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Mathematical Problems in Engineering
Volume 2015 (2015), Article ID 905761, 15 pages
Research Article

A Lower Extremity Exoskeleton: Human-Machine Coupled Modeling, Robust Control Design, Simulation, and Overload-Carrying Experiment

1School of Aeronautics and Astronautics, University of Electronic Science and Technology of China, Chengdu 611731, China
2Department of Fluid Control & Automation, Harbin Institute of Technology, Harbin 150001, China
3School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

Received 4 November 2014; Revised 8 May 2015; Accepted 10 May 2015

Academic Editor: Stanisław Migorski

Copyright © 2015 Qing Guo 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.


A robust control method and switched control algorithm for hydraulic actuator presents in human-machine coordinated motion to solve the motion delay of lower extremity exoskeleton. After the characteristic parameters synthesis of human limb and exoskeleton linkage, the human-machine coupled motion model is constructed to estimate the appropriate hydraulic pressure, which is considered as a structural uncertainty in hydraulic model. Then the robust controller is designed to improve the robust stability and performance under the structural and parametric uncertainty disturbances. Simulation results show that, in walking mode, this robust controller can achieve a better dynamic response and aid-force efficiency than PID controller. Then, according to gait divisions of person’s limb motion, the switched control algorithm is designed to reduce the delay of exoskeleton tracking person. Finally, the experimental results show that the human-machine coordinated walk with bearing 60 kg load and squat action with no external load are realized effectively by this proposed method.