Forward kinematics analysis of a novel 3-DOF parallel manipulator

Abstract

A novel spatial parallel manipulator designed to assemble diagnostic instruments in SG-III is introduced in this paper. Firstly, resorting to screw theory, mobility analysis is presented for this manipulator. Then, the inverse kinematics problem is determined by the method of RPY transformation with the singularity analyzed. As a key issue in parallel manipulators, it is more difficult to solve the forward kinematics problem, since it is highly nonlinear and coupled. In this work, three different approaches are presented to deal with this issue, namely, the back propagation neural network, the simplified ant colony optimization, and the proposed improved Newton iterative method. Simulation of each approach is conducted, and their merits and demerits are compared in detail. It is concluded that the improved Newton iterative method, which can provide good initial iteration values, shows the best performance in estimation of the nonlinear forward kinematic mapping of the considered parallel manipulator.