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Journal of Control Science and Engineering
Volume 2015 (2015), Article ID 405376, 12 pages
Research Article

Discrete Second-Order Sliding Mode Adaptive Controller Based on Characteristic Model for Servo Systems

1School of Automation, NUST, Nanjing 210094, China
2Electronic and Mechanical Technology Department, Nanjing Marine Radar Institute, Nanjing 210003, China

Received 17 December 2014; Revised 23 February 2015; Accepted 27 February 2015

Academic Editor: Seiichiro Katsura

Copyright © 2015 Zhihong Wang 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.


Considering the varying inertia and load torque in high speed and high accuracy servo systems, a novel discrete second-order sliding mode adaptive controller (DSSMAC) based on characteristic model is proposed, and a command observer is also designed. Firstly, the discrete characteristic model of servo systems is established. Secondly, the recursive least square algorithm is adopted to identify time-varying parameters in characteristic model, and the observer is applied to predict the command value of next sample time. Furthermore, the stability of the closed-loop system and the convergence of the observer are analyzed. The experimental results show that the proposed method not only can adapt to varying inertia and load torque, but also has good disturbance rejection ability and robustness to uncertainties.