Abstract
The volume of workspace is a significant kinematic index of parallel manipulator in some applications of engineering. However, the workspace degradation of the manipulator in extreme position is a demanding issue, which results in a fact that such manipulators cannot satisfy the machining requirement of the maximum limit position for the large-scale complex structural components. In this paper, a novel five degrees-of-freedom (DOF) 5PRR+5PUS-PRPU parallel manipulator (PM) is presented. First, the mobility analysis for the proposed manipulator is carried out, and the inverse kinematics as well as the Jacobian matrix is developed. Then, the workspace of the 5PRR+5PUS-PRPU PM and the 5PUS-PRPU PM is analyzed to study the workspace augmentation of the proposed PM. The workspace comparisons of these two PMs prove that the proposed PM not only can realize the large movement of the moving platform along the z-axis, but also possess larger workspace than the 5PUS-PRPU PM when the moving platform has a large movement along the z-axis. Furthermore, the singularity analysis is also conducted to show the singularity-free workspace of the proposed PM. By the introduction of the reconfigurable 5PRR PM, the proposed manipulator effectively augments the reachable workspace of the moving platform along the z-axis and to some extent also solves the issue of workspace degradation of the PM along z-axis.
