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Mathematical Problems in Engineering
Volume 2016, Article ID 9602483, 14 pages
http://dx.doi.org/10.1155/2016/9602483
Research Article

Novel Adaptive Sliding Mode Control with Nonlinear Disturbance Observer for SMT Assembly Machine

1School of Information Science and Technology, University of Science and Technology of China, Hefei 230036, China
2Institute of Advanced Manufacturing Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Changzhou 213164, China
3School of Electrical Engineering, Shanghai University of Electric Power, Shanghai 200090, China

Received 15 January 2016; Revised 3 March 2016; Accepted 6 March 2016

Academic Editor: Asier Ibeas

Copyright © 2016 Rongrong Qian 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

This paper presents a novel adaptive sliding mode control based on nonlinear sliding surface with disturbance observer (ANSMC-DOB) for precision trajectory tracking control of a surface mount technology (SMT) assembly machine. A two-degree-of-freedom model with time-varying parameter uncertainties and disturbances is built to describe the first axial mode of the pick-place actuation axis of the machine. According to the principle of variable damping ratio coefficient which makes the system have a nonovershoot transient response and a short settling time in the second-order system, the nonlinear sliding surface is designed for the sliding mode control (SMC). Since the upper bound value of the disturbances is unknown, the adaptive gain estimation is applied to replace the switching gain in the SMC. In order to settle the problem of SMC unrobust to the mismatched parameter uncertainties and disturbances, the nonlinear disturbance observer is introduced to estimate the mismatched disturbances and form the novel controller of ANSMC-DOB. The stability of sliding surfaces and control laws are verified by the Lyapunov functions. The simulation research and comparative experiments are conducted to verify the improvement of positioning accuracy and robustness by the proposed ANSMC-DOB in the SMT assembly machine.