Kinematic feature analysis of a 6-degree-of-freedom in-parallel manipulator for micro-positioning

This paper presents a kinematic analysis of a parallel manipulator we have been developing for the micro-positioning application that requires high control bandwidth and high precision. The developed manipulator is a class of in-parallel platforms with 3 PRPS (prismatic-revolute-prismatic-spherical joints) chain geometry. The main advantages of this manipulator, compared with the typical Stewart platform type, are the capability to produce pure rotation and the easy prediction of the moving platform motion. The purpose of this paper is to develop an efficient kinematic model which can be used for real-time control and to propose systematic design methods that considers the existence conditions of the forward kinematic solution, singularity, manipulability, and resistivity. A series of simulation are carried out to show the kinematic characteristics and performance of the mechanism. The proposed manipulator has potentials in a wide range of applications from micro surgery robots to highly dextrous wrist mechanism of assembly robots.