Research On Several Issues In Topology Structure Of Mechanisms With Innovative Methods

Topology structure of mechanisms (TSM) reflects the composition and workingprinciple of mechanisms. The description and analysis of TSM lays the foundation ofstructural research of mechanisms, and the synthesis of TSM plays a key role inmechanical products designing. Presently, the key points of research of stable TSMare expended to nonlinear and strong-coupling generalized mechanism systems.Meanwhile, the mechanism with variable topologies (MVT) is becoming the hotresearch area in mechanisms.Up to now, theory researches of different topology structures are mutuallyindependent in mechanisms, and some concepts related to TSM and their relationshipremain ambiguous. On the other hand, there are few integral analysis models of stableTSM and MVT that take driver and frame into account. The utilizing of patentresources, which is very important for engineering design, is unexplored in the designand synthesizing of mechanisms. As for research methods, it is difficult to applymathematical methods and mechanics principles directly to represent the detailedinformation of TSM system with non-numerical, non-linear, variable structure andstrong-coupling characteristics. Analyzing and synthesizing are extremely difficultfor systems with complex structure, such as multiple joint and metamorphic pair.This dissertation is focusing on improving research method and solving theseproblems on a broader perspective. Several innovative methods with differentstrengths are adopted in research. These methods combined with mathematicalmethods and mechanics principles are employed to describe, analyze and synthesizegeneralized mechanisms and variable topology mechanisms.The main works of the dissertation are as follows(1) In order to build a system model of stable TSM and MVT and explicaterelationships among different TSMs, based on the set theory, the dissertation gives therigorous mathematical definitions of TSM, TSKC, MVT, Reconfigurable Mechanism,Metamorphic Mechanism, etc. Based on the Su-field analysis, the hierarchical modelis established to describe a mechanism system. The functional domain model and thephysical domain model are also built to represent a kinematic pair by applying theAxiomatic Design theory. To improve the ideality of the Su-field models of a multiplejoint and a metamorphic pair, the evolution schemes are created according to standard solutions of TRIZ. The examples indicate that these definitions and models caneffectively describe and analyze TSM at different levels.(2) To describe the strong coupled relation of the topological structure ofkinematic chains with multiple joint and identify isomorphism, based on thefunctional autonomy principle, the dissertation introduces the Pin-link to decouplemultiple joints according to the evolution scheme of a multiple joint model. Thetransformed adjacency matrix is established to describe kinematic chains withmultiple joints, and a new method for isomorphism identification of planar kinematicchains is proposed by using some characteristic parameters of the converted adjacentmatrix. The application examples show that the converted adjacent matrix couldconveniently represent planar kinematic chains with multiple joints, and the eigenvalues and eigenvectors of the converted adjacent matrix can be used to efficientlyidentify the isomorphism of planar kinematic chains.(3) In order to completely represent the structural information of a metamorphickinematic pair, the dissertation introduces the complexity into the Su-field model ofkinematic pair to describe the “substance” in the model. By using the combinationmethod, the constraint function is defined to represent the “field” in Su-field model ofkinematic pair, which can be used to describe the properties, type, grade, DOF,direction, constraint efficiency, degree, and their changes. According to the evolutionscheme of a metamorphic pair model, the metamorphic gene is defined to determinewhether a kinematic pair is activated or not while the metamorphic models of basickinematic pairs are constructed to denote the metamorphic directions of a pair. Thephysical implementations of metamorphic gene elements are analyzed based on theeffect principles. The examples show that the theory and the method can be used torepresent and analyze a metamorphic pair effectively.(4) To analyze the non-numerical and non-linear configuration transformation ofvariable topological mechanisms, the dissertation considers six sufficient conditionsfor configuration switching according to the definition of TSM. Based on TRIZ, thephysical contradictions in the Su-field model of MVT are analyzed and a newapproach to create the metamorphic origin mechanism by using the stableconfigurations as internal resources is proposed. With constraint functions aselements, the adjacent matrix of the metamorphic origin mechanism is built and themetamorphic equations of six kinds of metamorphic forms are established. Theexamples show that the method can analyze the configuration transformation of MVTreasonably. (5) Focusing on the innovative mechanism synthesis by using of patentresources, based on the function trimming of TRIZ and Catalog Design, thedissertation proposes a patent oriented and competitive patent circumvented processmodel of mechanism synthesis re-innovating. The application example indicates thatthis process model can feasibly direct the mechanism synthesis in the innovativedesign of products.In summary, the dissertation develops the rigorous mathematical expression toTSM system and clarifies the relationship among different TSMs. By using severalinnovation methods and combining with mathematical methods as well as mechanicalprinciples, the dissertation conducts basic research works on the systematical modelsof stable and variable topological mechanisms. The problems for describing andanalyzing the topological structure with multiple joints and metamorphic kinematicpairs are investigated. A patent oriented and competitive patent circumvented processmodel of mechanism synthesis innovation in product design is proposed. Thisdissertation provides new theories and methods for mechanism research andinnovative design of mechanical products.