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Mathematical Problems in Engineering
Volume 2014, Article ID 872093, 8 pages
http://dx.doi.org/10.1155/2014/872093
Research Article

Nonlinear Disturbance Observer Based Robust Tracking Control of Pneumatic Muscle

1School of Automation, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan, Hubei 430074, China
2Department of Control Engineering, University of Alneelain, Gamhoria Street, 11121 Khartoum, Sudan

Received 4 December 2013; Accepted 9 February 2014; Published 20 March 2014

Academic Editor: Huaicheng Yan

Copyright © 2014 Youssif Mohamed Toum Elobaid et al. 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.

Abstract

Presently pneumatic muscles (PMs) are used in various applications due to their simple construction, lightweight, and high force-to-weight ratio. However, pneumatic muscles are facing various problems due to their nonlinear characteristics and various uncertainties in real applications. To cope with the uncertainties and strong nonlinearity of a PM model, a nonlinear disturbance observer (NDO) is designed to estimate the lumped disturbance. Based on the disturbance observer, the tracking control of PM is studied. Stability analysis based on Lyapunov method with respect to our proposed control law is discussed. The simulation results show the validity, effectiveness, and enhancing robustness of the proposed methods.