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Mathematical Problems in Engineering
Volume 2013 (2013), Article ID 951492, 8 pages
http://dx.doi.org/10.1155/2013/951492
Research Article

A Chattering Free Discrete-Time Global Sliding Mode Controller for Optoelectronic Tracking System

1School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China
2Information Engineering School, Inner Mongolia University of Science and Technology, Baotou 014010, China
3Beijing Aerospace Automatic Control Institute, Beijing 100854, China
4National Key Laboratory of Science and Technology on Aerospace Intelligence Control, Beijing 100854, China
5Beijing Institute of Space Launch Technology, Beijing 100076, China

Received 25 July 2013; Accepted 3 October 2013

Academic Editor: Xudong Zhao

Copyright © 2013 Yan Ren 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

Aiming at the uncertainties including parameter variations and external disturbances in optoelectronic tracking system, a discrete-time global sliding mode controller (DGSMC) is proposed. By the design of nonlinear switching function, the initial state of control system is set on the switching surface. An adaptive discrete-time reaching law is introduced to suppress the high-frequency chattering at control input, and a linear extrapolation method is employed to estimate the unknown uncertainties and commands. The global reachability for sliding mode and the chattering-free property are proven by means of mathematical derivation. Numerical simulation presents that the proposed DGSMC scheme not only ensures strong robustness against system uncertainties and small tracking error, but also suppresses the high-frequency chattering at control input effectively, compared with the SMC scheme using conventional discrete-time reaching law.