Title: An adaptive observer for a Stewart platform manipulator using leg position and force measurements

Authors: Shady A. Maged; Ahmed M.R. Fath El Bab; A.A. Abouelsoud

Addresses: School of Innovative Design Engineering, Mechatronics and Robotics Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), New Borg El-Arab, Alexandria, P.O. Box 21934, Egypt ' School of Innovative Design Engineering, Mechatronics and Robotics Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), New Borg El-Arab, Alexandria, P.O. Box 21934, Egypt; Mechanical Engineering Department, Assiut University, Assiut, Egypt ' School of Innovative Design Engineering, Mechatronics and Robotics Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), New Borg El-Arab, Alexandria, P.O. Box 21934, Egypt; Electronics and Communications Engineering Department, Faculty of Engineering, Cairo University, Egypt

Abstract: An adaptive observer for a Stewart manipulator using leg position and force measurements to estimate linear and angular position and velocity of the moving platform is proposed, tested and verified on the Stewart platform DELTALAB EX800 using MATLAB SimMechanics toolbox. The proposed adaptive observer is based on parameterising the dynamic model of a Stewart parallel manipulator with six degrees of freedom (DOF) via the estimated position and inertia parameters, thus yielding a nominal model plus perturbation. The update law for the adaptive observer is derived using Meyer-Kalman-Yakubovich (MKY) lemma and state variables filter approach. Persistency of excitation condition shows the convergence of the estimated parameters to the true values. Local asymptotic stability of the origin of the overall system is shown using converse Lyapunov theorem. Simulation results show the effectiveness of the proposed method as the designed adaptive observer state and the estimated parameters converge to their true values in less than 430 ms.

Keywords: Stewart platform; dynamic modelling; adaptive state observers; local asymptotic stability; excitation persistence; leg position measurement; force measurement; parallel manipulators; parallel robots; simulation; robot dynamics.

DOI: 10.1504/IJMIC.2015.071703

International Journal of Modelling, Identification and Control, 2015 Vol.24 No.1, pp.62 - 74

Received: 24 Oct 2014
Accepted: 22 Jan 2015
Published online: 15 Sep 2015 *

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