Analysis of a novel 6-DOF, 3-PPSP parallel manipulator

Abstract

A novel kinematic structure for a parallel manipulator with 6 DOF is proposed. It consists of a platform that is connected to a fixed base by means of 3-PPSP (P-prismatic joint, S-spherical joint) subchains. Each subchain is connected to a passive prismatic joint at the one end, and a passive spherical joint at the other. The spherical joint is then attached to perpendicularly arranged prismatic actuators that are fixed to the base. Due to the efficient architecture, the closed-form solutions of the inverse and forward kinematics can be easily obtained As a consequence, this new kinematic structure can be servo controlled using simple inverse kinematics, because forward kinematics allows for measuring the platform's position and orientation in Cartesian space. Manipulator workspace determination is carried out through the computation of displacements in the prismatic joints. A Jacobian matrix for the proposed structure is derived so the relationship between actuator forces and output forces/moments of the mechanism can be analyzed. A series of simulations were performed to verify the results of the kinematics analyses and to evaluate the load characteristics of the system.