Title: Workspace trajectory tracking control for two-flexible-link manipulator through output redefinition

Authors: Fareh Raouf; Saad Mohamad; Saad Maarouf

Addresses: Department of Electrical Engineering, École de technologie supérieure, 1100, rue Notre-Dame ouest, Montréal, Québec, H3C 1K3, Canada ' College of Engineering, Université du Québec en Abitibi-Témiscamingue, 445, boul. de l'Université Rouyn-Noranda, Québec, J9X 5E4, Canada ' Department of Electrical Engineering, École de technologie supérieure, 1100, rue Notre-Dame ouest, Montréal, Québec, H3C 1K3, Canada

Abstract: In this paper, a control strategy and stability analysis for two-flexible-link manipulator are presented to track a desired trajectory in the workspace. The inverse dynamics problem is solved using virtual space and the quasi-static approach. Flexible manipulators are non-minimum phase systems when the controlled output is the tip position. To overcome this problem, an output redefinition technique is used. Two steps are presented to control the manipulator's tip position. First, assuming that the first link is stable, we develop the control law for the last link to stabilise the error dynamics using the feedback linearisation approach. The weighted parameter defining the non-collocated output is selected to guarantee bounded internal dynamics such that the output is as close as possible to the tip. Second, the same strategy is followed for the first link. Simulation results are presented to show good tracking of desired trajectory in the workspace.

Keywords: flexible manipulators; flexible robots; dynamic inversion; output redefinition; feedback linearisation; passivity; trajectory tracking; tracking control; robot control; stability analysis; simulation.

DOI: 10.1504/IJMIC.2013.052328

International Journal of Modelling, Identification and Control, 2013 Vol.18 No.2, pp.119 - 135

Published online: 31 Jul 2014 *

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