Kinematic design of a six degree-of-freedom in-parallel manipulator for probing task

This paper presents a kinematic analysis of a parallel manipulator we have been developing for the probing task application that requires high bandwidth, active compliance, and high precision. Based on the concept of macro/micro manipulators, the parallel manipulator serves as a wrist of a macro manipulator. The developed manipulator is a class of in-parallel platforms with 3 PRPS( prismatic-revolute-prismatic-spheri~ joints ) chain geometry. The main advantages of this manipulator, compared with the typical Stewart platform type, are the capability of pure rotation generation and the easy prediction of the moving platform motion. The purpose of this paper is to develope an eflicient kinematic model which can be used for real-time control and to propose systematic methods to design the manipulator considering workspace, manipulability, resistivity, and the existence conditions of the forward kinematic solution. A series of simulation are carried out to show the kinematic characteristics and performance of the mechanism. A prototype manipulator has been built based on the kinematic design analysis.