| High speed, high accuracy and high speed material transportation system are the most important trends of manufacturing industry. It's urgent to improve the speed and accuracy of these equipments. But the traditional serial chain mechanisms can't fulfill these fast changing demands. The parallel machine tool, invented in 90's of the last century, is the breakthrough of mechanism. It brings new research direction and new prospect to NC manufacturing technology. Parallel machine tool has been the research hotpot of many studies in different fields, including robot, machine tool architecture and NC technology.Parallel machine tool, based on parallel mechanism, is a brand new concept. The theory and technology of them is far from prefect. In this dissertation, the following aspects on parallel mechanism are studied, including mechanism design, decoupling movement and Huston-Kane method in multibody system theory.Our research work on based a parallel machine tool prototype, named KD-2000. But not confined to it. Actually the research work in this dissertation can be applied to both parallel mechanism and generic mechanism.Subsequent research contents and innovations are presented in this dissertation.1. The research and application of parallel mechanism and parallel machine tool at present are summarized first. We enumerate the main research subjects and research methods.2. We give a brief but systematic introduction to differentiable geometry and Lie group, Lie algebra. Rigid body motion expressed with the notations from these theories is also introduced. They are the theoretical bases of the subsequent research contents.3. Graph theory is the most preliminary tool for mechanism design and mechanism analysis. With the use of incidence degree code, which based on graph theory, we studied the isomorphism of a few parallel mechanisms, including KD-2000/ECLIPSE, Behi 3-PRPS, Alizade 3-PRPS, Tahmasebi-Tsai, etc.4. We bring forward weighted stiffness matrix, which is the development of A.C Rao's stiffness matrix. It can compare the stiffness of mechanisms in a more quantitative manner. vWe use weighted stiffness matrix to compare the stiffness of traditional machine tool and parallel machine tool. And reach the conclusion that the stiffness of joints, especially spheric hinge, is the key to improve the stiffness of parallel machine tool.5. We draw the conclusion that isomorphism of mechanism can't express its motion in-out nature. Since the coupling of motion is the nature of parallel mechanism, we investigate the decoupling of motion, instead of the motion decoupling characteristic of mechanisms.6. The concept of decoupling motion is brought forward for the first time, together with its classification. We point out that the sub manifold corresponds to decouplingmotion is a canonical sub manifold of configuration manifold. We bring forward the necessary condition for mechanism to achieve decoupling motion. And conclusion is reached the ability of 6-DOF mechanism to implement motion and decoupling motion is decided not by its type but by its geometry constraints.7. The concept of serial degree is brought forward for the first time. It describes the resemblance of a mechanism to serial ones. So the motion in-out nature is described. For the so called exotic chain parallel mechanism, which was mentioned by Professor J.P Merlet, its motion nature is achieved.8. We demonstrate a mechanism 'design example of a 2-DOF rotating mechanism. It incarnates our research work on mechanism design and mechanism analysis.9. By the research of metric tensor and Riemann tensor on Riemann manifold, we get the inherent curvature of configuration space belonging to parallel mechanism. So the relative coordinates and generalized coordinates are inevitable choice for parallel mechanism.10. We studied the Huston-Kane method of multibody system theory by the means of differentiable geometry. And point out that Huston-Kane method can be fully imbedded into Lagrange's mechanics. Huston-Kane method is o...
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