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Mathematical Problems in Engineering
Volume 2016 (2016), Article ID 6182143, 9 pages
Research Article

Robust Observer for a Class of Nonlinear SISO Dynamical Systems

1Engineering Faculty, Autonomous University of Baja California, 21280 Mexicali, BC, Mexico
2Applied Physics Division, CICESE Research Center, 22860 Ensenada, BC, Mexico

Received 5 October 2015; Revised 7 February 2016; Accepted 9 February 2016

Academic Editor: Asier Ibeas

Copyright © 2016 David Rosas 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.


A procedure to design an asymptotically stable second-order sliding mode observer for a class of single input single output (SISO) nonlinear systems in normal form is presented. The observer converges to the system state in spite of the existence of bounded disturbances and parameter uncertainties affecting the system dynamics. At the same time, the observer estimates the disturbances without the use of an additional filter to recover the equivalent control. The observer design is modular; each module of the observer is applied to each equation of state of the plant. Because of this, the proposed observer can be applied to a broader class of dynamic systems. The performance of the observer is illustrated in numerical and experimental form.