Modular-Controller-Design-Based Fast Terminal Sliding Mode for Articulated Exoskeleton Systems

• Published in: IEEE transactions on control systems technology Vol. 25; no. 3; pp. 1133 - 1140
• Main Authors: Madani, Tarek, Daachi, Boubaker, Djouani, Karim
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Articulated system; Automatic; Control stability; Control systems design; Controllers; Convergence; Engineering Sciences; exoskeleton; Exoskeletons; fast terminal sliding mode (FTSM); finite-time convergence; Mathematical model; Medical treatment; modular control; Modular design; Rehabilitation; Robots; Robust control; Robustness; Sliding mode control; Stability analysis; Subsystems; fast terminal sliding mode (FTSM); finite-time convergence; modular control; Exoskeletons
• ISSN: 1063-6536; 1558-0865
• DOI: 10.1109/TCST.2016.2579603

This brief deals with a modular controller using a fast terminal sliding mode approach for articulated systems represented by exoskeletons to perform flexion/extension movements. The proposed controller supposes that all model functions are unknown except classical properties related to the boundedness of some parameters. On the other hand, the disturbances are assumed to be bounded. It permits finite-time convergence to the desired trajectories in both position and velocity. The system is divided into several subsystems and a particular unit controls each subsystem. A supervisor using the Lyapunov approach ensures the closed-loop stability of the overall system. The proposed robust controller has been applied in a real-time application to drive an upper limb exoskeleton having 3 DOF. The used device worn by a healthy subject performs flexion/extension movements often practiced for rehabilitation purposes. A strict security protocol, which is generally used by therapists, has been respected. The obtained results are satisfactory and prove the effectiveness and the robustness of the proposed controller.