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Mathematical Problems in Engineering
Volume 2012 (2012), Article ID 270649, 23 pages
Research Article

An Adaptive Variable Structure Control Scheme for Underactuated Mechanical Manipulators

1Department of Vehicle Engineering, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
2Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan

Received 10 August 2012; Accepted 20 October 2012

Academic Editor: Zhijian Ji

Copyright © 2012 Jung Hua Yang and Kuang Shine Yang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Mechanical arms have been widely used in the industry for many decades. They have played a dominant role in factory automation. However the control performance, or even system stability, would be deteriorated if some of the actuators fail during the operations. Hence, in this study, an adaptive variable structure scheme is presented to solve this problem. It is shown that, by applying the control mechanism proposed in this paper, the motion of robot systems can maintain asymptotical stability in case of actuators failure. The control algorithms as well as the convergence analysis are theoretically proved based on Lyapunov theory. In addition, to demonstrate the validity of the controller, a number of simulations as well as real-time experiments are also performed for Pendubot robot and Furuta robot systems. The results confirm the applicability of the proposed controller.