Modeling and Experimental Validation of a Generalized Stewart Platform by Bond-Graph Method

Abstract

This paper represents modeling and experimental validation of a Stewart platform manipulator by Bond-Graph method. Dynamic model includes all dynamic and gravity effects, linear motor dynamics as well as viscous friction at the joints. Following the modeling of actuation system and of main structure, merging of these two is accomplished. Linear DC motors are utilized and are modeled as the main part of the actuation system. Since the overall system consists of high nonlinearity originated from geometric nonlinearity and gyroscopic forces, resultant derivative causality problem caused by rigidly coupled inertia elements is addressed and consequential nonlinear system state-space equations are presented. Stability of the model is investigated by observing the variations of the system matrix eigen values which are utilized from the state-space equations. Four different trajectories are applied to the Bond-Graph model and to the experimental setup for validation purposes. Satisfactory close coordination between simulation and experimental system is achieved.