New Large Work Space Parallel Mechanism And Its Performance

In order to make the parallel manipulators successfully apply in practical, the research which developed to simple structure, large workspace, easy control and other characters has been paid more and more attention.In this paper, we construct a new three translational parallel mechanism with large workspace by attaching a redundant sliding method. And carry out related researches about the configuration optimization, position analysis, singularity, bearing capacity, stiffness and so on.Firstly, according to this type of manipulator's composition and structural characteristics, use the vector method to establish the forward and inverse solutions and velocity Jacobian matrix and analyze its singularity.Secondly, considering the constraint of the range of the adjustable stem, the limit of the spherical joint's angle and the interference of the member, search the machine's reachable workspace. Put forward the workspace volume as the evaluation index, analyze the basic parameters on the influence of workspace, find out the sensitive factors, and discuss how to realize the large workspace in detail.Finally, use the theory of mechanism to find out the Jacobian matrix of force, define the performance index of bearing capacity, depict the index's distribution in the workspace, and analyze the capacity characteristic of force bearing. Combined the Jacobian matrix, establish the stiffness model of the whole body and the single adjustable stem. Seek the distribution of the stiffness in workspace. Present the overall performance evaluation index of the average stiffness, and analyze the manipulator's structure parameters on the influence of the stiffness. Provide theoretical basis for improving the performance of the parallel manipulator and the structure.