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Mathematical Problems in Engineering
Volume 2014, Article ID 636934, 10 pages
http://dx.doi.org/10.1155/2014/636934
Research Article

Robust Redundant Input Reliable Tracking Control for Omnidirectional Rehabilitative Training Walker

1School of Information Science and Engineering, Shenyang University of Technology, Shenyang 110870, China
2Department of Intelligent Mechanical Systems Engineering, Kochi University of Technology, Kochi 7828502, Japan
3Department of Engineering, Faculty of Engineering and Science, University of Agder, 4898 Grimstad, Norway

Received 21 October 2013; Revised 16 December 2013; Accepted 17 December 2013; Published 30 January 2014

Academic Editor: Xiaojie Su

Copyright © 2014 Ping Sun 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

The problem of robust reliable tracking control on the omnidirectional rehabilitative training walker is examined. The new nonlinear redundant input method is proposed when one wheel actuator fault occurs. The aim of the study is to design an asymptotically stable controller that can guarantee the safety of the user and ensure tracking on a training path planned by a physical therapist. The redundant degrees of freedom safety control and the asymptotically zero state detectable concept of the walker are presented, the model of redundant degree is constructed, and the property of center of gravity constant shift is obtained. A controller that can satisfy asymptotic stability is obtained using a common Lyapunov function for admissible uncertainties resulting from an actuator fault. Simulation results confirm the effectiveness of the proposed method and verify that the walker can provide safe sequential motion when one wheel actuator is at fault.