副桿關(guān)聯(lián)桿組的一些簡單的拓撲胚圖,識別了同構(gòu)。提出基于特征字符串的方法來表示含六副桿及其它基本連桿的有效拓撲胚圖。解釋了拓撲胚圖與特征字符串的概念,確定了拓撲胚圖中頂點和邊的數(shù)量關(guān)系;定義了由特征字符串表示拓撲胚圖及判別同構(gòu)和無效拓撲胚圖的相關(guān)準則;通過特征字符串表示了由六副桿和其它基本連桿的簡單拓撲胚圖,并根據(jù)特征字符串和連桿的同構(gòu)排列關(guān)系判別出了同構(gòu)及無效的拓撲胚圖;列舉了一些簡單的拓撲胚圖的應(yīng)用實例,進一步證實所提出的判別準則的合理性和正確性。在對拓撲胚圖研究的基礎(chǔ)上,提出用特征字符串推導(dǎo)1-2自由度平面閉環(huán)機構(gòu)拓撲圖的方法。通過有效拓撲圖生成模擬機構(gòu),確定并驗證了特征字符串與機構(gòu)拓撲圖之間的等價條件。
[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.
【學(xué)位授予單位】:燕山大學(xué)
【學(xué)位級別】:博士
【學(xué)位授予年份】:2015
【分類號】:TH112

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