Direct Kinematics Solution of 2-(6UPS) Hybrid Manipulator based on Neural Network

This contribution addresses forward kinematic solution of modular hybrid manipulator which includes two same Stewart mechanism in serial form known as 2-(6UPS) manipulator. First, using geometrical and vectorial analysis, mathematical model of kinematic analysis for 2-(6UPS) is extracted. As mapping the length of pods to location (orientation and position) of moving mid and upper platforms (forward kinematic) in this specific mechanism is so difficult to solve, which it is related to complicated configuration of 2-(6UPS) and highly nonlinear characteristic of extracted mathematical model. Therefore, we proposed artificial neural network (ANN) based wavelet analysis to resolve forward kinematics of 2-(6UPS). Also, we used wavelet neural network (WNN) to approximate specific trajectory in circle path with oscillating amplitude in z direction and spiral path with elliptical base paths for mid and upper platforms movement respectively. Comparison between the results of proposed network and closed form solution (CFS) of kinematics for 2-(6UPS) shows proper performance of proposed network in less than %1 error.