Spatial imperfect-DOF parallel robots have received considerable scholars' attention of all the world and have a broad perspective in industry production and other fields for the advantages of their simple mechanism, easy control and low cost. In this dissertation, for two special imperfect-DOF parallel mechanisms, which are put forward by Zhao Tieshi, theory analysis especially kinematics characteristics are studied.At first, based on the analysis of characteristics and amount of DOF for the imperfect-DOF parallel mechanisms, 3-P(4U)and 4-UPU ,the accuracy of choosing input is considered, at meantime then reasons of wrong input are given. Secondly, then kinematics of the imperfect-DOF parallel mechanisms, especially the singular Configuration of 4-UPU are developed. The solutions of the forward and inverse position kinematics and corresponding numerical examples are given. Many position, velocity and acceleration curves versus typical input are showed, they illustrate the kinematics characteristics. Thirdly, the workspaces and operational capability at different conditions are studied, the appearance of workspaces are presented based on AutoCAD platform, some operational curves and curved surfaces are given, they show the capability of them. Finally, in the dissertation, the mathematical conditions of a screw whose components are continuous variables with respect to time can represent a physical kinematics pair is discussed. These conclusions are drawn from linking any two kinematics joint such as revolute joint, prismatic joint, special joint, universal joint.The research work of this thesis establishes theoretical basis for the further research and development of the imperfect-DOF mechanisms' practicality. It is of great leading significant with the innovation of new mechanisms. |