| Parallel Kinematics Machines(PKMs) are the perfect combination of modern CNC machine tools and parallel mechanism. And PKMs are most dazzing innovation in the machinery equipment areas at the end of last century. With traditional CNC machine tools, the PKMs have many advantages. They have great potential. However, in terms of design theory, the young PKMs are still relatively immature. In response to the situation, a number of key theories of design and analysis of PKMs are studied in the dessertation.The forward kinematic problem is one of the basic problems of PKMs. The forward kinematic equations are complicated and nonlinear. By introducing quaternion to represent the transformation matrix, the forward kinematics of a class of PKMs can be expressed in the form of a set of quadratic algebra equations, which decouples the positions and orientations of the mobile platform. There are eight symbolic solutions obtained from the approach. It is the most concise forward solutions for six DOF PKMs till now.Singulartiy has a significant impact on the properties of PKMs. Based on symbolic forward solutions, the singularities of a class of PKMs are expressed analytically, which are divided into architecture singularity, position singularity and orientation singularity. The results of singularity analysis are summarized to three theorems. The relationship between the assembly modes and the singularites of a class PKMs are investigated. It shows that the guess of every assembly mode is separated by singularity surface is wrong. It further studies the selfmotion of PKMs which have architecture singularities.Restrictions on the wider use of PKMs are attribute to small workspace. With the experimental analysis and computer simulation, the workspace of BJ-04-02(A) PKMs is studied. The impact of the workspace size is analyzed.Jacobian matrix is the base of force properties analysis of PKMs. However, forces and torques have different dimensions. To deal with them separately, the Jacobian is divided into the force Jacobian and the torque Jacobian. On the bases, force transmissibility and torque transmissibility of PKMs are discussed. This method avoids the confusion of two different dimensions in the process of analysis. The physics meanings of the two Jacobians are more perspicuity.Stiffness is a important performance criteria of PKMs. The scalar criteria of stiffness and its scope are derived. The stiffness can be considered as the weighted square root of six dimensions unit vector of deformation in the six-axis of hyperellipsoid. By the stiffness criteria, the general 6-SPS PKMs and the cross-leg type 6-SPS PKMs are compared. It shows that stiffness and its isotropy of the cross-leg type 6-SPS PKMs is superior to that of general 6-SPS PKMs.By using Kane's method, the dynamic model of parallel manipulators established in the task space. The partial velocities and partial angular velocities of six branches and moving platform are derived by using velocity and angular velocity of the origin point of moving platform as quasi-velocity of the system. ADAMS is used to validate the dynamic model. To improve the efficiency, dynamic models of two typical applications of parallel mechanism are simplified separately.Redundant freedom can make PKMs improve their kinematic and dynamic performances. By using redundant task freedoms of PKMs, the instantaneous energy and active joint force is optimized. From the results of the instantaneous energy optimization, it can not only decrease the kinetic energy, but also reduce the active joint force. The active joint optimization can effectively reduce the joint force and prevent the mutation of the force.Through the theoretical and experimental research work, the understanding of the forward kinematic, singularity, assembly modes, dynamic performances and redundancy optimization is deepened. The knowledge and practice of PKMs research are expanded. The research results can be referenced by parallel mechanism, parallel robot and other areas.
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