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Mathematical Problems in Engineering
Volume 2016 (2016), Article ID 2034923, 16 pages
http://dx.doi.org/10.1155/2016/2034923
Research Article

Adaptive Robust Posture Control of a 3-RPS Pneumatic Parallel Platform with Unknown Deadzone

1State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China
2School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China

Received 7 January 2016; Accepted 28 April 2016

Academic Editor: Tarek Ahmed-Ali

Copyright © 2016 Guoliang Tao 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

An adaptive robust controller integrated with online deadzone estimation is proposed. This controller provides trajectory tracking control for pneumatic parallel mechanisms. Due to the air compressibility and nonlinear characteristics of the pneumatic system, unknown parameters in the model are selected to build online estimation matrices with the robust parts considered in the design. As each proportional valve has specific values of deadzone boundary points, the deadzone parts are integrated into the online estimator, and an inverse deadzone compensator is used to overcome nonlinear limitations. The effectiveness of the method was verified by simulation and experiment, and theoretical stability was demonstrated using the Lyapunov method. Experiments in an actual plant with the proposed controller indicated that the performance of the pneumatic platform can be as good as that of ideal deadzone inverse compensation. The deadzone estimated parameters converged to the real values quickly. Additionally, this algorithm was effective under a compound reference input trajectory; thus, the controller is expected to perform well in actual working situations.